@article{shohan_zeng_chen_jin_shirwaiker_2022, title={Investigating dielectric spectroscopy and soft sensing for nondestructive quality assessment of engineered tissues}, volume={216}, ISSN={["1873-4235"]}, url={https://publons.com/wos-op/publon/52527065/}, DOI={10.1016/j.bios.2022.114286}, abstractNote={Non-destructive, inline quality monitoring techniques that can overcome the limitations of traditional, offline assays are essential to support the scale-up production of tissue engineered medical products (TEMP). In this work, we investigate a new soft-sensing approach with non-destructive dielectric spectroscopy (DS) that synergistically utilizes inline sensor data and predictive analytics to estimate unmeasured TEMP quality profiles. First, the performance of DS during the assessment of gelatin methacrylate (GelMA) constructs containing human adipose-derived stem cells was investigated in comparison to a traditional biochemical assay. The effects of two critical biofabrication parameters (photocrosslinking duration and volume of growth media) on a key scalar metric (Δϵ) were determined over 11 days of in vitro culture, where the metric was associated with the permittivity response of cells to alternating electric fields during DS and corresponding cellular metabolic activity. To enable accurate quality prediction while minimizing direct data collection to reduce the risk of cytotoxicity from prolonged exposure to the DS sensor electrodes and electric fields, we then developed a bilinear basis mixed model (BBMM) as a soft sensor. With comprehensive consideration of different variation sources, this model was designed to estimate missing permittivity profiles of constructs based on the measured DS dataset and biofabrication parameters. Results of benchmarking showed that BBMM outperformed state-of-the-art vector-prediction methods from literature in two different missing data estimation mechanisms. The high-accuracy BBMM provides a novel DS-driven soft sensing system as an inline monitoring tool suitable for scaled-up or scaled-out TEMP production systems.}, journal={BIOSENSORS & BIOELECTRONICS}, author={Shohan, Shohanuzzaman and Zeng, Yingyan and Chen, Xiaoyu and Jin, Ran and Shirwaiker, Rohan}, year={2022}, month={Nov} }
 @article{schuchard_pawar_anderson_pourdeyhimi_shirwaiker_2022, title={Multiphase CFD Modeling and Experimental Validation of Polymer and Attenuating Air Jet Interactions in Nonwoven Annular Melt Blowing}, volume={61}, ISSN={["0888-5885"]}, DOI={10.1021/acs.iecr.2c01710}, abstractNote={In annular melt blowing, fiber formation is achieved by accelerating a molten polymer via drag forces imparted by high velocity air that attenuates the polymer jet diameter. The interactions at the polymer-air interface, which govern the motion of the jets and impact the resulting fiber characteristics, are important but not well understood yet. This work details the development and validation of a multiphase computational fluid dynamics (CFD) model to investigate these interactions and the effects of three key melt blowing process parameters (polymer viscosity and throughput, and air velocity) on two critical fiber attributes - whipping instability and fiber diameter. Simulation results highlighted that whipping instability was driven by the polymer-air velocity differential, and the fiber diameter was primarily modulated by polymer throughput and air velocity. The CFD model was validated by modulating the polymer and air throughputs and analyzing the fiber diameter experimentally. Empirical results showed good agreement between fabricated and model-estimated fiber diameters, especially at lower air velocities. An additional CFD simulation performed using a melt blowing nozzle geometry and process parameters described in literature also confirmed good correlation between model estimates and literature empirical data.}, number={37}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Schuchard, Karl G. and Pawar, Advay and Anderson, Bruce and Pourdeyhimi, Behnam and Shirwaiker, Rohan A.}, year={2022}, month={Sep}, pages={13962–13971} }
 @article{chansoria_asif_gupta_piedrahita_shirwaiker_2022, title={Multiscale Anisotropic Tissue Biofabrication via Bulk Acoustic Patterning of Cells and Functional Additives in Hybrid Bioinks}, volume={1}, ISSN={["2192-2659"]}, DOI={10.1002/adhm.202102351}, abstractNote={Abstract}, journal={ADVANCED HEALTHCARE MATERIALS}, author={Chansoria, Parth and Asif, Suleman and Gupta, Nithin and Piedrahita, Jorge and Shirwaiker, Rohan A.}, year={2022}, month={Jan} }
 @article{brovold_keller_devarasetty_dominijanni_shirwaiker_soker_2021, title={Biofabricated 3D in vitro model of fibrosis-induced abnormal hepatoblast/biliary progenitors' expansion of the developing liver}, volume={12}, ISSN={["2380-6761"]}, url={http://dx.doi.org/10.1002/btm2.10207}, DOI={10.1002/btm2.10207}, abstractNote={Abstract}, journal={BIOENGINEERING & TRANSLATIONAL MEDICINE}, publisher={Wiley}, author={Brovold, Matthew and Keller, Dale and Devarasetty, Mahesh and Dominijanni, Anthony and Shirwaiker, Rohan and Soker, Shay}, year={2021}, month={Jun} }
 @article{maturavongsadit_narayanan_chansoria_shirwaiker_benhabbour_2021, title={Cell-Laden Nanocellulose/Chitosan-Based Bioinks for 3D Bioprinting and Enhanced Osteogenic Cell Differentiation}, volume={4}, ISSN={["2576-6422"]}, DOI={10.1021/acsabm.0c01108}, abstractNote={3D bioprinting has recently emerged as a very useful tool in tissue engineering and regenerative medicine. However, developing suitable bioinks to fabricate specific tissue constructs remains a challenging task. Herein, we report on a nanocellulose/chitosan-based bioink, which is compatible with a 3D extrusion-based bioprinting technology, to design and engineer constructs for bone tissue engineering and regeneration applications. Bioinks were prepared using thermogelling chitosan, glycerophosphate, hydroxyethyl cellulose, and cellulose nanocrystals (CNCs). Formulations were optimized by varying the concentrations of glycerophosphate (80-300 mM), hydroxyethyl cellulose (0-0.5 mg/mL), and CNCs (0-2% w/v) to promote fast gelation kinetics (<7 s) at 37 °C and retain the shape integrity of constructs post 3D bioprinting. We investigated the effect of CNCs and pre-osteoblast cells (MC3T3-E1) on the rheological properties of bioinks, bioink printability, and mechanical properties of bioprinted scaffolds. We demonstrate that the addition of CNCs and cells (5 million cells/mL) significantly improved the viscosity of bioinks and the mechanical properties of chitosan scaffolds post-fabrication. The bioinks were biocompatible and printable at an optimized range of printing pressures (12-20 kPa) that did not compromise cell viability. The presence of CNCs promoted greater osteogenesis of MC3T3-E1 cells in chitosan scaffolds as shown by the upregulation of alkaline phosphatase activity, higher calcium mineralization, and extracellular matrix formation. The versatility of this CNCs-incorporated chitosan hydrogel makes it attractive as a bioink for 3D bioprinting to engineer scaffolds for bone tissue engineering and other therapeutic applications.}, number={3}, journal={ACS APPLIED BIO MATERIALS}, author={Maturavongsadit, Panita and Narayanan, Lokesh Karthik and Chansoria, Parth and Shirwaiker, Rohan and Benhabbour, S. Rahima}, year={2021}, month={Mar}, pages={2342–2353} }
 @article{chansoria_asif_polkoff_chung_piedrahita_shirwaiker_2021, title={Characterizing the Effects of Synergistic Thermal and Photo-Cross-Linking during Biofabrication on the Structural and Functional Properties of Gelatin Methacryloyl (GeIMA) Hydrogels}, volume={7}, ISSN={["2373-9878"]}, DOI={10.1021/acsbiomaterials.1c00635}, abstractNote={Gelatin methacryloyl (GelMA) hydrogels have emerged as promising and versatile biomaterial matrices with applications spanning drug delivery, disease modeling, and tissue engineering and regenerative medicine. GelMA exhibits reversible thermal cross-linking at temperatures below 37 °C due to the entanglement of constitutive polymeric chains, and subsequent ultraviolet (UV) photo-cross-linking can covalently bind neighboring chains to create irreversibly cross-linked hydrogels. However, how these cross-linking modalities interact and can be modulated during biofabrication to control the structural and functional characteristics of this versatile biomaterial is not well explored yet. Accordingly, this work characterizes the effects of synergistic thermal and photo-cross-linking as a function of GelMA solution temperature and UV photo-cross-linking duration during biofabrication on the hydrogels' stiffness, microstructure, proteolytic degradation, and responses of NIH 3T3 and human adipose-derived stem cells (hASC). Smaller pore size, lower degradation rate, and increased stiffness are reported in hydrogels processed at lower temperature or prolonged UV exposure. In hydrogels with low stiffness, the cells were found to shear the matrix and cluster into microspheroids, while poor cell attachment was noted in high stiffness hydrogels. In hydrogels with moderate stiffness, ones processed at lower temperature demonstrated better shape fidelity and cell proliferation over time. Analysis of gene expression of hASC encapsulated within the hydrogels showed that, while the GelMA matrix assisted in maintenance of stem cell phenotype (CD44), a higher matrix stiffness resulted in higher pro-inflammatory marker (ICAM1) and markers for cell-matrix interaction (ITGA1 and ITGA10). Analysis of constructs with ultrasonically patterned hASC showed that hydrogels processed at higher temperature possessed lower structural fidelity but resulted in more cell elongation and greater anisotropy over time. These findings demonstrate the significant impact of GelMA material formulation and processing conditions on the structural and functional properties of the hydrogels. The understanding of these material-process-structure-function interactions is critical toward optimizing the functional properties of GelMA hydrogels for different targeted applications.}, number={11}, journal={ACS BIOMATERIALS SCIENCE & ENGINEERING}, author={Chansoria, Parth and Asif, Suleman and Polkoff, Kathryn and Chung, Jaewook and Piedrahita, Jorge A. and Shirwaiker, Rohan A.}, year={2021}, month={Nov}, pages={5175–5188} }
 @article{schuchard_joijode_willard_anderson_grondin_pourdeyhimi_shirwaiker_2021, title={Fabrication of drug-loaded ultrafine polymer fibers via solution blowing and their drug release kinetics}, volume={53}, ISSN={["2351-9789"]}, DOI={10.1016/j.promfg.2021.06.017}, abstractNote={Biocompatible polymer fibers have garnered significant interest due to their unique properties. Applications range from absorbent media to tissue engineering and drug delivery products. Many manufacturing processes produce such fibers, but a gap exists in highly scalable processes for fibers loaded with thermolabile additives like pharmaceuticals. This study investigates preliminary process-structure-function relationships of solution blown poly(ethylene oxide) fibers loaded with doxycycline, a drug that has demonstrated antibiotic, anti-inflammatory, and anti-tumoral properties. After parameter screening, a factorial experiment mapped the solution blowing design space with a multi-nozzle apparatus. A 1 mm-thick mat was fabricated comprising doxycycline loaded polymer fibers with a mean diameter of 552 ± 200 nm. Study of release kinetics showed the doxycycline released with a significant burst effect over approximately 1 minute. This study highlights solution blowing as a scalable manufacturing platform for fabricating poly(ethylene oxide) fibers loaded with this impactful drug.}, journal={49TH SME NORTH AMERICAN MANUFACTURING RESEARCH CONFERENCE (NAMRC 49, 2021)}, author={Schuchard, Karl and Joijode, Abhay and Willard, Vincent P. and Anderson, Bruce and Grondin, Pierre and Pourdeyhimi, Behnam and Shirwaiker, Rohan}, year={2021}, pages={128–135} }
 @article{shohan_harm_hasan_starly_shirwaiker_2021, title={Non-destructive quality monitoring of 3D printed tissue scaffolds via dielectric impedance spectroscopy and supervised machine learning}, volume={53}, ISSN={["2351-9789"]}, url={http://dx.doi.org/10.1016/j.promfg.2021.06.063}, DOI={10.1016/j.promfg.2021.06.063}, abstractNote={Majority of methods currently used for quality assessment of tissue engineered medical products (TEMPs) are offline and destructive in nature, which is one of the factors impeding the scale up and translation of these technologies. In this study, we investigate quality assessment of TEMP via dielectric impedance spectroscopy (DIS) and supervised machine learning (ML) as a non-destructive alternative that requires minimal human intervention. 3D printed, NaOH-treated polycaprolactone (PCL) scaffolds seeded with human adipose-derived stem cells (hASC), NIH 3T3, MG63, and human chondrocyte cells were assessed via DIS over 4 days of in vitro culture. The results showed that the cell type and duration in culture had a significant effect on the delta permittivity (Δε, an important DIS metric. Five supervised ML algorithms – K Nearest Neighbors (KNN), Logistic Regression, Random Forest Classifiers, Support Vector Machines, and artificial neural network – were then used to analyze the comprehensive structured permittivity datasets to determine their ability to discern between different cell types and culture durations. The KNN algorithm demonstrated the best accuracy (99%). The outcomes of this study demonstrate the approach of using DIS and supervised ML in conjunction for assessment of TEMPs in an automated manufacturing system.}, journal={49TH SME NORTH AMERICAN MANUFACTURING RESEARCH CONFERENCE (NAMRC 49, 2021)}, publisher={Elsevier BV}, author={Shohan, Shohanuzzaman and Harm, Jordan and Hasan, Mahmud and Starly, Binil and Shirwaiker, Rohan}, year={2021}, pages={636–643} }
 @misc{chansoria_schuchard_shirwaiker_2021, title={Process hybridization schemes for multiscale engineered tissue biofabrication}, volume={13}, ISSN={["1939-0041"]}, url={http://dx.doi.org/10.1002/wnan.1673}, DOI={10.1002/wnan.1673}, abstractNote={Abstract}, number={2}, journal={WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY}, publisher={Wiley}, author={Chansoria, Parth and Schuchard, Karl and Shirwaiker, Rohan A.}, year={2021}, month={Mar} }
 @article{manzi_shirwaiker_gungor_weinberger_2021, title={Steroid eluting biocompatible stent for subglottic stenosis}, volume={278}, ISSN={["1434-4726"]}, DOI={10.1007/s00405-020-06562-y}, abstractNote={{"Label"=>"OBJECTIVE", "NlmCategory"=>"OBJECTIVE"} Develop a prototype steroid eluting stent suitable for endoscopic treatment of subglottic stenosis. {"Label"=>"METHODS", "NlmCategory"=>"METHODS"} Rectangular-shaped spoke design stents thermally molded into horseshoe-shaped stents were developed using AutoCAD program, and printed on a Lulzbot 3D printer with polycaprolactone (PCL). Kenalog saturated AEROSIL 200 was embedded in the PCL filament. Horizontal radial force measurements were measured at baseline, 1 day, and 1 month when deformation switched from bending to compression. Amount of Kenalog eluted after 1 day, 1 week and 1 month were measured using HPLC. {"Label"=>"RESULTS", "NlmCategory"=>"RESULTS"} Horizontal pressure applied to the PCL stent corresponding to a 5-0 ET were 1.27 ± 0.38 lb. at baseline, 1.79 ± 0.045 lb. at 1 day, 1.94 ± - 0.22 lb. at 1 week and 2.07 ± 0.11 lb. at 1 month. The horizontal pressure applied to PCL stent corresponding to an 8-0 ET tube were 0.82 ± 0.018 lb. at baseline, 1.008 ± 0.045 lb. at 1 day, 0.95 ± - 0.064 lb. at 1 week and 1.078 ± 0.021 lb. at 1 month. The amount of Kenalog eluted increased from 5.78 µg/mL at 1 day to 15.01 µg/mL at 1 week to 19.35 µg/mL at 1 month. {"Label"=>"CONCLUSION", "NlmCategory"=>"CONCLUSIONS"} This proof-of-concept project is an initial step to demonstrate and create a novel stent in the treatment of subglottic stenosis that applies expansile force on the trachea, elutes steroids and dissolves. Over time the expansile force along the trachea increases allowing the PCL to mucosalize, while it dissolves and continues to elute steroids. The limitations of this in vitro study necessitate experiments on animal models, such as rabbit tracheas to observe for complications and histologic changes. {"Label"=>"LEVEL OF EVIDENCE", "NlmCategory"=>"METHODS"} This proof-of-concept project is a Level 5 mechanism-based reasoning study.}, number={4}, journal={EUROPEAN ARCHIVES OF OTO-RHINO-LARYNGOLOGY}, author={Manzi, Brian and Shirwaiker, Rohan and Gungor, Anil and Weinberger, Paul}, year={2021}, month={Apr}, pages={1153–1158} }
 @article{nordberg_huebner_schuchard_mellor_shirwaiker_loboa_spang_2021, title={The evaluation of a multiphasic 3D-bioplotted scaffold seeded with adipose derived stem cells to repair osteochondral defects in a porcine model}, volume={6}, ISSN={["1552-4981"]}, DOI={10.1002/jbm.b.34886}, abstractNote={Abstract}, journal={JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS}, author={Nordberg, Rachel C. and Huebner, Pedro and Schuchard, Karl G. and Mellor, Liliana F. and Shirwaiker, Rohan A. and Loboa, Elizabeth G. and Spang, Jeffery T.}, year={2021}, month={Jun} }
 @article{chansoria_shirwaiker_2020, title={3D bioprinting of anisotropic engineered tissue constructs with ultrasonically induced cell patterning}, volume={32}, ISSN={["2214-7810"]}, DOI={10.1016/j.addma.2020.101042}, abstractNote={As 3D bioprinting continues to evolve as a promising alternative to engineer complex human tissues in-vitro, there is a need to augment bioprinting processes to achieve the requisite cellular and extracellular organizational characteristics found in the original tissues. While the cell distribution within bioinks is typically homogeneous, incorporating appropriate cellular patterning within the bioprinted constructs is an essential first step towards the eventual formation of anisotropically organized tissue matrix essential to its biomechanical form and function. This study describes a new bioprinting technique that uses ultrasonic standing bulk acoustic waves (SBAW) to organize cells into controllable anisotropic patterns within viscous bioinks while maintaining high cell viability. First, we develop a 3D computational model to discern the SBAW pressure pattern in response to multiple ultrasonic frequencies (0.71–2 MHz). We then experimentally analyze the patterns and viabilities of human adipose-derived stem cells (hASC) and human osteosarcoma cells (MG63) in alginate as a function of the SBAW frequency. Computational results indicate the formation of parallel pressure strands with higher pressure amplitudes near the bottom of the deposited layer, which is corroborated by experimental images of cell patterning. The inter-strand spacing is found to be affected by the frequency (p < 0.0001), while an interaction effect between the cell type and frequency governs the width of the strands (p = 0.02). Further, we demonstrate the synergistic bioprinting and SBAW-induced patterning of hASC within alginate and gelatin methacrylate (GelMA) constructs in tandem with chemical and photo-crosslinking, respectively. Pertinent cellular patterning and viability of at least 80 % were noted in the alginate and GelMA constructs across the experimental design space. Finally, we demonstrate the vat photo-polymerization-based bioprinting of a 3-layered GelMA construct with hASC strand lay pattern of 0-45-90° across the layers. This work represents a step forward in advancing bioprinting capabilities to achieve biomimetic tissue constructs.}, journal={ADDITIVE MANUFACTURING}, author={Chansoria, Parth and Shirwaiker, Rohan}, year={2020}, month={Mar} }
 @article{chansoria_narayanan_wood_alvarado_lin_shirwaiker_2020, title={Effects of Autoclaving, EtOH, and UV Sterilization on the Chemical, Mechanical, Printability, and Biocompatibility Characteristics of Alginate}, volume={6}, ISSN={["2373-9878"]}, DOI={10.1021/acsbiomaterials.0c00806}, abstractNote={Sterilization is a necessary step during the processing of biomaterials, but it can affect the materials' functional characteristics. This study characterizes the effects of three commonly used sterilization processes-autoclaving (heat-based), ethanol (EtOH; chemical-based), and ultraviolet (UV; radiation-based)-on the chemical, mechanical, printability, and biocompatibility properties of alginate, a widely used biopolymer for drug delivery, tissue engineering, and other biomedical applications. Sterility assessment tests showed that autoclaving was effective against Gram-positive and Gram-negative bacteria at loads up to 108 CFU/mL, while EtOH was the least effective. Nuclear magnetic-resonance spectroscopy showed that the sterilization processes did not affect the monomeric content in the alginate solutions. The differences in compressive stiffness of the three sterilized hydrogels were also not significant. However, autoclaving significantly reduced the molecular weight and polydispersity index, as determined via gel permeation chromatography, as well as the dynamic viscosity of alginate. Printability analyses showed that the sterilization process as well as the extrusion pressure and speed affected the number of discontinuities and spreading ratio in printed and cross-linked strands. Finally, human adipose-derived stem cells demonstrated over 90% viability in all sterilized hydrogels over 7 days, but the differences in cellular metabolic activity in the three groups were significant. Taken together, the autoclaving process, while demonstrating broad spectrum sterility effectiveness, also resulted in most notable changes in alginate's key properties. In addition to the specific results with the three sterilization processes and alginate, this study serves as a roadmap to characterize the interrelationships between sterilization processes, fundamental chemical properties, and resulting functional characteristics and processability of hydrogels.}, number={9}, journal={ACS BIOMATERIALS SCIENCE & ENGINEERING}, author={Chansoria, Parth and Narayanan, Lokesh Karthik and Wood, Madison and Alvarado, Claudia and Lin, Annie and Shirwaiker, Rohan A.}, year={2020}, month={Sep}, pages={5191–5201} }
 @article{narayanan_shirwaiker_2020, title={Experimental Characterization and Finite Element Modeling of the Effects of 3D Bioplotting Process Parameters on Structural and Tensile Properties of Polycaprolactone (PCL) Scaffolds}, volume={10}, url={https://www.mdpi.com/2076-3417/10/15/5289}, DOI={10.3390/app10155289}, abstractNote={In this study we characterized the process–structure interactions in melt extrusion-based 3D bioplotting of polycaprolactone (PCL) and developed predictive models to enable the efficient design and processing of scaffolds for tissue engineering applications. First, the effects of pneumatic extrusion pressure (0.3, 0.4, 0.5, 0.6 N/mm2), nozzle speed (0.1, 0.4, 1.0, 1.4 mm/s), strand lay orientation (0°, 45°, 90°, 135°), and strand length (10, 20, 30 mm) on the strand width were investigated and a regression model was developed to map strand width to the two significant parameters (extrusion pressure and nozzle speed; p < 0.05). Then, proliferation of NIH/3T3 fibroblast cells in scaffolds with two different stand widths fabricated with different combinations of the two significant parameters was assessed over 7 days, which showed that the strand width had a significant effect on proliferation (p < 0.05). The effect of strand lay orientation (0° and 90°) on tensile properties of non-porous PCL specimens was determined and was found to be significantly higher for specimens with 0° lay orientation (p < 0.05). Finally, these data were used to develop and experimentally validate a finite element model for a porous PCL specimen with 1:1 ratio of inter-strand spacing to strand width.}, number={15}, journal={Applied Sciences}, publisher={MDPI AG}, author={Narayanan, Lokesh Karthik and Shirwaiker, Rohan}, year={2020}, month={Jul}, pages={5289} }
 @article{shirwaiker_fisher_anderson_schuchard_warren_maze_grondin_ligler_pourdeyhimi_2020, title={High-Throughput Manufacture of 3D Fiber Scaffolds for Regenerative Medicine}, volume={26}, ISSN={["1937-3392"]}, DOI={10.1089/ten.tec.2020.0098}, abstractNote={Engineered scaffolds used to regenerate mammalian tissues should recapitulate the underlying fibrous architecture of native tissue to achieve comparable function. Current fibrous scaffold fabrication processes, such as electrospinning and three-dimensional (3D) printing, possess application-specific advantages, but they are limited either by achievable fiber sizes and pore resolution, processing efficiency, or architectural control in three dimensions. As such, a gap exists in efficiently producing clinically relevant, anatomically sized scaffolds comprising fibers in the 1–100 μm range that are highly organized. This study introduces a new high-throughput, additive fibrous scaffold fabrication process, designated in this study as 3D melt blowing (3DMB). The 3DMB system described in this study is modified from larger nonwovens manufacturing machinery to accommodate the lower volume, high-cost polymers used for tissue engineering and implantable biomedical devices and has a fiber collection component that uses adaptable robotics to create scaffolds with predetermined geometries. The fundamental process principles, system design, and key parameters are described, and two examples of the capabilities to create scaffolds for biomedical engineering applications are demonstrated. Impact statement Three-dimensional melt blowing (3DMB) is a new, high-throughput, additive manufacturing process to produce scaffolds composed of highly organized fibers in the anatomically relevant 1–100 μm range. Unlike conventional melt-blowing systems, the 3DMB process is configured for efficient use with the relatively expensive polymers necessary for biomedical applications, decreasing the required amounts of material for processing while achieving high throughputs compared with 3D printing or electrospinning. The 3DMB is demonstrated to make scaffolds composed of multiple fiber materials and organized into complex shapes, including those typical of human body parts.}, number={7}, journal={TISSUE ENGINEERING PART C-METHODS}, author={Shirwaiker, Rohan A. and Fisher, Matthew B. and Anderson, Bruce and Schuchard, Karl G. and Warren, Paul B. and Maze, Benoit and Grondin, Pierre and Ligler, Frances S. and Pourdeyhimi, Behnam}, year={2020}, month={Jul}, pages={364–374} }
 @article{mellor_nordberg_huebner_mohiti-asli_taylor_efird_oxford_spang_shirwaiker_loboa_2020, title={Investigation of multiphasic 3D-bioplotted scaffolds for site-specific chondrogenic and osteogenic differentiation of human adipose-derived stem cells for osteochondral tissue engineering applications}, volume={108}, ISSN={["1552-4981"]}, DOI={10.1002/jbm.b.34542}, abstractNote={Abstract}, number={5}, journal={JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS}, author={Mellor, Liliana F. and Nordberg, Rachel C. and Huebner, Pedro and Mohiti-Asli, Mahsa and Taylor, Michael A. and Efird, William and Oxford, Julia T. and Spang, Jeffrey T. and Shirwaiker, Rohan A. and Loboa, Elizabeth G.}, year={2020}, month={Jul}, pages={2017–2030} }
 @article{huebner_warren_chester_spang_brown_fisher_shirwaiker_2020, title={Mechanical properties of tissue formed in vivo are affected by 3D-bioplotted scaffold microarchitecture and correlate with ECM collagen fiber alignment}, volume={61}, ISSN={["1607-8438"]}, DOI={10.1080/03008207.2019.1624733}, abstractNote={ABSTRACT Purpose: Musculoskeletal soft tissues possess highly aligned extracellular collagenous networks that provide structure and strength. Such an organization dictates tissue-specific mechanical properties but can be difficult to replicate by engineered biological substitutes. Nanofibrous electrospun scaffolds have demonstrated the ability to control cell-secreted collagen alignment, but concerns exist regarding their scalability for larger and anatomically relevant applications. Additive manufacturing processes, such as melt extrusion-based 3D-Bioplotting, allow fabrication of structurally relevant scaffolds featuring highly controllable porous microarchitectures. Materials and Methods: In this study, we investigate the effects of 3D-bioplotted scaffold design on the compressive elastic modulus of neotissue formed in vivo in a subcutaneous rat model and its correlation with the alignment of ECM collagen fibers. Polycaprolactone scaffolds featuring either 100 or 400 µm interstrand spacing were implanted for 4 or 12 weeks, harvested, cryosectioned, and characterized using atomic-force-microscopy-based force mapping. Results: The compressive elastic modulus of the neotissue formed within the 100 µm design was significantly higher at 4 weeks (p < 0.05), but no differences were observed at 12 weeks. In general, the tissue stiffness was within the same order of magnitude and range of values measured in native musculoskeletal soft tissues including the porcine meniscus and anterior cruciate ligament. Finally, a significant positive correlation was noted between tissue stiffness and the degree of ECM collagen fiber alignment (p < 0.05) resulting from contact guidance provided by scaffold strands. Conclusion: These findings demonstrate the significant effects of 3D-bioplotted scaffold microarchitectures in the organization and sub-tissue-level mechanical properties of ECM in vivo.}, number={2}, journal={CONNECTIVE TISSUE RESEARCH}, author={Huebner, Pedro and Warren, Paul B. and Chester, Daniel and Spang, Jeffrey T. and Brown, Ashley C. and Fisher, Matthew B. and Shirwaiker, Rohan A.}, year={2020}, month={Mar}, pages={190–204} }
 @article{review: modeling in situ liver cancer_2020, url={https://www.somatopublications.com/review-modeling-in-situ-liver-cancer.pdf}, journal={Annals of Gastroenterology and Digestive Disorders}, year={2020}, month={Oct} }
 @article{asif_chansoria_shirwaiker_2020, title={Ultrasound-assisted vat photopolymerization 3D printing of preferentially organized carbon fiber reinforced polymer composites}, volume={56}, ISSN={["2212-4616"]}, DOI={10.1016/j.jmapro.2020.04.029}, abstractNote={In this study, we present a new vat photopolymerization 3D printing process that uses acoustic radiation forces from ultrasonic standing waves to organize carbon short fibers within a photocurable resin. A chamber was developed to generate the standing bulk acoustic wave in the resin to align the carbon fibers along the nodes of the standing wave. The resin was then selectively cured to create constructs in the shape of a dog bone specimen by exposing to UV. The effect of fiber concentration (0.5 %, 1 %, 2 %, and 4 % w/v) and direction of alignment (parallel, perpendicular) on tensile strength of the carbon fiber reinforced polymer composites was determined. The constructs with 1 % w/v showed the highest gain in tensile strength due to the fiber alignment. For two-layered constructs with 1 % fiber concentration, 0°–0° constructs (fibers aligned along the uniaxial testing direction) demonstrated significantly higher tensile strength followed by 0°–90°constructs compared to constructs with randomly distributed fibers and without fibers.}, journal={JOURNAL OF MANUFACTURING PROCESSES}, author={Asif, Suleman and Chansoria, Parth and Shirwaiker, Rohan}, year={2020}, month={Aug}, pages={1340–1343} }
 @article{chansoria_shirwaiker_2019, title={Characterizing the Process Physics of Ultrasound-Assisted Bioprinting}, volume={9}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-019-50449-w}, abstractNote={Abstract}, journal={SCIENTIFIC REPORTS}, author={Chansoria, Parth and Shirwaiker, Rohan}, year={2019}, month={Sep} }
 @article{tan_orndorff_shirwaiker_2019, title={The Ion Delivery Manner Influences the Antimicrobial Efficacy of Silver Oligodynamic Iontophoresis}, volume={39}, ISSN={["2199-4757"]}, DOI={10.1007/s40846-018-0447-1}, abstractNote={Electrical activation of silver ions, known as oligodynamic iontophoresis, has shown broad-spectrum antimicrobial activities against bacteria, fungi, and viruses. However, it is not clear how the ion delivery manner, which is controlled by the electrical activation, influences the iontophoresis process. This paper focuses on this knowledge gap, aiming to characterize the interactive effects of electric current intensity and activation duration on the antimicrobial efficacy of a silver-based iontophoresis prototype against Gram-positive (S. aureus) and Gram-negative (E. coli) strains respectively. The modified Kirby–Bauer disc diffusion method was adopted to quantify the antimicrobial efficacy. A linear regression model was established and validated by empirical data. This study revealed that the antimicrobial activities of the device was more sensitive to current duration than current intensity, and the marginal antimicrobial efficacy of the device decreased as the current intensity increased. In addition, a sustained release of Ag + had superior antimicrobial efficacy compared to a fast release. These findings will contribute to the performance optimization of silver oligodynamic iontophoresis devices for antimicrobial applications.}, number={4}, journal={JOURNAL OF MEDICAL AND BIOLOGICAL ENGINEERING}, author={Tan, George Z. and Orndorff, Paul E. and Shirwaiker, Rohan A.}, year={2019}, month={Aug}, pages={622–631} }
 @article{chansoria_narayanan_schuchard_shirwaiker_2019, title={Ultrasound-assisted biofabrication and bioprinting of preferentially aligned three-dimensional cellular constructs}, volume={11}, ISSN={["1758-5090"]}, DOI={10.1088/1758-5090/ab15cf}, abstractNote={Abstract}, number={3}, journal={BIOFABRICATION}, author={Chansoria, Parth and Narayanan, Lokesh Karthik and Schuchard, Karl and Shirwaiker, Rohan}, year={2019}, month={Jul} }
 @article{narayanan_thompson_shirwaiker_starly_2018, title={Label free process monitoring of 3D bioprinted engineered constructs via dielectric impedance spectroscopy}, volume={10}, ISSN={["1758-5090"]}, DOI={10.1088/1758-5090/aaccbf}, abstractNote={Biofabrication processes can affect biological quality attributes of encapsulated cells within constructs. Currently, assessment of the fabricated constructs is performed offline by subjecting the constructs to destructive assays that require staining and sectioning. This drawback limits the translation of biofabrication processes to industrial practice. In this work, we investigate the dielectric response of viable cells encapsulated in bioprinted 3D hydrogel constructs to an applied alternating electric field as a label-free non-destructive monitoring approach. The relationship between β-dispersion parameters (permittivity change—Δε, Cole–Cole slope factor—α, critical polarization frequency—fc) over the frequency spectrum and critical cellular quality attributes are investigated. Results show that alginate constructs containing a higher number of viable cells (human adipose derived stem cells—hASC and osteosarcoma cell line—MG63) were characterized by significantly higher Δε and α (both p < 0.05). When extended to bioprinting, results showed that changes in hASC proliferation and viability in response to changes in critical bioprinting parameters (extrusion pressure, temperature, processing time) significantly affected ∆ε, α, and fc. We also demonstrated monitoring of hASC distribution after bioprinting and changes in proliferation over time across the cross-section of a bioprinted medial knee meniscus construct. The trends in ∆ε over time were in agreement with the alamarBlue assay results for the whole construct, but this measurement approach provided a localized readout on the status of encapsulated cells. The findings of this study support the use of dielectric impedance spectroscopy as a label-free and non-destructive method to characterize the critical quality attributes of bioprinted constructs.}, number={3}, journal={BIOFABRICATION}, author={Narayanan, Lokesh Karthik and Thompson, Trevor L. and Shirwaiker, Rohan A. and Starly, Binil}, year={2018}, month={Jul} }
 @article{tan_havell_orndorff_shirwaiker_2017, title={Antibacterial efficacy and cytotoxicity of low intensity direct current activated silver-titanium implant system prototype}, volume={30}, ISSN={["1572-8773"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85009513848&partnerID=MN8TOARS}, DOI={10.1007/s10534-017-9993-1}, abstractNote={Silver-based devices activated by electric current are of interest in biomedicine because of their broad-spectrum antimicrobial activity. This study investigates the in vitro antibacterial efficacy and cytotoxicity of a low intensity direct current (LIDC)-activated silver-titanium implant system prototype designed for localized generation and delivery of silver ions at the implantation site. First, the antibacterial efficacy of the system was assessed against methicillin-resistant Staphylococcus aureus (MRSA) over 48 h at current levels of 3 and 6 µA in Mueller-Hinton broth. The cytotoxicity of the system was then evaluated over 48 h in two phases using an in vitro model with in which the activated electrodes were suspended in growth medium in a cell-seeded tissue culture plate. In phase-1, the system was tested on human osteosarcoma (MG-63) cell line and compared to titanium controls. In phase-2, the cytotoxicity characteristics were validated with normal human diploid osteoblast cells. The LIDC-activated system demonstrated high antimicrobial efficacy against MRSA, but was also toxic to human cells immediately surrounding the electrodes. The statistical analysis showed that the cytotoxicity was a result of the presence of silver, and the electric activation did not make it worse.}, number={1}, journal={BIOMETALS}, author={Tan, Zhuo and Havell, Edward A. and Orndorff, Paul E. and Shirwaiker, Rohan A.}, year={2017}, month={Feb}, pages={113–125} }
 @article{mehendale_mellor_taylor_loboa_shirwaiker_2017, title={Effects of 3D-bioplotted polycaprolactone scaffold geometry on human adipose-derived stem cell viability and proliferation}, volume={23}, ISSN={["1758-7670"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85019575149&partnerID=MN8TOARS}, DOI={10.1108/rpj-03-2016-0035}, abstractNote={
Purpose
This study aims to investigate the effect of three-dimensional (3D)- bioplotted polycaprolactone (PCL) scaffold geometry on the biological and mechanical characteristics of human adipose-derived stem cell (hASC) seeded constructs.
}, number={3}, journal={RAPID PROTOTYPING JOURNAL}, author={Mehendale, Saahil V. and Mellor, Liliana F. and Taylor, Michael A. and Loboa, Elizabeth G. and Shirwaiker, Rohan A.}, year={2017}, pages={534–542} }
 @article{warren_huebner_spang_shirwaiker_fisher_2017, title={Engineering 3D-Bioplotted scaffolds to induce aligned extracellular matrix deposition for musculoskeletal soft tissue replacement}, volume={58}, ISSN={["1607-8438"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85011664862&partnerID=MN8TOARS}, DOI={10.1080/03008207.2016.1276177}, abstractNote={ABSTRACT Purpose: Tissue engineering and regenerative medicine approaches have the potential to overcome the challenges associated with current treatment strategies for meniscus injuries. 3D-Bioplotted scaffolds are promising, but have not demonstrated the ability to guide the formation of aligned collagenous matrix in vivo, which is critical for generating functional meniscus tissue. In this study, we evaluate the ability of 3D-Bioplotted scaffold designs with varying interstrand spacing to induce the deposition of aligned matrix in vivo. Materials and Methods: 3D-Bioplotted polycaprolactone scaffolds with 100, 200, or 400 μm interstrand spacing were implanted subcutaneously in a rat model for 4, 8, or 12 weeks. Scaffolds were harvested, paraffin-embedded, sectioned, and stained to visualize cell nuclei and collagen. Quantitative image analysis was used to evaluate cell density, matrix fill, and collagen fiber alignment within the scaffolds. Results: By 4 weeks, cells had infiltrated the innermost scaffold regions. Similarly, collagenous matrix filled interstrand regions nearly completely by 4 weeks. By 12 weeks, aligned collagen was present in all scaffolds. Generally, alignment along the scaffold strands increased over time for all three interstrand spacing groups. Distribution of collagen fiber alignment angles narrowed as interstrand spacing decreased. Conclusions: 3D-Bioplotted scaffolds allow for complete cell infiltration and collagenous matrix production throughout the scaffold. The ability to use interstrand spacing as a means of controlling the formation of aligned collagen in vivo was demonstrated, which helps establish a design space for scaffold-based meniscus tissue engineering.}, number={3-4}, journal={CONNECTIVE TISSUE RESEARCH}, author={Warren, Paul B. and Huebner, Pedro and Spang, Jeffrey T. and Shirwaiker, Rohan A. and Fisher, Matthew B.}, year={2017}, pages={342–354} }
 @article{mellor_huebner_cai_mohiti-asli_taylor_spang_shirwaiker_loboa_2017, title={Fabrication and Evaluation of Electrospun, 3D-Bioplotted, and Combination of Electrospun/3D-Bioplotted Scaffolds for Tissue Engineering Applications}, volume={2017}, ISSN={["2314-6141"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85018911833&partnerID=MN8TOARS}, DOI={10.1155/2017/6956794}, abstractNote={Electrospun scaffolds provide a dense framework of nanofibers with pore sizes and fiber diameters that closely resemble the architecture of native extracellular matrix. However, it generates limited three-dimensional structures of relevant physiological thicknesses. 3D printing allows digitally controlled fabrication of three-dimensional single/multimaterial constructs with precisely ordered fiber and pore architecture in a single build. However, this approach generally lacks the ability to achieve submicron resolution features to mimic native tissue. The goal of this study was to fabricate and evaluate 3D printed, electrospun, and combination of 3D printed/electrospun scaffolds to mimic the native architecture of heterogeneous tissue. We assessed their ability to support viability and proliferation of human adipose derived stem cells (hASC). Cells had increased proliferation and high viability over 21 days on all scaffolds. We further tested implantation of stacked-electrospun scaffold versus combined electrospun/3D scaffold on a cadaveric pig knee model and found that stacked-electrospun scaffold easily delaminated during implantation while the combined scaffold was easier to implant. Our approach combining these two commonly used scaffold fabrication technologies allows for the creation of a scaffold with more close resemblance to heterogeneous tissue architecture, holding great potential for tissue engineering and regenerative medicine applications of osteochondral tissue and other heterogeneous tissues.}, journal={BIOMED RESEARCH INTERNATIONAL}, author={Mellor, Liliana F. and Huebner, Pedro and Cai, Shaobo and Mohiti-Asli, Mahsa and Taylor, Michael A. and Spang, Jeffrey and Shirwaiker, Rohan A. and Loboa, Elizabeth G.}, year={2017} }
 @inproceedings{narayanan_thompson_bhat_starly_shirwaiker_2017, title={Investigating dielectric impedance spectroscopy as a non-destructive quality assessment tool for 3D cellular constructs}, DOI={10.1115/msec2017-2725}, abstractNote={In any three dimensional (3D) biofabrication process, assessing critical biological quality attributes of 3D constructs such as viable cell number, cell distribution and metabolic activity is critical to determine the suitability and success of the process. One major limitation in current state-of-the-art is the lack of appropriate methods to monitor these quality attributes in situ in a non-destructive, label-free manner. In this study, we investigate the feasibility of using dielectric impedance spectroscopy to address this gap. We first measured the relative permittivity of 3D alginate constructs with four different concentrations of encapsulated MG63 cells (1–6.5 million cells/mL) and found them to be statistically significantly different (p < 0.05). Within the tested range, the relationship between cell concentration and relative permittivity was noted to be linear (R2 = 0.986). Furthermore, we characterized the β-dispersion parameters for MG63-encapsulated in alginate (6.5 million cells/mL). These results demonstrate that dielectric impedance spectroscopy can be used to monitor critical quality attributes of cell-encapsulated 3D constructs. Owing to the measurement efficiency and non-destructive mode of testing, this method has tremendous potential as an in-process quality control tool for 3D biofabrication processes and the long-term monitoring of cell-encapsulated 3D constructs.}, booktitle={Proceedings of the ASME 12th International Manufacturing Science and Engineering Conference - 2017, vol 4}, author={Narayanan, L. K. and Thompson, T. L. and Bhat, A. and Starly, Binil and Shirwaiker, Rohan}, year={2017} }
 @inproceedings{narayanan_thompson_bhat_starly_shirwaiker_2017, title={Investigating dielectric impedance spectroscopy as a non-destructive quality assessment tool for 3D cellular constructs}, volume={4}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85027845254&partnerID=MN8TOARS}, DOI={10.1115/MSEC20172725}, booktitle={ASME 2017 12th International Manufacturing Science and Engineering Conference, MSEC 2017 collocated with the JSME/ASME 2017 6th International Conference on Materials and Processing}, author={Narayanan, L.K. and Thompson, T.L. and Bhat, A. and Starly, B. and Shirwaiker, R.A.}, year={2017} }
 @inproceedings{narayanan_starly_shirwaiker_2017, title={Non-destructive quality assessment of 3D-biofabricated constructs using dielectric impedance spectroscopy}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85030973322&partnerID=MN8TOARS}, booktitle={67th Annual Conference and Expo of the Institute of Industrial Engineers 2017}, author={Narayanan, L.K. and Starly, B. and Shirwaiker, R.A.}, year={2017}, pages={1846–1851} }
 @article{narayanan_huebner_fisher_spang_starly_shirwaiker_2016, title={3D-Bioprinting of Polylactic Acid (PLA) Nanofiber–Alginate Hydrogel Bioink Containing Human Adipose-Derived Stem Cells}, volume={2}, ISSN={2373-9878 2373-9878}, url={http://dx.doi.org/10.1021/ACSBIOMATERIALS.6B00196}, DOI={10.1021/acsbiomaterials.6b00196}, abstractNote={Bioinks play a central role in 3D-bioprinting by providing the supporting environment within which encapsulated cells can endure the stresses encountered during the digitally driven fabrication process and continue to mature, proliferate, and eventually form extracellular matrix (ECM). In order to be most effective, it is important that bioprinted constructs recapitulate the native tissue milieu as closely as possible. As such, musculoskeletal soft tissue constructs can benefit from bioinks that mimic their nanofibrous matrix constitution, which is also critical to their function. This study focuses on the development and proof-of-concept assessment of a fibrous bioink composed of alginate hydrogel, polylactic acid nanofibers, and human adipose-derived stem cells (hASC) for bioprinting such tissue constructs. First, hASC proliferation and viability were assessed in 3D-bioplotted strands over 16 days in vitro. Then, a human medial knee meniscus digitally modeled using magnetic resonance images was bioprinted and evaluated over 8 weeks in vitro. Results show that the nanofiber-reinforced bioink allowed higher levels of cell proliferation within bioprinted strands, with a peak at day 7, while still maintaining a vast majority of viable cells at day 16. The cell metabolic activity on day 7 was 28.5% higher in this bioink compared to the bioink without nanofibers. Histology of the bioprinted meniscus at both 4 and 8 weeks showed 54% and 147% higher cell density, respectively, in external versus internal regions of the construct. The presence of collagen and proteoglycans was also noted in areas surrounding the hASC, indicating ECM secretion and chondrogenic differentiation.}, number={10}, journal={ACS Biomaterials Science & Engineering}, publisher={American Chemical Society (ACS)}, author={Narayanan, Lokesh Karthik and Huebner, Pedro and Fisher, Matthew B. and Spang, Jeffrey T. and Starly, Binil and Shirwaiker, Rohan A.}, year={2016}, month={Jul}, pages={1732–1742} }
 @article{tan_xu_orndorff_shirwaiker_2016, title={Effects of Electrically Activated Silver-Titanium Implant System Design Parameters on Time-Kill Curves Against Staphylococcus aureus}, volume={36}, ISSN={["2199-4757"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84978971017&partnerID=MN8TOARS}, DOI={10.1007/s40846-016-0136-x}, number={3}, journal={JOURNAL OF MEDICAL AND BIOLOGICAL ENGINEERING}, author={Tan, Zhuo and Xu, Guangning and Orndorff, Paul E. and Shirwaiker, Rohan A.}, year={2016}, month={Jun}, pages={325–333} }
 @article{cavanaugh_tan_norris_hardee_weinhold_dahners_orndorff_shirwaiker_2016, title={Evaluation of silver-titanium implants activated by low intensity direct current for orthopedic infection control: An in vitro and in vivo study}, volume={104}, ISSN={["1552-4981"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84976501648&partnerID=MN8TOARS}, DOI={10.1002/jbm.b.33451}, abstractNote={Abstract}, number={5}, journal={JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS}, author={Cavanaugh, Daniel L. and Tan, Zhuo and Norris, James P. and Hardee, Amelia and Weinhold, Paul S. and Dahners, Laurence E. and Orndorff, Paul E. and Shirwaiker, Rohan A.}, year={2016}, month={Jul}, pages={1023–1031} }
 @article{johnson_sheshadri_ketchum_narayanan_weinberger_shirwaiker_2016, title={In vitro characterization of design and compressive properties of 3D-biofabricated/decellularized hybrid grafts for tracheal tissue engineering}, volume={59}, ISSN={["1878-0180"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84962441476&partnerID=MN8TOARS}, DOI={10.1016/j.jmbbm.2016.03.024}, abstractNote={Infection or damage to the trachea, a thin walled and cartilage reinforced conduit that connects the pharynx and larynx to the lungs, leads to serious respiratory medical conditions which can often prove fatal. Current clinical strategies for complex tracheal reconstruction are of limited availability and efficacy, but tissue engineering and regenerative medicine approaches may provide viable alternatives. In this study, we have developed a new “hybrid graft” approach that utilizes decellularized tracheal tissue along with a resorbable polymer scaffold, and holds promise for potential clinical applications. First, we evaluated the effect of our decellularization process on the compression properties of porcine tracheal segments, and noted approximately 63% decrease in resistance to compression following decellularization. Next we developed four C-shape scaffold designs by varying the base geometry and thickness, and fabricated polycaprolactone scaffolds using a combination of 3D-Bioplotting and thermally-assisted forming. All scaffolds designs were evaluated in vitro under three different environmental testing conditions to determine the design that offered the best resistance to compression. These were further studied to determine the effect of gamma radiation sterilization and cyclic compression loading. Finally, hybrid grafts were developed by securing these optimal design scaffolds to decellularized tracheal segments and evaluated in vitro under physiological testing conditions. Results show that the resistance to compression offered by the hybrid grafts created using gamma radiation sterilized scaffolds was comparable to that of fresh tracheal segments. Given that current clinical attempts at tracheal transplantation using decellularized tissue have been fraught with luminal collapse and complications, our data support the possibility that future embodiments using a hybrid graft approach may reduce the need for intraluminal stenting in tracheal transplant recipients.}, journal={JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS}, author={Johnson, Christopher and Sheshadri, Priyanka and Ketchum, Jessica M. and Narayanan, Lokesh K. and Weinberger, Paul M. and Shirwaiker, Rohan A.}, year={2016}, month={Jun}, pages={572–585} }
 @book{starly_shirwaiker_2015, title={3D Bioprinting Techniques}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84941777442&partnerID=MN8TOARS}, DOI={10.1016/B978-0-12-800547-7.00003-5}, abstractNote={3D bioprinting technologies enable the digital fabrication of living constructs encapsulating cells, biomolecules, and biological moieties in spatially patterned structures. Several 3D bioprinting techniques have been developed over the last decade utilizing ink-jet printheads, applied pressure, laser-induced, acoustic wave, and solenoid valve based methods to deposit cells onto substrates. The ability to digitally direct and deliver cells has opened up applications in the fabrication of tissue models for studying disease pathophysiology, as complex multicellular constructs to perform drug screening and as constructs to model cancer growth. Compared to traditional techniques, the single biggest advantage of 3D bioprinting is the ability to digitally define the tissue construct of interest and reproduce the physical 3D structure through automated techniques and at resolutions not possible through any conventional photolithography techniques.}, journal={3D Bioprinting and Nanotechnology in Tissue Engineering and Regenerative Medicine}, author={Starly, B. and Shirwaiker, R.}, year={2015}, pages={57–77} }
 @article{shirwaiker_springer_spangehl_garrigues_lowenberg_garras_yoo_pottinger_2015, title={A Clinical Perspective on Musculoskeletal Infection Treatment Strategies and Challenges}, volume={23}, ISSN={["1940-5480"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84937485196&partnerID=MN8TOARS}, DOI={10.5435/jaaos-d-14-00379}, abstractNote={Orthopaedic implants improve the quality of life of patients, but the risk of postoperative surgical site infection poses formidable challenges for clinicians. Future directions need to focus on prevention and treatment of infections associated with common arthroplasty procedures, such as the hip, knee, and shoulder, and nonarthroplasty procedures, including trauma, foot and ankle, and spine. Novel prevention methods, such as nanotechnology and the introduction of antibiotic-coated implants, may aid in the prevention and early treatment of periprosthetic joint infections with goals of improved eradication rates and maintaining patient mobility and satisfaction.}, journal={JOURNAL OF THE AMERICAN ACADEMY OF ORTHOPAEDIC SURGEONS}, author={Shirwaiker, Rohan A. and Springer, Bryan D. and Spangehl, Mark J. and Garrigues, Grant E. and Lowenberg, David W. and Garras, David N. and Yoo, Jung U. and Pottinger, Paul S.}, year={2015}, month={Apr}, pages={S44–S54} }
 @article{narayanan_kumar_tan_bernacki_starly_shirwaiker_2015, title={Alginate Microspheroid Encapsulation and Delivery of MG-63 Cells Into Polycaprolactone Scaffolds: A New Biofabrication Approach for Tissue Engineering Constructs}, volume={6}, ISSN={1949-2944 1949-2952}, url={http://dx.doi.org/10.1115/1.4031174}, DOI={10.1115/1.4031174}, abstractNote={Scaffolds play an important role in tissue engineering by providing structural framework and a surface for cells to attach, proliferate, and secrete extracellular matrix (ECM). In order to enable efficient tissue formation, delivering sufficient cells into the scaffold three-dimensional (3D) matrix using traditional static and dynamic seeding methods continues to be a critical challenge. In this study, we investigate a new cell delivery approach utilizing deposition of hydrogel-cell encapsulated microspheroids into polycaprolactone (PCL) scaffolds to improve the seeding efficiency. Three-dimensional-bioplotted PCL constructs (0 deg/90 deg lay down, 284 ± 6 μm strand width, and 555 ± 8 μm strand separation) inoculated with MG-63 model bone cells encapsulated within electrostatically generated calcium-alginate microspheroids (Ø 405 ± 13 μm) were evaluated over seven days in static culture. The microspheroids were observed to be uniformly distributed throughout the PCL scaffold cross section. Encapsulated cells remained viable within the constructs over the test interval with the highest proliferation noted at day 4. This study demonstrates the feasibility of the new approach and highlights the role and critical challenges to be addressed to successfully utilize 3D-bioprinting for microencapsulated cell delivery.}, number={2}, journal={Journal of Nanotechnology in Engineering and Medicine}, publisher={ASME International}, author={Narayanan, Lokesh K. and Kumar, Arun and Tan, Zhuo (George) and Bernacki, Susan and Starly, Binil and Shirwaiker, Rohan A.}, year={2015}, month={May} }
 @article{sheshadri_shirwaiker_2015, title={Characterization of material-process-structure interactions in the 3D Bioplotting of Polycaprolactone}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84942916374&partnerID=MN8TOARS}, DOI={10.1089/3dp.2014.0025}, abstractNote={Abstract Three-dimensional (3D) bioplotting is a melt-extrusion-based additive manufacturing process used to fabricate 3D scaffolds for tissue engineering applications. This study investigates the relationship between material rheology, process parameters, and scaffold characteristics during 3D bioplotting of polycaprolactone (PCL). The effects of two process parameters, extrusion temperature and nozzle diameter, on resultant scaffold structure and compression strength were studied using design of experiments. PCL scaffolds designed for a 24-well culture plate (O 14 mm × 2 mm) were bioplotted in a 0°/90° laydown pattern at three levels of extrusion temperature (80°C, 90°C, and 100°C) and two levels of nozzle inner diameter (0.3 and 0.4 mm) at a constant extrusion pressure (0.35 N/mm2) and nozzle speed (1.2 mm/s). The relationship between PCL dynamic viscosity and extrusion temperature during bioplotting was then determined using rheological measurements. The ANOVA results demonstrated that the strand widt...}, number={1}, journal={3D Printing and Additive Manufacturing}, author={Sheshadri, P. and Shirwaiker, R.A.}, year={2015}, pages={20–31} }
 @article{tan_ganapathy_orndorff_shirwaiker_2015, title={Effects of cathode design parameters on in vitro antimicrobial efficacy of electrically-activated silver-based iontophoretic system}, volume={26}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84921064936&partnerID=MN8TOARS}, DOI={10.1007/s10856-015-5382-x}, abstractNote={Post-operative infection is a major risk associated with implantable devices. Prior studies have demonstrated the effectiveness of ionic silver as an alternative to antibiotic-based infection prophylaxis and treatment. The focus of this study is on an electrically activated implant system engineered for active release of antimicrobial silver ions. The objective was to evaluate the effects of the cathode design, especially the cathode material, on the in vitro antimicrobial efficacy of the system. A modified Kirby-Bauer diffusion technique was used for the antimicrobial efficacy evaluations (24 h testing interval). In phase-1 of the study, a three-way ANOVA (n = 6, α = 0.05) was performed to determine the effects of cathode material (silver, titanium, and stainless steel), cathode surface area and electrode separation distance on the efficacy of the system against Staphylococcus aureus. The results show that within the design space tested, none of these parameters had a statistically significant effect on the antimicrobiality of the system (P > 0.15). Subsequently, one-way ANOVA (n = 6, α = 0.05) was conducted in phase-2 to validate the inference regarding the non-significance of the cathode material to the system efficacy using a broader spectrum of pathogens (methicillin-resistant S. aureus, Escherichia coli, Streptococcus agalactiae and Aspergillus flavus) responsible for osteomyelitis. The results confirmed the lack of statistical difference between efficacies of the three cathode material configurations against all pathogens tested (P > 0.58). Overall, the results demonstrate the ability to alter the cathode material and related design parameters in order to minimize the silver usage in the system without adversely affecting its antimicrobial efficacy.}, number={1}, journal={Journal of Materials Science: Materials in Medicine}, author={Tan, Z. and Ganapathy, A. and Orndorff, P.E. and Shirwaiker, R.A.}, year={2015}, pages={1–10} }
 @article{hunsberger_harrysson_shirwaiker_starly_wysk_cohen_allickson_yoo_atala_2015, title={Manufacturing Road Map for Tissue Engineering and Regenerative Medicine Technologies}, volume={4}, ISSN={["2157-6580"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84921807245&partnerID=MN8TOARS}, DOI={10.5966/sctm.2014-0254}, abstractNote={Abstract}, number={2}, journal={STEM CELLS TRANSLATIONAL MEDICINE}, author={Hunsberger, Joshua and Harrysson, Ola and Shirwaiker, Ronan and Starly, Binil and Wysk, Richard and Cohen, Paul and Allickson, Julie and Yoo, James and Atala, Anthony}, year={2015}, month={Feb}, pages={130–135} }
 @article{shirwaiker_wysk_kariyawasam_voigt_carrion_nembhard_2014, title={Interdigitated silver-polymer-based antibacterial surface system activated by oligodynamic iontophoresis - An empirical characterization study}, volume={16}, ISSN={["1572-8781"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84894410919&partnerID=MN8TOARS}, DOI={10.1007/s10544-013-9800-x}, abstractNote={There is a pressing need to control the occurrences of nosocomial infections due to their detrimental effects on patient well-being and the rising treatment costs. To prevent the contact transmission of such infections via health-critical surfaces, a prophylactic surface system that consists of an interdigitated array of oppositely charged silver electrodes with polymer separations and utilizes oligodynamic iontophoresis has been recently developed. This paper presents a systematic study that empirically characterizes the effects of the surface system parameters on its antibacterial efficacy, and validates the system's effectiveness. In the first part of the study, a fractional factorial design of experiments (DOE) was conducted to identify the statistically significant system parameters. The data were used to develop a first-order response surface model to predict the system's antibacterial efficacy based on the input parameters. In the second part of the study, the effectiveness of the surface system was validated by evaluating it against four bacterial species responsible for several nosocomial infections - Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Enterococcus faecalis - alongside non-antibacterial polymer (acrylic) control surfaces. The system demonstrated statistically significant efficacy against all four bacteria. The results indicate that given a constant total effective surface area, the system designed with micro-scale features (minimum feature width: 20 μm) and activated by 15 μA direct current will provide the most effective antibacterial prophylaxis.}, number={1}, journal={BIOMEDICAL MICRODEVICES}, author={Shirwaiker, Rohan A. and Wysk, Richard A. and Kariyawasam, Subhashinie and Voigt, Robert C. and Carrion, Hector and Nembhard, Harriet Black}, year={2014}, month={Feb}, pages={1–10} }
 @book{shirwaiker_purser_wysk_2014, title={Scaffolding hydrogels for rapid prototyping based tissue engineering}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84904083655&partnerID=MN8TOARS}, DOI={10.1533/9780857097217.176}, abstractNote={: 
Scaffolding hydrogels provides the ability to pattern cell suspensions directly within 3D configurations of hydrated polymer networks to mimic the physical and biological characteristics of natural extracellular matrices. This chapter first reviews the developments, key characteristics, and applications of some commonly used and emerging hydrogel biomaterials. It then discusses the compatibility between hydrogels and rapid prototyping (RP) scaffolding processes, and highlights some of the recent emerging trends in scaffolding biomaterials research.}, journal={Rapid Prototyping of Biomaterials: Principles and Applications}, author={Shirwaiker, R.A. and Purser, M.F. and Wysk, R.A.}, year={2014}, pages={176–200} }
 @article{samberg_tan_monteiro-riviere_orndorff_shirwaiker_2013, title={Biocompatibility analysis of an electrically-activated silver-based antibacterial surface system for medical device applications}, volume={24}, ISSN={["1573-4838"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84876410058&partnerID=MN8TOARS}, DOI={10.1007/s10856-012-4838-5}, abstractNote={The costs associated with the treatment of medical device and surgical site infections are a major cause of concern in the global healthcare system. To prevent transmission of such infections, a prophylactic surface system that provides protracted release of antibacterial silver ions using low intensity direct electric current (LIDC; 28 μA system current at 6 V) activation has been recently developed. To ensure the safety for future in vivo studies and potential clinical applications, this study assessed the biocompatibility of the LIDC-activated interdigitated silver electrodes-based surface system; in vitro toxicity to human epidermal keratinocytes, human dermal fibroblasts, and normal human osteoblasts, and antibacterial efficacy against Staphylococcus aureus and Escherichia coli was evaluated. The study concluded that the technological applications of the surface system for medical devices and surgical tools, which contact human tissues for less than 1.5 h, are expected to be self-sterilizing without causing toxicity in vivo.}, number={3}, journal={JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE}, author={Samberg, Meghan E. and Tan, Zhuo and Monteiro-Riviere, Nancy A. and Orndorff, Paul E. and Shirwaiker, Rohan A.}, year={2013}, month={Mar}, pages={755–760} }
 @inproceedings{tan_shirwaiker_orndoff_2013, title={Determining optimal current intensity and duration for electrically activated silver-based prophylactic hip implant prototype design}, volume={1 B}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84894644307&partnerID=MN8TOARS}, DOI={10.1115/sbc2013-14141}, abstractNote={Infections associated with medical prostheses result in notable morbidity, and traditional osteomyelitis treatments are often accompanied by high risk and cost. The probability of prosthetic joint infections is 1–2.5 % for primary hip or knee replacements and 2.1–5.8 % for revision surgeries, and the cost of treating such an infection is estimated to be over $50,000 per episode. [1] While the potential benefits of silver surfaces stimulated by low intensity direct current (LIDC) have been discussed in literature, we have recently utilized that concept in the actual design of prophylactic indwelling residual hardware prostheses for the very first time. [2–4] A modular titanium hip stem coated with silver at the anode (and titanium as the cathode) and activated by a watch battery encapsulated within the two electrode modules (Figure 1) will result in oligodynamic iontophoresis (OI) in the soft tissue surrounding the implant which is prone to infections. Preliminary in vitro and in vivo results have demonstrated the potency of silver-based OI as an effective local antibacterial therapy in osteomyelitis treatment with advantages over various antibiotics. However, the main challenge here is achieving the antibacterial potency while minimizing any potential toxic effects on local tissues. [4]}, booktitle={ASME 2013 Summer Bioengineering Conference, SBC 2013}, author={Tan, Z. and Shirwaiker, Rohan and Orndoff, P.E.}, year={2013} }
 @misc{shirwaiker_samberg_cohen_wysk_monteiro-riviere_2013, title={Nanomaterials and synergistic low-intensity direct current (LIDC) stimulation technology for orthopedic implantable medical devices}, volume={5}, ISSN={["1939-0041"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84876463086&partnerID=MN8TOARS}, DOI={10.1002/wnan.1201}, abstractNote={Abstract}, number={3}, journal={WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY}, author={Shirwaiker, Rohan A. and Samberg, Meghan E. and Cohen, Paul H. and Wysk, Richard A. and Monteiro-Riviere, Nancy A.}, year={2013}, pages={191–204} }
 @article{shirwaiker_tan_cohen_2013, title={Regenerative medicine manufacturing}, volume={45}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84882976891&partnerID=MN8TOARS}, number={8}, journal={Industrial Engineer}, author={Shirwaiker, R.A. and Tan, Z. and Cohen, P.H.}, year={2013}, pages={32–37} }
 @inproceedings{carrion_joshi_shirwaiker_fonash_2012, title={A novel fabrication method for embedding metal structures into polymers for flexible electronics}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900336522&partnerID=MN8TOARS}, booktitle={62nd IIE Annual Conference and Expo 2012}, author={Carrion, H. and Joshi, S. and Shirwaiker, R. and Fonash, S.J.}, year={2012}, pages={3212–3221} }
 @inproceedings{kazemi-tutunchi_wei_shirwaiker_dong_2012, title={A process engineering perspective of scaffold fabrication methods in regenerative medicine: A review}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900330276&partnerID=MN8TOARS}, booktitle={62nd IIE Annual Conference and Expo 2012}, author={Kazemi-Tutunchi, G. and Wei, C. and Shirwaiker, R.A. and Dong, J.}, year={2012}, pages={3096–3105} }
 @inproceedings{tan_shirwaiker_2012, title={A review of emerging industrial and systems engineering trends and future directions in biomanufacturing}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900322032&partnerID=MN8TOARS}, booktitle={62nd IIE Annual Conference and Expo 2012}, author={Tan, Z. and Shirwaiker, R.A.}, year={2012}, pages={2354–2361} }
 @inproceedings{shirwaiker_okudan_2011, title={Contributions of TRIZ and axiomatic design to leanness in design: An investigation}, volume={9}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79958757422&partnerID=MN8TOARS}, DOI={10.1016/j.proeng.2011.03.162}, abstractNote={Lean applications, which focus mostly on manufacturing, are deemed important contributors to industrial success. Today companies are striving for leanness in other functional areas such as product design and development. In this paper, we review the state of the art on lean design, and the appropriateness of two tools for lean design applications: Theory of Inventive Problem Solving (TRIZ) and Axiomatic Design (AD). The literature review section reveals the need and scope for more research on lean design. We also enunciate how the lean design approach fits within the traditional product design and development process, and then evaluate TRIZ and AD for their contributions to leanness. Our evaluation reveals a close correlation between these tools and the lean design metrics. The paper concludes by proposing the use of a synergistic problem solving approach based on TRIZ and AD to increase efficiency and quality of the process while also helping to achieve lean design goals for a company.}, booktitle={Procedia Engineering}, author={Shirwaiker, R.A. and Okudan, G.E.}, year={2011}, pages={730–735} }
 @inproceedings{shirwaiker_voigt_wysk_2011, title={Effects of critical design parameters on antibacterial efficacy of a silver ions-based antibacterial surface system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900320661&partnerID=MN8TOARS}, booktitle={61st Annual IIE Conference and Expo Proceedings}, author={Shirwaiker, R.A. and Voigt, R.C. and Wysk, R.A.}, year={2011} }
 @article{shirwaiker_wysk_kariyawasam_carrion_voigt_2011, title={Micro-scale fabrication and characterization of a silver-polymer-based electrically activated antibacterial surface}, volume={3}, ISSN={["1758-5090"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79958266233&partnerID=MN8TOARS}, DOI={10.1088/1758-5082/3/1/015003}, abstractNote={This paper reports the fabrication methodology and characterization results for an electrically activated silver-polymer-based antibacterial surface with primary applications in preventing indirect contact transmission of infections. The surface consists of a micro-scale grating pattern of alternate silver electrodes and SU-8 partitions with a minimum feature size of 20 µm, and activated by an external voltage. In this study, prototype coupons (15 mm × 15 mm) of the antibacterial surface were fabricated on silicon substrates using two sets of lithographies, and analyzed for their physical characteristics using microscopy and surface profilometry. The prototypes were also electrically analyzed to determine their current–voltage characteristics, and hence silver ion (Ag+) release concentrations. Finally, they were tested for their antibacterial efficacy against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) using a newly engineered microbiological testing procedure. The antibacterial efficacy testing results show significant reductions in the number of viable organisms of both the species after 45 min of testing with 15 µA system current. Due to the growing incidences of hospital-acquired infections and rising treatment costs, study and application of such alternative antibacterial systems in critical touch-contact and work surfaces (e.g., door push plates, countertops, medical instrument trays) for healthcare environments has become essential.}, number={1}, journal={BIOFABRICATION}, author={Shirwaiker, Rohan A. and Wysk, Richard A. and Kariyawasam, Subhashinie and Carrion, Hector and Voigt, Robert C.}, year={2011}, month={Mar} }
 @inproceedings{yang_shirwaiker_wysk_2011, title={Optimization of manufacturing operations using a new interactive computer-aided process planning program}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84900313847&partnerID=MN8TOARS}, booktitle={61st Annual IIE Conference and Expo Proceedings}, author={Yang, Z. and Shirwaiker, R.A. and Wysk, R.A.}, year={2011} }
 @inproceedings{shirwaiker_voigt_wysk_2010, title={Design of an electrically activated silver-based antibacterial surface system}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84901037163&partnerID=MN8TOARS}, booktitle={IIE Annual Conference and Expo 2010 Proceedings}, author={Shirwaiker, R.A. and Voigt, R.C. and Wysk, R.A.}, year={2010} }
 @article{fuller_wysk_charumani_kennett_sebastiennelli_abrahams_shirwaiker_voigt_royer_2010, title={Developing an engineered antimicrobial/prophylactic system using electrically activated bactericidal metals}, volume={21}, ISSN={0957-4530 1573-4838}, url={http://dx.doi.org/10.1007/S10856-010-4071-Z}, DOI={10.1007/s10856-010-4071-z}, abstractNote={The increased use of Residual Hardware Devices (RHDs) in medicine combined with antimicrobial resistant-bacteria make it critical to reduce the number of RHD associated osteomyelitic infections. This paper proposes a surface treatment based on ionic emission to create an antibiotic environment that can significantly reduce RHD associated infections. The Kirby-Bauer agar gel diffusion technique was adopted to examine the antimicrobial efficacy of eight metals and their ionic forms against seven microbes commonly associated with osteomyelitis. Silver ions (Ag(+)) showed the most significant bactericidal efficacy. A second set of experiments, designed to identify the best configuration and operational parameters for Ag(+) based RHDs addressed current and ionic concentrations by identifying and optimizing parameters including amperage, cathode and anode length, separation between anode and cathode, and surface charge density. The system demonstrated an unparalleled efficacy. The concept was then implemented during in vitro testing of an antimicrobial hip implant, RHD.}, number={7}, journal={Journal of Materials Science: Materials in Medicine}, publisher={Springer Science and Business Media LLC}, author={Fuller, Thomas A. and Wysk, Richard A. and Charumani, Charumani and Kennett, Mary and Sebastiennelli, Wayne J. and Abrahams, Rachel and Shirwaiker, Rohan A. and Voigt, Robert C. and Royer, Patricia}, year={2010}, month={Apr}, pages={2103–2114} }
 @article{shirwaiker_okudan_2008, title={Triz and axiomatic design: A review of case-studies and a proposed synergistic use}, volume={19}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-39449128294&partnerID=MN8TOARS}, DOI={10.1007/s10845-007-0044-6}, number={1}, journal={Journal of Intelligent Manufacturing}, author={Shirwaiker, R.A. and Okudan, G.E.}, year={2008}, pages={33–47} }
 @article{shirwaiker_okudan_2007, title={Using triz and axiomatic design synergistically: A case study}, volume={4}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84899832903&partnerID=MN8TOARS}, DOI={10.1142/S021987700700103X}, abstractNote={ With increasing global competition, expediting the problem solving process has become crucial in the industry. Techniques such as Theory of Inventive Problem Solving (TRIZ) and Axiomatic Design (AD) have been widely applied for this purpose. TRIZ and AD are very powerful tools with different but complementary strengths. A previously proposed synergistic approach based on TRIZ and AD enhances the individual strengths of these methods by using them within a common framework, thus providing a more powerful methodology for problem solving. In this paper, we demonstrate the effectiveness of the synergistic approach through a manufacturing related case-study. Considering the importance of validation of engineering models, a validation method for the synergistic approach is discussed based on review of design engineering validation literature. }, number={2}, journal={International Journal of Innovation and Technology Management}, author={Shirwaiker, R.A. and Okudan, G.E.}, year={2007}, pages={155–170} }
 @inproceedings{okudan_shirwaiker_2006, title={A multi-stage problem formulation for concept selection for improved product design}, volume={6}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-50249174519&partnerID=MN8TOARS}, DOI={10.1109/PICMET.2006.296850}, abstractNote={In this paper, a new concept selection method is proposed and its application is demonstrated. The utility theory based proposed method formulates the concept selection problem as a multi-stage decision. The proposed method has improvements in its ease of use, and accounting for potentially coupled decisions in comparison to other methods found in the literature. We first present a comprehensive review of the existing concept selection methods, and then explain the proposed approach. The paper concludes with its application on a case study along with recommendations for future work}, booktitle={Portland International Conference on Management of Engineering and Technology}, author={Okudan, G.E. and Shirwaiker, R.A.}, year={2006}, pages={2528–2538} }
 @inproceedings{okudan_ogot_shirwaiker_2006, title={An investigation on the effectiveness of design ideation using TRIZ}, volume={2006}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33751337036&partnerID=MN8TOARS}, booktitle={Proceedings of the ASME Design Engineering Technical Conference}, author={Okudan, G.E. and Ogot, M. and Shirwaiker, R.}, year={2006} }
 @inproceedings{shirwaiker_okudan_2006, title={TRIZ and axiomatic design: A review of manufacturing case-studies & their compatibility}, volume={6}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-50649089135&partnerID=MN8TOARS}, DOI={10.1109/PICMET.2006.296848}, abstractNote={With increasing competition in the market, expediting the problem solving process has become crucial in the industry. Techniques such as Theory of Inventive Problem Solving (TRIZ) and Axiomatic Design (AD) have been widely applied for this purpose. This paper reviews practical applications of TRIZ and AD in solving industrial problems related to designing and manufacturing. We propose that application of these two techniques synergistically to solve a problem will increase the efficiency and quality of the problem solving process. This has been demonstrated using a real life case-study of manufacturing tool design}, booktitle={Portland International Conference on Management of Engineering and Technology}, author={Shirwaiker, R.A. and Okudan, G.E.}, year={2006}, pages={2510–2520} }