@article{probst_twiddy_hatada_pavlidis_daniele_sode_2024, title={Development of Direct Electron Transfer-Type Extended Gate Field Effect Transistor Enzymatic Sensors for Metabolite Detection}, volume={96}, ISSN={["1520-6882"]}, url={https://doi.org/10.1021/acs.analchem.3c04599}, DOI={10.1021/acs.analchem.3c04599}, abstractNote={In this work, direct electron transfer (DET)-type extended gate field effect transistor (EGFET) enzymatic sensors were developed by employing DET-type or quasi-DET-type enzymes to detect glucose or lactate in both 100 mM potassium phosphate buffer and artificial sweat. The system employed either a DET-type glucose dehydrogenase or a quasi-DET-type lactate oxidase, the latter of which was a mutant enzyme with suppressed oxidase activity and modified with amine-reactive phenazine ethosulfate. These enzymes were immobilized on the extended gate electrodes. Changes in the measured transistor drain current (ID) resulting from changes to the working electrode junction potential (φ) were observed as glucose and lactate concentrations were varied. Calibration curves were generated for both absolute measured ID and ΔID (normalized to a blank solution containing no substrate) to account for variations in enzyme immobilization and conjugation to the mediator and variations in reference electrode potential. This work resulted in a limit of detection of 53.9 μM (based on ID) for glucose and 2.12 mM (based on ID) for lactate, respectively. The DET-type and Quasi-DET-type EGFET enzymatic sensor was then modeled using the case of the lactate sensor as an equivalent circuit to validate the principle of sensor operation being driven through OCP changes caused by the substrate-enzyme interaction. The model showed slight deviation from collected empirical data with 7.3% error for the slope and 8.6% error for the y-intercept.}, number={10}, journal={ANALYTICAL CHEMISTRY}, author={Probst, David and Twiddy, Jack and Hatada, Mika and Pavlidis, Spyridon and Daniele, Michael and Sode, Koji}, year={2024}, month={Feb}, pages={4076–4085} }
 @article{turner_twiddy_wilkins_ramesh_kilgour_domingos_nasrallah_menegatti_daniele_2023, title={Biodegradable elastomeric circuit boards from citric acid-based polyesters}, volume={7}, ISSN={["2397-4621"]}, DOI={10.1038/s41528-023-00258-z}, abstractNote={Abstract}, number={1}, journal={NPJ FLEXIBLE ELECTRONICS}, author={Turner, Brendan L. and Twiddy, Jack and Wilkins, Michael D. and Ramesh, Srivatsan and Kilgour, Katie M. and Domingos, Eleo and Nasrallah, Olivia and Menegatti, Stefano and Daniele, Michael A.}, year={2023}, month={Jun} }
 @article{queener_ahmmed_victorio_twiddy_dehn_brewer_lobaton_bozkurt_pozdin_daniele_2023, place={Vienna, Austria}, title={Conformal Micropatterned Organic-Metal Electrodes for Physiological Recording}, ISSN={["1930-0395"]}, url={http://dx.doi.org/10.1109/sensors56945.2023.10324963}, DOI={10.1109/SENSORS56945.2023.10324963}, abstractNote={Conformal electrodes provide a soft and conforming interface with the skin for reduced impedance, comfortable skin contact, and improved signal quality compared to commercial electrodes. In this paper, we present conformal micropatterned organic-metal (CMOM) electrodes and our investigation on the effect of perforation micropatterning and PEDOT:PSS coating. CMOM electrodes were characterized then evaluated in vivo against commercial-off-the-shelf electrodes. PEDOT:PSS was found to reduce the overall impedance in each electrode variant, resulting in a >97% decrease in impedance at low frequencies. The change in impedance at high frequencies was not significant for the control or $30\ \mu \mathrm{m}$ vias electrodes, but the impedance was significantly greater following EPD for $60\ \mu \mathrm{m}$ vias electrodes.}, journal={2023 IEEE SENSORS}, author={Queener, Kirstie M. and Ahmmed, Parvez and Victorio, Mauro and Twiddy, Jack and Dehn, Ashley and Brewer, Alec and Lobaton, Edgar and Bozkurt, Alper and Pozdin, Vladimir and Daniele, Michael}, year={2023} }
 @article{kimble_twiddy_berger_forderhase_mccarty_meitzen_sombers_2023, title={Simultaneous, Real-Time Detection of Glutamate and Dopamine in Rat Striatum Using Fast-Scan Cyclic Voltammetry}, volume={8}, ISSN={["2379-3694"]}, DOI={10.1021/acssensors.3c01267}, abstractNote={Glutamate and dopamine (DA) represent two key contributors to striatal functioning, a region of the brain that is essential to motor coordination and motivated behavior. While electroanalytical techniques can be utilized for rapid, spatially resolved detection of DA in the interferent-rich brain environment, glutamate, a nonelectroactive analyte, cannot be directly detected using electroanalytical techniques. However, it can be probed using enzyme-based sensors, which generate an electroactive reporter in the presence of glutamate. The vast majority of glutamate biosensors have relied on amperometric sensing, which is an inherently nonselective detection technique. This approach necessitates the use of complex and performance-limiting modifications to ensure the desired single-analyte specificity. Here, we present a novel glutamate microbiosensor fabricated on a carbon-fiber microelectrode substrate and coupled with fast-scan cyclic voltammetry (FSCV) to enable the simultaneous quantification of glutamate and DA at single recording sites in the brain, which is impossible when using typical amperometric approaches. The glutamate microbiosensors were characterized for sensitivity, stability, and selectivity by using a voltammetric waveform optimized for the simultaneous detection of both species. The applicability of these sensors for the investigation of neural circuits was validated in the rat ventral striatum. Electrically evoked glutamate and DA release were recorded at single-micrometer-scale locations before and after pharmacological manipulation of glutamatergic signaling. Our novel glutamate microbiosensor advances the state of the art by providing a powerful tool for probing coordination between these two species in a way that has previously not been possible.}, number={11}, journal={ACS SENSORS}, author={Kimble, Laney C. and Twiddy, Jack S. and Berger, Jenna M. and Forderhase, Alexandra G. and Mccarty, Gregory S. and Meitzen, John and Sombers, Leslie A.}, year={2023}, month={Nov}, pages={4091–4100} }
 @article{sharkey_twiddy_peterson_aroche_menegatti_daniele_2023, title={Towards electrochemical control of pH for regeneration of biosensors}, DOI={10.1109/BioSensors58001.2023.10281061}, abstractNote={Most affinity-based biosensors are designed to be single-use devices, based on the measurement of irreversible binding events, which makes longitudinal monitoring resource-intensive, and typically prohibits the measurement of analyte fluctuations over time using the same device. Selective reversal of biorecognition events, i.e., regeneration, may enable repeated and longitudinal use of affinity-based biosensors; however, typical regeneration methods utilize additional chemical reagents, requiring longer processing times and increasing the likelihood of operator error. The development of a “solid-state” regeneration method provides significant value for extending the utility of affinity-based biosensors, such as electrochemical immunosensors and aptasensors. Herein, we report the characterization of a method for electronically controlling pH without additional reagents. Palladium was used to induce pH swings in aqueous electrolytes and buffers by application of an electric potential. The developed system was able to affect acidic and basic pH changes of ± 4. The efficacy of this method was further demonstrated by reversing common affinity-binding complexes and compared to conventional glycine-based regeneration.}, journal={2023 IEEE BIOSENSORS CONFERENCE, BIOSENSORS}, author={Sharkey, Christopher and Twiddy, Jack and Peterson, Kaila L. and Aroche, Angelica F. and Menegatti, Stefano and Daniele, Michael A.}, year={2023} }
 @article{twiddy_peterson_maddocks_macpherson_pimentel_yates_armitano-lago_kiefer_pietrosimone_franz_et al._2022, title={A Low-Cost, Open Source Wireless Body Area Network for Clinical Gait Rehabilitation}, ISSN={["1930-0395"]}, DOI={10.1109/SENSORS52175.2022.9967362}, abstractNote={Wearable inertial sensors represent an opportunity to enable gait monitoring and feedback-based rehabilitation in real-world environments. Here, we describe the development of an inexpensive I MU-based wireless body area network capable of recording 9-axis motion data from 8 sites on the body simultaneously. This system can generate data comparable to existing commercial sensor networks and can distinguish varying loading conditions observed during real-time biofeedback-based human subject testing.}, journal={2022 IEEE SENSORS}, author={Twiddy, Jack and Peterson, Kaila and Maddocks, Grace and MacPherson, Ryan and Pimentel, Ricky and Yates, Max and Armitano-Lago, Cortney and Kiefer, Adam and Pietrosimone, Brian and Franz, Jason and et al.}, year={2022} }
 @article{suh_twiddy_mahmood_ali_lubna_bradford_daniele_gluck_2022, title={Electrospun Carbon Nanotube-Based Scaffolds Exhibit High Conductivity and Cytocompatibility for Tissue Engineering Applications}, volume={7}, ISSN={["2470-1343"]}, url={https://doi.org/10.1021/acsomega.2c01807}, DOI={10.1021/acsomega.2c01807}, abstractNote={Carbon nanotubes (CNTs) are known for their excellent conductive properties. Here, we present two novel methods, “sandwich” (sCNT) and dual deposition (DD CNT), for incorporating CNTs into electrospun polycaprolactone (PCL) and gelatin scaffolds to increase their conductance. Based on CNT percentage, the DD CNT scaffolds contain significantly higher quantities of CNTs than the sCNT scaffolds. The inclusion of CNTs increased the electrical conductance of scaffolds from 0.0 ± 0.00 kS (non-CNT) to 0.54 ± 0.10 kS (sCNT) and 5.22 ± 0.49 kS (DD CNT) when measured parallel to CNT arrays and to 0.25 ± 0.003 kS (sCNT) and 2.85 ± 1.12 (DD CNT) when measured orthogonally to CNT arrays. The inclusion of CNTs increased fiber diameter and pore size, promoting cellular migration into the scaffolds. CNT inclusion also decreased the degradation rate and increased hydrophobicity of scaffolds. Additionally, CNT inclusion increased Young’s modulus and failure load of scaffolds, increasing their mechanical robustness. Murine fibroblasts were maintained on the scaffolds for 30 days, demonstrating high cytocompatibility. The increased conductivity and high cytocompatibility of the CNT-incorporated scaffolds make them appropriate candidates for future use in cardiac and neural tissue engineering.}, number={23}, journal={ACS OMEGA}, publisher={American Chemical Society (ACS)}, author={Suh, Taylor C. and Twiddy, Jack and Mahmood, Nasif and Ali, Kiran M. and Lubna, Mostakima M. and Bradford, Philip D. and Daniele, Michael A. and Gluck, Jessica M.}, year={2022}, month={Jun}, pages={20006–20019} }
 @article{twiddy_taggart_reynolds_sharkey_rufty_lobaton_bozkurt_daniele_2022, title={Real-Time Monitoring of Plant Stalk Growth Using a Flexible Printed Circuit Board Sensor}, ISSN={["1930-0395"]}, DOI={10.1109/SENSORS52175.2022.9967167}, abstractNote={Monitoring of plant growth within agriculture is essential for ensuring the survival of crops and optimization of resources in the face of environmental and industrial challenges. Herein, we describe a low-cost and easily deployable flexible circuit board sensor for measurement of plant stalk growth, providing for remote tracking of plant development on an industrial scale. Three circuit topologies and measurement strategies - “ladder-type,” “multiplex-type,” and “mixed-type” - are initially assessed off-plant in a simulated growth experiment. Further development of the “multiplex-type” sensor and on-plant validation demonstrates its ability to quantify stalk growth as a proxy for plant development.}, journal={2022 IEEE SENSORS}, author={Twiddy, Jack and Taggart, Matthew and Reynolds, James and Sharkey, Chris and Rufty, Thomas and Lobaton, Edgar and Bozkurt, Alper and Daniele, Michael}, year={2022} }
 @article{iezzi_ankireddy_twiddy_losego_jur_2017, title={Printed, metallic thermoelectric generators integrated with pipe insulation for powering wireless sensors}, volume={208}, ISSN={["1872-9118"]}, DOI={10.1016/j.apenergy.2017.09.073}, abstractNote={The Internet of Things (IoT), coupled with advanced analytics, is poised to revolutionize manufacturing maintenance and efficiency. However, a practical route to powering these many IoT devices remains unclear. In this work, flexible thermoelectric generators (TEGs) are fabricated from low cost, screen printed silver and nickel inks before being integrated into a novel form factor device based on commercial steam pipe insulation. Through optimization of internal resistances and total device design, this 420-junction TEG device produces 308 µW of power at a temperature difference of 127 K. This is sufficient to power a temperature sensing circuit with wireless communication capabilities. In this report we demonstrate that, after an initial 4 h of charging, this TEG can power a standard RFduino microcontroller for 10 min while sending temperature readings every 30 s via Bluetooth Low Energy (BLE) to a cell phone. Additional optimization and scaling could further increase system efficiency and provide a viable route to powering an industrial wireless sensing network (WSN).}, journal={APPLIED ENERGY}, author={Iezzi, Brian and Ankireddy, Krishnamraju and Twiddy, Jack and Losego, Mark D. and Jur, Jesse S.}, year={2017}, month={Dec}, pages={758–765} }