@article{rosenberg_weiner_shahariar_li_peavey_mills_losego_jur_2022, title={Design of a scalable, flexible, and durable thermoelectric cooling device for soft electronics using Kirigami cut patterns}, volume={7}, ISSN={["2058-8585"]}, DOI={10.1088/2058-8585/ac48a0}, abstractNote={Abstract
               A flexible, soft thermoelectric cooling device is presented that shows potential for human cooling applications in wearable technologies and close-to-body applications. Current developments lack integration feasibility due to non-scalable assembly procedures and unsuitable materials for comfortable and durable integration into products. Our devices have been created and tested around the need to conform to the human body which we have quantified through the creation of a repeatable drape testing procedure, a metric used in the textile industry. Inspired by mass manufacturing constraints, our flexible thermoelectric devices are created using commercially available materials and scalable processing techniques. Thermoelectric legs are embedded in a foam substrate to provide flexibility, while Kirigami-inspired cuts are patterned on the foam to provide the drape necessary for mimicking the performance of textile and close to body materials. In total, nine different configurations, three different fill factors and three different Kirigami cut patterns were fabricated and inspected for thermal characterization, mechanical testing, flexibility and drape. Our studies show that adding Kirigami patterns can increase the durability of the device, improve the flexibility, decrease the drape coefficient, and have <1% of impact on cooling performance at higher fill factors (>1.5%), reaching temperature differences up to 4.39 °C ± 0.17 °C between the hot and cold faces of the device. These thermoelectric cooling devices show great flexibility, durability, and cooling for integration into soft cooling products.}, number={1}, journal={FLEXIBLE AND PRINTED ELECTRONICS}, author={Rosenberg, Z. B. and Weiner, N. C. and Shahariar, H. and Li, B. M. and Peavey, J. L. and Mills, A. C. and Losego, M. D. and Jur, J. S.}, year={2022}, month={Mar} }
 @article{li_ju_zhou_knowles_rosenberg_flewwellin_kose_jur_2021, title={Airbrushed PVDF-TrFE Fibrous Sensors for E-Textiles}, volume={3}, ISSN={["2637-6113"]}, url={https://doi.org/10.1021/acsaelm.1c00802}, DOI={10.1021/acsaelm.1c00802}, abstractNote={The low-temperature processing, inherent flexibility, and biocompatibility of piezoelectric polymers such as poly(vinylidene fluoride) (PVDF)-based materials enable the creation of soft wearable sensors, energy harvesters, and actuators. Of the various processing techniques, electrospinning is the most widely adopted process to form PVDF nanofiber scaffolds with enhanced piezoelectric properties such that they do not require further post-processing such as mechanical drawing, electrical poling, or thermal annealing. However, electrospinning requires long periods of time to form sufficiently thick PVDF nanofiber scaffolds and requires extremely high voltages to form scaffolds with enhanced piezoelectric properties, which limits the number of usable substrates, thus restricting the integration and use of electrospun PVDF scaffolds into wearable textile platforms. In this work, we propose a facile processing technique to airbrush PVDF–trifluoroethylene (TrFE) nanofiber scaffolds directly onto textile substrates. We tune the polymer concentration (4, 6, and 8 wt %) and the spray distance (5, 12.5, and 20 cm) to understand their effects on the morphology and crystal structure of the fibrous scaffolds. The characterization results show that increasing the polymer wt % encourages the formation of fibrous morphologies and a β-phase crystal structure. We then demonstrate how the airbrushed PVDF–TrFE scaffolds can be easily integrated onto conductive inkjet-printed nonwoven textile substrates to form airbrushed piezoelectric textile devices (APTDs). The APTDs exhibit maximum open-circuit voltages of 667.1 ± 162.1 mV under tapping and 276.9 ± 59.0 mV under bending deformations. The APTDs also show an areal power density of 0.04 μW/cm2, which is 40× times higher compared to previously reported airbrushed PVDF scaffolds. Lastly, we sew APTDs into wearable textile platforms to create fully textile-integrated devices with applications in sensing a basketball shooting form.}, number={12}, journal={ACS APPLIED ELECTRONIC MATERIALS}, publisher={American Chemical Society (ACS)}, author={Li, Braden M. and Ju, Beomjun and Zhou, Ying and Knowles, Caitlin G. and Rosenberg, Zoe and Flewwellin, Tashana J. and Kose, Furkan and Jur, Jesse S.}, year={2021}, month={Dec}, pages={5307–5326} }