Flexible Hybrid Electronics: Direct Interfacing of Soft and Hard Electronics for Wearable Health Monitoring |
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Authors: | Yasser Khan Mohit Garg Qiong Gui Mark Schadt Abhinav Gaikwad Donggeon Han Natasha A D Yamamoto Paul Hart Robert Welte William Wilson Steve Czarnecki Mark Poliks Zhanpeng Jin Kanad Ghose Frank Egitto James Turner Ana C Arias |
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Affiliation: | 1. Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA, USA;2. Department of Computer Science, Binghamton University, State University of New York, Binghamton, NY, USA;3. Department of Electrical and Computer Engineering, Binghamton University, State University of New York, Binghamton, NY, USA;4. i3 Electronics, Inc., Endicott, NY, USA;5. ExSys Technology, Inc., Endicott, NY, USA;6. Small Scale Systems Integration & Packaging Center, Binghamton University, State University of New York, Binghamton, NY, USA |
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Abstract: | The interfacing of soft and hard electronics is a key challenge for flexible hybrid electronics. Currently, a multisubstrate approach is employed, where soft and hard devices are fabricated or assembled on separate substrates, and bonded or interfaced using connectors; this hinders the flexibility of the device and is prone to interconnect issues. Here, a single substrate interfacing approach is reported, where soft devices, i.e., sensors, are directly printed on Kapton polyimide substrates that are widely used for fabricating flexible printed circuit boards (FPCBs). Utilizing a process flow compatible with the FPCB assembly process, a wearable sensor patch is fabricated composed of inkjet‐printed gold electrocardiography (ECG) electrodes and a stencil‐printed nickel oxide thermistor. The ECG electrodes provide 1 mVp–p ECG signal at 4.7 cm electrode spacing and the thermistor is highly sensitive at normal body temperatures, and demonstrates temperature coefficient, α ≈ –5.84% K–1 and material constant, β ≈ 4330 K. This sensor platform can be extended to a more sophisticated multisensor platform where sensors fabricated using solution processable functional inks can be interfaced to hard electronics for health and performance monitoring, as well as internet of things applications. |
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Keywords: | flexible electronics inkjet printing printed electrocardiography electrodes printed thermistors wearable sensor patches |
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