Stretchable Organic Transistor Based Pressure Sensor Employing a Porous Elastomer Gate Dielectric

Compliant pressure sensors are a key technology for wearable electronics and haptic interfaces. Making transistors pressure-sensitive provides an opportunity to combine sensing and matrix readout characteristics. However, there is typically a trade-off in pressure sensitivity, complexity of fabrication, and mechanical resilience. To overcome these challenges, an all solution-processed kirigami-inspired stretchable organic thin film transistor (OTFT) based pressure sensor array is introduced. The OTFTs integrate several novel processing and design strategies that include electrohydrodynamic (EHD) jet-printed Ag nanowire (NW) electrodes that are partially embedded in a polyimide (PI) matrix. The EHD printing provides fine pattern control and the NW/PI composite improves mechanical stability. The OTFTs are made pressure sensitive by employing a porous styrene-ethylene-butylene-styrene gate dielectric achieved using a breath figure method. The pore density can be controlled to achieve tunable pressure sensitivity. The OTFTs are shown to maintain performance under a small bending radius (1 mm) and can sense applied pressure from 0.75 to 25 kPa. Finally, a cut pattern is introduced into the substrate that imparts stretchability while maintaining pressure sensor functionality. The integration of the design features and processing methods introduced in this work enables mechanically resilient stretchable pressure sensors.