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.
The demand of cost‐effective fabrication of printed flexible transistors has dramatically increased in recent years due to the need for flexible interface devices for various application including e‐skins, wearables, and medical patches. In this study, electrohydrodynamic (EHD) printing processes are developed to fabricate all the components of polymer‐based organic thin film transistors (OTFTs), including source/drain and gate electrodes, semiconductor channel, and gate dielectrics, which streamline the fabrication procedure for flexible OTFTs. The flexible transistors with top‐gate‐bottom‐contact configuration are fabricated by integrating organic semiconductor (i.e., poly(3‐hexylthiophene‐2,5‐diyl) blended with small molecule 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene), conductive polymer (i.e., poly (3,4‐ethylenedioxythiophene) polystyrene sulfonate), and ion‐gel dielectric. These functional inks are carefully designed with orthogonal solvents to enable their compatible printing into multilayered flexible OTFTs. The EHD printing process of each functional component is experimentally characterized and optimized. The fully EHD‐printed OTFTs show good electrical performance with mobility of 2.86 × 10−1cm2V−1s−1and on/off ratio of 104, and great mechanical flexibility with small mobility change at bending radius of 6 mm and stable transistor response under hundreds of bending cycles. The demonstrated all printing‐based fabrication process provides a cost‐effective route toward flexible electronics with OTFTs.
more » « less- Award ID(s):
- 2134664
- NSF-PAR ID:
- 10441340
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Technologies
- Volume:
- 8
- Issue:
- 17
- ISSN:
- 2365-709X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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