Inkjet-printed, nanofiber-based soft capacitive pressure sensors for tactile sensing

The development of soft electronics is critical to the realization of artificial intelligence that comes into direct contact with humans, such as wearable devices, and robotics. Furthermore, rapid prototyping and inexpensive processes are essential for the development of these applications. We demonstrate here an additive, low-cost method for fabricating polydimethylsiloxane based soft electronics by inkjet printing. Herein, a novel approach using a water-soluble polyvinyl alcohol layer as the substrate, inexpensive, fully digital fabrication of capacitive pressure sensors is enabled by sandwiching mesh-like conductive layers and microstructured dielectric in a straightforward, convenient manner. These sensors exhibit improved sensitivity (4 MPa-1) at low pressures (< 1 kPa) in contrast to sensors with a flat elastomer dielectric and can still detect large pressures around 50 kPa, having excellent long-term repeatability over 2000 cycles, without significant hysteresis (≤ 8.5 %). The tactile sensing ability of the fabricated devices was demonstrated in a practical application. Moreover, sensor characteristics are easily adjustable, simply by changing printing parameters or tuning the ink solution. The proposed approach provides scalable solution for fabricating high-sensitivity printed sensors for e-skin and human-machine interfaces.