Polydimethylsiloxane Foam‐Based Fully 3D Printed Soft Pressure Sensors

Abstract

Highly sensitive pressure sensors, with a wide operating range, are needed in applications such as wearables, prostheses, and haptic‐based interactive systems. Herein, fully 3D printed capacitive pressure sensors comprising polydimethylsiloxane (PDMS) foam‐based dielectric layer, sandwiched between the poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate and silver nanowire‐based electrodes, are presented. The printed electrodes exhibit excellent electrical properties (1.6 Ω sq−1, 20.35 kS m−1) and bendability. Various ratios of PDMS to ammonium bicarbonate (NH4HCO3) are evaluated to obtain dielectric layer with optimum pore sizes for better performance and ease of fabrication. The device with a PDMS:NH4HCO3 ratio of 4:0.8 exhibits a linear response with a sensitivity of 0.0055 kPa−1 in the tested pressure range of 5–170 kPa. The fully 3D printed sensors also show excellent repeatability over 500 cycles with an average hysteresis of 1.53%, and fast response and recovery times of 89 and 195 ms, respectively. The superiority of the presented 3D printed foam‐based device is confirmed by 30% higher sensitivity in comparison with PDMS‐based sensors. Finally, as a proof‐of‐concept, the pressure sensors presented in this study are assessed for their suitability in underwater environments and touch‐based object recognition.

Keywords

• additive manufacturing
• capacitive sensors
• direct ink writing
• porous polydimethylsiloxane (PDMS)
• pressure sensors
• soft sensors