Wearable capacitive pressure sensor using interdigitated capacitor printed on fabric

Abstract

This paper presented a systematic approach to electro-textile pressure sensors dependent on interdigitated capacitors (IDCs) printed on fabric. In this study, we proposed a highly sensitive, broad-range pressure sensor based on the combination of porous Ecoflex, carbon nanotubes (CNTs), and interdigitated electrodes. Firstly, characterizations of the interdigitated capacitor using silver ink on Cotton and Polyester fabric were completed by precision LCR meter across the frequency range from 1 to 300 kHz. The effect of the fabric on the performance of sensor sensitivity was included. Secondly, estimating and optimizing the volume fraction of CNTs and air gaps on the properties of composites are included. The presence of volume fraction CNTs enhanced the bond strength of composites and improved sensor deformability. The robustness of the presented sensor was demonstrated by testing under high pressure at 400 kPa for more than 20,000 cycles. Thirdly, the combination of CNTs and porous dielectric achieved a broad detection range (400 kPa) with a sensitivity range from 0.035 (at 400 kPa) to 0.15 \({\mathrm{KPa}}^{-1}\) (at 50 kPa). Finally, the Cotton and Polyester substrate comparison demonstrates that selecting a suitable dielectric substrate affects sensor sensitivity and signal output.