Seamless Monolithic Design for Foam Based, Flexible, Parallel Plate Capacitive Sensors

Abstract

AbstractCapacitive pressure sensors received significant attention in line with advancements in wearable electronics. However, in the era of the wearable electronics, fabricated sensors fail to fulfill the absolute requirements. Significant portion of the previously reported capacitive pressure sensors suffer from excessive weight, lack of air permeability, and washing stability due to the use of separate electrode layers. A low‐cost, lightweight, parallel plate capacitive sensor with a unique seamless monolithic design that allows sensors to circumvent aforementioned problems is hereby demonstrated. The seamless monolithic capacitive sensor (MCS) with a density of as low as 10.78 mg cm−3 is fabricated using 3D masking technique on a commercially available melamine foam with silver nanowire electrodes and a protective thin layer of polydimethylsiloxane coating. In addition to its unique design, the MCSs show high sensitivity (up to 1.285 kPa–1), fast response/recovery time (18 ms/53 ms), very low‐pressure sensing ability (0.5 Pa) with ultra‐high mechanical (42 000 cycles), and washing stabilities (10 cycles) along with high air permeability. Moreover, finite element analysis simulations are conducted to reveal the deformation mechanism differences between the monolithic and classical design. Finally, in order to demonstrate their true potential, fabricated MCSs are utilized in real‐time body motion monitoring, word and proximity detection.