Flexible capacitive pressure sensor with chemically reduced graphene oxide on a pyramid-structured melamine sponge array by laser engraving

Abstract

Herein, we proposed a novel dielectric layer of pyramid-based melamine sponge (MSponge) obtained through simple laser engraving as a flexible capacitive pressure sensor. The sensor was then covered with chemically reduced graphene oxide (rGO), which effectively increased its sensitivity. The reduction degree of rGO on the pyramid-structured MSponge was carefully controlled by chemical reduction using sodium thiosulfate solution, leading to an improvement in its sensitivity. The sensor is sensitive to 0.302 kPa⁻¹ over 0–60 kPa (R² = 0.991), with a wide sensing range of 0–150 kPa; is capable of identifying pressures down to 7.1 Pa; and can be applied to detecting signal variations caused by the heart rate, puffing of cheeks, and limb joint motion as well as array sensing. In summary, these strategies for sensitivity improvement have broad applicability, extending to other flexible sensors requiring high sensitivity and a wide linear range, thereby offering great potential for further innovation and application expansion in flexible sensing technologies.