A hierarchically layered porous PDMS-based pressure sensor with an ultrawide detection range

A trilayer porous PDMS sensor with gradient porosity and modulus is developed for pressure sensing. • The sensor achieves a sensitivity of 4.87 kPa⁻¹ over 0–660 kPa with stable cycling performance. • The sensor enables wearable pulse monitoring and dual-channel PTT/PWV detection. Flexible pressure sensors for wearable biomedical applications require high sensitivity, a wide pressure detection range, and long-term mechanical stability. Here, we report a three-layer piezoresistive flexible pressure sensor with a hierarchical architecture and engineered composite materials. The device consists of a dense top layer, an intermediate porous layer, and a highly porous bottom layer based on a PDMS matrix. Conductive carbon fillers were selectively introduced to construct a CNT/CB-assisted conductive network, while ammonium bicarbonate was used as a sacrificial template to create the gradient porous structure. By tuning the ethyl cellulose/dibasic ester content (15 wt% and 7.5 wt%) in different layers, a modulus gradient along the thickness direction is achieved. This trilayer design enables progressive deformation and continuous reconstruction of conductive pathways under pressure, resulting in stable electrical responses over a broad pressure range. The sensor exhibits a sensitivity of 4.87 kPa −1 , calculated from the linear fitting slope of the loading branch over the full pressure range of 0–660 kPa, along with fast response and recovery times of approximately 60 and 80 ms, respectively. Moreover, excellent durability is demonstrated by stable performance over 5000 loading-unloading cycles. Owing to its capability to detect subtle pressure variations, the proposed sensor shows strong potential for wearable biomedical applications, particularly in physiological signal monitoring such as pulse detection. Download: Download high-res image (123KB) Download: Download full-size image