Dual-Microstructure Configuration Design Enabling Highly Sensitive Biotemplated Flexible Capacitive Pressure Sensors

Flexible capacitive pressure sensors (FCPSs) that resolve subtle pressure are central to soft robotics and human health monitoring. Their sensitivity is affected by microstructures incorporated at the interface between the electrode and dielectric layers, but fabricating fine artificial microstructures typically requires costly techniques. Biological templates offer a cost-effective way to form these microstructures, yet biotemplated FCPSs have remained limited in sensitivity. Efforts to improve sensitivity have predominantly focused on microstructure geometries, whereas the microstructure configuration in the sensor has not been well-studied. Here, we establish design insights for microstructure configurations through simplified computational analysis, revealing that amplifying the effective interelectrode distance variation rate and effective permittivity variation rate within the structured region is the key to enhancing overall sensitivity. Following this insight, we propose a dual-microstructure configuration that increases the air fraction within the structured region, leading to the amplified effective permittivity variation rate. Both computational and experimental assessments demonstrate that the dual-microstructure configuration outperforms conventional ones in sensitivity, with the fabricated sensor achieving the highest sensitivity of 4.3 kPa-1 among all the reported biotemplated FCPSs using the same dielectric materials (Table S1), along with a fast response/recovery time of 46/20 ms, a low detection limit of 1.2 Pa, and stable operation over 7500 cycles. These performance attributes enable the sensor for applications in robotic hand tactile sensing for soft objects and real-time physiological signal monitoring. Consequently, the proposed dual-microstructure configuration offers a generalizable pathway to enhance the sensitivity of biotemplated FCPSs, promoting the development of high-performance, cost-effective flexible pressure sensors.