Biomimetic Flexible Capacitive Sensor with Loop Electrode and Snail Tentacle Structure for Enhanced Proximity and Pressure Sensing

Flexible electronics have garnered significant attention due to their promising applications in embodied intelligence, smart interaction, and human-machine interface (HMI). In particular, flexible sensors with a detectability of proximity and pressure hold great potential in areas such as touchless control, health monitoring, and robotic perception. Here, we present a biomimetic flexible capacitive sensor, called the loop electrode bioinspired snail tentacle sensor (LEBSTS). The loop-patterned electrode layer enhances proximity sensing via the fringing field effect, while the bioinspired snail tentacle-structured polydimethylsiloxane (PDMS) dielectric layer provides high sensitivity for pressure detection. The above design significantly improves sensing performance, achieving long-range proximity detection of 140 mm, a wide pressure-detection range from 0.9 Pa to 500 kPa, a high sensitivity of 2.844 kPa-1 (0-1 kPa), and a fast response time of 87.5 ms. Moreover, the sensor demonstrates good durability, maintaining stable performance over 4500 cycles. Furthermore, the potential application of the sensor was explored, including human motion monitoring, touchless HMI, Morse code transmission via LoRa wireless communication, and pressure visualization systems. This work provides insights into the development of a high-performance and multifunctional flexible sensor, offering a promising platform for advanced intelligent sensing applications.