Low-Cost Magnetorheological Elastomer-Based Capacitive Flexible Sensor Arrays for Human--Machine Interaction and Wearable Sensing

Abstract

Flexible tactile sensor arrays are widely used in human–machine interaction (HMI) and wearable sensing; however, achieving both high sensitivity and a wide detection range while maintaining a simple fabrication process remains challenging. This work presents a cost-effective flexible piezocapacitive sensor array based on a bilayer magnetorheological elastomer (MRE) dielectric architecture. The device consists of a carbonyl nickel-filled silicone rubber layer and a polyvinyl alcohol hydrogel (PVA-H) layer, forming a mechanically heterogeneous interface that enhances pressure-induced capacitance modulation through improved mechanical–dielectric coupling. In addition, magnetically induced particle structuring within the MRE promotes interfacial polarization and contributes to the dielectric response under compression. Compared with conventional single-layer capacitive sensors, the proposed architecture improves sensing performance without requiring complex microstructuring processes. The fabricated $6\times 6$ sensor array demonstrates stable operation, achieving sensitivities of 0.713 kPa ^-1 in the low-pressure range (0–60 kPa) and 2.483 kPa ^-1 in the high-pressure range (60–100 kPa), together with response and recovery times of approximately 120 ms. The device also exhibits good repeatability and consistency among sensing units. Practical demonstrations, including spatial pressure mapping, motion trajectory recognition, and human activity monitoring, verify its capability for real-time tactile sensing. This work provides a simple and scalable MRE-based bilayer dielectric design strategy for flexible capacitive sensors and shows potential for applications in wearable electronics, electronic skin, and intelligent human–machine interfaces.