A Compact Multijoint Finger Motion Sensing Module for Flexible Exoskeleton Applications

Flexible hand exoskeletons commonly employ underactuated mechanisms to reduce system complexity, making accurate estimation of multijoint motions difficult. To address this, this work presents a compact, flexible multijoint sensing module for direct finger joint angle measurement. Unlike conventional discrete sensors causing redundant wiring clutter, the proposed sensor features a monolithically integrated multichannel layout on a polyimide (PI) substrate, covering eight joint locations of the thumb, index, and middle fingers for high spatial efficiency tracking. To overcome the intrinsic nonstretchability of PI without complex material synthesis, an optimized horseshoe geometry under an island‐bridge configuration is introduced to compliantly accommodate large joint skin deformations. Furthermore, a highly integrated readout circuit based on a programmable system‐on‐chip microcontroller unit (PSoC MCU) is proposed, which implements a double‐layer routing topology to compress the 11‐channel analog signals into a compact matrix, significantly reducing wiring complexity and electronic hardware footprints. The sensing principle, mechanical behavior, and structural reliability are evaluated via finite element simulations. A compact readout circuit with offset‐compensated amplification processes the strain‐induced voltage variations. Validation through experimental calibration and practical deployment trials demonstrates that the system achieves reliable dynamic joint tracking, showing high consistency with optical motion capture references.