Wearable Magnetic Flexonic Sensor Nodes for Simultaneous Normal Force and Displacement Measurements

Illustrated in the context of home-based stroke rehabilitation, this paper presents the design and development of magnetic flexonic sensor nodes (FSNs) with configurable parameters for simultaneous sensing of normal forces and displacement. The FSN is composed of a magnetic sensor in flexible elements that can be embedded in wearable devices and rapid-prototyped at a low cost to facilitate distributed force sensing applications. As an illustration, a shoe insole with 19 embedded FSN for monitoring the plantar force distribution and arch height has been designed, prototyped, and experimentally evaluated by comparing it with a commercial dynamometric platform. The FSN-embedded insole directly measures the arch height and captures the transients of the plantar forces in five different zones in real-time. Because of the simplicity and low cost, FSNs have the potential to facilitate fabricating low-cost sensing systems, for example, for home-based stroke rehabilitation where the insole stiffness and arch height of the embeddable electronic sensors can be configured according to the patient's specific abnormal plantar distribution to adapt to different range and distribution and wearable configuration during different rehabilitation state.