Multi-Field Surface Electrode for Selective Electrical Stimulation

: We designed a 24‐field array and an on‐line control box that selects which and how many of 24 fields will conduct electrical charge during functional electrical stimulation. The array was made using a conductive microfiber textile, silver two‐component adhesive, and the conductive ink imprint on the polycarbonate. The control box comprised 24 switches that corresponded one‐to‐one to the fields on the array. Each field could be made conductive or nonconductive by simple pressing of the corresponding push‐button type switch on the control box. We present here representative results of the selectivity of the new electrode measured in three tetraplegic patients during functional electrical stimulation of the forearm. The task was to generate finger flexion and extension with minimal interference of the wrist movement during lateral and palmar grasps. Therapists determined the appropriate pattern that lead to effective grasping, lasting on average 5 min per stimulation channel in the first session. This optimal conductive pattern (size and shape) provided effective finger flexion and extension with minimal wrist flexion/extension and ulnar/radial deviations (