gms | German Medical Science

Objective: To evaluate the feasibility of visual prosthesis with 1,000+ ch electrodes by employing the distributed architecture.

Materials and Methods: In our proposed distributed architecture, the electrode array consists of 160 modules, each with seven stimulating electrodes. Each module has a hermetically-sealed CMOS chip that generates an electrical current for stimulation when electrodes on its modules are selected. Stimulating electrodes are embedded into conducive lines formed by laser machining platinum foil sandwiched by PDMS insulation layers. An experimental stimulator based on the distributed architecture with two modules was developed, and the rat's retina was stimulated by the stimulator. The neural response was recorded from the superior colliculus (SC) of the animal.

Results: The distributed-architecture-based stimulator was successfully developed. Electrical stimulation from an electrode from one module elicited electrically evoked potentials (EEPs) in the rat SC. Simultaneous electrical stimulation from two electrodes on different modules resulted in a nonlinear summation of the EEPs of individual stimulations.

Discussion: The functionality of the developed stimulator was confirmed in a rat, suggesting the feasibility of the distributed architecture. The nonlinearity of EEPs by simultaneous stimulation was possibly due to the saturation of the visual nervous system by strong electrical stimulation.

Acknowledgment: This work was supported by AMED under Grant Number JP23gm1510010.