Towards addressable wireless microstimulators based on electronic rectification of epidermically applied currents

Abstract

Electrical stimulation has been explored to restore/nthe capabilities of the nervous system in paralysis patients. This/narea of research and of clinical practice, known as Functional/nElectrical Stimulation, would greatly benefit from further/nminiaturization of implantable stimulators. To that end, we/nrecently proposed and demonstrated an innovative electrical/nstimulation method in which implanted microstimulators/noperate as rectifiers of bursts of innocuous high frequency/ncurrent supplied by skin electrodes, thus generating low/nfrequency currents capable of stimulating excitable tissues. A/ndiode could suffice in some applications but, in order to broaden/nthe method’s clinical applicability, we envision rectifiers with/nadvanced capabilities such as current control and/naddressability. We plan flexible thread-like implants (diameters/n< 300 μm) containing ASICs. As an intermediate stage, we are/ndeveloping macroscopic implants (diameters 2 mm) made of/noff-the-shelf components. Here we present a circuit which/nresponds to commands modulated within the high frequency/nbursts and which is able to deliver charge-balanced currents./nWe show that a number of these circuits can perform/nindependent stimulation of segments of an anesthetized/nearthworm following commands from a computer.