Applicability of wireless injectable microstimulators based on volume conduction for high density neuromuscular stimulation

Abstract

This thesis was conducted within the framework of the eAXON project that is aimed at developing injectable wireless sub-millimetric single-channel addressable microstimulators based on volume conduction called eAXONs that could be inserted in large numbers to provide high density neuromuscular stimulation for restoring functional movement to paralyzed limbs with minimal invasiveness. It is demonstrated that multi-channel intramuscular stimulation significantly delays electrically–induced muscle fatigue, while single-channel stimulation does not. It is shown that the nerve supply of mammalian skeletal muscles appear to be extensively compartmentalized. Meaning, a large number of eAXONs can be implanted, while their independence is maintained. Lastly, the eAXONs are very thin because they act as rectifiers and perform neurostimulation by instantaneously transforming bursts of externally applied volume conducted high frequency currents into low frequency waveforms. Waveforms created with this approach are less current, charge, energy efficient than square waveforms conventionally used in neurostimulation. Therefore, with eAXONs, there is a tradeoff between device miniaturization and stimulation efficiency.