Miniaturized electrical stimulator with controllable duty cycles

Abstract

A stimulator with adjustable duty cycles is described for chronic electrical stimulation of skeletal muscles by way of a motor nerve. The stimulator is unique in that it can stimulate a muscle or group of muscles for 2-h intervals that alternate with variable periods of rest (2, 4, 6, 8, or 10 h). A given duty cycle is selected with a rotary switch at the beginning of an experiment and will continue automatically, without human intervention, for the duration of the experiment. Other features include an adjustable voltage output, a stimulation indicator light-emitting diode (LED), and a low-battery indicator LED. The stimulator is powered by two 9-V batteries or can be used with a bench-top power supply. The stimulation frequency (10 Hz) and pulse width (300 microseconds) are fixed in our design but can be changed to other values by substituting two of the resistors and one capacitor in accordance with simple formulas. We have used the stimulator in rat and rabbit experiments to stimulate the anterior tibialis and extensor digitorum longus muscles for up to 60 days. The timing and output of the stimulator were found to be stable and accurate over the entire 60-day period. The stimulator and batteries were carried in a jacket worn by the rabbits. In the rat experiments, the stimulator was used in a remote fashion with the electrical leads connected to the animals by way of a tethering system. In both animals, the electrodes were implanted adjacent to the common peroneal nerve.(ABSTRACT TRUNCATED AT 250 WORDS)