A Multidirectional Electrical Stimulator With Two Isolated Channels

Myocardial stimulation using electric field (E) is used not only clinically (e.g. defibrillation protocols) but also in in vitro experiments. Normally, to stimulate heart cells in vitro it is necessary that the cell is positioned in the same direction as the stimulus, in order to lower the intensity, and that is not always possible. In protocols that require multidirectional stimuli, the lack of space to position the electrodes is a major limitation, knowing that two electrodes are required for each stimulus direction, which makes it not always viable. This paper presents a multidirectional electrical stimulator that is capable of determining the stimulation threshold of a rat heart cell, using only 2 isolated channels, applying 3 stimuli in 3 directions by the principle of superposition. The stimulator is implemented through a microcontroller, responsible for processing the user interface data and controlling the intensity of the stimuli using PWM. The stimulator reaches voltages up to +/- 30 V. When comparing the intended voltage with the achieved voltage in the stimulator, we have a maximum error of 3%. The stimulator fulfills its objective which allows future experiments with isolated cardiac cells.