Influence of Electrodes Shape on Electrical Impedance Registration in Solving Bionic Control Problems

The choice of electrodes for neuromuscular activity signals registration is crucial to providing convenient and accurate control of bionic devices. This paper assesses the influence of the electrodes shape and size choice on the calculated value of the electrical impedance signal, which is gaining popularity in neuromuscular interface modules implementation. To analyze signal changes a physical model based on the finite element method was developed with the use of flat circular, flat elliptical and hemispherical electrodes. Physical modeling was also performed to determine the displacement depth for different electrode shapes with the same pressing force applied. As the result recommendations on the choice of the electrodes geometry were made taking into account affecting pressing force in the electrical impedance registration. As the result of study flat circular electrodes showed the smallest deviation of modeled electrical impedance value from analytical in the widest range of sizes. That implies the preference for using flat circular electrodes.