A model for human skin impedance during surface functional neuromuscular stimulation

Area of Science:

• Biomedical Engineering
• Electrical Engineering
• Human Physiology

Background:

• Functional neuromuscular stimulation (FNS) is a common clinical technique.
• Accurate modeling of human skin electrical impedance is crucial for effective FNS.
• Existing models may not fully capture the dynamic and nonlinear properties of skin during stimulation.

Purpose of the Study:

• To present a novel mathematical model for the bulk electrical impedance of human skin.
• To specifically model skin impedance during surface FNS using square stimulation pulses.
• To validate the model against experimental data obtained under various stimulation conditions.

Main Methods:

• Development of a new mathematical model for skin electrical impedance.
• Collection of experimental data on human skin impedance during current and voltage-controlled transcutaneous stimulation.
• Comparison of model predictions with experimental measurements under constant voltage and constant current protocols.

Main Results:

• The proposed model effectively describes skin impedance during FNS with square pulses.
• Experimental data revealed nonlinear dynamic properties of human skin during stimulation.
• The model successfully captured various nonlinear time-varying effects observed in skin impedance for both stimulation protocols.

Conclusions:

• The new mathematical model provides an accurate representation of human skin impedance during FNS.
• This model can enhance the precision of transcutaneous FNS modeling.
• It holds potential for integration into larger neuromusculoskeletal models for improved simulations.