Modifying a Transcutaneous Electrical Nerve Stimulation Unit into a Functional Electrical Stimulation Unit for Motor Neuron Research
Faculty Mentor Information
Dr. Benjamin Johnson, Boise State University
Presentation Date
7-15-2026
Abstract
Functional electrical stimulation (FES) is a neuromodulation technique that uses electrical pulses to activate motor neurons, restore muscle movement, and support rehabilitation after paralysis or stroke. However, many FES systems are clinical devices that are expensive, proprietary, and difficult for researchers to customize. In contrast, transcutaneous electrical nerve stimulation (TENS) units are widely available to consumers at low cost. Although TENS units are primarily intended for pain management, they can also activate motor neurons at higher stimulation intensities. The goal of this project was to evaluate whether low-cost TENS hardware could be modified into an open-source, multichannel stimulation platform for motor-system research. Because TENS and FES devices share similar circuit functions, we reverse engineered a commercial TENS unit and recreated its schematic in LTspice to identify potential modifications. The main design change was to convert the output stage to current-controlled stimulation, so that delivered charge would not be dependent on electrode impedance. This work provides a foundation for a low-cost, customizable FES research platform. Future versions could support multichannel stimulation for improved spatial control and closed-loop operation for patient-specific therapy development. By adapting accessible hardware for research use, this project may help expand experimental studies of electrical stimulation, muscle activation, and rehabilitation technologies.
Modifying a Transcutaneous Electrical Nerve Stimulation Unit into a Functional Electrical Stimulation Unit for Motor Neuron Research
Functional electrical stimulation (FES) is a neuromodulation technique that uses electrical pulses to activate motor neurons, restore muscle movement, and support rehabilitation after paralysis or stroke. However, many FES systems are clinical devices that are expensive, proprietary, and difficult for researchers to customize. In contrast, transcutaneous electrical nerve stimulation (TENS) units are widely available to consumers at low cost. Although TENS units are primarily intended for pain management, they can also activate motor neurons at higher stimulation intensities. The goal of this project was to evaluate whether low-cost TENS hardware could be modified into an open-source, multichannel stimulation platform for motor-system research. Because TENS and FES devices share similar circuit functions, we reverse engineered a commercial TENS unit and recreated its schematic in LTspice to identify potential modifications. The main design change was to convert the output stage to current-controlled stimulation, so that delivered charge would not be dependent on electrode impedance. This work provides a foundation for a low-cost, customizable FES research platform. Future versions could support multichannel stimulation for improved spatial control and closed-loop operation for patient-specific therapy development. By adapting accessible hardware for research use, this project may help expand experimental studies of electrical stimulation, muscle activation, and rehabilitation technologies.