Term of Award

Fall 2021

Degree Name

Master of Science, Mechanical Engineering

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


Department of Mechanical Engineering

Committee Chair

Jung Choi

Committee Member 1

Jinki Kim

Committee Member 2

Ermias Koricho


A study is presented on the design of compact sized signal distribution device for Hoffman reflex methodological applications in sports medicine. Established conventional method for measuring and recording human or animal nervous system response to external electrical stimulus was considered in this study. Challenges with measuring and recording techniques which introduces inaccuracies and unreliability of reflex response data obtained was analyzed, this work is aimed at improving the reliability of H-reflex d measuring and recording technique for the purpose of reducing inaccuracies introduced to data obtained because of conventional methodologic approach. Inaccuracies due to changes in subject muscle geometry and body part positioning was considered and method was devised to expand the stimulus signal delivery channels to cover entire limb length. Expanded output channels was achieved through designed signal distribution device which offers low impedance (≤ 150mΩ), low power dissipation (≤ 200mW), low inductance(≤1.00mH) and low resistance(≤100mΩ) signal travel path. The distribution sequence of the signal was controlled by Arduino controller in conjunction with multiplexer which determines the signal travel path through relay activation process. The device was tested with 5v input signal, data obtained establishes the minimum effective signal processing speed for the device to be 20ms.This processing time is lower than required processing speed (100ms), hence distributed stimulus was effectively distributed through the output channels of designed device. Device performance was evaluated in simulated environment by testing real electric stimulus from constant current stimulator at both minimum current amplitude (1mA), voltage amplitude (100v), pulse duration (50μs) and maximum current amplitude (10mA), voltage amplitude (400v), pulse duration (2ms) tested on simulated human body resistance and response at each setting monitored on oscilloscope. Results obtained confirms all expectations as designed device was able to deliver electric stimulus to the simulated human body resistance set up with minimum signal propagation delay at 75mΩ average resistance. Incorporation of designed multi-channel device in the methodological delivery of stimulus to human muscle was established to significantly improve reliability of response data obtained. Details of the methodology, simulation and real-time implementation results are presented and recommendation for future work briefly outlined.

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Research Data and Supplementary Material