Date of Award

Spring 2023

Document Type


Terms of Use

© 2023 Bryan T. Le. This work is freely available courtesy of the author. It may be used under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) license. For all other uses, please contact the copyright holder.

Creative Commons License

Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 4.0 International License.

Degree Name

Bachelor of Arts


Engineering Department

First Advisor

Joseph D. Towles


Twisted-and-coiled actuators (TCAs) have shown great potential as an artificial muscle for robotics in terms of material cost and production expenses. However, the power-to-force efficiency of these artificial muscles falls short of biological muscles. Soft robotics takes inspiration from biological organisms for more natural movement, and biological mimicry helps increase the efficiency of robotics. Taking inspiration from how sarcomeres are structured in natural muscles, improvements in the energy efficiency of artificial muscles are possible. In this paper, an experiment was designed to analyze the effects on the efficiency of emulating biological sarcomere structures in artificial muscles. Specifically, this experiment used a load cell to capture and compare data between conventional and biological-emulating applications of TCAs under concentric contraction conditions. The experiment used silver-plated sewing thread to fabricate TCAs. While many works have attempted to increase efficiency by changing the material of the TCA, we show that it is also possible to increase efficiency by changing the structure of the TCAs, and the electrical circuit that connects the TCAs. The resulting TCA was approximately seven times as effective as its unchanged counterpart. Additionally, for the same amount of input power, the changed TCA’s contraction is approximately three times as much force as the unchanged TCA. Optimizing the resulting efficiency of this new TCA requires further study of the thermoelectrical properties of the material used for the TCA. Nevertheless, the increased efficiency of changing the structure of the TCA to mimic biological muscles may be worth a new endeavor.


Artificial muscles, conductive thread, sarcomeres, twisted-and-coiled actuators (TCA)

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