Three-Layered Design of Electrothermal Actuators for Minimal Voltage Operation

Gal Tibi, Ela Sachyani Keneth, Michael Layani, Shlomo Magdassi, Amir Degani*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


By designing an actuator composed of thin layers with different coefficients of thermal expansion (CTE) together with an electrically conductive layer, the CTE mismatch can be utilized to produce soft electrothermal actuators (ETAs). These actuators have been typically implemented using only two layers, commonly relying on Timoshenko's analytic model that correlates the temperature to the actuator's curvature. In this study, we extend the analytic model to include the thermoelectric relation present in ETAs, that is, the conductive layer's properties with respect to the operation temperature. By applying the thermoelectric relation, a minimal voltage optimization can be applied to the analytic model. Using dimensionless analysis, we optimize the ETAs performance for both bi- A nd tri-layer ETAs with and without the thermal modeling. The bi-layer optimization not only predicts the maximal value for the bi-layer performance but also provides the optimal thickness of each layer for any couple of materials. We validate the tri-layer analytic model experimentally by measuring the curvature for different third layer thicknesses. Finally, we optimize the tri-layer design based on the analytic model, which can achieve an improvement in curvature per voltage of >3000% over the optimal bi-layer ETA.

Original languageAmerican English
Pages (from-to)649-662
Number of pages14
JournalSoft Robotics
Issue number5
StatePublished - Oct 2020

Bibliographical note

Publisher Copyright:
© Copyright 2020, Mary Ann Liebert, Inc., publishers 2020.


  • electrothermal actuators
  • minimal voltage actuation
  • soft actuators
  • thermal expansion actuation


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