Design of an artificial muscle for facial paralysis

INTRODUCTION
In brief, I am a student at EPFL studying microengineering, and I am currently conducting my research internship at the Integrated Actuators Laboratory. My subject concerns the use of soft actuators to reanimate the eyebrows of people suffering from facial paralysis.
AIM OF THE PROJECT
Bell’s palsy is a condition where the muscles on one or both sides of the face become immobile due to nerve damage. While treatments do exist, they often involve invasive transplant surgeries. However, there is a promising alternative to these invasive procedures that could be more cost-effective and less risky : the utilization of artificial muscles also referred to as soft actuators.
My objective is to restore one of the damaged functions (smiling, frowning, eyebrow raising...) by utilizing a soft actuator to replace the damaged muscles. An actuator refers to a machine component that induces motion. In my project, the actuator has muscle-like mechanical properties and interesting electrical properties.
DESCRIPTION OF THE PROJECT
If you would like to delve further into the details of my project, please feel free to contact me. In essence, my project aims to reanimate the eyebrows of a patient with Bell's palsy. I have divided my project into six parts.
First part : State of the art
The first part consists of a state of the art about Humanoid Facial Robot and soft actuator. I'm using Dielectric Elastomer Actuator (DEA) as a soft actuator for this project. DEAs are chosen as soft actuators due to their small size and thinness, enabling easy insertion between the skull and the skin. These actuators possess lightweight properties with a high power-to-weight ratio and operate swiftly and silently. It consists of an electro active polymer that is vertically compressed when applying a high voltage, causing the structure to expand laterally in both directions.
Figure 1: Working principle of a DEA *
Second part : Anatomy
The second part entails an in-depth analysis of the facial muscles responsible for eyebrow movement. This involves differentiating between active and passive muscles and creating a table of specifications for the active muscles. The specification table must specify the displacement and force required by the active muscle.
Third part : Design
The passive muscles are modeled with a silicone structure. Silicone is chosen for its muscle-like mechanical properties. The design is obtained from a calque of upper face muscles.
Fourth part : Optimisation
The design is modeled using beam theory and COMSOL Simulations to optimize its height and thickness for achieving the desired displacement corresponding to the required force. Once the optimal design is obtained, it will be manufactured in a controlled environment, commonly referred to as the grey room.
Fifth part : DEA implementation
The DEA is implemented into the design. It will be dimensioned to achieve the desired force through the use of COMSOL simulations and MATLAB modeling. After sizing the actuator, it will be manufactured in the grey room.
Sixth part : Tests and analysis
The sixth part involves testing the activation of the eyebrow on the setup and improving the DEA to attain the desired displacement.
CONCLUSION
To conclude the development of this technology opens up new opportunities to enhance the quality of life for individuals affected by facial paralysis. By harnessing DEA's capabilities, this innovative solution can effectively restore facial movements, empowering those affected to communicate, express emotions, and engage socially.
* image source : EPFL LAI. https://www.epfl.ch/labs/lai/research/uh-voltage-and-energy-recovery-for-dielectric-elastomer-actuators/.
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I find your project really fascinating and I’m eager to see your final results ! Good luck :)
Thanks Alixe! Good luck with your research project too.
This is so interesting! I must definitely come and visit your lab in the near future!! :) Looking forward to hearing more about it Baptiste.