Paintable Silicone-Based Corrugated Soft Elastomeric Capacitor for Area Strain Sensing.

Area of Science:

• Materials Science
• Mechanical Engineering
• Electrical Engineering

Background:

• Soft polymer materials are crucial for developing compliant machines and devices, particularly in flexible and stretchable electronics.
• Large-area electronics (LAE) based on soft polymers are explored for structural health monitoring (SHM) applications, requiring sensors that can conform to various surfaces and detect deformations.
• Previous work introduced a corrugated soft elastomeric capacitor (cSEC) using styrene-ethylene-butadiene-styrene (SEBS), but its reliance on epoxy for bonding limited its deployment.

Purpose of the Study:

• To develop a paintable corrugated soft elastomeric capacitor (cSEC) sensor.
• To create a solvent-free fabrication method for cSEC sensors suitable for direct application.
• To evaluate the performance of the new paintable silicone-based cSEC and compare it with the established SEBS-based cSEC.

Main Methods:

• A solvent-free fabrication method was employed using a room-temperature-vulcanizing silicone as the host matrix.
• Titania particles were incorporated into the silicone to form the dielectric layer, and carbon black was used for conductive stretchable electrodes.
• The sensor was applied by painting the silicone onto a surface, followed by deposition of the parallel plate capacitor structure.

Main Results:

• The painted silicone-cSEC exhibited good electromechanical behavior with high linearity (R2 = 0.9901), a gauge factor of 1.58, and a resolution of 70 με.
• Performance comparison with the SEBS-cSEC on a cantilever plate showed comparable results, though the silicone paint introduced more noise and a slight under-estimation of dominant frequency.
• The study demonstrated the feasibility of a paintable sensor for SHM, overcoming the limitations of solvent-based fabrication and epoxy bonding.

Conclusions:

• The developed paintable silicone-cSEC offers a promising alternative for structural health monitoring applications, enabling easier deployment on complex surfaces.
• While performance is comparable to existing technologies, further research may be needed to mitigate noise and frequency under-estimation issues associated with the silicone paint.
• This advancement paves the way for more accessible and versatile large-area electronics in structural health monitoring and other fields requiring flexible sensors.