Versatile Mechanochromic Sensor based on Highly Stretchable Chiral Liquid Crystalline Elastomer.

Area of Science:

• Materials Science
• Polymer Chemistry
• Soft Robotics

Background:

• Mechanochromic sensors offer visual feedback for strain detection.
• Liquid crystalline elastomers (LCEs) possess unique stimuli-responsive properties.
• Developing sensors that can distinguish complex deformations remains a challenge.

Purpose of the Study:

• To propose a novel mechanochromic strain sensor capable of discerning deformation orientation, location, and degree.
• To utilize a main-chain chiral liquid crystalline elastomer (MCLCE) for advanced sensing capabilities.
• To demonstrate the sensor's applicability in various configurations and potential for pattern display.

Main Methods:

• Fabrication of a highly stretchable MCLCE film via step-growth polymerization of liquid crystal oligomers.
• Phase-stabilization of the MCLCE in a solvent mesogen for uniform color shift.
• Integration of the MCLCE film onto a stretchable elastomer substrate.

Main Results:

• The MCLCE film exhibited uniform and significant color shift even under small strains.
• The sensor demonstrated multimodal, instantaneous color changes for in-plane deformation, out-of-plane bending, and nonzero Gaussian deformation.
• The sensor successfully displayed color patterns and encrypted images in response to localized stimuli.

Conclusions:

• The proposed MCLCE-based sensor effectively distinguishes complex deformation parameters.
• The sensor's design allows for versatile applications in wearable devices, displays, and soft robotics.
• This work presents a simple yet powerful platform for advanced visual strain sensing.