High-Sensitivity Flexible Sensor Based on Biomimetic Strain-Stiffening Hydrogel.

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Bioelectronics

Background:

• Flexible wearable and implantable electronic devices are crucial for biomedical applications.
• A significant challenge is the mechanical mismatch between current bioelectronic systems and soft tissues.
• Biomimetic hydrogels with tissue-like mechanical properties are highly sought after for improved tissue-electrode interfaces.

Purpose of the Study:

• To fabricate a biomimetic hydrogel with inherent strain-stiffening properties.
• To create a hydrogel-based sensor with tissue-like mechanical characteristics for bioelectronic devices.
• To investigate the potential of this hydrogel for detecting human movements.

Main Methods:

• Fabrication of a biomimetic hydrogel utilizing regional chain entanglements.
• Embedding highly swollen poly(acrylate sodium) microgels within a polyacrylamide matrix to induce strain-stiffening.
• Utilizing the Na+ ion release from poly(acrylate sodium) microgels to enable electrical signal transduction for strain sensing.

Main Results:

• The developed hydrogel exhibits a low Young's modulus (22.61-112.45 kPa) and high nominal tensile strength (0.99 MPa).
• The hydrogel-based sensors demonstrated high sensitivity, achieving a gauge factor of up to 6.77 at 300% strain.
• The material effectively detected various human movements, indicating its utility as a strain sensor.

Conclusions:

• The biomimetic hydrogel with strain-stiffening properties offers excellent mechanical compatibility for bioelectronic interfaces.
• The simple fabrication process and high performance make it suitable for large-scale applications.
• This material holds significant potential for advanced wearable and implantable electronic devices.