Zwitterionic Surfactant Enhanced Stable Hydrogels for Epidermal Sensors and External Contact Object Perception.

Area of Science:

• Materials Science
• Biomedical Engineering
• Polymer Chemistry

Background:

• Hydrogel-based epidermal sensors offer flexibility and biocompatibility for physiological monitoring.
• Challenges in hydrogel stability and conductivity limit their application in wearable electronics.

Purpose of the Study:

• To enhance the stability and conductivity of hydrogels for epidermal sensing applications.
• To maintain biocompatibility while improving material performance.

Main Methods:

• Incorporation of betaine (BA) into acrylamide (AA) and poly(2-acryloylamino-2-methyl-1-propanesulfonic acid) (AMPS) hydrogel matrices.
• Addition of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to restore ionic conductivity.

Main Results:

• Achieved high ionic conductivity (∼0.84 S m^-1) and excellent stability (retaining 78% weight after 14 days).
• Maintained exceptional electrical, mechanical (∼18.13 kPa tensile strength, ∼450% elongation), and adhesive (∼4.01 kPa) properties.
• Demonstrated reliable epidermal sensing with high signal-to-noise ratio (∼25 dB) and 97.5% accuracy in contact sensing.

Conclusions:

• The developed hydrogel offers a promising solution for advanced wearable electronics by overcoming stability and conductivity limitations.
• The material enables high-fidelity electrophysiological signal acquisition, unaffected by motion artifacts.