High-Precision Stretchable Ionic Temperature Sensor Passivated with a Liquid Metal/Block Copolymer Multilayer Film

Area of Science:

• Materials Science
• Electrochemical Engineering
• Wearable Technology

Background:

• Moisture significantly degrades ionic sensor stability and reliability.
• Developing effective stretchable moisture barriers for deformable ion gel sensors is a critical technological challenge.

Purpose of the Study:

• To develop and characterize a novel four-layer (4L) stretchable moisture barrier.
• To evaluate the barrier's performance under strain and repeated stretching.
• To demonstrate its application in a skin-attached, moisture-independent ionic sensor.

Main Methods:

• Fabrication of a four-layer barrier using poly(styrene-isobutylene-styrene) (SiBS) and eutectic gallium-indium liquid metal (LM) films.
• Measurement of water permeability under 50% uniaxial strain.
• Testing of barrier property retention during repeated stretching cycles.
• Integration into a skin-attached ion gel-based temperature sensor.

Main Results:

• Achieved a low water permeability of 9.09 × 10⁻²⁰ m²/Pa s at 50% strain.
• Demonstrated sustained barrier properties through repeated stretching cycles at 50% strain.
• Successfully created a precise ion gel temperature sensor unaffected by moisture or body motion.

Conclusions:

• The proposed 4L stretchable moisture barrier effectively protects ionic sensors from moisture.
• This barrier technology enables reliable performance of wearable sensors in diverse conditions.
• The developed sensor offers accurate temperature monitoring for skin-attached applications.