Water-Saturated Ion Gel for Humidity-Independent High Precision Epidermal Ionic Temperature Sensor

Area of Science:

• Materials Science
• Sensor Technology
• Biomedical Engineering

Background:

• Ion gels are promising for epidermal and implantable sensors.
• Environmental humidity changes significantly degrade ion gel sensor performance and reliability.

Purpose of the Study:

• To develop a highly deformable ion gel temperature sensor with stable, high-precision sensing performance.
• To ensure sensor reliability across a wide range of environmental humidity conditions.

Main Methods:

• A hydrophobic ion gel sensing layer was maintained in a water-saturated state by attaching a hydrogel layer.
• Investigated water concentration in the ion gel using mass transport analysis at the ion gel-hydrogel interface.
• Utilized the charge relaxation time of ionic molecules for temperature sensing.

Main Results:

• The ion gel sensor demonstrated consistent performance unaffected by environmental humidity (30%-100%).
• The sensor maintained its performance in both dry and submerged conditions.
• The sensor exhibited stable performance under large strains (up to 50%) during exercise.

Conclusions:

• A novel approach ensures stable, high-precision temperature sensing with deformable ion gel sensors.
• The developed sensor overcomes humidity-related reliability issues for wearable and implantable applications.
• This technology enables robust, high-performance temperature sensing for on-skin and in-body devices.