An Ultrastretchable Gradient Ionogel Induced by a Self-Floating Strategy for Strain Sensing

Area of Science:

• Materials Science
• Polymer Chemistry
• Flexible Electronics

Background:

• Fabricating gradient ionogels for flexible strain sensors is challenging due to complex procedures and limited stretchability.
• Achieving ionogels with ultrahigh stretchability (strain > 10000%) is a significant hurdle in materials science.

Purpose of the Study:

• To develop a facile strategy for fabricating gradient ionogels with ultrahigh stretchability.
• To apply these gradient ionogels in high-performance flexible strain sensors.
• To investigate the relationship between gradient composition and material properties like conductivity and adhesivity.

Main Methods:

• Utilized the self-floating character of polysiloxane cross-linker (poly(dimethylsiloxane) bis(2-methyl acrylate) - PDMSMA) in a one-step in situ photopolymerization.
• Engineered gradient composition distribution within the ionogel by leveraging PDMSMA's properties.
• Fabricated flexible strain sensors using the gradient ionogels.

Main Results:

• Achieved gradient ionogels with ultrahigh stretchability exceeding 14000%.
• Developed ionogels with gradient changes in conductivity and adhesivity, featuring a sticky bottom and non-sticky top surface.
• Demonstrated flexible strain sensors with high sensitivity (gauge factor 5.08), wide detection range (1-1500%), fast response, and excellent repeatability (>1000 cycles).

Conclusions:

• The proposed facile strategy enables the fabrication of gradient ionogels with exceptional stretchability and tunable surface properties.
• The gradient ionogels are successfully applied to flexible strain sensors, showcasing high performance for detecting mechanical strain and physiological signals.
• This work opens new avenues for advanced flexible electronics and wearable devices.