Tough double network gelatin-based hydrogel sensor via polyelectrolyte-induced Hofmeister effect for human-machine...

Area of Science:

• Materials Science
• Biomaterials Engineering
• Sensor Technology

Background:

• Hydrogel sensors for human-machine interaction (HMI) face challenges balancing mechanical strength and multi-functional sensing capabilities.
• Conventional methods often involve salt leakage and cytotoxicity, limiting their application in wearable electronics.

Purpose of the Study:

• To develop a robust and multifunctional hydrogel sensor for advanced HMI applications.
• To overcome the limitations of existing hydrogel sensors by employing a novel polyelectrolyte-induced Hofmeister effect strategy.

Main Methods:

• Fabrication of a gelatin-based double network hydrogel (Gelatin-PAANa hydrogel) using a polyelectrolyte-induced Hofmeister effect.
• Incorporation of sodium polyacrylate (PAANa) to induce localized salting-out of gelatin chains, enhancing crosslinking.
• Characterization of mechanical properties, ionic conductivity, and dual strain-temperature sensing capabilities.

Main Results:

• The optimized Gelatin-PAANa hydrogel demonstrated high toughness (1.9 MJ/m³), ionic conductivity (1.05 S/m), and excellent biocompatibility.
• Achieved fast strain response (329 ms) with a gauge factor of 0.42 for motion detection and a linear temperature response (-1.16%/°C) for fire warning.
• Integrated sensor enabled gesture recognition, Morse code transmission, and robotic control via a microcontroller.

Conclusions:

• The polyelectrolyte-induced Hofmeister effect provides a biofriendly strategy for designing robust, multifunctional hydrogels.
• This approach overcomes traditional limitations, paving the way for next-generation wearable electronics and intelligent interactive systems.
• The Gelatin-PAANa hydrogel sensor shows significant potential for advanced HMI applications.