Programmable Hydration Pathways Enable Reconfigurable Ionic Thermoelectrics for Energy Harvesting and Thermal-Tactile...

Area of Science:

• Materials Science
• Electrochemistry
• Soft Matter Physics

Background:

• Ionic thermoelectric (iTE) materials offer high thermovoltages but struggle with balancing thermopower, response speed, and long-term stability.
• Existing iTE materials often face inherent trade-offs between these critical performance metrics.

Purpose of the Study:

• To engineer reconfigurable iTE performance in polyquaternium hydrogels by precisely controlling hydration pathways.
• To decouple ion transport from water activity and thermal gradients using a novel hydration-gated protonics framework.

Main Methods:

• Programming hydration pathways across multiple scales (microscopic to macroscopic) within polyquaternium hydrogels.
• Coupling solvation, polymer-ion interactions, water channels, and boundary conditions to control iTE properties.
• Utilizing a thermo-hydration co-design approach, treating hydration boundaries as tunable parameters.

Main Results:

• Achieved two distinct operating states in hydrogels: an open, breathable state with ultrahigh thermopower (44.8 mV K⁻¹) and a sealed state with subsecond dynamics and long-term stability (>90 days).
• Demonstrated a wearable energy-harvesting module generating ~0.6 V with a 3.0 K temperature difference.
• Integrated a high-sensitivity, fast-response (0.5 s) iTE sensor array into a robotic hand for thermal-tactile interaction.

Conclusions:

• The hydration-gated protonics framework successfully decouples ion transport barriers from water activity and thermal gradients, enabling reconfigurable iTE performance.
• The developed hydrogel system offers a versatile platform for both efficient energy harvesting and advanced sensing applications.
• This work paves the way for next-generation wearable electronics and intelligent robotic systems.