Electrochemically Controlled Hydrogels with Electrotunable Permeability and Uniaxial Actuation

The unique properties of hydrogels enable the design of life-like soft intelligent systems. However, stimuli-responsive hydrogels still suffer from limited actuation control. Direct electronic control of electronically conductive hydrogels can solve this challenge and allow direct integration with modern electronic systems. An electrochemically controlled nanowire composite hydrogel with high in-plane conductivity that stimulates a uniaxial electrochemical osmotic expansion is demonstrated. This materials system allows precisely controlled shape-morphing at only -1 V, where capacitive charging of the hydrogel bulk leads to a large uniaxial expansion of up to 300%, caused by the ingress of & AP;700 water molecules per electron-ion pair. The material retains its state when turned off, which is ideal for electrotunable membranes as the inherent coupling between the expansion and mesoporosity enables electronic control of permeability for adaptive separation, fractionation, and distribution. Used as electrochemical osmotic hydrogel actuators, they achieve an electroactive pressure of up to 0.7 MPa (1.4 MPa vs dry) and a work density of & AP;150 kJ m-3 (2 MJ m-3 vs dry). This new materials system paves the way to integrate actuation, sensing, and controlled permeation into advanced soft intelligent systems. The unique properties of hydrogels enable the design of life-like soft intelligent systems. This work demonstrates how the swelling of hydrogels from cellulose nanofibrils and carbon nanotubes can be electrochemically controlled to achieve electrochemical osmotic actuation. This new materials system paves the way for integrated actuation, sensing, and controlled permeation in electrotunable separation membranes or soft actuators.image

Automated summary

By electronically controlling conductive hydrogels, the limitations of stimuli-responsive hydrogels can be overcome and enable direct integration with modern electronic systems. This materials system allows precise shape-morphing, with high tunability and adaptability, paving the way for the design of advanced soft intelligent systems.