Electricity Generation and Self-Powered Sensing Enabled by Dynamic Electric Double Layer at Hydrogel–Dielectric Elastomer Interfaces

Abstract

The electric double layer (EDL) at liquid−solid interfaces is fundamental to many research areas ranging from electrochemistry and microfluidics to colloidal chemistry. Here, we demonstrate the electricity generation by mechanically modulating the EDL at the hydrogel−dielectric polymer interfaces. It is found that contact electrification between the hydrogel and the dielectric polymer could charge the dielectric polymer surface at first; the mechanical deformation of the pyramid-shaped hydrogel results in the periodic variation of the EDL area and capacitance, which then induces an alternative current in the external circuits. This mechano-to-electrical energy conversion mechanism is then utilized to construct soft stretchable self-powered pressure sensors by designing dynamic EDL at hydrogel−dielectric elastomer interfaces. The sensitivity is optimized to 1.40 kPa −1 in the low-pressure range of 31−300 Pa by increasing the elastomer roughness. Its antifreeze performance is also improved by adding ethylene glycol into the hydrogel. The capability in detecting subtle human activities is further demonstrated. This mechano-electrical energy conversion and the corresponding self-powered sensor can be widely applied in future soft electronics.

Skin bioelectronics towards long-term, continuous health monitoring

“…108,109 An EDL-based self-powered triboelectric sensor was developed using a pyramid-structured hydrogel and dielectric polymer. 110 2.1.3. Optical sensing.…”

Light-Controlled Triple-Shape-Memory, High-Permittivity Dynamic Elastomer for Wearable Multifunctional Information Encoding Devices

“…A strong and stable electrical signal output is beneficial for transmitting information. High-permittivity polymers contributed to enhancing the electrical output performance of electronic devices. − The electrical output ability of the prepared IEDs was evaluated. The peak output open-circuit voltage ( V oc ) of the IED was 44.5 V at different frequencies, indicating that the V oc was unaffected by the frequency (Figure a). , The V oc increased with increasing triboelectric contact area of the IED (Figure S13).…”

Emerging Iontronic Sensing: Materials, Mechanisms, and Applications

“…According to the EDL capacitive sensing mechanism, similar strategy of structure engineering on iontronic capacitive sensors is also applicable to ionic TENG. Jia et al introduced pyramid patterns to PAM hydrogel-based TENG to enhance the pressure sensing performance [ 144 ]. The top surface of the hydrogel pyramid forms dynamic EDL together with the PDMS, while the bottom hydrogel surface forms static EDL together with a metal wire.…”