Catalyst-free ionogel turns bamboo to 11-MPa “super-skin” for IoT sensors

Researchers have unveiled a plant-based ionogel strong enough to support a 1.5-tonne car yet sensitive enough to detect a 20-gram pulse, promising a leap forward in sustainable wearable electronics. Writing in the Journal of Bioresources and Bioproducts, the team led by Jianguo Li describes a “catalyst-free” route that turns ordinary cellulose and an ionic liquid into a transparent, stretchable conductor. By letting the ionic liquid itself supply acidic protons, they eliminated the toxic catalysts and multi-step purifications that have limited earlier cellulose gels.

The breakthrough hinges on a simple substitution: glutaraldehyde cross-links cellulose chains while 1-allyl-3-methylimidazolium chloride ([AMIM]Cl) acts simultaneously as solvent, proton donor and ionic conductor. The resulting robust cellulose ionogel (RCI) registers a tensile strength of 11 MPa—ten times higher than uncross-linked counterparts—and a toughness of 2.8 MJ m⁻³. Despite its dense network, the gel conducts ions at 29.1 mS cm⁻¹, outperforming many synthetic analogues.

When compressed, the material’s internal ion distribution shifts, generating a voltage that rises linearly with pressure from a feather-light touch to a firm handshake. Mounted in a 4 cm × 4 cm sensor array, the gel accurately distinguished loads from 20 g to 2 kg with near-zero error, whereas commercial PVDF sensors failed below 20 g. Trials on boxing gloves and shoe insoles translated punches and gaits into crisp electrical signals, while rhythmic tapping spelled out “SOS” and “HELP” in Morse code without an external battery.

Because cellulose is the planet’s most abundant biopolymer and the process avoids harsh reagents, the gel is both low-cost and eco-friendly. The authors say the same strategy could toughen other natural polymers, opening a path to fully compostable, high-performance electronics for the Internet of Things.

See the article:

DOI

https://doi.org/10.1016/j.jobab.2025.08.001

Original Source URL

https://www.sciencedirect.com/science/article/pii/S2369969825000568

Journal

Journal of Bioresources and Bioproducts