Wood becomes a high-strength conductor through metal-based eutectic gels

Flexible conductive gels have attracted intense research interest as core components in wearable electronics, soft robotics, and human–machine interfaces. Their ability to convert mechanical deformation into electrical signals makes them ideal for motion detection and tactile sensing. However, conventional hydrogels and ionogels typically suffer from a trade-off between mechanical robustness, electrical conductivity, and environmental stability. Many synthetic gels fracture easily, lose performance due to dehydration or freezing, or rely on expensive and potentially hazardous ionic liquids.
A recent article published in Journal of Bioresources and Bioproducts introduces a fundamentally different strategy by using natural wood as a structural scaffold for high-performance conductive eutectogels. Rather than treating wood as a passive substrate, the study exploits its intrinsic hierarchical architecture to construct a mechanically reinforced and ion-transport-efficient gel system.
In the reported approach, a wood skeleton was first extracted from natural basswood through a low-temperature alkali treatment that selectively removed lignin and hemicellulose while preserving the aligned cellulose nanofiber framework. This treatment generated a porous, anisotropic structure with continuous micro- and nanochannels. The wood skeleton was then infiltrated with a ternary metal-based deep eutectic solvent composed of zinc chloride, acrylic acid, and ethylene glycol. Subsequent ultraviolet irradiation triggered in situ polymerization of acrylic acid without the use of chemical initiators or crosslinkers.
The resulting eutectogel integrates multiple reinforcing mechanisms. Poly(acrylic acid) chains form dense hydrogen bonds with cellulose nanofibers, while Zn²⁺ ions create coordination crosslinks with carboxylate groups, producing a physically and chemically entangled network. This synergistic structure leads to a tensile strength of up to 41.5 MPa and a toughness of 8.4 MJ m⁻³—values that exceed those of most reported conductive gels and rival some structural polymer composites.
Electrical performance is equally notable. The inherent ionic conductivity of the metal-based deep eutectic solvent, combined with the aligned transport channels of the wood skeleton, enables efficient ion migration. The eutectogel achieves an ionic conductivity of 2.82 × 10⁻² S m⁻¹, higher than many conventional wood-based or hydrogel-based conductors. Importantly, conductivity is anisotropic, reflecting the directional architecture of the wood, and remains stable across a wide temperature range.
Environmental tolerance represents a key advance of the study. Differential scanning calorimetry and long-term aging tests show that the eutectogel resists freezing and dehydration, maintaining flexibility and conductivity from –60 to 100 °C. Even after thermal aging, mechanical strength retention exceeds 97%, highlighting the material’s suitability for real-world operating conditions where temperature fluctuations are unavoidable.
Leveraging this combination of properties, the researchers demonstrated the eutectogel as a flexible sensor capable of detecting diverse human motions, applied pressures, and temperature stimuli with stable and repeatable electrical responses. The material also enabled programmable signal transmission, illustrated by Morse code input based on pressure modulation, suggesting potential applications in information interfaces and smart sensing systems.
By integrating renewable wood resources with metal-based deep eutectic solvent chemistry, the study establishes a new paradigm for sustainable conductive materials. It shows that high strength, high conductivity, and environmental resilience need not be mutually exclusive, and that natural hierarchical materials can play an active role in next-generation flexible electronics.

See the article:

DOI

https://doi.org/10.1016/j.jobab.2026.100237

Original Source URL

https://www.sciencedirect.com/science/article/pii/S2369969826000095

Journal

Journal of Bioresources and Bioproducts