Researchers have developed a sustainable, highly conductive copper-doped nano biochar (Cu@LNB) from industrial lignin, offering a low-cost alternative for flexible electronics. This innovation addresses the rising demand for efficient materials in the Internet-of-Things (IoT) era, where sensors are vital for applications like health monitoring and robotics.

Using hydrothermal coordination and carbonization, the team transformed lignin, a byproduct of the paper industry, into Cu@LNB. Copper ions (Cu²⁺) enhanced the conductivity and morphology of the material, forming uniform spherical nanoparticles of 69 nm. After carbonization at 800°C, the biochar achieved a conductivity of 30.2 S/m under 5 MPa pressure. When integrated into a carboxy nitrile rubber (XNBR) matrix, Cu@LNB created a 3D segregated conductive network capable of sensing strain and liquids.

The resulting sensor exhibited exceptional performance, with a gauge factor (GF) of 1693 in higher strain ranges (6–80%), rapid response, and stability over repeated cycles. Additionally, it effectively distinguished between various organic liquids, making it suitable for diverse applications.

This study demonstrates the potential of lignin, an underutilized biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More, to produce renewable, scalable, and high-performance conductive materials. By leveraging such bio-based resources, researchers are paving the way for affordable, sustainable solutions in flexible electronics and IoT devices. This approach not only reduces dependency on fossil-derived materials but also valorizes lignin, contributing to waste reduction and circular economy goals.