High ratio carbon nanotube-carboxymethyl cellulose composite grid for Joule heating device

This study reports on the fabrication and characterization of a carbon nanotube (CNT)-carboxymethyl cellulose (CMC) composite grid structure for transparent Joule heating electronic applications. Using flexible polydimethylsiloxane mold, we fabricated a large-scale 4-inch CNT-CMC composite grid with 500 µm line pattern. The grid structure achieved an overall average transmittance of 67.87% at 550 nm, with variations ranging from 43.61% to 92.80% across different measurement zones. The electrical properties were optimized by varying CNT content from 20–40%, achieving a significant resistance reduction from 26 MΩ to 4 kΩ. The CNT-CMC grid structures demonstrated complete resistance recovery after 30-degree bending deformation. For Joule heating characteristics, the device reached 25.0 °C at 600 mW (30 V, 20 mA) and 25.7 °C at 900 mW (30 V, 30 mA), demonstrating long-term stability by maintaining 34.5 °C for over two hours. These results highlight the potential of CNT composite grids in wearable devices, automotive defrosters, and other flexible electronics requiring stable electrical and thermal performance.