Biodegradable Thin-Film Conductive Composites Based on Chitosan and Carbon Nanomaterials for Transdermal Bioimpedance Sensors

Introduction: The development of transient biomedical electronics requires flexible, biocompatible, and biodegradable materials capable of stable signal transduction. Transdermal bioimpedance sensors offer a non-invasive pathway for real-time physiological monitoring. This study focuses on synthesizing and laser-modifying thin-film electrically conductive biopolymer composites based on a chitosan matrix filled with single-walled carbon nanotubes (SWCNTs) and graphene oxide (GO) to optimize their electrophysical characteristics.

Materials and Methods: The composite films (thickness 0.02–0.03 mm) were fabricated using a 4 wt.% chitosan succinate matrix dissolved with sodium deoxycholate as a surfactant. The functional conductive phase consisted of carbon nanomaterials with a total concentration of 0.1 wt.%, with the SWCNT-to-GO ratio varied. Electrical conductivity was measured using the four-probe method and with a multimeter. To enhance conductivity, the samples were subjected to localized laser modification using an infrared laser with a wavelength of 1064 nm and output power ranging from 0.035 to 0.14 W.

Results: Electrophysical testing showed that the hybrid filler approach substantially outperforms single-component configurations. The optimal initial electrical conductivity was achieved at a ratio of 75% SWCNTs (0.075 wt.%) to 25% GO (0.025 wt.%). Following targeted laser exposure at 0.07 W, controlled photoreduction and structural modification occurred. This treatment led to a pronounced fourfold (4x) decrease in electrical resistance in the hybrid SWCNT/GO composite, markedly improving its sensitivity without inducing thermal degradation or burning of the biopolymer matrix.

Conclusion: The combination of a biodegradable chitosan matrix with a hybrid carbon network optimized by targeted laser processing provides a reliable platform for skin-interfaced bioelectronics. The achieved low electrical resistance and high flexibility make these thin-film materials highly promising for the creation of disposable, eco-friendly transdermal biometric sensors for continuous bioimpedance tracking.

The work was carried out at NRU MIET in the frame of government university support program “Priority-2030”