Laser induced graphene (LIG) biosensors derived from chitosan: Towards sustainable and green electronics

Modern biosensors can provide real-time monitoring of individuals' health status, revolutionizing traditional healthcare diagnostics. As demand for these devices is continuously growing, the development of novel green materials and processes is mandatory to ensure sustainability. In this work, a simple laser direct writing approach was utilized to fabricate a novel green Laser Induced Graphene (LIG) glucose biosensor, whereby chitosan-based biofilms were used as writing feedstock material. Careful optimization of the biofilm composition was carried out in conjunction with the optimization of laser irradiation parameters to obtain bio-LIG structures with low sheet resistance and spectral characteristics of graphene-like materials. The surface of bio-LIG electrodes was modified with Prussian Blue nanoparticles and the electrocatalytic performance of bio-LIG sensors towards H2O2 was investigated using voltammetric techniques. The response of H2O2 was linear in the range 3 μM - 1 mM (sensitivity, 103.4 μA mM−1 cm−2 and the limit of detection (LOD), 1.9 μM). Following immobilization of glucose oxidase, the bio-LIG sensors showed a linear response of glucose in phosphate buffer (PBS) in the relevant physiological range of 25–300 μM (sensitivity, 457 nA mM−1 cm−2). The LOD was calculated as 9.6 μM. Additionally, the biosensor showed comparable results in artificial sweat.