Eco-friendly and cytocompatible graphene composite based on water-soluble biopolymers for modern printed electronics and beyond

A growing demand for sustainable electronics has emerged to facilitate electronic waste management, reduce the use of toxic materials and minimize environmental impact, along with enabling the development of new applications. In this study, six biopolymers — sodium alginate (SA), sodium carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), methylcellulose (MC), sea-source water-soluble chitosan hydrochloride (CS), and fungal water-soluble chitosan (CF) — were investigated as polymer binders for sustainable, highly conductive, and cytocompatible graphene-based composites for screen printing applications. The study focused on optimizing graphene dispersion in water solutions using SDS surfactant and two distinct sonication methods to enhance printability, surface coverage, and conductivity. Rheological tests and surface tension analyses characterized the composites, which were primarily printed on paper substrates to achieve biodegradable structures. Electrical tests, SEM and microscopic imaging identified the probe sonication method as more effective in the deagglomeration of graphene. CMC-based layers exhibited the lowest resistance (58 Ω/□), followed by HEC-based and SA-based. Accelerated aging tests showed minor changes in resistance, indicating a 1-year shelf life. Cytotoxicity tests indicated the potential use of these composites in medical devices in contact with human skin. The findings highlight the promising applicability of natural biopolymers as sustainable polymer matrices in developing biodegradable electronics and reducing environmental impact.