Integration of Graphene into Calcium Phosphate Coating for Implant Electronics

Bone injuries remain a significant challenge, driving the development of new materials and technologies to enhance healing. This study presents a novel approach for incorporating graphene into calcium phosphate (CaP) coatings on titanium alloy (Ti) substrates, with the aim of creating a new generation of materials for bone implant electronics. The stability of the composite coating under physiological conditions, long-term electrical and mechanical durability, and biocompatibility were systematically investigated. We integrated graphene into the CaP coating through the laser processing of diazonium-functionalized graphene films applied to the surface of CaP-coated Ti. The laser treatment induced several processes, including the removal of aryl groups, the formation of conductive pathways, and chemical bonding with the CaP film. As a result, the graphene-CaP nanocomposite demonstrated excellent mechanical durability, withstanding a 2 h sand abrasion test. It also exhibited excellent biocompatibility, as shown by the proliferation of human fibroblast cells for 7 days. The electrical properties remained stable under physiological conditions for 12 weeks, and the material maintained electrochemical stability after 1 million pulse cycles. Furthermore, it withstood the stress of 100,000 bending cycles without compromising electrical performance. This work highlights the versatility of the biocompatible graphene composite and its potential for a range of applications including free-form electronic circuits, electrodes, bending sensors, and electrothermal heaters.