Highly Conductive Biomaterial for the Safe Printing of Wireless Biosensors and Antennas Inside the Body

This paper investigates a conductive biomaterial for a new wireless biosensor fabrication paradigm in which relatively large (order of 2-5 cm) electromagnetic components are printed intracorporeally, meaning inside the body, using minimally invasive robotics. A conductive biomaterial for intracorporeal printing of electromagnetic components must: have a high conductivity, σ, of greater than 10⁴ S m^-1; solidify in a safe manner; exhibit rheological properties suitable for printing at the correct feature resolution; and be biocompatible. This study demonstrates the effect of poly(3,4-ethylenedioxythiophene):polystyrenesulfonate, ethylene glycol, and polyethylene glycol diacrylate with a photoinitiator on the biomaterial conductivity, mechanical properties, and cytotoxicity in a benchtop environment. Optimized formulations satisfy the requirements for intracorporeal printing of conductors and have a σ > 10⁴ S m^-1, which is 1 order of magnitude larger than other intracorporeally printable biomaterials. The material Young's modulus approximates that of many soft tissues (approximately 2.5 kPa) and does not induce a cytotoxic effect. These capabilities enable minimally invasive, intracorporeal printing of electromagnetic components and provide a new material option for rapid, safe printing of high-conductivity interconnects and electromagnetic components for myriad energy storage and wireless communication applications.