Evaluation of time-dependent properties of biodegradable materials for transient implantable biosensors

Current magnesium and silk materials used in transient devices limit the design possibilities. Proper material choice will give transient electronics greater functionality and a wider range of applications. Time-dependence of electrical and physical properties due to dissolution was tested for Al, Zn, W, and Fe, alone and in combination with magnesium. PLGA, collagen, gelatin and a gelatin/PVA hydrogel were tested for physical degradation. Aluminum was the best choice for extending the lifetime of magnesium traces, and tungsten had the slowest dissolution rate of any pure materials tested. Slowly degrading metals could enable fully degradable devices with direct contact with external tissue. PLGA and collagen were moderately functional as encapsulation materials. PLGA was detrimental to magnesium when used as a substrate, but gelatin and the gelatin/PVA hydrogel are both fully biodegradable and have potential as flexible or stretchable (respectively) substrates