A Fully Biodegradable Hybrid Nanogenerator with Mo Nanoparticle-Mediated Dielectric Enhancement for Improved In Vivo Energy Harvesting.

Implantable medical devices that fully degrade in the body eliminate the need for removal surgeries, yet powering them transiently remains a challenge due to low energy harvesting efficiency. Here, we introduce a fully biodegradable hybrid nanogenerator (FB-HNG) with dramatically enhanced output, enabled by biodegradable molybdenum (Mo) nanoparticle-mediated dielectric modulation. By incorporating Mo nanofillers into a PLGA triboelectric layer, we significantly enhance its dielectric constant, surface roughness, and electronegativity. When integrated with a self-assembled polyvinyl alcohol/glycerol/polyvinyl alcohol (PVA/Gy/PVA) piezoelectric heterostructure film, the synergistic hybrid device achieves a record output charge density of 9.6 nC/cm2 among fully biodegradable nanogenerators to date. The entire system, comprising fully degradable components, including the absorbable Mo metal, undergoes complete dissolution after its functional lifespan. In vitro and in vivo biocompatibility assessments confirm its excellent biosafety. This work presents a dielectric-modulation strategy to boost the output of fully biodegradable electronics, highlighting the potential of nanogenerators for powering transient implantable medical devices.