Unibody flexible hydrogel sensor in vivo via NIR three-dimensional printing

Implantable biosensors as pivotal medical devices are designed to monitor physiological signals in vivo . However, their invasive nature often leads to potential tissue damage and biocompatibility risk for patients. Therefore, we explored in vivo fabrication of a unibody flexible hydrogel biosensor via near-infrared (NIR) 3D printing. The most salient feature of our sensor is its in vivo unibody molding, facilitated by core-shell upconversion nanoparticles (UCNPs) combined with indocyanine green (ICG) to serve as an embedded ultraviolet light source for direct photopolymerization. The sensor, printed directly within the body of a murine, can capture locomotive movements and convert them into electrical signals in real time. Accordingly, this approach of in vivo 3D printing of flexible sensors represents a non-invasive methodology for the bespoke fabrication of hydrogel-based sensors, thereby greatly promoting the potential of versatile hydrogels for personalized health monitoring and disease diagnostics.