Self-reinforced piezoelectric chip for scaffold-free repair of critical-sized bone defects.

The use of piezoelectric materials to treat critical-sized bone defects typically requires additional stimulation to generate their piezoelectric properties and the implantation of scaffolds to promote bone repair. Here we present a self-reinforced piezoelectric chip and demonstrate its efficacy in the treatment of critical-sized bone defects. Specifically, the chip is comprised of the third-generation semiconductor aluminum nitride (AlN) as a piezoelectric layer, molybdenum (Mo) electrodes, and a silicon substrate with an optimized internal cavity structure. All these components are confirmed to be non-cytotoxic. This design enables the chip to provide self-sustained and long-term electrical signals in response to physiological vibrations. After being implanted into a rabbit critical-sized femoral defect model, the chip creates a localized bioelectric microenvironment, thereby promoting vascularized bone repair within 4 weeks without using any scaffolds and additional tools. Moreover, the chip can be fixed onto the clinically used orthopedic plate system, representing a universal plug-and-play strategy.