Patient-Specific Self-Powered Metamaterial Implants for Detecting Bone Healing Progress

There is an unmet need for developing a new class of smart medical implants with novel properties and advanced functionalities. Here, the concept of "self-aware implants" is proposed to enable the creation of a new generation of multifunctional metamaterial implantable devices capable of responding to their environment, empowering themselves, and self-monitoring their condition. These functionalities are achieved via integrating nano energy harvesting and mechanical metamaterial design paradigms. Various aspects of the proposed concept are highlighted by developing proof-of-concept interbody spinal fusion cage implants with self-sensing, self-powering, and mechanical tunability features. Bench-top testing is performed using synthetic biomimetic and human cadaver spine models to evaluate the electrical and mechanical performance of the developed patient-specific metamaterial implants. The results show that the self-aware cage implants can diagnose bone healing process using the voltage signals generated internally through their built-in contact-electrification mechanisms. The voltage and current generated by the implants under the axial compression forces of the spine models reach 9.2 V and 4.9 nA, respectively. The metamaterial implants can serve as triboelectric nanogenerators to empower low-power electronics. The capacity of the proposed technology to revolutionize the landscape of implantable devices and to achieve better surgical outcomes is further discussed.