A System-Level Feasibility Study of a Lead-Free Ultrasonically Powered Light Delivery Implant for Optogenetics

Body implants play a crucial role in clinical applications, encompassing data acquisition, diagnosis, and disease treatment. However, challenges in size, power consumption, and biocompatibility, particularly in brain applications requiring small, battery-free devices for deep areas, hinder their development. Despite potential advances through simplified, single-purpose devices, such as recording or stimulation, overcoming the power and biocompatibility issues remains a hurdle. Addressing this, the article introduces an ultrasonically powered light delivery implant (LDI) utilizing lead-free piezoelectric material (Li_0.08K_0.46Na_0.46) NbO₃ to harvest energy from external ultrasonic waves. The prototype includes a piezoelectric cube, a chip fabricated in 180 nm CMOS technology, and a microscale light-emitting diode (μ-LED) for optogenetics. Achieving an end-to-end efficiency of 0.75%, the LDI holds promise for various optogenetic studies, particularly in animal studies targeting specific brain areas for treating Parkinson's disease. The delivered optical power on the μ-LED surface, at 14.1 mW mm⁻², presents applicability to diverse studies involving specific opsins.