Fabrication and Assembly Techniques for Sub-mm Battery-Free Epicortical Implants

Abstract

Over the past three decades, we have seen significant advances in the field of wireless implantable medical devices (IMDs) that can interact with the nervous system. To further improve the stability, safety, and distribution of these interfaces, a new class of implantable devices is being developed: single-channel, sub-mm scale, and wireless microelectronic devices. In this research, we describe a new and simple technique for fabricating and assembling a sub-mm, wirelessly powered stimulating implant. The implant consists of an ASIC measuring 900 × 450 × 80 µm3, two PEDOT-coated microelectrodes, an SMD inductor, and a SU-8 coating. The microelectrodes and SMD are directly mounted onto the ASIC. The ultra-small device is powered using electromagnetic (EM) waves in the near-field using a two-coil inductive link and demonstrates a maximum achievable power transfer efficiency (PTE) of 0.17% in the air with a coil separation of 0.5 cm. In vivo experiments conducted on an anesthetized rat verified the efficiency of stimulation.

Harnessing metamaterials for efficient wireless power transfer for implantable medical devices

“…Various strategies have been explored to surmount these challenges. One notable method employs multi-objective optimization algorithms to maximize PTE for specific transmitter and receiver geometries (Khalifa et al 2023 ; Xu et al 2022 ). One method to increase the PTE is to use an array of coils or antennas.…”