Fabrication and Assembly Techniques for Distributed Battery-Free Brain Implants

In the past three decades, we have witnessed unprecedented progress in wireless implantable medical devices (IMDs) that can interface with the nervous system. To provide an even more stable, safe, and distributed interface, a new class of implantable devices is being developed; single-channel sub-mm scale wireless devices. In this research, we describe a new and simple technique for the fabrication and assembly of a sub-mm wirelessly powered stimulating implant. The fabricated implant is composed of an ASIC that measures
$\mathbf{900} \times \mathbf{450}\times \mathbf{80}\ \boldsymbol{\mu} \mathbf{m}^{\mathbf{3}}$
, two PEDOT-coated microelectrodes, an SMD inductor, and a SU-8 coating. The electrodes and the SMD are directly mounted onto the ASIC. The ultra-small device is powered via electromagnetic (EM) in near-field using a 2-coil inductive link and shows a power transfer efficiency (PTE) of 0.17% in the air with coil separation of 0.5 cm.