MEMS micro-coils for magnetic neurostimulation

Xiyuan Liu, Andrew J Whalen, Sang Baek Ryu, Seung Woo Lee, Shelley I Fried, Kayeon Kim, Changsi Cai, Martin Lauritzen, Nicolas Bertram, Bingdong Chang, Tianbo Yu, Anpan Han*

*Corresponding author af dette arbejde


Micro-coil magnetic stimulation of brain tissue presents new challenges for MEMS micro-coil probe fabrication. The main challenges are threefold; (i) low coil resistance for high power efficiency, (ii) low leak current from the probe into the in vitro experimental set-up, (iii) adaptive MEMS process technology because of the dynamic research area, which requires agile design changes. Taking on these challenges, we present a MEMS fabrication process that has three main features; (i) multilayer resist lift-off process to pattern up to 1800-nm-thick metal films, and special care is taken to obtain high conductivity thin-films by physical vapor deposition, and (ii) all micro-coil Al wires are encapsulated in at least 200 nm of ALD alumina and 6-μm-thick parylene C such the leak resistance is high (>210 GΩ), (iii) combining a multi-step DRIE process and maskless photolithography for adaptive design and device fabrication. The entire process requires four lithography steps. Because we avoided SOI wafers and lithography mask fabrication, the design-to-device time is shortened significantly. The resulting probes are 4-mm-long, 60-μm-thick, and down to 150 μm-wide. Selected MEMS coil devices were validated in vivo using mice and compared to previous work.

Sider (fra-til)1-8
Antal sider8
StatusUdgivet - 2023


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