We report a miniaturized, minimally invasive high-density neural recording interface that occupies only a 1.53 mm2 footprint for hybrid integration of a flexible probe and a 256-channel integrated circuit chip. To achieve such a compact form factor, we developed a custom flip-chip bonding technique using anisotropic conductive film and analog circuit-under-pad in a tiny pitch of 75 μm. To enhance signal-to-noise ratios, we applied a reference-replica topology that can provide the matched input impedance for signal and reference paths in low-noise aimpliers (LNAs). The analog front-end (AFE) consists of LNAs, buffers, programmable gain amplifiers, 10b ADCs, a reference generator, a digital controller, and serial-peripheral interfaces (SPIs). The AFE consumes 51.92 μW from 1.2 V and 1.8 V supplies in an area of 0.0161 mm2 per channel, implemented in a 180 nm CMOS process. The AFE shows > 60 dB mid-band CMRR, 6.32 μVrms input-referred noise from 0.5 Hz to 10 kHz, and 48 MΩ input impedance at 1 kHz. The fabricated AFE chip was directly flip-chip bonded with a 256-channel flexible polyimide neural probe and assembled in a tiny head-stage PCB. Full functionalities of the fabricated 256-channel interface were validated in both in vitro and in vivo experiments, demonstrating the presented hybrid neural recording interface is suitable for various neuroscience studies in the quest of large scale, miniaturized recording systems.
|Number of pages||13|
|Journal||IEEE Transactions on Biomedical Engineering|
|Publication status||Published - 2022 Jan 1|
Bibliographical noteFunding Information:
Manuscript received February 10, 2021; revised May 14, 2021, June 21, 2021, and June 24, 2021; accepted June 27, 2021. Date of publication June 30, 2021; date of current version December 23, 2021. This work was supported in part by NSF 1545858 and in part by NIH 1RF1NS113283-01, and Kavli Foundation. (Corresponding author: Euisik Yoon.) Sung-Yun Park is with the Center for Wireless Integrated Micro Sensing and Systems, Department of Electrical Engineering and Computer Science, University of Michigan, USA and also with the Department of Electronics Engineering, Pusan National University, Korea.
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All Science Journal Classification (ASJC) codes
- Biomedical Engineering