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A mm-Sized Free-Floating Wirelessly Powered Implantable Optical Stimulation Device

Title
A mm-Sized Free-Floating Wirelessly Powered Implantable Optical Stimulation Device
Author
이병훈
Keywords
Free-floating; implantable; inductive link; mu LED array; mm-sized; optogenetic switched-capacitor based stimulation; Stimulated emission; Light emitting diodes; Biomedical optical imaging; Optical sensors; Optical resonators; Telemetry
Issue Date
2019-08
Publisher
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Citation
IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS, v. 13, no. 4, page. 608-618
Abstract
This paper presents a mm-sized, free-floating, wirelessly powered, implantable optical stimulation (FF-WIOS) device for untethered optogenetic neuromodulation. A resonator-based three-coil inductive link creates a homogeneous magnetic field that continuously delivers sufficient power (>2.7 mW) at an optimal carrier frequency of 60 MHz to the FF-WIOS in the near field without surpassing the specific absorption rate limit, regardless of the position of the FF-WIOS in a large brain area. Forward data telemetry carries stimulation parameters by on-off-keying the power carrier at a data rate of 50 kb/s to selectively activate a 4 x 4 mu LED array. Load-shift-keying back telemetry controls the wireless power transmission by reporting the FF-WIOS received power level in a closed-loop power control mechanism. LEDs typically require high instantaneous power to emit sufficient light for optical stimulation. Thus, a switched-capacitor-based stimulation architecture is used as an energy storage buffer with one off-chip capacitor to receive charge directly from the inductive link and deliver it to the selected mu LED at the onset of stimulation. The FF-WIOS system-on-a-chip prototype, fabricated in a 0.35-mu m standard CMOS process, charges a 10-mu F capacitor up to 5 V with 37% efficiency and passes instantaneous current spikes up to 10 mA in the selected mu LED, creating a bright exponentially decaying flash with minimal wasted power. An in vivo experiment was conducted to verify the efficacy of the FF-WIOS by observing light-evoked local field potentials and immunostained tissue response from the primary visual cortex (V1) of two anesthetized rats.
URI
https://ieeexplore.ieee.org/document/8721104https://repository.hanyang.ac.kr/handle/20.500.11754/160764
ISSN
1932-4545; 1940-9990
DOI
10.1109/TBCAS.2019.2918761
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > ELECTRICAL AND BIOMEDICAL ENGINEERING(전기·생체공학부) > Articles
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