2015 Fiscal Year Annual Research Report
神経回路の刺激と記録を同時に実行できる半導体オプトエレクトロニックデバイスの開発
| Project/Area Number |
15J02011
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| Research Institution | Tohoku University |
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Principal Investigator |
郭 媛元 東北大学, 医工学研究科, 特別研究員(DC2)
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| Project Period (FY) |
2015-04-24 – 2017-03-31
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| Keywords | microscopy device / deep brain imaging / field effect sensor / polymer fiber |
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| Outline of Annual Research Achievements |
In the year 2015, the light-addressable potentiometric sensor (LAPS) based optoelectronic microscopy device was designed and fabricated for deep brain imaging. The LAPS, as a surface potential sensor, is able to convert the brain activity to carrier redistribution due to the field effect with high sensitivity. In addition, thanks to the photoelectronic effect within the semiconductor, localized surface potential change at the brain-insulater interface of the LAPS can be read out in the form of a photocurrent induced by a modulated light beam, in this way, the imaging of brain activity can also be performed by mapping the photocurrent at each measurement spot illuminated by light modulated at different frequencies. The LAPS, with surface dimensions of < 800 um, as sensing element, was integrated on the tip of the polymer fiber fabricated via thermal drawing process. It has good mechanical flexibility, and was capable of delivering 16 modulated light to the LAPS and leading the electrical signal out for imaging process. This microscopy device performance was characterized. In addition, its in vivo implantation in the hippocampal formation of the mice brain was carried out and delta band of brain oscillations, which were commonly observed in the anesthetized mice, were successfully captured, which demonstrated its usefulness for deep brain study.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
1) Optimization of the performance of the light addressable potentiometric sensor (LAPS) was carried out at Professor Tatsuo Yoshinobu Laboratory at Tohoku University,where the superior signal-to-noise ratio, high speed of the measurement and high spatial resolution were achieved for making LAPS as an suitable platform to capture delicate neural activities with precise temporal and spatial resolution. Necessary electrical circuits for driving lasers were also designed and successfully accomplished.
2) Multimodality fibers with good mechanical flexibility and biocompatibility was fabricated via thermal drawing process which was done at Professor Polina Anikeeva and Professor Xiaoting Jia's groups at Massachusetts Institute Technology and Virginia Polytechnic Institute and State University. A Polyethylenimine(PEI) based fiber with a hollow channel for inserting optical fiber bundles and a ring of Tin based electrodes for leading out the electrical signal was fabricated to integrate with LAPS sensor, which realized implantation into deep brain regions.
3) The LAPS based microscopy device was implanted into the hippocampal formation of the mice and the delta-band of brain oscillations were successfully captured. (In vivo experiments were carried out at MIT under approval of the MIT Committee on Animal Care and in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals.)
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| Strategy for Future Research Activity |
1) In vivo implantation of LAPS-based microscopy device will be carried out and 16 modulated light beam will be delivered to the LAPS chip to achieve deep brain imaging with spatial resolution down to 50 um and frame rate up to 1000 fps, which will be capable of obtaining cellular level brain imaging with precise temporal resolution to study brain functions on the circuitry level.
2) Currently the collaboration with Professor Harald Sontheimer, whose expertise is glia biology and its association with development and progression of neurological disorders, is actively ongoing, this microscope device can be extremely helpful, for example, to examine the pharmaceutical effects on the neurological disorders by implanting it in the deep brain regions where glia cells malfunction.
3) Chronic implantation will be extremely important and interesting. Both device performance and immunological response will be evaluated to demonstrate its long-term stability and biocompatibility.
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