• Title/Summary/Keyword: Optoelectronic stimulation

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Feasibility of Optoelectronic Neural Stimulation Shown in Sciatic Nerve of Rats (흰쥐의 좌골 신경 자극을 통한 광전 자극의 가능성에 대한 연구)

  • Kim Eui tae;Oh Seung jae;Baac Hyoung won;Kim Sung june
    • Journal of Biomedical Engineering Research
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    • v.25 no.6
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    • pp.611-615
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    • 2004
  • A neural prostheses can be designed to permit stimulation of specific sites in the nervous system to restore their functions, lost due to disease or trauma. This study focuses on the feasibility of optoelecronic stimulation into nervous system. Optoelectronic stimulation supplies, power and signal into the implanted optical detector inside the body by optics. It can be effective strategy especially on the retinal prosthesis, because it enables the non-invasive connection between the external source and internal detector through natural optical window 'eye'. Therefore, we designed an effective neural stimulating setup by optically based stimulation. Stimulating on the sciatic nerve of a rat with proper depth probe through optical stimulation needs higher ratio of current spreading through the neural surface, because of high impedance of neural interface. To increase the insertion current spreading into the neuron, we used a parallel low resistance compared to load resistance organic interface and calculated the optimized outer parallel resistance for maximum insertion current with the assumption of limited current by photodiode. Optimized outer parallel resistance was at a range of 500Ω-700Ω and a current was at a level between 580uA and 650uA. Stimulating current efficiency from initial photodiode induced current was between 47.5 and 59.7%. Various amplitude and frequency of the optical stimulation on the sciatic nerve showed the reliable visual tremble, and the action potential was also recorded near the stimulating area. These result demonstrate that optoelectronic stimulation with no bias can be applied to the retinal prosthesis and other neuroprosthetic area.

Recent Progress of Light-Stimulated Synapse and Neuromorphic Devices (광 시냅스 및 뉴로모픽 소자 기술)

  • Song, Seungho;Kim, Jeehoon;Kim, Yong-Hoon
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.35 no.3
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    • pp.215-222
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    • 2022
  • Artificial neuromorphic devices are considered the key component in realizing energy-efficient and brain-inspired computing systems. For the artificial neuromorphic devices, various material candidates and device architectures have been reported, including two-dimensional materials, metal-oxide semiconductors, organic semiconductors, and halide perovskite materials. In addition to conventional electrical neuromorphic devices, optoelectronic neuromorphic devices, which operate under a light stimulus, have received significant interest due to their potential advantages such as low power consumption, parallel processing, and high bandwidth. This article reviews the recent progress in optoelectronic neuromorphic devices using various active materials such as two-dimensional materials, metal-oxide semiconductors, organic semiconductors, and halide perovskites

Photoresponsive Characteristics of N-channel Pseudomorphic HEMT and MESFET Under Optical Stimulation for Possible Applications to Millimeter-Wave Photonics

  • 김동명;김희종;이정일;이유종
    • Electrical & Electronic Materials
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    • v.12 no.8
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    • pp.39-45
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    • 1999
  • Comparative photoresponsive current-volt-age characteristics of n-channel PHEMT and MESFET on GaAs substrate. with (W/L)=200${\mu}{\textrm}{m}$/1${\mu}{\textrm}{m}$ of gates, are reported as a function of electro-optical stimulation (P\ulcorner, λ=830nm) for the first time as far as we know. Significantly different photoresponses are observed in MESFET and PHEMT, mainly due to different optoelectronic mechanisms in the formation and current conduction of channel carriers. Under high optical power, high photoresponsity with a strong non-linearity with P\ulcorner, predominantly due to a parallel conduction via a heavily doped Al\ulcornerGa\ulcornerAs donor layer, was observed in PHEMT while the optically induced drain current has been very small but monotonically increasing with optical stimulation in GaAs MESFET. We also investigated differences in optically stimulated gate leakage currents and photonic gate responses on gate voltage and drain voltage as a function of P\ulcorner. Based on the drain and gate responses to electro-optical stimulation. PHEMTs are expected to be a better candidate for high performance photonically responsive microwave device compared with MESFETs.

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Fabrication, Optoelectronic and Photocatalytic Properties of Some Composite Oxide Nanostructures

  • Zou, C.W.;Gao, W.
    • Transactions on Electrical and Electronic Materials
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    • v.11 no.1
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    • pp.1-10
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    • 2010
  • This is an overview paper reporting our most recent work on processing and microstructure of nano-structured oxides and their photoluminescence and photo-catalysis properties. Zinc oxide and related transition metal oxides such as vanadium pentoxide and titanium dioxide were produced by a combination of magnetron sputtering, hydrothermal growth and atmosphere controlled heat treatment. Special morphology and microstructure were created including nanorods arrays, core-brushes, nano-lollipops and multilayers with very large surface area. These structures showed special properties such as much enhanced photoluminescence and chemical reactivity. The photo-catalytic properties have also been promoted significantly. It is believed that two factors contributed to the high reactivity: the large surface area and the interaction between different oxides. The transition metal oxides with different band gaps have much enhanced photoluminescence under laser stimulation. Use of these complex oxide structures as electrodes can also improve the energy conversion efficiency of solar cells. The mixed oxide complex may provide a promising way to high-efficiency photo emitting materials and photo-catalysts.