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開催日 2014/9/13
時間 11:00 - 12:00
会場 Poster / Exhibition(Event Hall B)

A Multi-channel Stimulation System with Wireless Communication and Power Transmission for Visual Cortical Prostheses

  • P3-369
  • 亀田 成司 / Seiji Kameda:1 鎌田 隆嗣 / Takatsugu Kamata:1 林田 祐樹 / Yuki Hayashida:2 武内 良典 / Yoshinori Takeuchi:3 今井 正治 / Masaharu Imai:3 八木 哲也 / Tetsuya Yagi:2 
  • 1:大阪大・MEIセンター / MEI Center, Osaka Univ, Osaka, Japan 2:大阪大院工電気電子情報工学 / Grad Eng, Osaka Univ, Osaka, Japan 3:大阪大院情報科学 / Grad Info, Osaka Univ, Osaka, Japan 

For visual prostheses by means of intracortical microstimulation, it is necessary to develop devices that can generate spatio-temporal patterns of electrical stimuli to drive a large number of electrodes according to frame-sampled images. Here, we developed a prototype stimulation system consisting of a multi-channel current stimulator and wireless data/power transmitter and receiver controlled with microprocessors. The stimulator chip with the die size of 3.5×3.5 mm2 was fabricated with 0.25-μm CMOS VLSI technology, to implement parallel eight current generators and multiplexers. The chip generates biphasic stimulus pulses through 64 electrodes in time-sharing mode at up to 200 frames/sec. The stimulus parameters can be set for each electrode by digital codes stored in built-in registers. On demand, the combination of anode and cathode electrodes for passing the stimulus current can be changed online. The maximal amplitude of the stimulus pulse is ˜±400 μA/phase at ±2.5 V supply. As for the wireless power transmission, a pair of 20-mm-diameter coils with a 5-mm gap was employed and the operational frequency is adjustable by programming on embedded microprocessors, in a range from 250 to 425 kHz with 1-kHz step. The available output power at ±2.5 V supply is up to 0.25 W. The wireless data communication was realized with discrete System-on-a-Chip components, by which the stimulus parameters as well as any data set via SPI bus format are transmitted/received between the transmitter and receiver. The signal quality of 2-Mbps data rate at 2.4-GHz band without packet/bit error was verified by using random 19-byte-length data with 0-dBm transmit power, with an inter-module distance of 1 cm or less. The receiver without the coil is 23×26×3 mm in width, length and height, respectively, and the total weight is 5 g including the coil.

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