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Neurophotonics • Open Access

Rearrangeable and exchangeable optical module with system-on-chip for wearable functional near-infrared spectroscopy system
Author(s): Tsukasa Funane; Takashi Numata; Hiroki Sato; Shinsuke Hiraizumi; Yuichi Hasegawa; Hidenobu Kuwabara; Kiyoshi Hasegawa; Masashi Kiguchi

Paper Abstract

We developed a system-on-chip (SoC)-incorporated light-emitting diode (LED) and avalanche photodiode (APD) modules to improve the usability and flexibility of a fiberless wearable functional near-infrared spectroscopy (fNIRS) system. The SoC has a microprocessing unit and programmable circuits. The time division method and the lock-in method were used for separately detecting signals from different positions and signals of different wavelengths, respectively. Each module autonomously works for this time-divided-lock-in measurement with a high sensitivity for haired regions. By supplying +3.3  V of power and base and data clocks, the LED module emits both 730- and 855-nm wavelengths of light, amplitudes of which are modulated in each lock-in frequency generated from the base clock, and the APD module provides the lock-in detected signals synchronizing with the data clock. The SoC provided many functions, including automatic-power-control of the LED, automatic judgment of detected power level, and automatic-gain-control of the programmable gain amplifier. The number and the arrangement of modules can be adaptively changed by connecting this exchangeable modules in a daisy chain and setting the parameters dependent on the probing position. Therefore, users can configure a variety of arrangements (single- or multidistance combinations) of them with this module-based system.

Paper Details

Date Published: 9 September 2017
PDF: 10 pages
Neurophoton. 5(1) 011007 doi: 10.1117/1.NPh.5.1.011007
Published in: Neurophotonics Volume 5, Issue 1
Show Author Affiliations
Tsukasa Funane, Hitachi, Ltd. (Japan)
Takashi Numata, Hitachi, Ltd. (Japan)
Hiroki Sato, Hitachi, Ltd. (Japan)
Shinsuke Hiraizumi, Hitachi Kokusai Electric Inc. (Japan)
Yuichi Hasegawa, Hitachi Kokusai Electric Inc. (Japan)
Hidenobu Kuwabara, Hitachi Kokusai Electric Inc. (Japan)
Kiyoshi Hasegawa, Hitachi High-Technologies Corp. (Japan)
Masashi Kiguchi, Hitachi, Ltd. (Japan)

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