Wireless high definition neuroimaging system for fNIRS using a single photosensor
Abstract
We present a high spatiotemporal resolution system for neuroimaging using functional near-infrared spectroscopy (fNIRS). The system is configured as bundled optodes with a single photodiode (PD) and 128 dual-wavelength LEDs in a module. This system is developed using a modular approach where a single module can cover approximately 7 cm × 7 cm, while multiple modules can be used to a broader area. The system has the capacity to measure concentration changes of oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) at different brain depths ranging from 2 cm to 3.5 cm. The system also provides the superficial layer information by measuring the short-separation channels. The short-separation channels allow removal of noise and enhancement of signals. The drive circuit of LEDs is carefully designed to switch the light with appropriate intensity, which provides a stable reception for each channel. MOSFET based switching is implemented that allows sharp current switching for high-speed data acquisition. The system can display the acquired HbO and HbR signals as well as activation maps in real-time on a lab-developed Windows-based software. The hardware connects to the software using Wi-Fi. Phantom model with known optical properties and a human subject were used for testing the functionality and efficacy of the device. A complete 128 channel fNIRS sample was recorded in 25 ms. The phantom results showed reduced signal intensity when the channel separation was increased that provides the HbO and HbR. The activation was seen using HbO in the human subject while performing hand tapping task.
- Publication:
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Neural Imaging and Sensing 2020
- Pub Date:
- February 2020
- DOI:
- 10.1117/12.2544729
- Bibcode:
- 2020SPIE11226E..1QY