Development of a Noninvasive Device for Detection of Degenerative Brain Disorders

A new neuroimaging device has been developed to diagnose and monitor brain disorders using functional near-infrared spectroscopy (fNIRS). The system has enhanced spatial as well as temporal resolution, and it is configured in a tightly arranged mesh, which consists of a single photodiode (PD) and 128 dual-wavelength LEDs. The developed device can span a square-shaped area of nearly 49 cm 2 . Multiple source-detector separations are used that enable us to reach multiple depths inside the brain 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 the 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. Low-side switching ICs based on MOSFET technology are used for high-speed fNIRS signal recording. 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.