A Wireless fNIRS Patch with Short-Channel Regression to Improve Detection of Hemodynamic Response of Brain

The functional near-infrared spectroscopy (fNIRS) utilizes near-infrared (NIR) light sources and light detectors to non-invasively image hemodynamic responses of the brain. The unique advantages of fNIRS over the other existing brain imaging technologies led to widespread adoption of fNIRS in various brain research studies including neurology, neuroscience, clinical psychology, and psychiatry. The fNIRS systems are portable, inexpensive and provide higher temporal resolution for scanning a brain. In this paper, we present a wireless wearable fNIRS patch that has the capability of short channel regression to improve the detection of hemodynamic responses of the brain. The patch has two targeted fNIRS channels and a short-channel. The short-channel measures the background hemodynamic responses explicitly from the extracerebral region. Then it performs a regression process to eliminate background interferences from the targeted fNIRS channels to reduce the influence of the interferences. We have interfaced the patch with our laboratory-developed portable fNIRS controller. The patch and the controller are wearable. The controller is wirelessly connected to a host computer to receive commands from it and to wirelessly transmit measurement data to the host computer for the data processing and visualization. The graphical user interface (GUI) in the host computer helps the user to record and visualize fNIRS data. The experimental results of imaging prefrontal cortex of the brain using the fNIRS patch show that the patch has the potential to reduce unrelated hemodynamic activity from the targeted fNIRS channels.