One of the main techniques for measuring and monitoring mental activity, called functional near infrared spectroscopy (fNIRS), can often be impaired because a person's hair gets in the way. A team of researchers at the University of Texas at Dallas and the University of Texas at Arlington have developed a novel device called a "brush optrode" that provides increased sensitivity with fiber tips designed to thread through hair to enhance scalp contact. fNIRS is a noninvasive optical technique that measures oxygen levels in the brain to chart neurological activity. The difference between oxygenated hemoglobin and deoxygenated hemoglobin can be used as a correlate of brain activity. Using fNIRS, this difference in blood oxygen level is determined using a relative spectroscopic measurement at two near infrared wavelengths.
"The conventional fibers used in fNIRS systems terminate in a large, flat bundle, and it is easy for a patient's hair to get in the way and block the signal," explained Duncan MacFarlane, professor of electrical engineering in the Erik Jonsson School of Engineering and Computer Science at the University of Texas at Dallas. "So we developed a new tip for the fNIRS fibers - a brush optrode that slides the fibers between the hair follicles. Signal levels increase 3- to 5-fold, and patients report that the brush optrode is considerably more comfortable than the conventional fiber ends. And the brush optrode is easier to set up, which saves time and money." The research is expected to open the door to portable, easy-to-use, high-density optical scanning of brain activity.
