First Demonstration of GaN HEMT-Based Handheld System for Noninvasive Detection of Traumatic Brain Injury Using Saliva

Traumatic brain injury (TBI) is an insult to the brain caused by an external mechanical force that is neither congenital nor degenerative leading to morbidity and mortality among people of various age groups globally. The work reports design, development, and validation of novel GaN HEMT on Si-based handheld system for noninvasive detection of food and drug administration (FDA)-approved TBI biomarkers UCH-L1 and GFAP in clinically relevant concentration ranges. The developed system can detect and differentiate TBI biomarkers in saliva in almost imperceptible amount of pg/mL using specific conjugation of TBI antibody and target analyte over biofunctionalized chips. The platform offers a peak sensitivity of
$17.42 ~\mu \text{A}$
/pg/mL with high resolution and a pre-eminent selectivity toward target TBI biomarkers. The system is portable, easy to handle, ultrasensitive with volant response time of less than 5 s, and compact with a potential for point-of-care applications. It can be utilized for clinical analysis and on-field application areas for TBI diagnosis and prognosis. The system can be imperative in early medical diagnosis, patient management, and decision-making for computed tomography (CT) or magnetic resonance imaging (MRI). To the best of our knowledge, this is the first-time reporting of a label-free noninvasive TBI detection system based on GaN HEMT on Si.