Date of Award

Spring 2026

Document Type

Thesis

Publisher

Santa Clara : Santa Clara University, 2026

Departments

Bioengineering; Electrical Engineering; Electrical and Computer Engineering

First Advisor

Andrew Wolfe

Second Advisor

Julia Scott

Abstract

Concussion is the most common form of traumatic brain injury, and a substantial fraction of those affected develop post-concussion syndrome (PCS), a condition characterized by persistent cognitive, emotional, physical, and sleep symptoms for which no definitive treatment currently exists. Transcranial photobiomodulation (tPBM), the delivery of near-infrared (NIR) light to brain tissue, has shown promise for addressing the metabolic dysfunction that underlies concussion. Still, commercially available tPBM devices rely on fixed, open-loop protocols and do not integrate electroencephalography (EEG), limiting a clinician’s ability to monitor neural biomarkers during treatment. Our team’s objective was to develop a system that utilizes tPBM to deliver NIR to the brain safely, enables the use of a full-cap or in-ear EEG to collect data to verify neural entrainment, and supports a long-term goal of developing a closed-loop EEG/tPBM system. NeuroGen IV is a modular, headband-style tPBM device designed to deliver 1070 nm NIR stimulation to the prefrontal cortex while remaining compatible with concurrent in-ear EEG monitoring. Two LED-panel prototypes were developed to explore a dose-delivery tradeoff: a low-current board (a 6×6 array of 60 mA LEDs) that distributes light broadly, and a high-current board (a 2×2 array of 700 mA LEDs) that concentrates optical power over a smaller area; both are driven with a 10 Hz, 90% duty-cycle pulse intended to induce neural entrainment in the alpha band. The low-current boards were successfully assembled and met all individual safety benchmarks. They emitted an irradiance of 22 mW/cm² and peak skin-contact temperatures below the 40 °C IEC 60601-1 limit. However, the two boards exhibited a persistent ~6 °C temperature difference, which our team determined was not yet safe or repeatable enough for human-subject testing. The high-current board completed the schematic and layout design, but did not produce functional light emission. Because neither in-house prototype met the functional requirements, the device's performance was compared with that of an industry-standard device, the Neuronic LIGHT. Its irradiance was lower than the Neuronic’s irradiance of 26.36 mW/cm² near the ultra-strong LEDs. A pilot study was conducted with the Neuronic device to evaluate the outcome metrics: 10 Hz power spectral density amplitude, working memory, and sustained attention performance. This work delivers a low-profile tPBM form factor, two documented driver architectures, Arduino-controlled stimulation, and EEG compatibility. It identifies the manufacturing-consistency and high-current-driver challenges that future NeuroGen teams must resolve before human studies can proceed.

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