Development of a Gamma Oscillation-Synchronized 40Hz Audiovisual Stimulation Device

Abstract

Based on the neuromodulatory mechanism of gamma oscillations, this study designed a 40 Hz audiovisual intervention device to improve cognitive function in patients with chronic disorders of consciousness. The device delivers synchronized audiovisual stimulation: auditory stimuli are triggered 2 ms after visual stimulus onset, generating 40 Hz steady-state pulses with sound intensity of 60-80 dB and blue light at 472 nm wavelength (0.03 mW/cm²). The hardware incorporates an STM32L1 microcontroller, DAC8830 digital-to-analog converter, MIX3022 audio amplifier, and voltage-controlled constant-current LED driver circuit. Software-controlled PWM dimming and timer interrupts achieve audiovisual synchronization. Integrated within a wearable eye mask, the device features a bone-conduction speaker and lens-focused LED. Testing confirmed precise audiovisual synchronization (2 ms delay) and stable audio waveforms, demonstrating compliance with safety standards and providing a novel non-invasive approach for neurological disorder treatment.