Photobiomodulation system under EEG observation
Sergey V. Popov1, Egor V. Ilukov1, 1Saratov State University, Scientific Medical Center, laboratory “Smart Sleep” (Saratov, Russia)
Abstract
The aim of this study was to create a fully autonomous photobiomodulation (PBM) system for the mouse brain during deep sleep. PBM is a promising approach for treating brain disorders, particularly Alzheimer's disease. Recent findings indicate that PBM should be applied during deep sleep to maximize its therapeutic effects. However, no commercial solutions for sleep PBM currently exist. Thus, the objective was to develop a portable PBM technology with electroencephalographic (EEG) control to deliver photo-exposure specifically during the deep sleep stage.
The PBM device is built using commercially available hardware components. The EEG signal is captured by an integrated circuit for digital biopotential measurement, the ADS1293 (Texas Instruments, USA). This ADS1293 chip contains three independent EEG recording channels, each featuring a low-noise instrumental amplifier with programmable gain and a 24-bit delta-sigma analog-to-digital converter. The converter's sampling frequency is 2.4 kHz, with an input range of 1mV and a channel bandwidth of 250 Hz. The biopotential measurement circuit connects to the Atmega328 microcontroller via the SPI (Serial Peripheral Interface). The Atmega328, in turn, communicates with the ESP-01 WI-FI module via the UART interface. The power subsystem of the device includes a Li-ion battery, a step-up voltage stabilizer, and a step-down voltage stabilizer. The boost stabilizer converts 3.4 - 3.7V (depending on the battery charge) into 5V to power the microcontroller, while the step-down stabilizer converts 3.4 - 3.7V to 3.3V to power the WI-FI module and the biopotential measurement circuit. The PBM employs an LED with a wavelength of 1050 nm and an output power of 50 mW, housed in a 2853 SMD package. The LED driver is controlled via pulse width modulation by the microcontroller. The LED is connected to the device with a 0.3 m flexible two-wire cable and is mounted in a miniature 3D-printed frame with two cylindrical magnets, each measuring 3 mm in diameter and 3 mm in height.
Key words: photobiomodulation, electroencephalogram.
Acknowledgements: The research was supported by the Russian Science Foundation (project No. 23-75-30001).
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Sergey
Saratov State University, Scientific Medical Center, laboratory “Smart Sleep”
Russia
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