Realization of device for IR head stimulation

Abstract

U ovom radu opisan proces apsorpcije valnih duljina svijetlosti u fotoakceptorima na kojemu se temelji fotobiomodulacija, nabrojane su primjene fotobiomodulacije u medicini općenito, te su objašnjeni načini, istraživanja i moguće primjene fotobiomodulacije mozga. Nadalje, prikazan je komercijalan uređaj za fotobiomodulaciju mozga, te su objašnjeni pojedini parametri koji su krucijalni pri izvođenju pravilnog tretmana fotobiomodulacije. Nakon toga je napravljen dizajn kod kojega su proračunate i odabrane vrijednosti potrebnih elemenata, te je realiziran sklop za generiranje pravokutnog valnog oblika radnog ciklusa od 50% s mogućim odabirom između tri frekvencije modulacije napona i struje napajanja blisko infracrvenih svijetlećih dioda. Realizirani su LED klasteri spajanjem svijetlećih dioda u seriju radi smanjivanja gubitaka i uklanjanja potrebe za prilagodbu napona napajanja, koji su onda spojeni paralelno. Svi su moduli montirani na kacigu „Ultracortex IV“ kao nosivu strukturu, klasteri su pozicionirani na potrebna mjesta iznad željenih dijelova mozga koji se žele stimulirati, a napajanje je realizirano prijenosnim USB napajanjem radi jednostavnosti i lakšeg korištenja. Potom su izvedena mjerenja na dvije osobe pri dva različita stanja mozga, opušteno stanje pri kojem se koristila foto stimulacija od 10 Hz i koncentrirano stanje pri kojem se koristila foto stimulacija od 20 Hz, pri čemu se je mjerio EEG signal mozga prije i tijekom foto stimulacije mozga. Nakon toga su izmjereni EEG signali obrađeni na način da se dobije spektri frekvencija prije i tijekom foto stimulacije čijom usporedbom se došlo do zaključka ukoliko fotobiomodulacija radi smetnje mjerenju EEG signala te ukoliko postoji utjecaj na rad mozga odnosno na spektar EEG signala. Pri čemu se smatra da fotobiomodulacija nije radila smetnje na EEG te je kod jednog ispitanika zapažena značajan utjecaj fotobiomodulacije na spektar EEG signala.This paper describes the process of absorption of wavelengths of light in photo acceptors, on which photo biomodulation is based, lists the applications of photo biomodulation in medicine in general, and explains the methods, studies and possible applications of brain photo biomodulation. Furthermore, a commercial device for brain photo biomodulation is shown, and some parameters that are crucial in performing the proper photo biomodulation treatment are explained. After that, a circuit was designed and the values of the required elements were calculated and selected, circuit for generating a rectangular duty cycle waveform of 50% was realized, with a possible choice between three frequencies of modulating the supply voltage and current for the near-infrared LED-s. LED clusters were implemented by connecting LED-s in series to reduce losses and eliminate the need to adjust the supply voltage, which were then connected in parallel. All modules were mounted on the "Ultracortex IV" helmet as a load-bearing structure, the clusters are positioned in the necessary places above the desired parts of the brain to be stimulated, and the power is provided by using portable USB power because of its simplicity and ease of use. Measurements were made on two persons and were performed with two different brain states, a relaxed condition using 10 Hz photo stimulation and a focused condition using 20 Hz photo stimulation, measuring the brain's EEG signal before and during the brain photo stimulation. Afterwards, the measured EEG signals were processed to obtain the frequency spectrum of before and during photo stimulation, which were compared to conclude if photo biomodulation interferes with the measurement of EEG signals and if there is an effect on brain function through the spectrum of EEG signals. Photo biomodulation was considered not to have interfered with EEG measurement, and a significant effect of photo biomodulation on the frequency spectrum of the EEG signal was observed in one subje