Design and development of a wireless EEG device and open source software

In the last century, EEG has been a diagnostic method used in the detection of many diseases. Today, with the rapid development of computer technologies, EEG technology has begun to be used not only for disease diagnosis but also as a method to establish a connection between the brain and the computer. Humanity has long dreamed of connecting with computers and controlling them efficiently just by thinking without any physical interaction. It seems clear that one of the most suitable methods for this purpose is non-invasive EEG measurements, as it is easy to apply and does not require a medical procedure. This study aims to design a cost-effective and open-source device, to create a prototype, and to test the accuracy and consistency of the resulting device for researchers who want to measure EEG signals and make various researches on them or develop devices that will serve various special purposes. The design and production of the device can be grouped under three main groups; electronics, mechanics, and software parts. In the electronics part; ADS1299, an 8-channel integrated chip that offers low-noise 24-bit analog-to-digital conversion resolution, produced by Texas instrument company, which is currently used in many EEG devices, ESP32-WROOM microcontroller, which controls this integrated chip, reads, processes and transfers the data to the computer via Bluetooth communication, provides power to the system. 2 18650 Li-po 3.7 volt batteries and battery control system and dry type electrode produced by OpenBCI Company were used as the electrode. In the mechanical part, a cap was designed inspired by the Ultracortex Mark III and Ultracortex Mark IV cap of OpenBCI Company, and boxes providing enclosures for the produced circuits were designed and all of them were manufactured using a 3D printer. In the software part; there is embedded software written in C language on the chip that runs on the device, receives the data, processes it, and sends it to the computer. In addition, a Visual user interface that works on the computer side, receives and processes the data sent by the device, displays them in graphics, and saves them to a file, has been designed and coded in C# using Visual Studio. After the prototype of the device was revealed, the signals received from the device were examined and their consistency was evaluated. Keywords: eeg, visual stimulation, esp32, ads1299, dry electrode