device update — february 2018

​Here’s an update on the hardware and some of the software design so far!

Current circuit design: oscillator circuit, amplifier board, filter board

This picture shows the current circuit design. The black box is an oscillator circuit that produces a square wave output; one knob controls the frequency of the wave, and the other controls the amplitude. It produces waves between 10 µV and 3 mV, with frequency between 1 Hz and 80 Hz. In other words, it’s a near-perfect simulation of a human brain.

The output of the circuit gives a filtered, amplified “brain” signal. This is sent to the analog-to-digital converter, which (as the name suggests) digitizes the signal. It can then be graphed on a computer. The signal also undergoes a fast Fourier transform (FFT). This isolates the frequency components of the signal by separating it into different bins.

We wrote some simple code that lit up a red LED if theta waves (4-8 Hz) were detected, or a yellow LED if beta waves (13-30 Hz) were present. It worked beautifully! Although it’s an extremely basic form of neurofeedback, it allows us to show that changes in the signal frequency can create real-time, visual changes.
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The next steps will be to create a more robust, complex form of visual feedback. We will also begin to condense the electronics onto a single chip and create a self-contained wearable device. Stay tuned!