The term brain-computer interface is well known among engineers, tinkerers, and specifically among researchers. Companies like BackYard Brains made it accessible for all at a relatively affordable price, with their initiative of neuroscience for all. The price of their device and the ease of usability it comes with is pretty good for a school student who's just looking for an introduction to neuroscience but, the resolution of Arduino's ADC (10bit) doesn't allow it to be used for any real neuroscience research project. The company called OpenBCI also creates some good hardware for Biopotential amplification (4/8ch 24bit) and their hardware is much more capable but, it's very costly and certainly not for everybody.
As an engineer myself, I believe we can create much cheaper hardware for Brain-Computer interface devices than currently available in the market without losing any signal quality. I have started working on some prototypes already and one of the devices is called BioAmp v1.5 (github.com/upsidedownlabs/udlabsBioAmpv1.5) which takes benefit of the already available high-resolution ADC input of your computer which is normally used to record audio. The device basically converts the muscle into an audio source and provides us with the option to directly listen to it using earphones OR to visualize/record the signal on our mobile/laptop using Audacity/BYB Spike Recorder.
Speakers: Deepak Khatri