While I was improving and researching, I got to know about 2 OpAmp design which requires only 2 pairs of matched resistors and 2 operational amplifiers.

I used this to create the very first BioAmp EMG Pill at home and it was able to record my muscle signals accurately. Out of curiosity, I tried recording other biopotential signals as well like ECG, EOG, and EEG by configuring the bandpass filters and instrumentation amplifiers and it worked out pretty well. 

Again for this design, the BOM cost was less than ₹100 ($1.25) which will revolutionize the way students and researchers explore the field of neuroscience by making various HCI and BCI projects.

After dozens of prototypes and countless experiments, what started as a project for recording just the muscle signals (EMG) became a BioAmp EXG Pill that was capable of recording all the biopotential signals (ECG, EMG, EOG, EEG). All these designs were prototyped at home with a toner transfer method.