You guy’s are correct the energy density of those chips is extreme low and probably not enough to power anything long enough to collect data. The MAX30003CWV+T as analog front end is very need. I experimented around with those devises somewhat and it delivers usable results with astonishing primitive conditions. Two electrodes the size of a dime about two inch apart are enough to get usable results and the heart rate detection is already build in which means one don’t need to waste time with implementing it into the μController. Now, I’m not sure how implanted electrodes will work with it, but it only can get better.