The shitty prototype I cobbled together worked at first go! Never before has something at this level of complexity (not exactly complicated, but with so many variables that could go wrong) all checked out green.

I hand soldered male headers onto the reflow soldered board and connected it to an Arduino Uno. I ran the sample code from Maxim and lo – The chip shone red (and IR on the phone) and the serial monitor was populated with rows of data showing Red, IR, HR, SpO2!

It was another thing that the data was super noisy – A heart rate variability of 30bpm is just not done. It’s super easy to get data from sensors and be ecstatic, but making that data reflect something physical is the tough part.

Now that I can extract data from the IC, after I figure out a reliable method for housing, I need to start working on getting this data to matlab and start over with Rajbabu’s DSP fundae again. Additionally, I probably should start thinking about making it wireless using a bluetooth serial link to not have the finger/wrist always close to the computer. Something like this might work great!

Thinking about housing – Easiest to probably buy a wooden clip, and place the optical part of the PCB into a hole drilled in. Which side of the finger? Nail or flesh? Does the whole thing need to be covered by a black sleeve? Which of the approved FDA pulse oximeters use reflectance PPG?

Now onwards to make as many boards as I can and start thinking about putting this PCB onto a housing that can be put around the wrist or the finger.