Keeping track of your basic vital statistics used to involve a trip to the doctor’s office where you would be subjected to expensive equipment that you couldn’t hope to understand. But now, with the rise of modular and kit electronics, you can build some of those devices right on your desk using a microcontroller like Arduino or Raspberry Pi Pico. With the return of winter and the rise of respiratory illness, it might be beneficial to have an easy-to-reach pulse oximeter. Granted, you won’t get medical-level accuracy with your home-built pulse oximeter, but when has perfection ever stood in the way of a good project? (We’ve got quite a few if you’re interested.)