-
Zach Fredin authoredZach Fredin authored
Pulse Oximetry
Pulse oximetry devices use several LEDs to measure pulse rate and blood oxygen content. The LEDs are tuned to specific wavelengths corresponding to the absorbance bands of oxygenated and reduced hemoglobin; by cycling through the LEDs rapidly the device compensates for skin differences and ambient light, returning saturation and pulse rate.
This project examines the practicality of a fabricatable pulse oximeter. A variety of approaches will be considered, but preference is given to designs that are not dependent on manufacturer-specific sensors and proprietary algorithms.
Status
An initial prototype apparatus has been fabricated and compared with a commercial version:
The apparatus uses an OpenMV board to watch the commercial device's display and exports the data over UART to the Teensy datalogger. Here is an SpO2 log while holding my breath, showing a dip from 99% down to 91% over the course of a ~minute:
The apparatus also records raw analog sensor data from the commercial pulse oximeter, and compares it to data from the fabricated sensor. Here is a close-up of these two curves:
