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Pulse oximeters are standard instruments for hospital settings. Using the relative absorbances of oxygenated and deoxygenated hemoglobin, these devices determine the percentage of a patient’s blood that is oxygenated (a healthy range being 94-98%). This figure can be lifesaving in a clinical setting, as a sudden drop in blood oxygenation indicates a critical medical problem that needs addressed immediately.

In this project, we attempt to construct a pulse oximeter using parts that are easy to find online/in a local hardware store. The final product is by no means as accurate as those used in hospitals, but can provide enough information for someone to monitor blood oxygenation over time. The original plan was to make the device fully wearable, but due to factors outside of our control, this wasn’t possible in our timescale. Given a few more components and a bit more time, this project could become completely wearable and communicate wirelessly to an external device.

Essential Parts List - Things you probably need to buy (It is recommended to have a few spare of each component, especially the surface mount pieces)

Arduino Nano $1.89_
Dual-LED - $1.37
Photodiode - $1.67
150 Ohm Resistor - $0.12
180 Ohm Resistor - $0.12
10 kOhm Resistor - $0.10
100 kOhm Resistor - $0.12
47 nF Capacitor - $0.16
(Our Nano is stuck in China at the moment, so we used an Uno, but both will work)

Total Cost: $5.55 (But… we had a bunch of things lying around and bought a few spare parts as well)

Secondary Parts List - Things that were lying around for us, but you might need to buy
Copper Clad Board - Fairly cheap (Example). In place of this, you can make and order a PCB.
PVC - Something at least an inch in diameter. The thinner kind works great.
Wires - Including some jumper wires for the breadboard and some longer ones to connect the oximeter to the board. In step 20 I show my solution to this.
Female Pin Header - These are optional, if you just want to solder wires to the boards it will work just fine.
Foam - I used L200, which is pretty specific. You can really use anything you think will be comfortable. Old mousepads are great for this!
LEDs and Resistors - Pretty cheap if you need to buy them. We used 220Ω resistors and had a few colors lying around.

Recommended Tools and Equipment
Heat Gun
Soldering Iron with a Fine Tip
Dremel Tool with Routing and Cutting bits (You can get by with a utility knife, but not as quickly)
Pliers, Wire cutters, Wire Strippers, etc.”

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