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6.131 Final Project
6.131 Final Project
For my final project for 6.131, I built a comprehensive power supply for an end-tidal CO2 measuring system. As an EMT, I see how important it is to have a full picture of a patient's respiratory vital signs, and measuring exhaled CO2 is one of the best ways to assess this.
For this project, I built a flyback converter with a multi-winding transformer that boosted 3V up to 20V and 10V, and then regulated that down to 12V and 5V to power an Arduino, a NDIR CO2 sensor, control circuitry, LCD display, an alarm system, and more. Aside from the Arduino, which I needed for some computing power, I aimed to keep this project as analog as possible.
I used the Gravity DFR Infrared CO2 sensor to measure diluted exhaled CO2, an Arduino Nano, and several ICs to make the electronics. I'm happy to share my work doing the actual engineering of this project- it is helpful to note that the work on pages 59-68 is WRONG! I wanted to show where I went wrong, how I caught it, and how I corrected it, so I included it, but the CORRECT work starts on page 69 in GREEN INK.
Shameless plug that I am a really good documenter of my engineering work. I filled over 200 pages of notebooks with my in-lab work/diagrams/math/to-dos etc this semester, and I think that's a strength of mine.
final131work.pdfmvi_0042.MOVFor the demo, I'm reading exhaled CO2 diluted in room air (as opposed to CO2 directly deposited into a nasal cannula, for example). This is also in some sense a proof-of-concept- the sensor samples at 2 Hz, which is not fast enough to be clinically significant (as in, enough to show the waveform of CO2 levels changing over the course of a breath).
A narrated walkthrough of my project, graciously filmed by Professor Leeb. Video acquired from the lab computer- all rights go to Prof. Leeb.
A big thank you to those who helped me solve some challenging problems in this project: Professor Leeb, Professor Banzaert, all of the 6.131 TAs and LAs (especially Ian), and EDS (especially Alec). Honorary mention to my wonderful roommate and classmate in .131, lilisun, for making me paranoid (this is a good thing!) and always inspired to grind harder.
IMG_0321.MOVA silent video walkthrough of my project (captured mostly for my own sanity and less for explanation).
Me, during the fever pitch of this project :P
Yayyyyyyy I love EE (repping the 2.678 shirt too!)
Inductor core (aesthetic).
Primary winding of the transformer (2 more windings not shown).
One of many scope shots from this project- this one is looking at the delay in my control circuitry, hitting just perfectly around 1us.
Bench 22, where I definitely spent more time this semester than sleeping.
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