ENGR337 Lab 2020 Spring
Lab 4 Oximeter
Name: Jesse Duran
Email: JIDuran@fortlewis.edu

1. Oximeter

2. Introduction:
The purpose of this lab was to use an oximeter and amplifers to show our pulse on an oscilloscope as well as blink and LED. The oximeter used an IR led and an IR reader to read the oxygen saturation(SO2) levels of our finger. The SO2 changes as our heat beats. The input and output signals were probed and displayed on the oscilloscope. The same output signal was fed into an Arduino where we used the serial plotter to plot our heat beat.

3. Materials and Methods:

Materials

LED

2x 1NA128PA instrument amplifer

741 Op Amp

4.7uF capacitor

458nF capacitor

68kΩ resistor

100kΩ resistor

3x 1kΩ resistor

1N370 Zener Diode

Breadboard

Jumper Wires

ADC 0-5V

Ardunio Uno

Methods:
We took this signal from the oximeter, ran it through a high pass, low pass, two instrument amplifers and finally a comparitor. At each instrument amp we amplifed the signal 50x. The output signal was probed at the output of the second instrument amp. The output signal was fed into the OpAmp which compared the SO2 singal to the vref proved by the zener diode.
This blunk the led to our heart beat.


4. Results

Figure 1. Filterd and amplifed heatbeat signal and the orignal input.


Video 1. Led blinking to heart beat and Serial plotter of Arduino

5. Discussion
This lab showed the usefullness of amplifying small signals for a pracitcal purpose. This could have implications in medical sciences. Plotting with the Arduino showed how different devices can be used to organize data. The Blinking LED was a fun use of a comparitor again linking what we've been learning in lecture to actual pracitce.