I am 16 years old and am absolutely certain that I want to be an engineer. I have an uncontrollable love for machines and so I decided to come to blue stamp, a great place to further explore my passion!
This week, I want to be a biotech engineer, so I chose to make a pulse sensor. I’ve had some experience with making circuits and soldering and so was able to move straight to my main project. In the package I ordered there was one pulse sensor, an OLED (an LED screen), and a couple other material things that would help me hold up my project. Basically, you would need to hold the sensor to some area on your skin where your pulse can be felt. The sensor measures your pulse and displays it on LEDs.
Start Off- Day One:
First I had to attach the pulse sensor to the Arduino and wire it in correctly. I was using the Arduino Leonardo and was having difficulty uploading the code of the sensor on the Arduino. Also, the heart beat could not be seen physically, so it was hard to tell whether the sensor was actually picking up my heart beat.
I switched to an Arduino Uno, and strange enough the code uploaded right on to it, no problem. I also decided to attach a couple of LEDs to the Arduino- the LEDs would pick up the reading of the pulse and would light up accordingly.
This sensor is a light sensor, which also has a sensor that measures the bounce back of light- when you put the sensor to your skin, the light is sent to your skin, and when there is blood there, is absorbs the light, but when there isn’t too much blood, the light bounces back. Therefore the sensor can sense a person’s pulse.
The sensor picks up a lot of movement because it continues to remain on when the Arduino is connected to the computer. So the lights keep blinking by themselves.
Now that the actual sensor is working, I need to attach an OLED that would numerically display the actual heart rate on the screen.
I found the code necessary to connect the OLED to the Arduino, however the screen was displaying animations rather than text. I had to remove all of the excess “setup” commands so that only text would show up the way I wanted. The OLED screen and the pulse sensor couldn’t work at the same time though, so I had to incorporate the code of the OLED into the code of the pulse sensor. There were a lot of issues however, for example the correct data was not being displayed on the OLED screen.
After that was fixed, the basic project was done, but there is no practical use of this project unless the numbers have a relative meaning. I want to let people know if there heartbeat is on par, too high, or too low, according to their age. Before creating the final box and hardware I would have to do that. Also, I would need to make a way for the user to input his or her age without me having to carry my laptop around (again, not so practical).
Today I would start the modification of my project. I had to learn a little more about coding than I already did (which wasn’t much) in order to understand how to make my project work.
First I wanted to make a way to allow the user to input his age into the system. With the help of my instructors, we decided that using three buttons controlled to have certain outputs would work best. We put put an “average” age, for example 30, and then have one button that when pressed would increase the number by one (so, 30 and then pressed becomes 31, and then 32 and so on so forth). That would be for those above the age of 30. The second button would be used for decreasing the age by one each time (so, 30 and then pressed becomes 29, and then 28 and so on so forth). The third button would be pressed when you’ve reached your current age and would like to move to the next step.
Just by doing this however, will not make this more practical (the users should already know their age without having to input it on the system). Now I had to do something to connect the age of the user to their heart rate. I decided to show the user whether their heart rate was slower than the average heart rate of people their age, similar, or higher. I will use an RGB LED to show them this. If the blue light shines then their heart rate is slower than the average rate, if its green its “good to go”, and if the red light shines then its too fast and unhealthy.
Both of these modifications need a lot of coding, so after I finish wiring I should be able to code everything. As my final project I would like to make the entire jumble of wires look more neat. So I would make a box in which I could put the Arduino, the OLED, and all of my LEDs, which are currently connected through a breadboard. I would be required to completely transfer all my connections to a “Perf Board” to make it better and neater. This box would also allow me to carry my project around more efficiently.