We started this week off by beginning the code for the Optoco device. The eventual goal is that the device can detect contractions and have an LED display that shows how many contractions occur in each 10 minute period and how long each contraction lasts. We also want three warning lights that light up when either of the three conditions that can indicate uterine rupture occur: more than five contractions in ten minutes, a contraction that lasts more than two minutes, or contractions that happen less than 60 seconds apart.
The code generally works by measuring the voltage through the photoresistor which depends on how much light is getting to it from the LED through the fiber optic cable (which decreases when the boxes are pulled apart during a contraction). We set a threshold for the voltage that indicates a contraction is happening (for now we have chosen an arbitrary number to get the code working) and when the voltage goes below the threshold we record the start time and when it returns to above the threshold we record the end time. From this we obtain the duration, frequency, and number of contractions.
By the end of the day Monday, we had the three warning lights working when we manually moved the boxes apart and together. Then on Tuesday we returned to the physical aspect of the design by building a smaller prototype so that we could test taping it to a stomach. We found that the kinesiology tape (like what beach volleyball players often wear) is much more effective than regular athletic tape, but we intended to make some modifications to improve taping.
(this is a table but we did try putting it on my stomach)
Every group did a formal presentation on Thursday so we spent time on Tuesday and Thursday creating the slides and rehearsing the presentation. It was interesting hearing all of the other groups present because I hear snippets of their projects during the day and get overviews at our morning meetings, but it was nice to hear an organized explanation of what was going on. I feel like I can talk to everyone about their projects more effectively now.
After the presentations we returned to thinking about our code for displaying the information we want to make available for doctors. We began looking into LED matrices as a way to have many LEDs while still all fitting into the Arduino board. We continued that discussion today, Friday, and started some of the Arduino code, however we are waiting on an LED matrix display that we ordered. We also began a new prototype that uses a stretchy rubber tube in the middle instead of sewing elastic and we will finish this Tuesday morning.
Happy Fourth of July!