Week four: July 1, 2016
Lucas Gutembergue da Costa
void OptocoUpdate(){
During this week I spent most of my time working on the Optoco with my team and we were able to accomplish a lot.
On Monday we worked on the code that will run on the Arduino to detect the contraction. It took a lot of work from all members of the team but we did in one day. By the end of Monday the Arduino was able to count the contractions, monitor the interval and duration of those contractions and record these values. We also had 3 alarm LED that light up if critical conditions (given by the Malawian hospital staff) occur.
The next step was to make our prototype smaller to be able to tape it on someone’s belly and test the response of the device. So we laser cut smaller box, cut shorter pieces of fiber optic cable, sewed the fabric elastic and assembled the second medium fidelity prototype. It looks like this:
Fig 1, 2 and 3 – Second (and smaller) prototype with the 3 alarm LEDs
After the prototype was finished we tested its sensitivity, so we made a curve of signal vs displacement as we did with the first prototype. The smaller prototype had a stronger signal and the same behavior as the first one, an inverse squared decrease (y = x^-2) on the signal as the length of the gap increases.
Then we tested the prototype by taping it to a team member’s belly. The tape was able to hold it in place very well but we realized the fiber optic cable and the hypotube that covers the fiber optic cable are very rigid. So we started looking for alternatives, so far we have ordered plastic tube to substitute the metallic hypotube and we are looking for more flexible fiber optic cable.
On Thursday every group gave a presentation covering their design problem and the progress so far. All presentations were very interesting and we could see that every team has made a lot of progress on their design challenge.
After the presentations we started to work on how to display the information for the doctors and nurses, we decided to use a LED matrix to simulate a partogram, basically a bar graph of contractions over time in which the color of the LED corresponds to the duration of the contraction. Then we made the code necessary to use the LED matrix and ordered one LED matrix.
Lastly, the rubber accordion tube we ordered arrived so we started to make another prototype that would use the accordion tube instead of the sewing elastic. We are waiting the glue to dry on this last prototype as I type this now.
Fig 4 – Rubber accordion tube.
Future plans include: making the LED matrix display when it arrives, meeting our client to get feedback and clarify some questions and test the sewing elastic versus the rubber accordion tube.
Have a happy 4th of July and see you next week!
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