Sameen Yusuf is a junior honors student at Mason, majoring in bioengineering. This summer, she is participating in the Engineering World Health’s Summer Institute in Nicaragua. She is also receiving funding from OSCAR's Undergraduate Research Scholars Program to continue her design project for a low-cost oxygen analyzer using zinc-air batteries. Here's a snapshot of her experience so far.
June 7, 2015
Last week we worked on building a variable power supply, and though it was one of the most frustrating labs we’ve done this month, I think it’s been the most beneficial. We built a circuit including a variable resistor and a transformer so that if we find ourselves in the hospital with a piece of equipment that can only use DC voltage, we can convert the AC voltage from wall sockets to the necessary DC voltage (ranging from 2 V – 25 V approximately). I think the most frustrating part was just fitting/laying everything out on the perf board correctly, along with soldering the parts down correctly. My partner and I ended up shorting our circuit the first time…lots of sparks to say the least!
Here are some pictures of the hospital equipment I've helped repair as a part of the Institute. First is the neonatal vital signs monitor we worked on. We didn't actually fix the monitor itself, but I worked on replacing parts of the pulse oximeter and I got to see the NICU too! Didn't get to take pictures but was still awesome to see the inside of the unit (interesting how patient confidentiality/privacy is nonexistent here).
|Neonatal vital signs monitor|
|Incubator temperature alarm|
The second is of an incubator temperature alarm; we used a PIC microcontroller to make a standalone alarm. While calibrating it, a group tried placing it in a ziplock bag and then in the hot coffee pot to get a warmer temperature measurement, let's just say the ziplock bag wasn't coffee-proof...but somehow it was still working which was pretty cool.
|Developing world "lab"|
This is my developing-world "lab." I ran the experiment for the effect of temperature on the battery's accuracy in measuring O2 at atmospheric concentration 8 times now -- turns out my hypothesis was wrong: fluctuation up to 5 degrees +/- the room temperature has not made a difference in the measurements. At 26 degrees C the voltage was .31 V from the battery (which is what it normally is at 20% Concentration). It was the same for 24 degrees C, 28 degreesC, 30 degrees C, 33 degrees C and 35 degrees C (I did these particular numbers by using the hand warmers in a container but instead did not seal it airtight). I'm going to try to get some ice and boiling water for tomorrow to get a wider temperature gradient but overall I'm coming to the conclusion that my original hypothesis was wrong. Now the analyzer happens to have a temperature component, which I think makes it useful for verifying other respiratory equipment (nebulizers, ventilators, neonatal incubators, etc).
A point of hope: I haven't yet seen oxygen concentrators at the hospital's we've visited so far. However, I spoke to our on the ground coordinator and she said that if I do find concentrators at my hospital in Jinotega I can talk to my technician about using it/open it up and see what's going on inside/possibly running a couple experiments using it. I'm REALLY hoping they have at least one that's broken so I can try repairing one but that'll be a long shot. Luckily my Spanish has improved significantly and since my partner speaks fluently, I think I may have a chance at convincing the technical staff!
|Problem solving in the field|
This past weekend, a huge group of us visited the treehouse hostel, which is about 30 minutes away from central park in Granada. Two pick up trucks came by to get a group of 24 of us, and we had about 8 people sitting in the back for each. The ride was pretty fun since it started raining half way there! Once we got there, it was super dark and we didn’t realize how much hiking (or as we say, subrir-ing), we would be doing just to get around the hostel grounds. To summarize, though I didn’t sleep a wink, spending a few hours in a hammock in the middle of a jungle with monkeys for the night was an adventure itself.
Follow Sameen on her journey in Nicaragua by reading her blog.