Hi y’all! Another Monday, another blog post from Nairobi, Kenya! This past week at Medevice, I was finally able to order the parts for my pulse oximeter prototype, and they are expected to arrive today (fingers crossed). I have also been working on writing the Arduino code for the pulse oximeter that will be needed to implement the necessary hardware functions. To summarize, the microcontroller will need to flash two LEDs on and off at a controlled rate, convert the analog signals generated by the photodiode into digital signals that can be processed by the microcontroller, differentiate between the red and infrared signals when collecting data, split these signals into their AC (variable) and DC (constant) components, use the processed signals to calculate SpO2 (% oxygen saturation), and display the final SpO2 measurement on the LCD screen. While I have worked with microcontrollers before, I haven’t used Arduino much, so I have gotten to learn a lot about how to structure the code to perform these functions. Since my parts haven’t arrived yet, I haven’t been able to upload the code to a real Arduino, but I have used TinkerCAD to create a simulated Arduino and circuits where I was able to test the functionality of some parts of my code. I’m looking forward to building and testing my physical prototype this week!
Outside of work, my roommates and I had to navigate a difficult challenge this week: trying to set up an Mpesa account. Mpesa is the mobile money transfer app commonly used as a payment method in Kenya. It is so widespread in Kenya that many businesses actually don’t accept payments by debit/credit card and instead force you to pay via Mpesa. However, to create an Mpesa account, you need a Kenyan SIM card and phone number, and you cannot simply transfer money from an American bank account to an Mpesa account. We wanted to book an all-inclusive travel package to visit Diani beach in a couple weeks, but since it is intended for Kenyan residents, we had to find a way to set up an Mpesa account. We first tried to use an app called Wise that would allow you to transfer money from the U.S. to Kenya, but it had high fees and would have taken too long to complete the transfer (we didn’t want the beach package to no longer be available). Next, we discovered you could use your passport to get a Safaricom eSIM and Mpesa account. Colin and I went to the mall to try this on Thursday, but he couldn’t get an eSIM because his phone was locked by his carrier. We tried to install it on my phone instead, but the eSIM system was down and the installation couldn’t be completed, so we had to return the next day. Friday afternoon, we go back to the mall, and the system is still down, so we try another mall instead. At this mall, after being helped by four different workers, I was finally able to install the eSIM, but the Mpesa system was down at this mall, so we had to return again the next day. Saturday morning we show up determined to make Mpesa work. We successfully set up the account, but then still can’t just directly transfer money to the account, so we have to find an ATM to withdraw and deposit cash. The first ATM didn’t work. We search the mall for another one. We find one. It works. We go back upstairs to the Safaricom store and deposit the cash to Mpesa. We finally book the beach trip. Great success.
After setting up Mpesa and booking our beach trip, we were finally able to relax for the rest of the weekend. We went to Ngong Hills, a popular park southwest of Nairobi. The 12km trail consisted of seven peaks (hills) and took us a few hours to complete. Luckily, we arrived early enough to not be rushed (the park closes at 6pm) and we had plenty of time to enjoy the 65 degree weather, the expansive views from the peaks of the hills, and the cows and sheeps grazing along the paths. We took a break to have a nice picnic lunch and also got to enjoy fresh oranges from a vendor at the top of the 4th hill. I love physical activity and spending time in the outdoors, so I’m glad we were able to do this hike. The only negative was that the 30km drive from our apartment to the hills took 1.5 hours each way (thanks Nairobi traffic!). On Sunday, I had a relaxing day of waking up at 4am to watch UFC 317, buying groceries, and meal prepping for the week.