Welcome back y’all! I have completed my seventh week in Nairobi and have been making progress on my Medevice project slowly but surely. This past week, a short week for me due to a long weekend trip, I have continued testing my breadboarded circuits and my Arduino code. I have implemented a tentative algorithm for calculating SpO2, but because my circuits still need refinement, the calculated SpO2 values are not accurate so far. I was struggling the most with wiring the photodiode because the optical filter the first photodiode had was throwing off the values, so it was difficult to confirm whether or not I was wiring it correctly based off of the voltage readings. I was finally able to get a new photodiode on Thursday, which seems to not have the optical filter (although it also did not have a part number listed with it, so I couldn’t confirm if it had the same specs as the one I requested), so I have switched to using the new one and the results seem better so far. I have also been trying to add the analog filters and additional amplification to my circuit as well. Prototyping the pulse oximeter has been challenging due to part limitations and equipment limitations–I have no oscilloscope or function generator, just a multimeter and the Arduino IDE, so validating the circuit design has been slow, but I am excited to continue making progress this upcoming week and hopefully have my breadboard working correctly.
This weekend, I took my first multi-day trip with Colin and Katherine. We traveled to Diani Beach via the Standard Gauge Railway (SGR) train. SGR operates daily trains from Nairobi to Mombasa and Mombasa to Nairobi at 8am, 3pm, and 10pm. The train stations operate very similarly to airports, with multiple security checkpoints, a waiting area with restrooms and restaurants, and a boarding time 30 minutes prior to departure. We took the 8am train, which makes several stops along the route, on Friday. The ride was a long 6 hours without AC and with the sun shining directly at me through the window, but I got to enjoy the views across the Kenyan countryside as I read a book that Colin lent me. From the station in Mombasa, it was about an hour drive to reach our airbnb in Diani. Our return trip was at 3pm on Sunday, which somehow felt longer even though the 3pm express train does not make all the stops that the morning train does. We started the return trip at 12pm with our airbnb pickup and did not arrive back at our Nairobi apartment until 9:30pm. Overall, the train was a very cost effective method of reaching Mombasa, 1500 shillings or about 12 USD each way, but you do get what you pay for as far as comfort.
While the process of getting to and from Diani was a bit rough, our time at the beach was incredible! Diani Beach has gorgeous white sands and turquoise waters that we enjoyed many hours of. We arrived to our airbnb around 4pm on Friday. Our travel package included the transportation, lodging, and meals, so our chef, Sue, was preparing our lunch when we arrived. We had stew, chapati, and vegetables; the rest of our meals were similar. We got to spend a couple hours at the public beach near our airbnb that evening and had the beach mostly to ourselves although there were still people out trying to sell us coconut water and boat rides. The waves at that beach were large and rough–I lost my goggles 5 minutes in to wearing them–so the next day we decided to go further South and buy a resort day pass to access part of the beach with calmer waters. For only $2 we were able to use the lounge chairs and not have to worry about leaving our stuff out along the beach while we swam. We arrived around 11am during low tide when the waves were nonexistent, the water was clear, and the walk from our chairs to the water was quite far. At low tide, it is easy to swim to the areas of water with lots of plants, rocks, coral, and sea urchins, so we spent a lot of time swimming and trying to look for fish. As the day went on, the tide began to get higher and higher, and the waves eventually reached the point where they were almost touching the edge of the resort lawn. The waves also got larger and more rough, so we got to swim and body surf without worry of touching the bottom or stepping on any sea urchins. We left around sunset and instead of ubering back, we took a tuk tuk, a small three-wheeled vehicle where the driver sits in the single open air seat in the front and the back seat is enclosed and can squeeze three people across. In the morning, we woke up at 6am to see the sunrise and enjoy a morning swim before breakfast, and while the sunrise itself was a bit lackluster, the rainbow that arrived around 7am made up for it. Diani was amazing, and I’m looking forward to making the most of my last 4 weeks in Nairobi!