In his final week as an intern at Seoul National University, Alejandro maximized his work time. He stayed until at least 9pm every day, including the final day, in order to finish collecting data from not only the experiment he had been working on over the previous couple of weeks, but also a couple of new electrodeposition experiments in which he modified part of the electrodeposition process to see how it affected the impedance and CSCc of electrodes after electrodeposition. More specifically, he modified the pulse widths of the rectangular pulses used to change electrode impedance and CSCc during electrodeposition. Alejandro ultimately found that iridium oxide electrodeposition increased a CSCc and decrease impedance in targeted electrodes and was able to elaborate on this finding by determining that increasing rectangular pulse width increased the extent to which electrodeposition affected the targeted electrodes and decreasing it did the opposite.
In the case of the neural stimulator circuit that Alejandro assembled on a breadboard, the completed circuit was connected to an Arduino Uno microcontroller, which he programmed to simulate stimulation by light. He achieved this by connecting the photocells to the Uno as inputs and the outputs of the Uno to two pairs of p-channel transistors. The circuit was connected to a power source, and using an oscilloscope, Alejandro was able to confirm that his circuit and program worked correctly; the circuit produced a biphasic pulse with an amplitude of about 1.6 mA (just above the target of 1 mA) which disappeared when the light hitting the photocells was blocked. This means that the circuit, with the help of the Uno, successfully simulated retinal stimulation by light.
Alejandro considered all of these results to be successful; as such, he was content with his work at SNU and was ready to head back home.
Much like the previous week, Alejandro was unable to do much in terms of extracurricular activities during his final full week in Seoul due to the work that still had to be done on his research. He said goodbye to two of his roommates early in the week and focused on wrapping up data collection for his work. After his final day as an SNU intern (during which he had pizza with his labmates), Alejandro ended his incredible summer trip by going to the Namsan Seoul Tower with William. The view, even from below the observation deck, was incredible! Alejandro also scheduled a tour to the famous Demilitarized Zone (DMZ) for his final full day in Korea, but unfortunately he slept through it. With that, the 10-week internship and cultural experience in South Korea was over, and the next day Alejandro returned home, stopping briefly in Hawaii on the way.