Senior Project Week 9

Last weekend marked the assembly of the AED circuit in its entirety. An image of the circuit has been reproduced below. The objectives for this week include coding the relay (intermediary circuit in the middle of the breadboard) to follow commands from the Arduino (the circuit below). For the purposes of testing the functionality of the components, both the Arduino and relay were replaced with a wire that was physically operated.

The initial testing began with connecting a 9V battery to the socket, which in turn charged the capacitor. Using a voltmeter, I measured the charge across the capacitor. Initially, our results yielded 0.5 V, which wasn't enough energy to power the LED. After two-three minutes, the capacitor reached a potential difference of 8V, which after connecting the AED briefly lit the LED.

The testing of the Arduino has brought another investigative question to the table. Since the battery source we are using (the 9V battery) is supposed to be representative of an actual lithium ion battery in a smartphone (which averages around 3.7-4.2V), the question of how fast to charge and discharge the capacitor to produce meaningful shocks comes into play. Normal AEDs use a much bigger energy source and hold a network of several capacitors to provide simultaneous current. Technology being the hindering factor, as smartphones do not yet have the 5kV power required, I hypothesize that one could use an amplifier or transformer to potentially increase the voltage. Implementation of such technology, however, is beyond the scope of the project and serves as a stimulus for further research.