While constructing this circuit, we had to create a single capacitor plate which we could plug into CCustom . We decided, for the purposes of ensuring our circuit design operated as expected, that we would use a single copper-zinc penny as the plate, soldered to a single cord. With this design, we were able to accurately create a touch-sensitive capacitance sensor. Our testing also revealed a needed change in our resistor values. The higher value resistors lead to more sensitive readings, with the tradeoff of higher read times. Fortunately, the read times for the level of capacitance sensing which we desired were already at ~1 ms, allowing us to adjust the resistors as needed. We ended on a 1MΩ for our R1, giving us consistent readings across the board for our first iteration. Table 1 displays the data for this sensor when touched over 15 seconds, with a corresponding graph of the data in Fig. 2. An important note is that the units used for capacitance are entirely arbitrary throughout the testing before the conclusion and final device design.
The code used to run the capacitance sensor on the Arduino was not of our own design, as capacitance sensing is a common task for Arduinos. We used starter code from the Arduino website, which we edited slightly to meet our needs. The first major edit was using pulse width modulation to visualize the capacitance with a single green LED. This was original to give an idea of when the capacitor was being overloaded and proved to be a fairly useful tool for testing. The circuit with the LED is included in Fig. 3. The code was lost as we moved past using the LED in our circuit.