CHAPTER 4

Capacitive Touch Grid

EXPERIMENT 4.1

Process: Explored the MPR121 sensor to detect skin contact without pressure. Created multiple touch zones on a non-conductive surface.

Construction: The prototype grid used copper tape wired to the breakout board, creating a dense matrix of touch zones.

Conclusion: Technically difficult. Custom wiring and capacitive sensitivity led to high noise and unstable data. The concept is strong, but execution requires refinement for reliability.

Copper Tape Grid

EXPERIMENT 4.2

Pivot: Shifted to Piezo sensors, which detect vibration and physical impact. Unlike buttons, Piezo outputs a continuous analog value proportional to hit force.

Calibration: Tested resistor values to "tune" the sensor. High resistance = noise; low resistance = dead signal.

Piezo Sensor

Results: Discovered that a 10M ohm resistor was the perfect solution. It maximized voltage reading while keeping the signal clean, allowing detection of subtle vibrations.