C = εr ε0 (A/d)
This demo shows capacitive coupling using water as a variable dielectric (εᵣ ≈ 80). The human body completes the circuit by touching the water, acting as the second conductor with its capacitance to ground. Hand/finger movement changes the effective area A and distance d, while ripples dynamically modulate C.
This varying capacitance alters an oscillator’s frequency, which is converted into audio tones or MIDI in real time.
Educational fluid-based sensors and interactive MIDI controllers for bio-signal acquisition and gesture-controlled music. Ideal for physics demos and human-interface experiments.