A small art project controlled by someone's heartbeat.
Using an AD8232, an Arduino estimates the moment of each heartbeat. This is fed to a raspberry pi which triggers each outward pulse. These pulses flow outward, eventually rippling back in toward the "heart". When they come back, each of them has a chance to drag in a small particle, which will be pushed and pulled by the currents triggered by the user's heartbeat. If these particles are either pulled in to the center or pushed out past the edge of the lights, they trigger a change in the colors used for the heartbeat waves.