In Philadelphia a group of people used Kickstarter to successfully fund the MIDI Sprout, a device capable of turning the biofeedback from a plant into midi that can be set to scales to control your synth.
"This is the beginning of the global DIY biofeedback movement."
How it works
Each MIDI Sprout comes with two probes that measure small electrical currents across the surface of a plant's leaf. When applied to a human this is called the galvanic skin response (GSR). GSR readings provide insight into humans’ inner emotional states and are the basis of simple lie detector circuits.
The MIDI Sprout converts these fluctuations into MIDI notes and controls that can be read by synthesizers and computers. This information can be scaled and played through synthesizers or used to activate pre-programmed sonic environments.
Links
Using MIDI Sprout with Moog Synth; https://www.youtube.com/watch?v=WN833bCXXJk
Kickstarter ; https://www.kickstarter.com/projects/datagarden/midi-sprout-biodata-sonification-device