It is always nice to see stuff you have been involved in pop up in the wild.
A couple of years ago I developed a method for swept frequency capacitance analysis for Arduino. The system was inspired by Disney Research Touché which uses a somewhat more advanced hardware. My colleague Mads Høbye challenged me to make a version that would be simple to implement on Arduino. Mads then added gesture analysis functionality (for processing) and made a Instructable describing how to build and use the system.
Over the years I have been delighted to see a few applications of the system by others as well as some further developments. To mention a few:
David Mellis Usage examples
Philipp Schmitt Usage
Tore Knudsen (et al) Pour reception
Nick Arner Talking to plants
First experiments before implementing on Arduino:
The effect shown in the video is something I had noticed earlier when working with Tesla Coils. The resonance frequency of a coil/electrode system is greatly affected by nearby people and objects.
Originally it was thought that the frequencies needed for the analysis could not be generated by the humble Arduino. While working with some other projects I realized that they indeed could.
At the end og the day it is very motivating to make something that gives a broad range of users access to new inventions.