What does the Theremin of the new millennium look like?
In current gestural systems based on ultrasonic distance or optical sensing the breadth and nuance of human interaction is often limited by too simplistic sensing technology. Rebus is a sensing system that uses sophisticated microwave technology to detect both phase and power of an emitted and received electromagnetic wave, allowing new dimensions of interactivity for audiences and expression for performers.

Rebus creates a sensitive space where any subtle interaction is detected independently of external light or sound. When the instrument is turned on, the electromagnetic field transmitted forms an immaterial interface where invisible affordances can be touched and manipulated with the hands and the body. The analogue detected amplitude and phase are then connected to the Bela digital music processor system that can control and manipulate any designed composition.

Rebus can be reminiscent of a Theremin (one of the earliest electronic musical instrument and the first to be played without being touched) and can be programmed to emulate one, but the compositional possibilities and applications of this digital instrument are potentially infinite.

https://research.gold.ac.uk/id/eprint/35996