This Unique Gesture Sensor Works Through Other Objects

Non-contact gesture sensing is a unique method of interaction and the consumer technology industry has only scratched the surface of its potential. You probably don’t own a single product that integrates that capability, unless you still have something like a Microsoft Kinect kicking around. But the potential is definitely there for anyone with the creativity to make use of the technology — which doesn’t even require expensive Kinect-style cameras. And as Corebb shows in a recent video, it is possible to build an affordable non-contact gesture sensor that can even “see” through objects.

This works similarly to capacitive touch sensing. In fact, you may have experienced the phenomenon yourself if you’ve ever had a capacitive touchpad, touchscreen, or touch button register input before you made physical contact. Manufacturers of those components usually try to tune their sensitivity to prevent such occurrences. The ideal sensitivity for a touchpad, for example, is just enough to register with light contact. But if you use the same basic technology tuned to be very sensitive to electric fields, you can “see” nearby movement. You can even detect the distance from the sensor, enabling 3D gesture sensing. That still works when an object is in the way, so long as the object doesn’t block the electric fields.

In this case, Corebb used a Microchip MGC3130 E-field sensor designed specifically for 3D tracking and gesture control. The MGC3130 comes packaged in a handy 28-pin 5×5mm QFN SMD chip. Using the reference design from Microchip as a starting point, Corebb designed a four-layer PCB to host that chip, its accompanying resistors and capacitors, connectors, and the circuit for creating the necessary electric field.

The MGC3130 communicates through I2C, so Corebb started with an I2C-to-USB converter from Microchip that has official support. With that and Microchip’s GestIC SDK software, Corebb was able to track gestures on his PC. From there, he could use those gestures in other software. In one example, he used two of these gesture sensors to control Minecraft. In another, he made a program to turn gestures into alphanumeric characters, like a non-contact version of the stylus “typing” feature that was on old Palm Pilot PDAs.

But this gesture sensor design doesn’t require an entire computer. Remember, it communicates via I2C. Therefore, it will work with just about any microcontroller on the market and is useful for embedded projects, too. Corebb wrote an example sketch for Arduino-compatible microcontrollers and uploaded that to GitHub so you can get started.