Pneumatic control is a very useful technique, enabling a potentially massive amount of force to be placed on an object in a short amount of time. Pneumatics is generally used as an output method, not for sensing or user input. Recently, however, researchers in Denmark and Belgium have come up with a way to detect up to 12 input points using changes in air pressure.
The approach is ingeniously simple, embedding a 3D-printed figure with a series of pressurized tubes and differently sized air holes that are touched for sensing duties. AirTouch also uses pre-trained machine learning models to identify interactions with the fabricated objects, therefore no calibration is necessary once printing is complete. This allows the 3D-printed item to be made instantly responsive with no electronics directly attached whatsoever. As outlets are covered, the inlet air pressure changes, giving it the ability to differentiate between up to a dozen points based on distinct pressure signatures.
The system uses a Panasonic PS-A barometric sensor to pick up touches and an Arduino Uno to sample pressure readings at 5 kHz. The objects were printed on a Form 2 STL printer, as FDM machines aren’t up to the task of precisely creating the needed tiny holes in arbitrary orientations. The length of the tubes does affect pressure results, which is quite small when compared to the effect of different diameters.
Applications for such technology could be “manifold” and researchers have tested the method on an interactive bar chart, interactive animal figures, a grasp-sensing sphere, and even a 12-point circular hue selector. You can see a short demo in the video below, while the full research paper for the project is available here.