Researchers from North Carolina State University have developed a new technological prototype called EpiPad, which turns the owner's forearm into a touch panel. Thanks to this, smartwatch users can scroll through pages, zoom images, and tap elements without having to touch the device's tiny screen.
How EpiPad works
The system is based on a compact millimeter-wave radar sensor approximately 5 by 4 millimeters in size, which is attached to the wrist in the form of a bracelet. Instead of a conventional touchscreen, the radar tracks finger movements and measures the force of pressure on the forearm skin through changes in reflected signals.
To recognize gestures and interpret input, the scientists developed a special signal processing method based on the phase dynamics of millimeter waves, as well as lightweight machine learning models. Before starting to use it, the user must undergo a short calibration that lasts less than four minutes (3 minutes and 54 seconds).
Testing results
During experiments involving 20 volunteers, the system demonstrated strong results:
In comparative real-time tests (where the usual touchscreen, a cursor based on device tilt, and EpiPad were compared), the researchers' development outperformed other methods in terms of efficiency and number of errors.
Prospects and cost
The current prototype resembles a bracelet with an exposed board, but in the future the components could be integrated into the design of ordinary smartwatches. According to preliminary estimates by the scientists, the cost of the functional components (in particular the radar array) could be less than $10.
The technology also opens up possibilities for controlling screenless devices — for example, smart glasses — allowing the skin to be used as an interactive surface for entering commands without physical buttons or displays. At the same time, the developers note that this is currently a conceptual prototype and a study of a small group of people, not a ready-made commercial product.