NC State Turns Forearm Into Smartwatch Trackpad
Researchers at North Carolina State University presented EpiPad, a wristband radar system that lets users control a smartwatch by touching their own skin.
Updated on Nov. 10, 2026 in Consumer Electronics
North Carolina State University researchers developed EpiPad, a technology that turns a smartwatch user's forearm into a trackpad. The work was presented at the UbiComp/ISWC conference in Shanghai on Oct. 13-15 and published in the Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies.
Why it matters
Smartwatch screens are too small for the touch interactions people use on phones and laptops. The researchers suggest the wearer's skin could serve as a larger touch surface for future smartwatches and screenless wearables.
The prototype uses a compact millimeter-wave radar sensor array of about 5 by 4 millimeters that costs less than $10 and needs under four minutes of calibration per new user. Testing involved 20 participants, and the study does not report results beyond that proof-of-concept group.
The players
North Carolina State University
A public research university in Raleigh, North Carolina, whose researchers developed the EpiPad technology.
The details
EpiPad uses a radar system worn on a wristband to track finger movement on the forearm and measure the pressure of finger presses on the skin, enabling force-touch input. The existing prototype resembles a wristband with a circuit board attached, and a short set of standard actions lets the system adapt to each new user.
Timeline
Oct. 13-15: UbiComp/ISWC conference held in Shanghai, where EpiPad was presented.
The Tech Race
EpiPad extends the wearable-input research presented at the ACM UbiComp/ISWC conference by proposing the skin as an interaction surface for smartwatches. It positions skin-based input as an alternative to shrinking screens as device makers compete on wearable interfaces.
If the skin-input approach reaches commercial devices, smartwatch users could control their watches without tapping a tiny screen. The technology remains a research prototype, so no consumer product or pricing has been announced.
The takeaway
Wearable input is shifting toward the body itself, and the research suggests that cheap radar sensors could make skin-based controls practical for everyday devices. Readers interested in smartwatch controls should watch whether this approach moves from prototype to product.
Further reading
For more on device interfaces, see Consumer Electronics coverage across the wearable market.
