A standard smartwatch packs its functions onto a small round face that stays fixed in place all day, yet Ping-Jhao Hsu and Shan-Yuan Teng at National Taiwan University have added a mechanical tentacle that stays coiled underneath until the moment it is needed. Their prototype, shown as a demo at UIST 2026 under the name Augmenting Smartwatch with a Rollable Tentacle, keeps the entire assembly inside a 50 mm rounded casing that matches the watch diameter.
One of three continuous rotation servo motors propels the tentacle out through a gear system, and in less than a second, its length can reach 90mm. The tentacle’s body is constructed of 3D printed PLA segments, which makes it firm, and the insides are built of a flexible TPU core, so when you tell the other two motors to pull the cables and curl it left or right, it doesn’t just bend out of shape. There’s an ESP32-S3 microcontroller driving the whole show, a 1.28 inch capacitive display put on top, and a compact LiPo battery powering the entire 146.6 gram operation that fits in at 44mm thick.
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When the tentacle is fully extended, it creates a visual signal that is more easier to see out of the corner of your eye than the watch face alone. Its length can display the remaining time on a Pomodoro timer, and its angle can lead you in the right direction when traveling.
You can also use the tentacle to manipulate buttons, with the motors detecting how much force and which direction you’re pushing or tugging on them. This allows you to play Pong with the item, and the motors roll it back and forth to provide some good haptic feedback.
In the demos, the tentacle has done a variety of tasks, such as functioning as an extra finger to grab your coffee cup while leaving your hands free, or tugging a tea bag out of a cup once the timer has gone off. When making phone calls, you can add a physical gesture to the conversation by giving a small wave. Hsu and Teng claim that this is the first independent tentacle they’ve been able to create that folds all the way back in, and that they believe this is only the beginning of incorporating robotics into everyday wearables without having the mechanisms hanging out all the time.
