Tiny Sensor to Precisely and Discreetly Control Mobile On-Body Devices

Mobile end-user devices, such as the latest version of the “Apple Watch”, have a downside: their small screen size makes them hard to use. Computer Scientists at Saarland University have recently created an alternative, which they refer to as “DeformWear”.

A miniature switch, no bigger than the head of a pin, is fabricated into a ring for instance, and worn on the body. It can be moved in all directions, pinched, pressed and pushed toward the left, right, up and down.

The Saarbrücken researchers’ prototypes can be controlled precisely and discreetly using minimal movements.

With mobile devices such as the smartwatch, the interactive screens are so small that only a few control commands can be triggered by individual touches.

Jürgen Steimle, Professor of Human-computer Interaction, Saarland University

With his research team in the Cluster of Excellence “Multimodal Computing and Interaction,” he is seeking new ways to work small body-worn mobile devices as quickly and discreetly as possible. In a previous research project, Steimle, along with his colleague Martin Weigel, already demonstrated that human skin can also function as an input device. During this research, the idea for the present project dawned on him.

We found out that our study participants did not just use the already-known smartphone gestures on their skin, but also pushed it to the side or even pinched it with two fingers, in order to control mobile devices.

Martin Weigel

Additional investigations led to a sensor that was essentially envisioned to make robot hands more sensitive. “Although the sensor was developed for robotics, we found its small form factor promising for body-worn mobile devices,” explains Weigel. The small form factor, in this case, describes a sensor that has a diameter of just 10 mm – roughly the size of a pea – and that can be deformed like a balloon. From within, an infrared light-emitting diode illuminates the deformable membrane. Four photodiodes are used to measure the light that is reflected. These measurements can then be used to analyze how the sensor is being deformed.

To test their idea, the team incorporated this sensor into a bracelet, a ring and a charm, which was barely larger than a 50 cent piece. The challenge was to create gestures and apply them to control mobile devices. The Researchers did this for virtual reality glasses and for a smartwatch. They also described motion sequences to play music and to control a television without having to look at the device. The Saarbrücken Computer Scientists then had 24 people test these, a total of 18,141 times. Their results are flawless.

Despite the tiny surface, the interactions are precise and expressive, since they make use of the fine motor control of the fingertips and of the three primitives pressing, pushing, and pinching.

Martin Weigel

Professor Jürgen Steimle is convinced that, “when only a tiny sensor needs to be deformed for input, mobile devices can be worn at places on the body that enable quick and discreet input. This will help the industry bring even smaller control devices to the market.”

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