The Postman Always Taps Twice

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How would you like to tap your wrist to engage the clock embedded in the OLED wall? Rub your fingers together to request a text message with your bank account’s balance? Or rub your ear to have the speaker phone in the center of the table adjust the volume?

The Hasso Plattner Institute out of Potsdam, Germany recently published a paper on Disappearing Mobile Devices. The paper does not attempt to act as a proof of concept but instead outlines the possibilities of interactions with mobile devices as technology becomes smaller and embedded into the very fabric of our lives, whether it be our buildings, our clothing, or ourselves.

A brief history of mobile devices

Focus has changed over the last few decades from the development of Notebook computers to PDAs and mobile smart devices to wearable technology and gestural interfaces. Wearable technology is starting to pick up momentum with niche items like the Bluetooth headset that doubles as a ring (scheduled to be available early in 2010). Likewise, gestural interfaces have received acclaim in the media—thanks to the box office success of movies like Minority Report—and have begun receiving more attention in the IxD field itself as books like Dan Saffer’s Designing Gestural Interfaces have become available.


By focusing on how a user interacts with a device over what the device looks like, Ni and Baudisch outline three main interactions that disappearing mobile devices could make possible. These are:

  1. Touch Scanner
  2. Motion Scanner
  3. Directon Scanner

The image below illustrates some of the key factors that differentiate each scanner type.

Types of Scanners

  • On a high level, touch scanners can sense if the device is being touched by an input device or if any input device is out of range. This simplifies to binary input of On/Off. While this is not a practical method of inputting long streams of data such as text, this allows simple switches to be engaged and simple combinations, such as two long taps followed by one short tap, to allow slightly more complex actions.
  • Motion sensors are one step more advanced than touch scanners, where a touch and motion sensor work in union. Rather than simply measure On/Off, motion scanners can also detect general direction. Complex interaction such as drafting text it still limited with motion scanners but the technology would allow scrolling through a list or setting a dimmer switch with more ease than a simple touch scanner.
  • Still more complex, direction scanners employ three non-linear touch sensors. With this triangle pattern, the technology can sense more complex shapes and gestures. This allows for not only the capabilities of touch and motion scanners but allows with more ease complex data input such as shapes and basic text.

Possible applications include embedding sensors under a person’s skin for text input and signalling different applications within an environment. Studies performed by the authors investigated opportunities of using Graffiti style of input methods with various degrees of success. Implications surrounding the dexterity of individuals, memory of a purely gestural system, and tiny finger constraints are just a few breakdowns of this new technology. Still, the studies performed outline a lot of potential for where embedded sensors and interfaces can move on both a personal and a social level.


Amy and Dr.Peter Elliot (Dylan Walsh), Congo, 1995

Amy and Dr.Peter Elliot (Dylan Walsh), Congo, 1995

Think back to the 1995 movie Congo and the backpack the gorilla Amy wore to sign to the human cast. Now imagine the same technology with embedded sensors: no more heavy backpack or intrusive technology reminding others of a physical limitation. On a more casual level, imagine your public transit pass being embedded into your fingertip. No more fumbling for a metro card, taking off gloves to get into your pocket; instead, you could simply swipe your finger over the scanner as you hurried to catch your train.

While we won’t see this technology implemented at our local grocery store just yet, it is interesting to see how the simple models outlined by the authors can open the doors to new interactions and technologies in a more natural and social manner than mobile devices presently allow.

Image from Disappearing Devices

David Farkas

David is an interaction(s) designer working in the online and mobile realm. He focuses on the relation between the digital and the physical. Usability, goal oriented design, and consistency are key.

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