About SMI

Topic Keywords:

Smart material interfaces, reality-based interfaces, organic user interfaces, programmable matter, smart textiles, interaction design.

About Smart Material Interfaces

Every day we are getting closer to Mark Weiser’s [1] vision of Ubiquitous Computing that motivated researchers to augment everyday objects and environments with computing capabilities to provide Tangible User Interfaces (TUIs) [2], organic interfaces [3] and reality-based [4] interaction possibilities. That is, HCI researchers are developing a wide range of new interfaces that tend to separate from the “window, icon, menu, pointing device” (WIMP).

We can find many different examples of these post-WIMP interaction styles such as: mixed and augmented reality, tangible interaction, ubiquitous and pervasive computing, handheld and mobile interaction, perceptual and affective computing etc. [4]. As mentioned in [4], many of these interaction styles seem to proceed in different and unrelated ways, but they share a common important knowledge. All of these interaction styles try to take advantage on users’ pre-existing knowledge of everyday life. They employ themes of reality such as users’ understanding of naïve physics, their own bodies, the surrounding environment, and other people trying to mimic the real world for making the users more comfortable, creating an interaction more close to what they are used to do already.

To foster and experiment new kinds of interfaces and interaction styles, a vision called Smart Material Interfaces (SMIs) (see e.g. [5], [6]) has been introduced. This vision takes advantage of the latest generation of engineered materials that has special properties defined “smart”. Partly introduced to provide an answer to the limitations present in common Tangible User Interfaces, SMIs try to overcome common pattern of interaction and leave behind the “digital feeling” by a more analogical and continuous space of interaction, tightly coupling digital and physical world by means of the materials’ properties. And not just to copy reality-based patterns, but also to create new possible way to reach the users’ needs and satisfaction.

The technology push of smart materials created a new kind market for innovative materials, available now to the large public. Many different fields already started to create interfaces with these smart materials, creating new way of expression and new languages to communicate with the users.

The main focus of a SMI is being able to make changes in the physical and material properties, creating channels for new input/output modalities. SMI proposes the use of materials that have inherent or “self-augmented” capabilities of changing physical properties such as color, shape and texture, under the control of some external stimulus such as, among other things, electricity, magnetism, light, pressure and temperature.

Examples of SMI

Considerable efforts have been made to explore the possibilities of applying smart materials in interfaces. For example, Surflex [7] consists of a foam with coiled nitinol muscle wires embedded. The muscle wires can be used to reshape the foam into different shapes. This principle has been applied as a way to use SpeakCup [8], a device used to record and replay messages by physically manipulating its shape (shape-changing interfaces [8]). Another suggested application of Surflex is as a form of physical computer- aided design. Indeed, Parkes and Ishii [9] presented just such a design tool for motion prototyping and form finding, named Bosu. Bosu consists of a number of flexible modules that can be physically manipulated (e.g. bending, twisting). The physical manipulations can then be played back thanks to nitinol muscle wires embedded in the modules. Smart materials have been used in the creation of novel ambient displays. Shutters [10]) is a curtain with a grid of shutters that are actuated by nitinol wires. Shutters can be used to regulate the amount of light and air flow that enters a room, as well as serves as an ambient display by creating patterns using the grid of shutters. An ambient display that aims for a more tangible experience is Lumen [11]. A grid of cylindrical physical pixels is actuated to move up and down, using nitinol wires. The physical pixels contain LED’s that allow Lumen to display animations both visually, and physically. While nitinol is by far the most widely applied smart material, others have used ferro fluids to create physical ambient interfaces as well as thermo-chromic materials. WeMe [12] for example, is an ambient display that visualizes the presence of members of remote families represented by bubbles of ferro fluid. Another display that makes use of magnetic fluids is Programmables Blobs [15] by Wakita, that try to force the blobs to change shape using electromagnets. Wakita [13] also notes how in design the materials and colors are felt as part of the emotional communication of the interface. Using the property (in this case colors) of the material directly, their aim is to communicate mood by changing the color of Jello Display-Keyboard using IR-chromic material. Several other examples can be found over arts and design installations, as for example Sachiko Kodama’s artwork with ferro fluid [14].


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  13. Wakita, A., Shibutani, M., and Tsuji, K. Emotional smart materials. In Human-Computer Interaction. Ambient, Ubiquitous and Intelligent Interaction, J. Jacko, Ed., vol. 5612 of Lecture Notes in Computer Science. Springer Berlin / Heidelberg, 2009, 802–805.
  14. Kodama, S. and M. Takeno. Protrude, Flow. Proceedings of SIGGRAPH’2001 Electronic Arts and Animation Catalogue. 2001: ACM: pp. 138.
  15. Wakita, A., Nakano, A.: Programmable blobs: a rheologic interface for organic shape design. In Proceedings of the 5th International Conference on Tangible, Embedded, and Embodied Interaction, TEI ’11, ACM (New York, NY, USA, 2011), 273-276.
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