Can there be materials that change shape according to one’s desire? If yes, then you could, for instance, make comfortable chairs and mattresses that never cause bedsores.
Indeed, there are ‘programmable materials’ that adjust themselves to pressure, says the Fraunhofer Cluster of Excellence Programmable Materials, (CPM), Germany. The CPM comprises six core institutes that aim to design and produce programmable materials.
How to programme materials?
“Essentially, there are two key areas where adjustments can be made: the base material — thermoplastic polymers in the case of mattresses and metallic alloys for other applications, including shape memory alloys — and, more specifically, the microstructure,” explains Dr Heiko Andrä, in a press release. “The microstructure of these metamaterials is made up of unit cells that consist of structural elements such as small beams and thin shells.” While the size of each unit cell and its structural elements in conventional cellular materials, like foams, vary randomly, the cells in the programmable materials are also variable — but can be precisely defined or programmed. This programming, for example, can be such that pressure on a particular position will result in specific changes in other regions of the mattress — that is, increase the size of the contact surface and provide optimal support to certain areas of the body.
Materials can also react to temperature or humidity.
The desired change in shape of the material and the stimuli to which it reacts — mechanical stress, heat, moisture or even an electric or magnetic field — can be determined by the choice of material and its microstructure. “The programmable materials allow adapting products to the specific application or person, so that they are more multifunctional than before. As such, they do not need to be swapped as often. It is particularly interesting in the context of material saving and sustainability,” says Franziska Wenz, deputy spokesperson on the topic at the Fraunhofer Institute for Mechanics of Materials IWM, another core institute of Fraunhofer CPM. This can also create added value, whereby products are adapted to individual needs.
A single piece of material can take the place of entire systems of sensors, regulators and actuators. The goal of Fraunhofer CPM is to reduce the complexity of systems by integrating their functionalities into the material and reducing material diversity. “We always have industrial products in mind when developing the programmable materials. As such, we take mass production processes and material fatigue into account, among other things,” says Wenz.
The research team expects that, initially, programmable materials will act as replacements for components in existing systems or find use in special applications such as medical mattresses, comfortable chairs, variable damping shoe soles and protective clothing. “Gradually, the proportion of programmable materials used will increase,” says Andrä. Ultimately, they can be used everywhere — from medicine and sporting goods to soft robotics and even space research.