Additive manufacturing Additively manufactured structure changes its properties at the push of a button

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Jongen Werkzeugtechnik GmbH

Programmable materials are true shape-shifters, changing their properties in a controlled and reversible way at the touch of a button. What this means is explained here by the researchers currently working on it.

Programmable materials adapt independently to changing conditions, according to the report. They can, for instance, provide a more comfortable sitting or lying position that prevents patients or nursing home residents from developing bedsores. In doing so, the underlay deforms in such a way that the contact surface is increased and the pressure on the body parts of the person is reduced. The hardness of the structure can also be influenced in this way. Researchers of the Fraunhofer Cluster of Excellence Programmable Materials (CPM) develop such programmable systems and then bring them to market with industrial partners. The goal is to use resources more efficiently.

A smart combination of materials and microstructures

But how can materials be programmed in the first place? The researchers at Fraunhofer IWM have two basic methods, they say. On the one hand, there is the base material - in the case of the mattresses, thermoplastics, i.e. plastics that can be melted again, and for other applications, metallic alloys, which also include so-called shape memory alloys that form the microstructure in particular. Secondly, it is the microstructure of the so-called metamaterials, which is composed of individual cells, which in turn consist of structural elements such as small beams and thin shells, as they go on to say. While the size of the individual cells and their structural elements varies randomly in conventional cellular materials - think of foams - it is also variable in programmable materials, but precisely fixed - i.e. programmed, the explanation goes. This programming takes place, for example, in such a way that pressure at a certain position leads to desired changes in shape at other points, to stay with the mattress. This is how the support surface can be adjusted.

Materials also react to other “stimuli”

The change in shape that the material should undergo and the stimuli to which it ultimately reacts - mechanical stress, heat, moisture or even an electric or magnetic field - can also be determined by the choice of materials and their microstructure. The programmable materials then also make it possible to adapt objects to the respective application or person, which brings added value, and thus make things more multifunctionally usable than before. They would therefore not have to be replaced as often. Especially against the backdrop of resource consumption, this is a welcome feature.

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