The material is the machine

The shape memory effect

A shape memory alloy can be deformed in a cold state and automatically returns to its "shape memory" state when heated.

One material with two faces

Even more function in less and less space - this is the challenge faced by different industries. memetis enables space-saving and powerful microactuators by using specifically structured thin films of shape memory alloy (SMA). A shape memory alloy (SMA) is also known as a smart material or memory metal. This is due to their ability to "remember" their original shape. Actuators are components that perform a movement or action in the smallest of spaces. memetis thin-film actuators exist at unequal temperatures in two different crystal structures and "remember" an earlier shape even after strong deformation. A shape memory alloy is thus a metallic alloy that can easily be deformed in the cold state, for example by pressure. However, as soon as it is heated, for example by a current pulse, it returns to its original state, to their "shape memory" - the so-called shape memory effect. The forces involved can be used to control the movements of very small components. memetis GmbH uses this behaviour for its work.

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The shape memory effect
Illustrative
  • Martensite (low temperature phase)

    In the cold state (martensite), the shape memory alloy can easily be deformed by yielding to the forces acting on it (e.g. a weight).

  • Martensite (low temperature phase)

    In the cold state, the shape memory alloy can easily be deformed by yielding to the forces acting on it (e.g. a weight).

  • Martensite (low temperature phase)

    In the cold state, the shape memory alloy can easily be deformed by yielding to the forces acting on it (e.g. a weight).

  • Phase transformation

    With increasing temperature of the shape memory alloy, the microstructure of the material transforms into austenite and assumes its "shape memory".

  • Phase transformation

    With increasing temperature of the shape memory alloy, the microstructure of the material transforms into austenite and assumes its "shape memory".

  • Phase transformation

    With increasing temperature of the shape memory alloy, the microstructure of the material transforms into austenite and assumes its "shape memory".

  • Austenite (high temperature phase)

    If a certain temperature is exceeded, the shape memory alloy unfolds its full force. In this high-temperature phase, the material remembers an external shape exactly.

  • Austenite (high temperature phase)

    If a certain temperature is exceeded, the shape memory alloy unfolds its full force. In this high-temperature phase, the material remembers an external shape exactly.

  • Austenite (high temperature phase)

    If a certain temperature is exceeded, the shape memory alloy unfolds its full force. In this high-temperature phase, the material remembers an external shape exactly.

  • Austenite (high temperature phase)

    If a certain temperature is exceeded, the shape memory alloy unfolds its full force. In this high-temperature phase, the material remembers an external shape exactly.

In diagnostics and analytics, there is a trend towards miniaturisation and increased portability with a constant or even increased range of functions, particularly in the field of microfluidics. So-called lab-on-a-chip systems are designed to enable complex analyses in the smallest possible space - smart, handy and decentralised. memetis GmbH focuses on making such a system even more intelligent and available for a broad spectrum of applications by using foil-based miniature actuators made of shape memory alloys in the form of miniature valves and miniature actuators. However, applications with similar requirements for component compactness can also be found in the field of automation technology, e.g. in robotics.

Further information on shape memory technology

Shape memory actuation is our core competence - we are happy to assist our customers and interested parties with any questions they may have. If you are further interested in the shape memory effect and our work, please refer to the following publications:

  • C. Megnin, M. Kohl; Shape memory alloy microvalves for a fluidic control system; Journal of Micromechanics and Microengineering; vol. 24; pp. 025001, 2014;
  • C. Megnin, J. Barth, M. Kohl; A bistable SMA microvalve for 3/2-way control; Sensors and Actuators A; vol. 188; pp. 285-291, 2012;
  • M. Gueltig, H. Ossmer, M. Ohtsuka, H. Miki, K. Tsuchiya, T. Takagi, and M. Kohl; Thermomagnetic Actuation by Low Hysteresis Metamagnetic Ni-Co-Mn-In Films; Materials Today: Proceedings; vol. 2, pp. S883–S886, 2015;
  • M. Kohl, M. Gueltig, V. Pinneker, R. Yin, F. Wendler, and B. Krevet; Magnetic Shape Memory Microactuators; Micromachines; vol. 5, no. 4, pp. 1135–1160, 2014;
  • H. Ossmer, F. Lambrecht, M. Gueltig, C. Chluba, E. Quandt, M. Kohl; Evolution of temperature profiles in TiNi films for elastocaloric cooling; Acta Materialia; vol. 81, pp. 9-20, 2014;
  • H. Ossmer, F. Wendler, M. Gueltig, F. Lambrecht, S. Miyazaki, M. Kohl; Energy-efficient miniature-scale heat pumping based on shape memory alloys; Smart Materials and Structures; vol. 25, pp. 1-13, 2016;