• Programmable structures from the printer

    From ScienceDaily@1:317/3 to All on Fri Jul 9 21:30:38 2021
    Programmable structures from the printer

    Date:
    July 9, 2021
    Source:
    University of Freiburg
    Summary:
    Research team develops new method for 3D-printing materials systems
    that move like a climbing plant.



    FULL STORY ========================================================================== Researchers at the University of Freiburg and the University of Stuttgart
    have developed a new process for producing movable, self-adjusting
    materials systems with standard 3D-printers. These systems can undergo
    complex shape changes, contracting and expanding under the influence
    of moisture in a pre-programmed manner. The scientists modeled their development based on the movement mechanisms of the climbing plant known
    as the air potato (Dioscorea bulbifera).

    With their new method, the team has produced its first prototype:
    a forearm brace that adapts to the wearer and which can be further
    developed for medical applications. This process has been collaboratively developed by Tiffany Cheng and Prof. Dr. Achim Menges from the Institute
    of Computational Design and Construction (ICD) and the Integrative Computational Design and Construction for Architecture Cluster of
    Excellence (IntCDC) at the University of Stuttgart, together with
    Prof. Dr. Thomas Speck from the Plant Biomechanics Group and the Living, Adaptive and Energy-autonomous Materials Systems Cluster of Excellence (livMatS) at the University of Freiburg. The researchers are presenting
    their results in the journal Advanced Science.


    ========================================================================== 4D-printing defines shape changes 3D-printing has established itself as
    a manufacturing process for a wide range of applications. It can even be
    used to produce intelligent materials and material systems that remain in motion after printing, autonomously changing shape from external stimuli
    such as light, temperature or moisture. This so- called '4D-printing',
    in which predetermined shape changes can be triggered by a stimulus,
    immensely expands the potential applications of material systems.

    These changes in shape are made possible by the chemical composition of
    the materials, which consist of stimuli-responsive polymers. However,
    the printers and base materials used to produce such materials systems
    are usually highly specialized, custom-made and expensive -- until now.

    Now, using standard 3D-printers, it is possible to produce materials
    systems that react to changes in moisture. Given their structure, these materials systems can undergo shape changes in the entire system or
    simply in the individual parts. The researchers at the Universities of
    Freiburg and Stuttgart combined multiple swelling and stabilizing layers
    to realize a complex movement mechanism: a coiling structure that pulls
    tighter by unfolding 'pockets' as pressors and which can loosen up again
    on its own when the 'pockets' release and the coiled structure returns
    to the open state.

    Natural movement mechanisms transferred to technical material systems
    For this new process, the scientists used a mechanism from nature: the
    air potato climbs trees by applying pressure to the trunk of the host
    plant. To do this, the plant first winds loosely around a tree trunk. Then
    it sprouts 'stipules', basal outgrowths of the leaves, which increase the
    space between the winding stem and the host plant. This creates tension
    in the winding stem of the air potato. To imitate these mechanisms,
    the researchers constructed a modular material system by structuring
    its layers so that it can bend in different directions and to different degrees, thereby coiling and forming a helix structure. 'Pockets' on
    the surface cause the helix to be pushed outwards and put under tension, causing the entire material system to contract.

    "So far, our process is still limited to existing base materials that
    respond to moisture," says Achim Menges. "We're hoping," Thomas Speck
    adds, "that in the future, inexpensive materials that also respond to
    other stimuli will become available for 3D-printing and can be used
    with our process." Living, Adaptive and Energy-autonomous Materials
    Systems Cluster of Excellence (livMatS) Researchers at the University
    of Freiburg's Living, Adaptive and Energy- autonomous Materials Systems
    Cluster of Excellence (livMatS) are developing life-like materials
    systems that are inspired by nature. Like living structures they
    adapt autonomously to different environmental factors, generate clean
    energy from their environment and are impervious to damage or can heal themselves. Nevertheless these materials systems will be purely technical objects, so they can be produced using synthetic methods and deployed
    in extreme conditions. Thomas Speck is a member of the team of speakers
    at the Cluster of Excellence.

    ========================================================================== Story Source: Materials provided by University_of_Freiburg. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Tiffany Cheng, Marc Thielen, Simon Poppinga, Yasaman Tahouni,
    Dylan Wood,
    Thorsten Steinberg, Achim Menges, Thomas Speck. Bio‐Inspired
    Motion Mechanisms: Computational Design and Material Programming
    of Self‐Adjusting 4D‐Printed Wearable Systems. Advanced
    Science, 2021; 8 (13): 2100411 DOI: 10.1002/advs.202100411 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2021/07/210709094459.htm

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