American researchers at Rice University have developed a method for printing objects whose shape can be manipulated under the effect of temperature, electricity or mechanical stress. Are flexible reconfigurable robots close to reality?
In 2018, the research team presented a material capable of deforming under the effect of heat and returning to its initial shape after cooling . Their recent work goes much further: this material can now be 3D printed , which makes it possible to imagine all kinds of shapes and applications.
A single material, 2 shapes that can be controlled at will
The two-step manufacturing method presented in this new study consists first of all of printing a liquid crystal elastomer (LCE) precursor in a catalyst bath. This operation thus makes it possible to obtain a complex 3D architecture.
The second step concerns the “programming” of the shapes. The printed structure is thus deformed under the effect of mechanical stresses and then stabilized by UV irradiation.
Under the effect of heat, this structure is able to resume its initial shape. As the process is reversible, the structure returns to its “programmed” form as it cools. It is therefore indeed a material with 2 totally controllable shapes!
Operation Specific to Liquid Crystal Elastomers
How is such a phenomenon possible? It all hinges on a nanoscale battle between liquid crystals and the elastomeric matrix in which they are trapped. As it cools, the shape given to the liquid crystals dominates. When the structure is heated, the crystals are released inside the elastomer which then regains all its flexibility.
An interesting avenue for flexible robotics
Rafael Verduzco and Morgan Barnes, the researchers who carried out this work, continue to improve their invention. Some blocking points still need to be addressed, such as the current impossibility of printing vertical structures, due to the lack of rigidity. Indeed, this material being flexible, during the printing phase, the manufacture of complex shapes is not yet topical.
However, these problems are far from insurmountable and could be resolved quickly. Responsive 4D printing is still in its infancy, but researchers are already imagining the creation of flexible actuators and the manufacture of flexible robots that could swim jellyfish or carry fluids for drug-dropping.
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