Transforming circles into squares | Livescience.Tech! Science News

IMAGE: Researchers encoded patterns and styles into the product by making small, undetectable tweaks to the geometry of the triangular lattice.
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Credit: (Image thanks to Shucong Li/Bolei Deng/Harvard SEAS)

Reconfigurable products can do fantastic things. Flat sheets change into a face. An extruded cube changes into lots of various shapes. But there’s something a reconfigurable product has yet to be able to alter: its hidden geography. A reconfigurable product with 100 cells will constantly have 100 cells, even if those cells are extended or compressed.

Now, scientists from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have actually established an approach to alter a cellular product’s basic geography at the microscale. The research study is released in Nature.

“Creating cellular structures capable of dynamically changing their topology will open new opportunities in developing active materials with information encryption, selective particle trapping, as well as tunable mechanical, chemical and acoustic properties,” stated Joanna Aizenberg, the Amy Smith Berylson Professor of Materials Science at SEAS and Professor of Chemistry & Chemical Biology and senior author of the paper.

The scientists utilized the very same physics that clumps our hair together when it gets damp — capillary force. Capillary force works well on soft, certified product, like our hair, however battles with stiff cellular structures that need the flexing, extending or folding of walls, particularly around strong, linked nodes. Capillary force is likewise momentary, with products tending to go back to their initial setup after drying.

In order to establish a lasting yet reversible technique to change the geography of stiff cellular microstructures, the scientists established a two-tiered vibrant technique. They started with a stiff, polymeric cellular microstructure with a triangular lattice geography, and exposed it to beads of an unpredictable solvent picked to swell and soften the polymer at the molecular scale. This made the product briefly more versatile and in this versatile state, the capillary forces enforced by the vaporizing liquid drew the edges of the triangles together, altering their connections with one another and transforming them into hexagons. Then, as the solvent quickly vaporized, the product dried and was caught in its brand-new setup, restoring its tightness. The entire procedure took a matter of seconds.

“When you think about applications, it’s really important not to lose a material’s mechanical properties after the transformation process,” stated Shucong Li, a college student in the Aizenberg Lab and co-first author of the paper. “Here, we showed that we can start with a stiff material and end with a stiff material through the process of temporarily softening it at the reconfiguration stage.”

The brand-new geography of the product is so resilient it can endure heat or be immersed in some liquids for days without taking apart. Its toughness in fact presented an issue for the scientists who had actually wanted to make the change reversible.

To go back to the initial geography, the scientists established a method that integrates 2 liquids. The initially briefly swells the lattice, which peels apart the adhered walls of the hexagons and permits the lattice to go back to its initial triangular structure. The 2nd, less unpredictable liquid hold-ups the introduction of capillary forces till the very first liquid has actually vaporized and the product has actually restored its tightness. In in this manner, the structures can be put together and dismantled consistently and caught in any in-between setup.

“In order to extend our approach to arbitrary lattices, it was important to develop a generalized theoretical model that connects cellular geometries, material stiffness and capillary forces,” stated Bolei Deng, co-first author of the paper and college student in the laboratory of Katia Bertoldi, the William and Ami Kuan Danoff Professor of Applied Mechanics at SEAS.

Guided by this design, the scientists showed set reversible topological improvements of different lattice geometries and responsive products, consisting of turning a lattice of circles into squares.

The scientists checked out different applications for the research study. For example, the group encoded patterns and styles into the product by making small, undetectable tweaks to the geometry of the triangular lattice.

“You can imagine this being used for information encryption in the future, because you can’t see the pattern in the material when it’s in its unassembled state,” stated Li.

The scientists likewise showed extremely regional change, putting together and taking apart areas of the lattice with a small drop of liquid. This technique might be utilized to tune the friction and moistening homes of a product, alter its acoustic homes and mechanical strength, and even trap particles and gas bubbles.

“Our strategy could be applied to a range of applications,” stated Bertoldi, who is likewise a co-author of the paper. “We can apply this method to different materials, including responsive materials, different geometries and different scales, even the nanoscale where topology plays a key role in designing tunable photonic meta-surfaces. The design space for this is huge.”


This research study was co-authored by Alison Grinthal, Alyssha Schneider-Yamamura, Jinliang Kang, Reese S. Martens, Cathy T. Zhang, Jian Li, and Siqin Yu.

It was supported by the National Science Foundation through the Designing Materials to Revolutionize and Engineer our Future (DMREF) program under award no. DMR-1922321, the Harvard University Materials Research Science and Engineering Center (MRSEC) under award no. DMR-18 2011754, and by the United States Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES) under award number DE-SC0005247.

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