You Don't Need Glue to Hold These Materials Together—Just Electricity
taylorvich writes:
https://phys.org/news/2024-03-dont-materials-electricity.html
Is there a way to stick hard and soft materials together without any tape, glue or epoxy? A new study published in ACS Central Science shows that applying a small voltage to certain objects forms chemical bonds that securely link the objects together. Reversing the direction of electron flow easily separates the two materials. This electroadhesion effect could help create biohybrid robots, improve biomedical implants and enable new battery technologies.
When an adhesive is used to attach two things, it binds the surfaces either through mechanical or electrostatic forces. But sometimes those attractions or bonds are difficult, if not impossible, to undo. As an alternative, reversible adhesion methods are being explored, including electroadhesion (EA).
Though the term is used to describe a few different phenomena, one definition involves running an electric current through two materials causing them to stick together, thanks to attractions or chemical bonds. Previously, Srinivasa Raghavan and colleagues demonstrated that EA can hold soft, oppositely charged materials together, and even be used to build simple structures. This time, they wanted to see if EA could reversibly bind a hard material, such as graphite, to a soft material, such as animal tissue.
[...] For EA to occur, the authors found that the hard material needs to conduct electrons, and the soft material needs to contain salt ions They hypothesize that the adhesion arises from chemical bonds that form between the surfaces after an exchange of electrons. This may explain why some metals that hold onto their electrons strongly, including titanium, and some fruits that contain more sugar than salts, including grapes, failed to adhere in some situations.
A final experiment showed that EA can occur completely underwater, revealing an even wider range of possible applications. The team says that this work could help create new batteries, enable biohybrid robotics, enhance biomedical implants and much more.
Journal Reference:
Wenhao Xu, Faraz A. Burni, and Srinivasa R. Raghavan, Reversibly Sticking Metals and Graphite to Hydrogels and Tissues, ACS Central Science (2024). https://doi.org/10.1021/acscentsci.3c01593
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