In the study that followed, published in Advanced Materials, the researchers constructed a kind of simple “microrobot”, one which can assume different shapes and change stiffness. The researchers began with a gel material called alginate. On one side of the gel, a polymer material is grown. This material is electroactive, and it changes its volume when a low voltage is applied, causing the microrobot to bend in a specified direction. On the other side of the gel, the researchers attached biomolecules that allow the soft gel material to harden. These biomolecules are extracted from the cell membrane of a kind of cell that is important for bone development. When the material is immersed in a cell culture medium – an environment that resembles the body and contains calcium and phosphor – the biomolecules make the gel mineralise and harden like bone.
One potential application of interest to the researchers is bone healing. The idea is that the soft material, powered by the electroactive polymer, will be able to manoeuvre itself into spaces in complicated bone fractures and expand. When the material has then hardened, it can form the foundation for the construction of new bone. In their study, the researchers demonstrate that the material can wrap itself around chicken bones, and the artificial bone that subsequently develops grows together with the chicken bone.
By making patterns in the gel, the researchers can determine how the simple microrobot will bend when voltage is applied. Perpendicular lines on the surface of the material make the robot bend in a semicircle, while diagonal lines make it bend like a corkscrew.
“By controlling how the material turns, we can make the microrobot move in different ways, and also affect how the material unfurls in broken bones. We can embed these movements into the material’s structure, making complex programmes for steering these robots unnecessary”, says Edwin Jager.
In order to learn more about the biocompatibility of this combination of materials, the researchers are now looking further into how its properties work together with living cells.
Source: Linköping University
Source: Healthcare in Europe