14 Sep 2016 |
Research article |
Materials & Manufacturing
3D printed memory‐shape materials at hand
A new technology developed by MIT and SUTD allows to 3D-print materials that can remember their shape after being bent or twisted from their original state. The team of engineers from the Massachusetts Institute of Technology (MIT) and the Singapore University of Technology and Design (SUTD) recently presented 3D-printed objects made of pliable shape-memory polymers that are flexible in size and shape with unprecedented printing resolution for this type of base materials.
To achieve this, they take advantage of the structural characteristics of these shape-memory polymers. At room temperature, the cool state, the material remains amorphous. At higher temperatures, the material turns into a kind of rubber that is soft and malleable. Moreover, after the material is deformed it will stay there until is heated, when recoiling takes place and the material goes back to its original printed shape. This process then, involves 3D-printing at higher temperatures to be able to manipulate the polymer. The team studied and characterized the polymer to find the right temperature to trigger its change. This allows for controlled processing that facilitates bringing this technology in several consumer and industrial fields.
The ability to 3D-print memory‐shape polymers has interesting applications in medicine where drug delivery could be potentially controlled by local triggers like the body temperature. This is important considering that for many ailments, drug administering timing is essential to maximize the effect of a drug. Imagine this scenario: If the body temperature increases due to an infection, a capsule containing a specific healing agent opens and releases this agent to fight against the said infection exactly at the right time.
Notably, the team optimized 3D-print of the polymers to achieve the smallest features to date using these components. This means printing features as small as the human hair. This is a milestone in 3D-printing of memory‐shape materials using a technique called microstereolithography, which employs the light from a projector, illuminating only certain areas of a resin pool and repeating the process to make layer-by-layer structures. Using similar approaches to that of optical lithography, one can achieve very fine details on the micron regime.
The shape-memory polymers are a mix of two specific polymers. One that is flexible and one that offers support to prevent breaking. When mixed and cured the result is a polymer with great tolerance to bending and stretching. Even more, the mix will kick back to its original curing shape after being subject to heat within a range of 40-180 °C (104 – 356 °F). By using microstereolithography to print, very small features favor this memory‐shape process and its easier for a printed structure to go back to its original printed form.
Other applications emerge in the aerospace fields where the need for lightweight and smart materials is mandatory. Imagine actuators that doesn’t require any mechanics and at the same time, are durable and lightweight. Even more, manufacturing can take place on-site, directly on space. Just by applying heat to a grabbing claw, which is abundant in space, it will close and get a hold of whatever object needs manipulation.
Possible applications for this technology are just beginning to emerge. We certainly hope to see more of this project in the near future.
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Luis Felipe Gerlein Reyes
Luis Felipe Gerlein R. is a Ph.D. candidate at ÉTS. His research interests include nanofabrication and characterization of optoelectronic devices based on lead chalcogenides, carbon-based nanostructures and perovskite materials.
Program : Electrical Engineering