Researchers at Massachusetts Institute of Technology and Singapore University of Technology and Design developed a technique for 3D printing of shape-memory objects. Shape-memory is a property of some materials, allowing them to snap back to a certain shape after being deformed. In medicine, nitinol stents are probably the most commonly used application for shape-memory materials, but there is a lot more potential for shape-memory technology to influence clinical care. There could be surgical tools, drug delivery methods, and devices placed within the body that activate only when their environment changes in a certain way.
The team used polymers as the material, resulting in soft devices that can gently grab onto things. They respond to changes in temperature, morphing between two different states as heat is applied and removed. They can be bent, stretched, or compressed and when at the lower temperature they’ll stay that way. Once the temperature rises, the device returns to its original shape before being deformed.
The 3D printing technique the scientists used is called microstereolithography that utilizes light to make patterns within a resin. Computer designed layers of the material are created this way that together form the wanted shape.
They picked two polymers, one composed of long-chain polymers, or spaghetti-like strands, and the other resembling more of a stiff scaffold. When mixed together and cured, the material can be stretched and twisted dramatically without breaking.
What’s more, the material can bounce back to its original printed form, within a specific temperature range — in this case, between 40 and 180 degrees Celsius (104 to 356 degrees Fahrenheit).
Going forward, [Nicholas X. Fang, associate professor of mechanical engineering at MIT] hopes to find combinations of polymers to make shape-memory materials that react to slightly lower temperatures, approaching the range of human body temperatures, to design soft, active, controllable drug delivery capsules. He says the material may also be printed as soft, responsive hinges to help solar panels track the sun.