Engineers from the Massachusetts Institute of Technology, working in conjunction with researchers from the Singapore University of Technology and Design, announced on Friday that they have used light to produce 3D-printable structures that “remember” their original shapes and are capable, at certain temperatures, of springing back to their original forms. The goal is to achieve a material that can be a response to body temperature since this result could be translated into relevant medical appliances such as creating fever-response drugs, artificial muscles or soft robotics as a biomedical device.
Advertisement
Ge says the process of 3-D printing shape-memory materials can also be thought of as 4-D printing, as the structures are created to change over the fourth dimension – time.
The changes in shape are possible thanks to to the special properties of so-called “shape-memory polymers”, which have the ability to “remember” their original shape even after that shape has been radically distorted.
The researchers are “printing with light” in much the same way dentists now do. “For example, a flower can release pollen in milliseconds”. The current range is just outside that of the human body, and hitting that range would be tremendously helpful in terms of creating custom drug delivery mechanisms.
But the crucial step is the microstereolithography 3D printing process, which is far more advanced than nozzle or ink-jet based 3D printing. The new technology is expected to have applications in different fields such as aerospace structure, solar cells and in biomedical.
To use light for printing, in a method they call microstereolithography, researchers fed the layer-by-layer model of the structure into a projector, each individual layer a separate image file. The object can be twisted or bent to irregular forms but due to the use of light in the making process, the material will be able to regain their original shape when heat is applied. 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 easily withstand stretching and bending without breaking.
The material can bounce back to its original printed form, within a specific temperature range – in this case, between 40 and 180 degrees Celsius.
Taking 3D printing to another level, the MIT has managed to use the 3D-printed objects’ memory shape to practical applications.
The 3D printed structures could be stretched to three times their original length without breaking. The speed of the response is related to small dimensions, the smaller the object, the faster the response.
Advertisement
“Because we’re using our own printers that offer much smaller pixel size, we’re seeing much faster response, on the order of seconds”, Nicholas X. Fang, one of the MIT researchers, told MIT news. But when placed in a warm environment, the gripper’s hands closed around whatever the engineers placed beneath it. “So we think there will probably be more applications that we can demonstrate”.
