Researchers at Rutgers University are hard at work on developing a new means of making metamaterials. As part of a new study published in Scientific Reports the paper details a means of 4D printing with hydrogel structures. The researchers printed the hydrogels with a lithography based process with the ability to change shape and size in proportion increases and decreases in temperature.
The researchers used the intrinsic water-based properties of the hydrogel to create the shape-shifting effect. When the gel increases in temperature, it begins to expel its moisture and thus shrink. Conversely, as it cools, it absorbs moisture from the air and begins to grow again. The hydrogel itself has been a relatively common one in terms of lab use. It is the method of printing that sets the research apart from its contemporaries.
Firstly, they combined the hydrogel with a photosensitive chemical and a binding agent. The photosensitive chemical allowed it to solidify during lithography. Next, the engineers built up the objects and cured the gel in resin form, producing the chess piece below.
“The full potential of this smart hydrogel has not been unleashed until now,” explained lead researcher Howon Lee. “We added another dimension to it, and this is the first time anybody has done it on this scale. They’re flexible, shape-morphing materials. I like to call them smart materials.” Lee is a professor of Mechanical and Aerospace Engineering at Rutgers.
Applications of Temperature Sensitive Hydrogels
Hydrogels are all the rage in medical research these days. Since they change shape and size, they present solutions to a lot of medical problems. For example, bioengineers could use this to develop artificial tissue for the human body. Another possible application is in biomedical devices that need to maintain exponential growth. Controlled drug delivery applications are also possible with such a material.
Outside of medicine, there are also engineering functions that it could serve. Space exploration always needs materials that can adapt to heat or absorb moisture. Similarly, it could serve as a soft robot building material. It could even allow for objects that can be transported in a cold container as small parts and later grown to full size. There are clearly a lot of possibilities with shapeshifting materials. They also provide a unique way 3D printing outshines traditional manufacturing. We’re sure to see more work on metamaterials in the coming years.