3D printed object made from hydrogel shapeshifts after it has been printed.
Engineers at Rutgers, the state university of New Jersey, and the New Jersey Institute of Technology have developed a 4D printing method which may find application in tissue engineering and targeted drug delivery systems.
The 4D printing method uses a hydrogel which can change shape after being 3D printed. The shapeshifting is temperature regulated.
Hydrogels are traditionally used in everyday applications such as contact lenses or diapers. One of their benefits is that they retain their shape despite containing water (hence the name ‘hydro’).
The invention offers huge potential for the 3D bio-printing of organs. Alternatively, it could be used to transport drugs into the body as the gel can contain molecules.
According to Howon Lee, assistant professor in the Department of Mechanical and Aerospace Engineering at Rutgers, there’s even room for soft robotics development using the new method.
“The full potential of this smart hydrogel has not been unleashed until now,” he explains. “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.”
Hydrogel shrinks and grows as temperature changes
Up until now, the use of hydrogel manufacturing has focused on using 2D methods such as lithography or molding techniques.
The latest study published in Scientific Reports by Lee and his colleagues highlights a new application for lithography methods to shape 3D objects.
As part of their testing, the engineers printed layers of a specialist resin to create a 3D object. The resin consisted of a hydrogel to act as a binder, as well as a light-activated bonding chemical and a controlling dye.
During testing, the researchers found that the hydrogel would retain more water and consequently grow at temperatures below 32 degrees Celsius. At higher temperatures, the gel would expel water and shrink.
That means, even the smallest objects such as human hair can be printed and subsequently grown in size.
Lee adds: “If you have full control of the shape, then you can program its function. I think that’s the power of 3D printing of shape-shifting material. You can apply this principle almost everywhere.”
Schematic of 3D hydrogel printing. (Image: Scientific Reports/Nature.com)
Source: Rutgers & Nature
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