Create an intelligent gel that changes shape

Enables the creation of soft robots and drug delivery systems

A small chess piece, printed with this system, remains solid, despite being formed in 73% of water. Image credit: Daehoon Han/Rutgers University-New Brunswick
A team of scientists at Rutgers University, led by Howon Lee, has developed a 4D printing method for an intelligent gel that could lead to the development of "live" structures in human organs and tissues, soft robots and targeted drug delivery.
The 4D printing system involves printing a 3D object with a hydrogel (water-containing gel) that changes shape as temperatures change.

The study, published in Scientific Reports, explains how to perform a fast, easy to produce, high-resolution 3D hydrogel print that remains solid and retains its shape despite containing water.
The "smart gel" could provide structural rigidity in organs such as the lungs, and may contain small molecules such as water or drugs to be transported by the body and released at selected sites. It could also create an area of soft robotics and allow new applications in flexible sensors, biomedical devices and platforms for cells to grow.

We just started exploring the full potential of this hydrogel,"Lee explains in a statement. We add another dimension to it, and this is the first time anyone has done so on this scale. They are flexible and shape-changing materials. I like to call them intelligent materials.
Lee's team learned how to accurately control hydrogel growth and shrinkage. At temperatures below 32ºC, the hydrogel absorbs more water and increases its size. When the temperature exceeds 32ºC, it starts to expel water and contracts. Objects that can be created with hydrogel vary from the width of a human hair to several millimeters.
"If you have full control of the form - Lee concludes - then you can program its function. I think that's the power of 3D printing of shape-shifting material.