Preliminary study of infinite reversibility without external force, reversible 4D printing of double-layer components

On March 9, 2020, Singapore University of Technology and Design (SUTD) and Nanyang Technological University (NTU) collaborated on a study to make3D printingAfter the shape of the material changes, it can be returned countless times without any electrical input.
The title of this study is “
Preliminary research on reversible 4D printing of double-layer components
“, co-authored by Amelia Yilin Lee, Jia An, Chee Kai Chua and Zhang Yi. It was published in “Engineering” magazine in December 2019.

(A) Irreversible (one-way) shape memory effect; (b) Reversible (two-way) shape memory effect.

Reversible 4D printing

when3D printingWhen the shape of the object changes over time, it is called 4D printing.Reversible 4D printing refers to the ability to change back to the original3D printingThe ability to shape. The initial shape change is usually caused by heat or water, but to restore the shape, manual input is usually required in the form of stretching or pulling, which can be time-consuming and laborious.
In recent years, researchers have paid certain attention to automatic reversible 4D printing, and hydrogel is the main stimulus for achieving reversibility without manual intervention. However, due to the lack of mechanical strength of the hydrogel, its application is limited.

The research of SUTD and NTU has achieved reversible 4D printing without the need for hydrogel or artificial pressure to solve these challenges.

In the programming phase, there are three steps.

Step 1: Expose the first permanent shape to ethanol;

Step 2: Remove the shape from ethanol and heat it in water at 60°C to form a second permanent shape;

Step 3: Cool the component to fix the component in the second permanent shape.

In the recovery phase, there are two steps.

Step 4: Dry the components.

Step 5: Heat the part to return to the first permanent shape.

VeroWhitePlus and TangoBlackPlus

The materials used in the study are VeroWhitePlus and TangoBlackPlus, which are easily available and compatible with the 3D polyjet process. The team first demonstrated that these materials can maintain considerable mechanical strength during and after their shape changes.

This method involves swelling the elastomer with ethanol to replace the swelling function of the hydrogel. This is to create stress on the transition material. When heated, the transition material changes its shape to the second form. When the ethanol evaporates and the elastomer dries, the secondary heating of the transition material restores it back to its original shape, because the elastomer pulls the transition material back due to the elastic energy stored in it after drying. Elastomers play a dual role in work, because it can not only cause stress during the programming phase, but also store elastic energy in the material during the recovery process.

△The two main stages of the reversible cycle: programming and recovery.

The study also concluded that this method is more accurate when compared to manual forced restoration. Reversible 4D printing is still in its early stages, but this collaborative project provides insights into the mechanism behind automatic reversible 4D printing. The team hopes to continue experimenting with the technology with new materials.

Professor Chua Chee Kai, SUTD’s principal researcher and head of engineering product development, said: “Although reversible 4D printing itself is a big step forward, being able to use stronger materials while ensuring more precise reversal during shape changes is revolutionary. Because it enables us to produce complex structures that cannot be easily achieved by traditional manufacturing. By relying on environmental conditions instead of electricity, it has changed the rules of the game in various industries, thereby completely changing our design, creation, and packaging. And the way the product is transported,”

Reversible 4D printing structure, photo taken by SUTD.

By merging the next dimension, 4D printing is naturally3D printingThe next step.However, to make 4D printing compatible with the current3D printingTo match the advanced nature of the technology, researchers must improve the ability to create smooth and complex surfaces in a given period of time. Scientists at Harvard University have previously experimented on smooth and complex surfaces with 4D printed structures that have the shape of a human face when placed in salt water. Elsewhere at Rutgers University, researchers have created bioinspired programmable microneedles that can use projection micro-stereolithography to enhance tissue adhesion.

(Editor in charge: admin)

Preliminary study of infinite reversibility without external force, reversible 4D printing of double-layer components

0 Comments for “Preliminary study of infinite reversibility without external force, reversible 4D printing of double-layer components”

Leave a Reply Cancel reply