Who knew that children's pop-up books could provide so much knowledge. According to researchers, scientists can now make complex microscopic 3D shapes that model brain circuitry and blood vessels by mimicking classic children's pop-up books.
These complex and intricate structures resemble tiny flowers and peacocks, and may one day even help scientists control living tissue electronically.
Structures in biology are quite often naturally curved, thin and flexible 3D structures such as the circuits of brain cells and networks of veins. Materials scientist John Rogers at the University of Illinois at Urbana-Champaign, and his colleagues wanted to create devices that are similar in complexity so that they can better understand complex biological structures to potentially support or even improve their function.
But these types of devices are difficult to create on microscopic scales. So, with the help of a great microscope and a precise laser, Rogers has developed a strategy to create these structures that uses flat 2D structures that pop up into 3D shapes.
"Our focus has been on the brain, heart and skin," Rogers says. "The analogy would best be children's pop-up books."
To create these structures, scientists create 2D patterns of ribbons on stretched elastic silicone rubber. Some of these ribbons were as small as 100 nanometers wide, or about 1,000 times thinner than the average human hair, and could be made from a variety of materials.
The patterns are designed with both strong and weak points of stickiness between the patterns and the silicone rubber they sit on. After the designs are fabricated, they release the tension of the rubber and the weak points of stickiness break "and up pops a 3D structure," study co-author, Yonggang Huangsays. "In just one shot, you get your structure."
The researchers have created more than 40 different designs thus far from single and multiple spirals and rings to spherical baskets, cubical boxes, flowers and more. According to investigators this new strategy is fast, inexpensive and can use different materials to create a wide variety of microscopic structures.
"We are excited about the fact that these simple ideas and schemes provide immediate paths to broad and previously inaccessible classes of 3D micro- and nano-structures in a way that is compatible with the highest-performance materials and processing techniques available," Rogers says. "We feel that the findings have potential relevance to a wide range of microsystems technologies biomedical devices, optoelectronics, photovoltaics, 3D circuits, sensors and so on."
While scientists believe that this strategy is complimentary to 3D printing, the technique has many advantages over 3D printers. Although 3D printing has been increasing in popularity, they are slow and it is difficult for them to build objects using more than one material.
The scientists are currently using this pop-up assembly strategy to build electronic scaffolds that can monitor and control the growth of cells in lab experiments, Rogers says.
"We are also using these ideas to form helical, springy metal interconnect coils and antennas for soft electronic devices designed to integrate with the human body."
