Mechanical computers rely on kirigami cubes, not electronics

Researchers at North Carolina State University have developed a kirigami-inspired mechanical computer that uses a complex structure of rigid, interconnected polymer cubes to store, retrieve and erase data without relying on electronic components. The system also includes a reversible feature that allows users to control when data editing is allowed and when data should be locked in place.

Mechanical computers are computers that operate using mechanical components rather than electronic ones. Historically, these mechanical components were things like levers or gears. However, mechanical computers can also be made using structures that are multistable, meaning that they have more than one stable state. Think of anything that can be folded into more than one stable position.

“We were interested in doing a few things here,” said Jie Yin, co-corresponding author of a paper on the work and associate professor of mechanical and aerospace engineering at NC State. “First, we were interested in developing a stable, mechanical system for storing data.

“Second, this proof-of-concept work focused on binary computing functions where a cube is pushed up or down – it’s a 1 or a 0. But we think there’s potential here for more complex computing, where data is transferred by how high a given cube has been pushed up. We have shown within this proof-of-concept system that cubes can have five or more different states. Theoretically, this means that a given cube can convey not only a 1 or a 0 but also a 2, 3 or 4.”

The article is published in the magazine Scientific progress.

The fundamental units of the new mechanical computer are 1 centimeter plastic cubes, grouped into functional units consisting of 64 interconnected cubes. The design of these units is inspired by kirigami, the art of cutting and folding paper. Yin and his collaborators applied the principles of kirigami to three-dimensional materials cut into connected cubes.

When one of the cubes is pushed up or down, it changes the geometry (or architecture) of all the connected cubes. This can be done by physically pushing one of the cubes up or down, or by attaching a magnetic plate to the top of the functional unit and applying a magnetic field to remotely push it up or down. These functional units of 64 cubes can be grouped into increasingly complex metastructures that allow for more data to be stored or more complex computations to be performed.

The cubes are connected to each other by thin strips of elastic tape. To edit data, you must change the configuration of functional units. That requires users to pull on the edges of the metastructure, which stretches the elastic tape and allows you to push cubes up or down. When you release the metastructure, the tape contracts, locking the cubes (and the data) in place.

“One potential application of this is that it allows users to create three-dimensional, mechanical encryption or decryption,” said Yanbin Li, first author of the paper and postdoctoral researcher at NC State. “For example, a specific configuration of functional units could serve as a 3D password.

“And the information density is quite good,” says Li. “Using a binary framework – where cubes are up or down – a simple metastructure of 9 functional units has over 362,000 possible configurations.”

“But we’re not necessarily limited to a binary context,” says Yin. “Each functional unit of 64 cubes can be configured in a wide variety of architectures, with cubes stackable up to five cubes high. This enables the development of computing that goes far beyond binary code. Our proof-of-concept work here demonstrates the potential range of these architectures, but we have not developed code that addresses these architectures. We would like to collaborate with other researchers to explore the coding potential of these metastructures.

“We are also interested in exploring the potential usefulness of these metastructures to create haptic systems that display information in a three-dimensional context, rather than as pixels on a screen,” says Li.

Co-corresponding author of the article is Hao Su, associate professor of mechanical and aerospace engineering at NC State. The paper was co-authored by Shuangye Yu and Yaoye Hong, former Ph.D. students at NC State; Haitao Qing and Fangjie Qi, current Ph.D. students at NC State; and Yao Zhao, a former postdoctoral researcher at NC State.