Artistic illustration of a meta-mechatronic unit cell and an array of unit cells creating an autonomous system that can ‘think’ for itself.
Photo of a unit cell and its electrical signal output as a logic gate.Researchers believe that they have taken the first step towards a new type of autonomous, self-powered, intelligent material based on mechanical metamaterials that can perform basic computational operations [Zhang et al., Materials Today (2023), https://doi.org/10.1016/j.mattod.2023.03.026].
The team from the University of Pittsburgh, Johns Hopkins University, Georgia Institute of Technology, Beijing Institute of Nanoenergy and Nanosystems, New Mexico State University, and Zhejiang University have been working on the development of a new field they call mechanical metamaterial electronics or ‘meta-mechanotronics’.
“An intelligent material is a system that can self-sustain its operation, offer designated structural behavior, and realize functionalities such as sensing, energy harvesting, actuating, processing and communication to create a sense-decide-respond loop,” explains Amir H. Alavi, who led the effort.
When combined with self-powering, nano energy-harvesting technologies, the team hope to create meta-mechanotronic devices that can operate autonomously and ‘think’ for themselves. As a first step, the researchers have created a basic building block or ‘digital unit cell’ consisting of an open cylindrical origami-inspired metamaterial with a built-in nanogenerator, which generates an electrical signal in response to an externally applied mechanical movement. The electrical signals can be translated into binary signals for digital computation and data storage.
The researchers designed digital cells that can create standard logic gates, such as AND, OR, XOR, NAND, etc., which can perform Boolean logic operations. For example, motion changes in each layer of two-layer meta-mechanotronic cells produce either ‘open (0)’ or ‘closed (1)’ binary signals that can be used to encode and store data without any additional electronic input or external power supply.
“While we don’t expect meta-mechanotronics circuitry to compete with the speed and information density of semiconductor electronics, it can complement them and find applications in many fields including medical devices, robotics, and construction,” points out Alavi.
Meta-mechatronic devices could, for example, be useful in extreme environments like space or under high pressure or temperature. However, the field is very much in its infancy, Alavi emphasizes, and there will be many challenges ahead. His team now plan to develop simple digital circuits and use 3D printing to fabricate miniaturized meta-mechanotronic circuits, with the support of a recent National Science Foundation CAREER Award.
“These proof-of-concept prototypes and design principles provide new road maps,” says Alavi, “paving the way toward autonomous metamaterials that derive their operational power from the working environment.”