Computing’s Past to Unlock 3D-Printed Mechanical Logic Gates for the Future

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Panas, the project’s principal investigator, said the flexures behave like switches. The flexures are chained together and, when stimulated, trigger a cascade of configurations that can be used to perform mechanical logic calculations without external power. The gates themselves work due to displacement, taking in an external binary signal from a transducer, such as a pressure pulse or pulse of light from a fiber optic cable and performing a logical calculation. The result is translated to movement, creating a domino effect throughout all the gates that physically changes the shape of the device.

“Many mechanical logic designs have substantial limitations and you run into fanciful designs that could not be fabricated,” Panas said. “What we’re doing is using these flexures, these flexible elements that are 3D printed, which changes how the logic structure can go together. We eventually realized we needed a displacement logic setup (to transfer information). Surprisingly, it actually worked.”

The flexures’ buckling action allows the structure to be preprogrammed or store information with no need for an auxiliary energy flow, Panas said, making them well-suited for environments with high radiation, temperature or pressures. Panas said logic gates could be used to collect temperature readings in vaccines or foods and notify when certain thresholds have been reached, or inside bridges to collect data on structural loading, for example.

“We see this as simple logic being put into high-volume materials, potentially getting readings in places where you can’t normally get data,” Panas said.

At UCLA, Hopkins used a 3D printing process called two-photon stereolithography, where a laser scans within a photocurable liquid polymer that cures and hardens where the laser shines, to print a set of gates at a sub-micron level.

“Once the structure was printed, we then deformed it in place using different lasers that act as optical tweezers,” Hopkins explained. “We then actuated the switches using those optical tweezers as well. It's a revolutionary new approach for making these materials at the micro-scale.”

The design was driven by computationally modeling the gates’ buckling behavior, and although they were designed in two dimensions, Pascall said he would like to move to 3D. Pascall hopes the technology can be used to design secure, personalized control systems, and said plans are to release the design as open source. The technology also could be a teaching tool for students, who could print their own logic gates using commercial 3D printers and learn about how computers work, he added.

The researchers have begun a new Laboratory Directed Research and Development (LDRD) project to explore scaling and examine transduction chemistry. Other contributors included Julie Jackson Mancini of LLNL, and Yuanping Song, Samira Chizari and Lucas Shaw of UCLA.

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