Kirigami-inspired mechanical computer; TMD defects; switching magnetite with light.
Researchers from North Carolina State University 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 uses 1-centimeter plastic cubes, grouped into functional units consisting of 64 interconnected cubes.
When cubes are pushed up or down, which can be done either physically or with a magnetic field, the geometry of all the connected cubes are changed.
“We were interested in doing a couple things here,” said Jie Yin, an associate professor of mechanical and aerospace engineering at NC State, in a press release. “First, we were interested in developing a stable, mechanical system for storing data. Second, this proof-of-concept work focused on binary computing functions with a cube being either pushed up or pushed down – it’s either a 1 or a 0. But we think there is potential here for more complex computing, with data being conveyed by how high a given cube has been pushed up. We’ve shown within this proof-of-concept system that cubes can have five or more different states. Theoretically, that means a given cube can convey not only a 1 or a 0, but also a 2, 3 or 4.”
The researchers released a video showing the system in action.
“One potential application for this is that it allows for users to create three-dimensional, mechanical encryption or decryption,” added Yanbin Li, a postdoctoral researcher at NC State, in a press release. “For example, a specific configuration of functional units could serve as a 3D password. And the information density is quite good. Using a binary framework – where cubes are either up or down – a simple metastructure of 9 functional units has more than 362,000 possible configurations.” [1]
Researchers from the Princeton Plasma Physics Laboratory and University of Delaware examined common defects in 2D transition-metal dichalcogenides (TMDs) and are working to design plasma-based manufacturing systems for TMD-based electronics.
“When bulk TMDs are made, they have excess electrons,” said Shoaib Khalid, an associate research physicist at PPPL, in a release. “In this work, we explain that the excess electrons can be caused by hydrogen.”
The team investigated how each defect configuration might impact the electrical charge of the material, finding that one of the defect configurations involving hydrogen provides excess electrons, which creates an n-type semiconductor material.
They also explored chalcogen vacancy defects. “This is a common defect. They can often see it from the images of scanning tunneling microscopes when they grow the TMD film,” Khalid said in a release. “Our work provides a strategy to investigate the presence of these vacancies in the bulk TMDs. We explained past experimental results shown in molybdenum disulfide, and then we predicted a similar thing for other TMDs.” [2]
Researchers from École Polytechnique Fédérale de Lausanne (EPFL) and Politecnico di Milano found that magnetite can be made more or less conductive to electricity by shining different wavelengths of light on it.
The team used two different wavelengths of light: near-infrared (800 nm) and visible (400 nm). When excited with 800 nm light pulses, the magnetite’s crystal lattice structure compressed rapidly, creating a mix of metallic and insulating regions. The transition took place in three stages that happened over 50 picoseconds. 400 nm light pulses caused the lattice to expand and made the magnetite a more stable insulator.
The researchers anticipate that the ability to induce and control hidden phases in magnetite could point the way to new materials for computing and memory that can switch between different electronic states rapidly. [3]
[1] Yanbin Li et al., Reprogrammable and reconfigurable mechanical computing metastructures with stable and high-density memory. Sci. Adv. 10, eado6476(2024). https://doi.org/10.1126/sciadv.ado6476
[2] Shoaib Khalid, Anderson Janotti, Bharat Medasani. Role of chalcogen vacancies and hydrogen in the optical and electrical properties of bulk transition-metal dichalcogenides. 2D Materials, 2024; 11 (3): 031003 http://dx.doi.org/10.1088/2053-1583/ad4720
[3] B. Truc, P. Usai, F. Pennacchio, G. Berruto, R. Claude, I. Madan, V. Sala, T. LaGrange, G. M. Vanacore, S. Benhabib, F. Carbone. Ultrafast generation of hidden phases via energy-tuned electronic photoexcitation in magnetite. Proceedings of the National Academy of Sciences, 2024; 121 (26) http://dx.doi.org/10.1073/pnas.2316438121
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