A scanning electron microscope (SEM) picture exhibits an origami tetrahedra microstructure that self-folded after it was uncovered to hydrogen. Credit score: Cornell College
Cornell researchers have devised a approach to make the most of chemical reactions for the self-folding of microscale origami machines, permitting them to work in dry, room-temperature situations. This breakthrough may pave the way in which for the creation of tiny, autonomous gadgets that quickly reply to their chemical environment.
A Cornell-led collaboration harnessed chemical reactions to make microscale origami machines self-fold – releasing them from the liquids by which they normally perform, to allow them to function in dry environments and at room temperature.
The method may at some point result in the creation of a brand new fleet of tiny autonomous gadgets that may quickly reply to their chemical surroundings.
The group’s paper, “Gasoline-Part Microactuation Utilizing Kinetically Managed Floor States of Ultrathin Catalytic Sheets,” was printed on Might 1 in Proceedings of the Nationwide Academy of Sciences. The paper’s co-lead authors are Nanqi Bao, Ph.D. ’22, and former postdoctoral researcher Qingkun Liu, Ph.D. ’22.
The venture was led by senior writer Nicholas Abbott, a Tisch College Professor within the Robert F. Smith Faculty of Chemical and Biomolecular Engineering in Cornell Engineering, together with Itai Cohen, professor of physics, and Paul McEuen, the John A. Newman Professor of Bodily Science, each within the School of Arts and Sciences; and David Muller, the Samuel B. Eckert Professor of Engineering in Cornell Engineering.
“There are fairly good applied sciences for electrical to mechanical power transduction, equivalent to the electrical motor, and the McEuen and Cohen teams have proven a method for doing that on the microscale, with their robots,” Abbott mentioned. “However in the event you search for direct chemical to mechanical transductions, really there are only a few choices.”
Prior efforts trusted chemical reactions that would solely happen in excessive situations, equivalent to at excessive temperatures of a number of 100 levels Celsius, and the reactions were often tediously slow – sometimes as long as 10 minutes – making the approach impractical for everyday technological applications.
However, Abbott’s group found a loophole of sorts while reviewing data from a catalysis experiment: a small section of the chemical reaction pathway contained both slow and fast steps.
“If you look at the response of the chemical actuator, it’s not that it goes from one state directly to the other state. It actually goes through an excursion into a bent state, a curvature, which is more extreme than either of the two end states,” Abbott said. “If you understand the elementary reaction steps in a catalytic pathway, you can go in and sort of surgically extract out the rapid steps. You can operate your chemical actuator around those rapid steps, and just ignore the rest of it.”
The researchers needed the right material platform to leverage that rapid kinetic moment, so they turned to McEuen and Cohen, who had worked with Muller to develop ultrathin platinum sheets capped with titanium.
The group also collaborated with theorists, led by professor Manos Mavrikakis at the University of Wisconsin, Madison, who used electronic structure calculations to dissect the chemical reaction that occurs when hydrogen – adsorbed to the material – is exposed to oxygen.
The researchers were then able to exploit the crucial moment that the oxygen quickly strips the hydrogen, causing the atomically thin material to deform and bend, like a hinge.
The system actuates at 600 milliseconds per cycle and can operate at 20 degrees Celsius – i.e., room temperature – in dry environments.
“The result is quite generalizable,” Abbott said. “There are a lot of catalytic reactions which have been developed based on all sorts of species. So carbon monoxide, nitrogen oxides, ammonia: they’re all candidates to use as fuels for chemically driven actuators.”
The team anticipates applying the technique to other catalytic metals, such as palladium and palladium gold alloys. Eventually this work could lead to autonomous material systems in which the controlling circuitry and onboard computation are handled by the material’s response – for example, an autonomous chemical system that regulates flows based on chemical composition.
“We are really excited because this work paves the way to microscale origami machines that work in gaseous environments,” Cohen said.
Reference: “Gas-phase microactuation using kinetically controlled surface states of ultrathin catalytic sheets” by Nanqi Bao, Qingkun Liu, Michael F. Reynolds, Marc Figueras, Evangelos Smith, Wei Wang, Michael C. Cao, David A. Muller, Manos Mavrikakis, Itai Cohen, Paul L. McEuen and Nicholas L. Abbott, 1 May 2023, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2221740120
Co-authors include postdoctoral researcher Michael Reynolds, M.S. ‘17, Ph.D. ‘21; doctoral student Wei Wang; Michael Cao ’14; and researchers at the University of Wisconsin, Madison.
The research was supported by the Cornell Center for Materials Research, which is supported by the National Science Foundation’s MRSEC program, the Army Research Office, the NSF, the Air Force Office of Scientific Research, and the Kavli Institute at Cornell for Nanoscale Science.
The researchers made use of the Cornell NanoScale Facility, a member of the National Nanotechnology Coordinated Infrastructure, which is supported by the NSF; and National Energy Research Scientific Computing Center (NERSC) resources, which is supported by the U.S. Department of Energy’s Office of Science.
The project is part of the Nanoscale Science and Microsystems Engineering (NEXT Nano) program, which is designed to push nanoscale science and microsystems engineering to the next level of design, function and integration.
