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Abstract Microtubules and catalytic motor proteins underlie the microscale actuation of living materials, and they have been used in reconstituted systems to harness chemical energy to drive new states of organization of soft matter (e.g., liquid crystals (LCs)). Such materials, however, are fragile and challenging to translate to technological contexts. Rapid (sub‐second) and reversible changes in the orientations of LCs at room temperature using reactions between gaseous hydrogen and oxygen that are catalyzed by Pd/Au surfaces are reported. Surface chemical analysis and computational chemistry studies confirm that dissociative adsorption of H2on the Pd/Au films reduces preadsorbed O and generates 1 ML of adsorbed H, driving nitrile‐containing LCs from a perpendicular to a planar orientation. Subsequent exposure to O2leads to oxidation of the adsorbed H, reformation of adsorbed O on the Pd/Au surface, and a return of the LC to its initial orientation. The roles of surface composition and reaction kinetics in determining the LC dynamics are described along with a proof‐of‐concept demonstration of microactuation of beads. These results provide fresh ideas for utilizing chemical energy and catalysis to reversibly actuate functional LCs on the microscale.
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This content will become publicly available on August 1, 2026
Zero‐standby power hydrogen sensing using event‐driven micromechanical switches
Abstract Zero‐standby power sensors are crucial for enhancing the safety and widespread adoption of hydrogen (H2) technologies in chemical processes and sustainable energy applications, given the flammability of H2at low concentrations. Here, we report an event‐driven hydrogen sensing system utilizing palladium (Pd)‐based micromechanical cantilever switches. The detection mechanism relies on strain generation in the Pd layer, which undergoes reversible volume expansion upon hydrogen adsorption. Our experimental and simulation results demonstrate that the bistable micromechanical switch‐based sensor generates a wake‐up signal with activation time depending on hydrogen concentration in the target environment while always remaining active for events without any standby power consumption under normal conditions. The H2adsorption‐induced subsequent switching of the multi‐cantilever‐based switch configuration on the sensor resulted in the quasi‐quantification of hydrogen concentrations. The reported zero‐standby power sensor's operational lifetime is limited by the frequency of detection events and exposure to concentrations exceeding hydrogen's flammability limit. This work advances the development of high‐density, maintenance‐free sensor networks for large‐scale deployment with Internet of Things devices, enabling unattended continuous monitoring of hydrogen generation, transportation, distribution, and end‐user applications.
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- Award ID(s):
- 2102027
- PAR ID:
- 10628509
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Responsive Materials
- Volume:
- 3
- Issue:
- 3
- ISSN:
- 2834-8966
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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