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Boyue Su

Publications and source records attributed to Boyue Su.

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Particle manipulations based on acoustic valley topological rainbow defect-state trapping

Acoustic microfluidic is an important technology in particle manipulations in biomedical analyses and detections. However, the particle-movement manipulations achieved by the standing surface acoustic wave is suitable for particles in a thin layer of fluids, however it is difficult to manipulate particles in deeper solutions due to the energy loss of surface acoustic waves. The traditional standing bulk wave method can realize the particle manipulation in deep solutions, but it cannot work properly for particle manipulation within a long distance due to the energy loss. In this work, the topological rainbow defect-state trapping is realized, the results show that an effect of point accumulation of acoustic pressure in the waveguide path exists, the position of maximum acoustic pressure can be adjusted flexibly by changing the frequency of the incident acoustic wave, based on which, long-distance movement and capture manipulations of particles in deep solution have been realized. The phenomenon presented in this work can provide a reliable method for manipulations of continuous long-distance particle movement and capture to meet the demand of multiple processing steps in biochemical analyses and detections. The experiment verification results will be presented in the near future.

physics.class-ph

Anomalous size effects with fixed criticality in bistable flexible mechanical metamaterials

When the structure deformation is dominated by the low-energy deformation mode, the structure hardens with the increase in the size (number of units) at small sizes. This anomalous behavior will eventually disappear with the decay length of the finite structure converging to a size-independent characteristic quantity, but the specific critical point at which the anomalous behavior disappears still cannot be accurately and concisely described. Here, under two steady states of the bistable chain, we observed anomalous size effects with constant and oscillating criticality (the proportion of inhomogeneous deformation), two criticalities exactly separate the increasing and decreasing intervals of stiffness variation. They are interrelated due to the implied symmetries between the two steady states. On the other hand, they are distinguished because of the opposite superposition modes under the two steady states. Specifically, the constant criticality corresponds to the anomalous size effect achieved by the competition mechanism, while the oscillating criticality reveals an anomalous size effect achieved by the new mechanism (cancellation mechanism). In the anomalous size effect achieved by the cancellation mechanism, the singular characteristics generated by the completely cancelled deformation make it very robust. This robustness reflects in that the anomalous effect is no longer limited to linear small deformation, but it can still be observed stably in nonlinear large deformation. Our study reinterprets the anomalous size effect at a quantitative level, and the proposed cancellation mechanism expands the possible application range of this anomalous effect.

physics.app-ph

Elastic fractal higher-order topological states

Fractal is an intriguing geometry with self-similarity and non-integer dimensions, the elastic-wave topological phase based on fractal structures has not been revealed up to now. In this work, elastic-wave higher-order topological states in fractal structures are investigated. Elastic real-space quantized quadrupole moment is calculated and used to characterize the topology of elastic fractal metamaterials, and formation conditions of topological phase transitions in elastic fractal systems are revealed. The topological edge and corner states of elastic waves in fractal structures are realized theoretically and experimentally. It is found that different from the acoustic fractal system, the topological outer and inner edge states can emerge separately in elastic fractal systems, which is important for the integrated sensing and particle manipulation in microfluidics. Besides, the results show that the robustness of the topological corner states in rhombus fractal structures is obviously stronger than that in Sierpinski fractal structures, and the physical mechanism is clarified. Compared with traditional elastic-wave topological insulators based on periodic structures, the richness of topological states in elastic fractal structures is much higher (for the Sierpinski fractal structure, the number of topological states is 156, much greater than that of the periodic structure (only 28)), which is vital in integrated sensing and energy-location applications. The topological phenomena of elastic fractal systems revealed in this work, provides an unprecedented way of controlling elastic waves, enriches the topological physics of elastic systems and breaks the limitation of that relying on periodic elastic structures. The results have great application prospects in high-Q resonators, high-resolution elastic-wave energy locations, energy harvester, and high-sensitivity sensors.

physics.app-ph