Qiwen Liu

How to Make a Fast, Efficient Bubble-Driven Micromotor: A Mechanical View

Micromotors, which can be moved at a micron scale, have special functions and can perform microscopic tasks. They have a wide range of applications in various fields with the advantages of small size and high efficiency. Both high speed and efficiency for micromotors are required in various conditions. However, the dynamical mechanism of bubble-driven micromotors movement is not clear, owing to various factors affecting the movement of micromotors. This paper reviews various factors acting on micromotor movement, and summarizes appropriate methods to improve the velocity and efficiency of bubble-driven micromotors, from a mechanical view. The dynamical factors that have significant influence on the hydrodynamic performance of micromotors could be divided into two categories: environment and geometry. Improving environment temperature and decreasing viscosity of fluid accelerate the velocity of motors. Under certain conditions, raising the concentration of hydrogen peroxide is applied. However, a high concentration of hydrogen peroxide is not applicable. In the environment of low concentration, changing the geometry of micromotors is an effective mean to improve the velocity of micromotors. Increasing semi-cone angle and reducing the ratio of length to radius for tubular and rod micromotors are propitious to increase the speed of micromotors. For Janus micromotors, reducing the mass by changing the shape into capsule and shell, and increasing the surface roughness, is applied. This review could provide references for improving the velocity and efficiency of micromotors.

A Viscosity-Based Model for Bubble-Propelled Catalytic Micromotors

Micromotors have shown significant potential for diverse future applications. However, a poor understanding of the propelling mechanism hampers its further applications. In this study, an accurate mechanical model of the micromotor has been proposed by considering the geometric asymmetry and fluid viscosity based on hydrodynamic principles. The results obtained from the proposed model are in a good agreement with the experimental results. The effects of the semi-cone angle on the micromotor are re-analyzed. Furthermore, other geometric parameters, like the length-radius aspect ratio, exert great impact on the velocity. It is also observed that micromotors travel much slower in highly viscous solutions and, hence, viscosity plays an important role.

First-Principles Study on the Tensile Properties and Failure Mechanism of the CoSb3/Ti Interface

The mechanical properties of the CoSb3/Ti interface play a critical role in the application of thermoelectric devices. To understand the failure mechanism of the CoSb3(001)/Ti(01

Peridynamic simulation of transient heat conduction problems in functionally gradient materials with cracks

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Molecular dynamics simulations of the microstructure of the aluminum/alumina interfacial layer

1¯0) interface, we investigated its response during tensile deformations by first-principles calculations. By comparison with the result between the perfect interface and the interface after atomic migration, we find that the atomic migration at the interface has an obvious influence on the mechanical properties. The tensile tests indicate the ideal tensile stress of the CoSb3/Ti interface after atomic migration decreases by about 8.1% as compared to that of the perfect one. The failure mechanism of the perfect CoSb3/Ti interface is different from that of the migrated CoSb3/Ti interface. For the perfect CoSb3/Ti interface, the breakage of the Co-Sb bond leads to the failure of the system. For the CoSb3/Ti interface after atomic migration, the breakage of the Sb-Sb bond leads to the failure of the system. This is mainly because the new ionic Ti-Sb bonds make the electrons redistributed and weaken the stiffness of the Co-Sb bonds.

A non-ordinary state-based peridynamics modeling of fractures in quasi-brittle materials

Interfacial structure plays a critical role in the application of thermoelectric (TE) devices. To understand the bonding character of the CoSb3/Ti interface, we investigated its lattice structure, interface bonding energy, and electronic properties by first-principles calculations. Six possible models for CoSb3/Ti interfaces with an orientation relationship of [1 0 0](0 0 1)CoSb3//[2

Mechanism for amorphization of boron carbide under complex stress conditions

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