## 4 Micromanipulation by Vibration-Induced Steaming Flow
### Vibrated Geometric Substrates  
The vibrated geometric substrate (VGS) refers to the terminal performing the operation function being the substrate or being mounted on the substrate. This kind of manipulating device has a variety of shapes and structures. Figure 1f shows a typical substrate manipulating structure. Micromanipulation using a structure mounted on a substrate is suitable for many specific operational tasks. Micropillars, micro line-shaped strips, and special-shaped cavities are all common structures that expand upon the substrate. Although the VGS manipulator is similar to the general in-plane manipulating device in shape, the former is more inclined to use the vibration-induced phenomenon of fluid rather than ARF.  
The VGS manipulator proposed by [PERSON] et al. [69; 70] has a typical structure (Figure 6a). By applying a circular vibration to the spiral pattern of the micropillars array, a swirling flow is induced around the micropillars, and target particles or cells are transported toward the catcher placed at the center of the spiral. [PERSON] et al. [71] similarly used line-shape strips structures, which are illustrated in Figure 6b. High-frequency vibration induces strong turbulence at sharp corners of the strips, with linear flow near the long straight side. So, the particles around the strips can be driven in the linear region at a stable speed. Their acoustic robotic platform allows large-scale parallel transport for microparticles and cells along given paths. A human-microbot interface was designed that enables the manipulator to respond promptly to the users' command inputs for accurate transport. The two methods above can be applied to cell transport. The lower operating frequency (<1 MHz), simpler operation mode, and potential programmability have certain advantages for application. However, its particular structure requires complex manufacturing processes and limited execution capabilities. Every proposed new structure oriented to the operation target has to do all the work from beginning to end.  
Figure 6: Vibrated geometric substrates by [PERSON] et al. [69; 70], [PERSON] et al. [71], and [PERSON] et al. [72; 73]. (**a**) Very small micropillers are machined equidistantly along two symmetrical spiral lines. When the substrate is vibrated, microfluidic forms between the two helixes, which drives the particles to move. (This figure is republished reference [70] of [PERSON] et al. and licensed under CC BY-NC-SA 3.0. Copyright © 2014, The Authors) (**b**) A programmable substrate manipulator. The vibration of the geometry substrate can simultaneously manipulate particles. (Republished with permission of American Chemical Society from reference [71]. Copyright © 2019, American Chemical Society; permission conveyed through Copyright Clearance Center, Inc.) (**c**) The substrate is composed of glass instead of traditional LiNbO3. The vibration of the substrate forms a ring-shaped potential well so that particles are concentrated here.  
Using silicon substrate vibration to control particle motion is another method. The vibration generated or propagated through the substrate can induce the ARF. This effect can be observed in the vibration of the drumhead. [PERSON] et al. [72; 73] proposed a manipulator where a vibrating glass substrate was used. Cells amass along with the node of resonance vibration when the vibration is excited on the substrate, since with the resonance vibration, the antinode position largely vibrates while the node position does not. The concept is schematically illustrated in Figure 6c. This resonance-based device is effortless in patterning, but not flexible enough and hard to apply. The related research is also less popular, but provides significant inspiration for directly exciting the vibration on the glass substrate, which significantly reduces the complexity of transducer production.