Guan Zhang

Two-Dimensional Motor Based on Surface Acoustic Wave

With the development of high precision processing, the miniaturization demand of motors with super-precision positioning and simple fabrication become an urgent problem. This paper illustrates a surface acoustic wave (SAW) motor for two-dimensional positioning. The SAW motor include a SAW stator and a slide. In order to realize the two-dimensional moving, four Interdigital Transducer (IDTs) are fabricated on the four directions of a 0.5-mm thick, 128°YX- LiNbO3 substrate. Comparing the aluminum material, the copper material selected to be used as IDT in our experiment has many advantages. Each of the four copper IDTs has 10 straight finger pairs in a simple repeating pattern, the IDT aperture is 10mm and the pitch is 400μm. The SAW stator is fabricated by the lift-off process. The dimension of the device is 29mm (width) X29mm (length). The slide consists of three ruby balls with the diameter of 1mm and an plastic disc with the thickness of 0.5mm and the diameter is 8mm. With the four radio frequency driving sources, two-dimensional motion is possible. The maximum speed of the slide that was placed on the SAW propagating surface was 5mm/s when the applied driving power was 28W and the applied driving frequency was 9.6MHz. The experiments indicate the two-dimensional motor based on SAW would be applicable to miniature motor and improve the resolution.

Micro mixer based on surface acoustic wave driving

A resonance frequency of 8.9MHz copper Interdigital Transducer (IDT) is fabricated on a 127.8°YX type LiNbO3 substrate by lift-off process and the rapid droplet mixing is experimentally realized using the surface acoustic wave(SAW). The droplet mixing principle and the manufacturing process of the mixer are illustrated in detail. The droplet generates one swirl when only portion of the droplet is located on the saw propagating surface. The droplet generates two swirls when the whole of droplet is located on the saw propagating surface. The mixing between red particles with an average diameter of 1.5μm and a droplet with a volume of 3 μl is successfully implemented. No matter the droplet covers whole or just partly the saw propagating surface, the mixing process can be completed in one second when the applied driving power is 9W. The applications of SAW micro fluidics should be greatly enhanced using the rapid mixing process proposed in this paper.