| 摘要 |
An ultrasonic wave (9) is transmitted through the substrate (1) towards the fluid film (7) to mix or promote exchange. Ultrasound coupling from the ultrasonic generator causes fluid movement at two or more poles of motion (15). The source is directed at an angle with respect to the plane of the fluid film. The ultrasound emitter is bidirectional; it is preferably an interdigital transducer (3). The sound undergoes reflection, the substrate being selected for total internal reflection. On the opposite fluid interface, imperfect reflection occurs, with non-zero loss, whereas within the substrate, losses are minimal. Two or more poles of motion result from variation of the propagation direction (alpha, alpha', theta, theta') with time. In the interdigital transducer producing ultrasonic waves, interdigital spacing is varied. By varying the applied frequency, the location of sound injection is varied. Location and direction of injection are varied using curved electrode fingers. These effects are caused by piezoelectric element with interdigital fingers, on the side of the film opposite the substrate. The arrangement may be used on an end face of the substrate (1). Diffusers or reflectors spread the waves. Film thickness is from a few microns up to 5 mm, preferably up to a few 100 microns in the direction of propagation. Ultrasound frequency is a few MHz to a few 100 MHz. An Independent claim is included for corresponding equipment.
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