Pump using ultrasonic transducer and opposing surface (1st report : observation of pump effect)

Currently, pumps are used in various fields to supply air and liquid. These pumps include sliding parts and there is a limit of life time due to friction and wear. To solve this problem, a number of pumps using ultrasonic vibration have been proposed. A common feature of ultrasonic pumps is having no sliding parts. Therefore, the life time seems longer than those of the conventional pumps. In the present study, we found an occurrence of pump effect when an opposing block faces ultrasonically vibrating surface with a small gap. The ultrasonic transducer has a hole to provide the path for fluid flow and the opposing surface was a tapered end of an aluminum cylinder. According to the measurement results of gauge pressure, when circumference of the opposing block is tapered, air was discharged from the gap of two surfaces. On the other hand, when center of the block is tapered, air was sucked into the gap. Microscopic quasi-static behavior of the two surfaces is observed by using a digital microscope during pump operation.