Patent ID: 7674630
Filing Date: 2010-03-09
Classification: A61M,B01D,Y10T

Abstract:
1. A method for separation of particles of a particle mixture suspended in a medium, comprising the steps of: subjecting medium in a chamber to ultrasonic energy generating a first ultrasonic standing wave at a first frequency having first pressure nodes; placing the particle mixture in the chamber, so that a concentration of the particle mixture is placed at or in the vicinity of a first pressure node of the ultrasonic standing wave at said first frequency or anywhere between the first pressure node and a wall of the chamber ( switching the frequency of the ultrasonic standing wave to a second frequency generating a second ultrasonic standing wave having at least one second pressure node, so that a first set of particles of the particle mixture is experiencing a smaller acceleration towards said second pressure node, and a second set of particles of the particle mixture is experiencing a greater acceleration towards said second pressure node; maintaining the second frequency during a time duration t switching back to the first frequency; wherein the smaller first distance is so small that the first set of particles of the particle mixture is experiencing a greater acceleration towards the first pressure node, and the greater second distance is so great that the second set of particles of the particle mixture is experiencing a smaller acceleration towards the first pressure node; maintaining the first frequency during a time duration t repeatedly switching the ultrasonic standing waves between the first and second frequencies with a duty cycle involving their respective time durations t