Driver and control for variable impedence load

Abstract

An acoustic standing wave is utilized to separate components from a multi-component fluid, such as oil from an oil-water mixture, or cells entrained in a fluid, in a fluid flow scheme with an acoustophoresis device. For example, the flow scheme and device allows for trapping of the oil as the oil coalesces, agglomerates, and becomes more buoyant than the water. A driver and controller for the acoustophoretic device accommodate variable loading as the components are separated, thereby improving separation efficiency.

What is claimed is: 
     
         1 . An acoustophoresis system, comprising:
 a chamber for receiving a fluid mixture that includes cells or particles in a fluid;   an ultrasonic transducer coupled to the chamber and configured to be excited to generate an acoustic wave in the chamber;   a driver electrically connected to the ultrasonic transducer and configured to provide an excitation to the ultrasonic transducer to generate the acoustic wave in the chamber, the driver including an amplifier; and   a controller for controlling the amplifier based on reactance determined from feedback signals from the ultrasonic transducer.   
     
     
         2 . The system of  claim 1 , wherein at least one ultrasonic transducer comprises a plurality of transducers, each of the plurality of transducers individually electrically connected to its own amplifier. 
     
     
         3 . The system of  claim 1 , wherein the amplifier further comprises an inverter. 
     
     
         4 . The system of  claim 1 , further comprising a capacitor electrically connected between the amplifier and the at least one ultrasonic transducer. 
     
     
         5 . The system of  claim 1 , further comprising a filter electrically connected between the amplifier and the at least one ultrasonic transducer. 
     
     
         6 . The system of  claim 3 , wherein the amplifier further comprises a DC-DC converter coupled to an input of the inverter. 
     
     
         7 . The system of  claim 6 , further comprising a filter between the DC-DC converter and the inverter. 
     
     
         8 . A method for controlling an acoustophoretic device that uses an ultrasonic transducer, the method comprising:
 driving an amplifier electrically connected to the ultrasonic transducer to send an output signal to the ultrasonic transducer;   receiving at a controller a feedback signal from the ultrasonic transducer; and   adjusting the output signal from the amplifier with the controller to obtain a desired reactance of the ultrasonic transducer.   
     
     
         9 . The method of  claim 8 , further comprising determining the phase angle of the impedance of the ultrasonic transducer. 
     
     
         10 . A system for controlling an associated ultrasonic transducer, comprising:
 an amplifier that produces an output signal to the ultrasonic transducer;   a controller connected to the amplifier for controlling the amplifier; and   the controller being electrically connected to receive an impedance measurement from the ultrasonic transducer.   
     
     
         11 . The system of  claim 10 , further comprising the amplifier being configured to produce an RF output. 
     
     
         12 . The system of  claim 10 , further comprising the controller being configured to measure power delivered to the ultrasonic transducer and to control the amplifier to control a power level of the output signal. 
     
     
         13 . The system of  claim 10 , further comprising the controller being configured to control a frequency of the output signal. 
     
     
         14 . The system of  claim 12 , further comprising the controller being configured to identify a frequency of the output signal that produces a predetermined impedance measurement from the ultrasonic transducer and to control the amplifier to provide the output signal at the frequency.