A silicon microfluidic ultrasonic separator

Ultrasonic standing waves can be used to generate forces on particles within a fluid. Such forces have a number of potential applications in microfluidic devices. This paper describes a device that provides filtration on a microfluidic scale. It is microfabricated and uses ultrasound in the megahertz frequency range to concentrate particles at a node within the flow. It offers the possibility of a functional equivalent of a centrifugal separator for microfluidic systems. It is constructed using silicon and Pyrex, and hence is compatible with established microfabrication techniques. The modelling, design, fabrication and control of the device are discussed. (C) 2003 Elsevier B.V All rights reserved.