Abstract: A device for performing the manipulation of particles suspended in a fluid is disclosed. The device comprises a duct for the flow of a fluid in which particles are suspended, an acoustic transducer, and a reflector for establishing an acoustic standing wave field across the width of the duct. It has been unexpectedly found that optimum performance of the device occurs when the spacing between the transducer and a reflector is 300 microns or less. The device seeks to overcome prior engineering difficulties that prevented one from observing the individual particle bands or separating the individual particle bands from the duct.

Abstract: There is disclosed an acoustic device for manipulation of fluid samples including fluid samples comprising particles characterised in that it comprises a flexible member, a sound wave generator for generating a sound wave and a sound wave coupler for coupling the sound wave from the generator into the flexible member, in which the device, flexible member and the coupler are adapted to excite a predetermined acoustic mode of pure resonant vibration in the flexible member at a predetermined frequency of the sound wave.

Abstract: A device for performing the manipulation of particles suspended in a fluid is disclosed. The device comprises a duct for the flow of a fluid in which particles are suspended, an acoustic transducer, and a reflector for establishing an acoustic standing wave field across the width of the duct. It has been unexpectedly found that optimum performance of the device occurs when the spacing between the transducer and a reflector is 300 microns or less. The device seeks to overcome prior engineering difficulties that prevented one from observing the individual particle bands or separating the individual particle bands from the duct.

Abstract: There is disclosed apparatus for directing particles entrained in a fluid, comprising a chamber having a first wall, including means for generating a sound wave having a frequency v, and a second, opposite wall capable of reflecting the sound wave in which the first and second wall define a conduit for the passage of the fluid, and in which the thickness of the second wall is such that the path length of the standing wave in the second wall is a multiple of about ½ the wavelength ?r of the sound wave therein.

Abstract: A device for performing the manipulation of particles suspended in a fluid is disclosed. The device comprises a duct for the flow of a fluid in which particles are suspended, an acoustic transducer, and a reflector for establishing an acoustic standing wave field across the width of the duct. It has been unexpectedly found that optimum performance of the device occurs when the spacing between the transducer and a reflector is 300 microns or less. The device seeks to overcome prior engineering difficulties that prevented one from observing the individual particle bands or separating the individual particle bands from the duct.

Abstract: A device for performing the manipulation of particles suspended in a fluid, comprises a chamber forming a duct for the flow of the fluid, and an acoustic transducer (10) and a reflector (12) for establishing an acoustic standing wave field across the width of the duct the spacing between the transducer and reflector is 300 microns or less. With such a small spacing, the device is particularly effective at concentrating the particles and lower operating voltages are required.

Abstract: An apparatus which manipulates particles suspended in a fluid includes a duct for the flow of the fluid in which the particles are suspended, and a mechanism for establishing an acoustic standing wave field across the width of the duct, the duct being formed with an expansion in width downstream of the standing wave field. In use, the particles in the fluid are displaced into a series of parallel bands by the acoustic standing wave field. The particles remain in these bands as the fluid flows downstream from the section in which the standing wave field is present. When the fluid reaches the expansion of the duct, the stream of fluid expands accordingly in width and, in so doing, the bands of particles are spread further apart, so increasing the spacing between adjacent bands. The bands can then be observed or separated from the duct.