An acoustic focusing capillary includes a capillary coupled to at least one vibration source possessing a groove. A method of manufacturing such an acoustic focusing capillary includes providing a capillary and a vibration source, machining a groove into the vibration source, and coupling the vibration source to the capillary at the groove. Another method relates to focusing a particle stream and includes flowing a sheath fluid into an outer confine of a capillary, flowing a particle stream into a central core of the capillary, and acoustically focusing the particle stream by applying acoustic radiation pressure to the particle stream at a first location along the capillary. The particle stream may be further focused by hydrodynamically focusing it at a second location along the capillary downstream of the first location.