Robust acoustic particle manipulation: A thin-reflector design for moving particles to a surface.

Existing ultrasonic manipulation devices capable of pushing particles to a surface ("quarter-wave" devices) have significant potential in sensor applications. A configuration for achieving this that uses the first thickness resonance of a layered structure with both a thin reflector layer and thin-fluid layer is described here. Crucially, this mode is efficient with lossy reflector materials such as polymers, produces a more uniform acoustic radiation force at the reflector, and is less sensitive to geometric variations than previously described quarter-wave devices. This design is thus expected to be suitable for mass produced, disposable devices.