Analysis of the ultrasonic collection of small particles by a tapered metal strip

This paper presents the analysis of ultrasonic collection of small particles by a tapered metal strip in vibration. The tapered metal strip, which is mechanically driven by one of the four corners of a sandwich-shaped ultrasonic transducer, is used to trap small particles. A physical model is built for the acoustic radiation force acting on a spherical small particle near the sharp edge of the metal strip. Experimental and theoretical results of the smallest vibration velocity for trapping particles in air agree very well. Based on the physical model, the effects of vibration velocity, particle density, particle radius, driving frequency, and gravitation on the trapping capability are theoretically investigated and discussed for different fluids and useful guidelines for the optimum design are proposed.