Fluid streaming and microparticles manipulating based on piezoelectric arrays excitation with various switching frequencies and duty cycles

Acoustic vortices can transfer angular momentum and trap particles. Here, we establish an annular arrays consisting of 64 piezoelectric ceramics to produce planar acoustic vortices and control the angular velocity and direction of streaming in fluid by excitation of piezoelectric. The particles in fluid chamber are trapped and move along lower pressure area. The angular velocities of them are theoretical analyzed by Bessel Function and experimentally observed by microscope. Also the PIV (Particle Image Velocimetry) method is adopted to evaluate the movement of particles in experiments and stable angular velocity of streaming by tools of MATLAB. The results show that vortices exist in fluid chamber with the excitation of piezoelectric arrays and the angular velocity is influenced by parameters of switching frequency and duty cycle of excitation. This research is helpful to realize the angular velocity and direction manipulation of particles which are trapped in fluid streaming and helpful to guide the design of acoustic tweezers.