Mechanism And Experiment Research Of Micro And Nano Particles Trapping By Ultrasonic Standing Wave

Rapid and real-time detection of micro or nano particles is more and moreconcerned with the development of environmental protection and anti-terroristconsciousness. Rapid aggregation of micro/nano particles in fluid is the primaryproblem to be solved in the rapid disease diagnosis as well as the pollutantsscreening. Microfluidic technologies, such as dielectrophoresis, hydrodynamicfocusing, have obvious advantages in precise manipulation of micro/nano particles.Of which, the ultrasonic standing wave based particles collection technology isfocused due to its simplicity in structure and high efficiency. The basic mechanismand experimental studies were presented herein.First, several microfluidic technologies for particle manipulation are reviewed,and the research status and main problems of ultrasonic standing wave basedparticles collection technology is presented in details. Basic particle collectionmechanism and main influence factors on acoustic radiation force is revealed;particle and surrounding solution properties play decisive roles in particleaggregation locations. Expressions of first and second order radiation forces areproposed and the key parameters are analyzed herein. In addition, the acousticstreaming affected on the small particles is analyzed to show the effective range ofacoustic streaming and its working principles.Then, the particle aggregation chip structures are designed using square crosssection capillary tubes, and proper materials of piezoelectric ceramics chips areused via acoustic impedance analysis of the system. The standard productionprocess of the ultrasonic standing wave based particle aggregation chips is proposedand resonance frequencies of the capillary tubes are numerical simulated, providingbasis for the following experimental studies.And then, particles(0.5μm,3μm,5μm,10μm and20μm in diameter) suspensionswith different concentrations in water are used for rapid aggregation to analyze theeffects of particle diameters, concentration, and frequencies on the gatheringefficiency, showing agreement of basic theories and simulation analysis.Finally, rapid collection of HELA cells and human hepatoma cells areexperimental performed in details. It shows that the ultrasonic standing wavetechnology can be well used for bio-particle collections, providing broad potentialapplications in biotechnologies.