Acoustic Levitation Characteristics Of Hexagon Ultrasonic Arrays And Their Manipulate Methods

Ultrasonic near-field levitation can be applied to realize non-contact clamping or transportation by using a high-intensity sound field formed between the radiation end and a flat suspended object by using sound waves excited by the vibration of an ultrasonic transducer.Compared with other levitation methods,ultrasonic near-field levitation technology has the advantages of strong levitation ability,no electromagnetic interference,and no special requirements on the electromagnetic properties of the suspended material.It has broad application prospects in the semiconductor industry and high precision processing.Acoustic levitation in air and fluid have varieties of potential applications through contactless processing.Base on the acoustic levitation technology,concept of contactless transport could be achieved by assembling transducers array which charged with spatiotemporal modulation of the acoustic field.It allows continuous planar transport and manipulation of multiple granule objects or small droplets.In this paper,we present a unique faveolate ultrasonic array to enlarge the transport efficiency and control flexibility.The main research contents and progress are as follows:1.Aiming at the limitations of the rectangular radiation end commonly used in ultrasonic arrays,this paper designs a transducer including a regular hexagonal ultrasonic radiation end based on a traditional Langevin oscillator,and optimizes its structural parameters through numerical calculations and finite element simulations.The simulation results show that the transducer using a regular hexagonal radiation end has an end face amplitude that is about 20% higher than a transducer using a rectangular radiation end of the same size.At the same time,under the condition of a certain perimeter,compared with a rectangle,a regular hexagon can enclose the largest area through dense arrangement.Therefore,from the perspective of geometric topping,using the radiating end of the hexagon can obtain higher array topping efficiency and space utilization;2.Using COMSOL multi-field coupling finite element software,a coupling model of piezoelectric and acoustic fields of ultrasonic transducers was established,and the acoustic fields excited by uniaxial transducers and hexagonal transducer arrays under different acoustic field boundary conditions were explored Distribution characteristics.The fluid flow particle tracking module in COMSOL was used to discuss the sound field manipulation characteristics based on the element phase and amplitude control,which laid the foundation for future hexagonal ultrasonic array acoustic suspension manipulation experiments;3.Eight sets of transducers were processed and assembled,and the pretension force was adjusted by using an impedance analyzer and a two-dimensional laser vibrometer.The measured first-order longitudinal vibration frequency was in the range of 34.37 k Hz to 34.9k Hz,and the finite element simulation was performed.The results differ by about 2%,with good consistency.An array near-field acoustic levitation experiment was carried out using an ordinary disc with a diameter of 80 mm as a load.The stable suspension height was measured at 908 micrometers and the rotational angular velocity was 0.997 rad / s.The near-field levitation capability of the array was studied through near-field levitation experiments of suspension sheets of different diameters,masses,and materials.The diameter of the radiating end surface of the hexagonal transducer array was 38 mm to 46 mm and 66 mm to 98 mm.Acrylic discs can be suspended stably.Acrylic discs with diameters below 18 mm are difficult to suspend,while the rest are in a metastable suspension state.The suspension height of the plexiglass sheet of the same mass is lower than that of the wood chip,and the influence of the quality of the wood chip on the suspension height of the plexiglass sheet is relatively large.