Veröffentlichungen und Präsentationen

Microfluidic devices based on acoustophoresis have garnered significant attention due to their potential applications in biomedical and chemical analysis. Acoustophoresis employs acoustic waves to manipulate and separate particles within microfluidic channels according to their size, mass, and density with respect to the suspending fluid. Among the various types of surface acoustic waves (SAWs), Rayleigh waves are highly effective due to their superior coupling efficiency in transmitting mechanical energy from the piezoelectric substrate to the fluid. This work aimed to design and optimize a piezoelectric transducer device for the generation of standing Rayleigh waves to enhance particle sorting efficiency. The COMSOL Multiphysics® software was used to address this complex problem, providing rapid results before device fabrication and overcoming the costly and time-consuming trial-and-error approach currently prevalent in the manufacturing of these devices. The COMSOL Compiler™ was used to simulate the generation of standing waves between two sets of aluminum interdigitated transducers (IDTs) deposited on a lithium niobate substrate with a 128° YX cut. The geometry and design of the simulated device were selected starting from those already studied in literature from similar applications. The employed modules include Structural Mechanics and Electrostatics, coupled through the Piezoelectricity Multiphysics module. As first step, a reduced unit domain based on the device's geometric periodicity was considered. The resonance frequency of Rayleigh waves was determined through a modal analysis followed by a harmonic study. The obtained frequency was then used as the operating frequency to study the frequency response of a transverse section of the device, in the reduced domain. By exciting the two IDTs at the resonance frequency, standing waves between the two sets of IDTs were observed, with most of the mechanical energy confined within this region. Furthermore, the device's admittance was examined. At the identified resonance frequency, a parametric study was conducted to verify the linear dependence of the oscillation amplitude on the applied excitation. Applying a sinusoidal potential to the IDTs at the resonance frequency, a time-dependent analysis was performed to study the transient phase before the generation of the standing wave. Finally, the entire device was designed (full domain) and the harmonic study replicated at the previously determined resonance frequency, to obtain a digital twin of the real device for comparison. These preliminary results are extremely promising for the application of the device for acoustophoresis.