Particle Separation using Acoustic Wave Device for Microfluidic Applications

Abstract

Particle separation and sorting has become an essential step in many fields especially in medical field, biology and biochemical analysis. One of the successfully proven methods to separate the particles is through labelling process. However, this method has its limitations. One of them is that it can damage the physical properties and shorten the lifetime of the particles. Meanwhile, chip separation method by surface acoustic wave (SAW) device provides an automated and fast response process. In this separation process, standing surface acoustic waves (SSAW) induced by annular interdigitated transducer (AIDT) on piezoelectric substrate provides several distributions of pressure nodes and anti-pressure nodes in microfluidic medium. The operation frequency for AIDT is at 30.6 MHz while the RF power supply is at 20 dBM. This present study used this phenomenon to study the effects of SSAW in manipulating and separating polystyrene particles in a confined area. The separation efficiency of SAW device was analysed from various experiments conducted. A mixture of two polystyrene particles with different size suspended in deionised water was used in each experiment. The suspended particles in the liquid medium experienced acoustic radiation force within the generated SSAW. The particles with positive acoustic contras factor will move toward pressure nodes, whereas those with negative acoustic contras factor will move toward anti pressure nodes. Based on the efficiency of the separation process, it was shown that two polystyrene particles with different diameter (1 μm and 9.9 μm) have the highest separation efficiency. Thus, it can be concluded that contactless aggregation method is suitable for microfluidic applications especially in coculture cell biology, which does not affect the physical condition of cells.