Separation of particles using the focused acoustic sorting chip based on the wettability treatment

Combining the focusing energy characteristics of the focused interdigital transducer with the self-cleaning function of the wettability surface, a focused acoustic sorting chip based on the surface wettability treatment is proposed in this work. In the laboratory, two kinds of focused acoustic sorting chips based on the hydrophilic and hydrophobic wall characteristics were designed and fabricated separately. The corresponding separation experiments were carried out using polystyrene microparticles with diameters of 1 and 10 µm. Moreover, the particle adhesion characteristics based on different surface wettability and the effects of average velocity (Va) and input power (P) on particle deflection were investigated. The relevant optimum separation conditions were confirmed, namely under the hydrophilic treatment of the micro-channel surface, when the work frequency (f) was 131.83 MHz, Va = 4 mm/s, and P = 320 mW. Under these conditions, the optimal separation efficiency can reach 99.17%. The proposed chip has the advantages of simple structure, high separation accuracy, self-cleaning, and focusing energy.