Figure 5.

Focusing performance of the BAW device as a function of applied voltages at the transducer: (a) UV–Vis characterization and (b) image analysis. During the experiments, 4MPs concentrated at 5.68 $\times$ 10⁵ particles/mL were injected at 3 μL/min into the device actuated at its resonant frequency of 4.623 MHz, while 56.92 Vpp, 50.59 Vpp, 37.95 Vpp, 25.29 Vpp and 12.65 Vpp were applied at the transducer.