Fig. 1.

(A) Integrated lysis and PCR set up. Device architecture showing the IDT used to generate the SAW on the LiNbO₃ piezoelectric wafer. The SAW is coupled into a superstrate. A microliter-sized droplet is positioned and coated with a layer of oil to prevent evaporation during processing. SI Appendix, Fig. S1 illustrates the interaction of the SAW with the drop. SI Appendix, Fig. S2 shows patterned hydrophilic tracks on the hydrophobic silicon superstrate, used to position the sample in place (3 mm disk, surrounded by a 200-μm wide annulus, 1 mm away). (B–E) Depending on the excitation frequency of the SAW, the square phononic lattice, machined into the superstrate, either filters or transmits the ultrasonic wave. Under conditions of SAW attenuation (9.5 MHz) the blood cells in the sample are lysed (B–C), whereas under transmission the ultrasonic wave causes heating (D–E) in a power-dependant manner. The lysis function occurs as a consequence of the propagation of the acoustic wave being hindered at a frequency within the stop-band of the phononic lattice, breaking the symmetry of the SAW and creating a rotational movement within the sample (B). This rotation results in shear flows that contribute to the disruption of the cell membrane. (C) The images are stills from SI Appendix, Movie S1 (9.5 MHz, 3.1 W) obtained through reflection microscopy. The first image (0 s) is taken before SAW actuation, whereas the last image (3.78 s) is taken after the SAW actuation has been turned off, to better show the increased transparency of the sample due to the disappearance of scattering cells after lysis. (Scale bar, 1 mm.) (D) Outside of the stop-band, the SAW propagates symmetrically and can be used to heat the sample. (E) The infrared image shows the drop at the denaturation temperature (95 °C, 1.3 W at 18 MHz). (Scale bar, 5 mm.)