The breakup of digital microfluids on a piezoelectric substrate using surface acoustic waves

A new method for the breakup of a digital microfluid (a discrete droplet) is presented and a device for splitting the digital microfluid is fabricated on a 128° yx-LiNbO3 piezoelectric substrate using microelectronic technology. Together with the surface tension of the digital microfluid, the inertia of acoustic streaming caused by the sudden disappearance of the electric signal for generating the surface acoustic wave breaks up the digital microfluid. The escape angle of the daughter digital microfluids is calculated. A sound-absorption film is coated on the acoustic path to prevent the further breakup of the daughter digital microfluids. Droplet breakups are demonstrated using red dye solution digital microfluids. Results show that digital microfluids can be broken up by suddenly decreasing the power of the electrical signal from 12.3 dBm to -3.98 dBm, and the average escape angle of daughter digital microfluids is 68.5° for 4 μL of initial digital microfluid. The results also show that the escape angle is affected by the initial volume of the digital microfluid.