声表面波跨越式输运数字微流体

Surface Acoustic Wave Transporting Digital Microfluid with Leap-type

研究了声表面波实现数字微流体在压电基片上跨越障碍物的方法。在128°YX-LiNbO3压电基片上采用微电子工艺制作了中心频率为25.5MHz的叉指换能器和反射栅,在声传播路径上涂覆Teflon AF 1600疏水薄膜,聚二甲基硅氧烷垫块贴合于压电基片上。经功率放大器放大的射频信号加于叉指换能器激发声表面波,并作用在声路径上的数字微流体,在其内产生声流,当瞬间减少射频信号功率,部分液体因惯性力大于表面张力而飞离微流体,跃过聚二甲基硅氧烷障碍物,实现在压电基片上跨跃障碍输运。采用油包红色染料溶液微流体进行了实验,结果表明,当射频信号功率从12.3dBm瞬间下降到-3.98dBm时,油包红色染料溶液微流体可跃过高度1mm的障碍物。

A method for the transportation of a digital microfluid by jumping an obstacle on piezoelectric substrate is studied.An IDT with center frequency of 25.5 MHz and a reflecting grating are fabricated on a 128°YXLiNbO3 piezoelectric substrate by the micro-electronic process.Hydrophobic film is coated on the acoustic path and a polydimethylsilicone（PDMS） obstacle is mounted on it.A radio frequency signal amplified by a power amplifier is applied to the IDT to generate surface acoustic wave.When the surface acoustic wave meets with the digital microfluid on the piezoelectric substrate during transportation,part of acoustic wave energy is radiated into the digital microfluid,leading to internal acoustic streaming.Once the radio frequency signal power with appropriate amplitude is suddenly decreased,part of the digital microfluid will jump the obstacle due to inertial force.Red dye solution digital microfluids with oil encapsulation are demonstrated for transportation experiments.Results show that the digital microfluids can be transported from one side to another of the obstacle with 1 mm height when the power of radio frequency signal power is suddenly reduced from 12.3 dBm to-3.98 dBm.