基于声表面波驱动器的液体单方向驱动

Liquid Unidirectional Actuation Based on Surface Acoustic Wave Actuators

设计了一种浮动电极型单向换能器(FEUDT)结构,用于激发单向声表面波(SAW),从而实现液体的单向驱动。通过对FEUDT结构模型的阻抗分析与SAW传播分析,获得了SAW驱动器的谐振频率、最佳驱动频率和最优指条宽度。利用剥离工艺,在128°旋转Y切向X方向传播的铌酸锂基板上,制作了周期为80μm、指条对数为40对、指条金属层厚度为1μm、指条宽度为7.3μm的FEUDT型SAW驱动器。搭建了SAW驱动器的驱动系统,实现了液体在器件表面上单向驱动。实验结果表明:FEUDT型SAW驱动器在驱动功率为4 W、驱动频率为48.8 MHz的电信号激励下,液滴在SAW驱动器表面上的驱动速度可达50 mm/s;在驱动功率为6.2 W、驱动频率为48.8 MHz的电信号激励下,液体在微流道中的驱动速度约为20 mm/s。

A structure of floating electrode type unidirectional transducer（FEUDT）was designed,which can excite a unidirectional surface acoustic wave（SAW）to realize the liquid unidirectional actuation.Through the impedance and SAW propagation analysis of the FEUDT structural model,the resonant frequency,optimum driving frequency and optimum strip width of the SAW actuator were obtained.The FEUDT SAW actuator with the period of 80μm,the strip pair of 40,and the strip metal of 1μm layer thickness and7.3μm strip width was fabricated on a 128°rotated Y-cut X-propagation LiNbO3 substrate using lift-off process.A driving system of the SAW actuator was built,and the unidirectional actuation of the liquid on the surface of the device was realized.The experiment results show that the driving speed of the droplets on the surface of the SAW actuator are up to 50 mm/s under the FEUDT SAW actuator excited by the electrical signal with the driving power of 4 W and the driving frequency of 48.8 MHz,and the driving speed of the liquid in the micro channel is about 20 mm/s under the driving power of 6.2 W and the drive frequency of 48.8 MHz.