关键词: 生物医学超声/
单微泡/
振动/
声微流
English Abstract
Microbubble oscillation induced acoustic micromixing in microfluidic device
Zhao Zhang-Feng1,Zhang Wen-Jun1,2,
Niu Li-Li2,
Meng Long2,
Zheng Hai-Rong2
1.Key Laboratory of E & M, Ministry of Education and Zhejiang Province, Zhejiang University of Technology, Hangzhou 310014, China;
2.Paul C Lauterbur Research Center for Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen
Fund Project:Project supported by the National Natural Science Foundation of China (Grant No. 11674347), the Youth Innovation Promotion Association, Chinese Academy of Sciences (Grant No. 2018393), the Natural Science Foundation of Guangdong Province, China (Grant No. 2017B030306011), and the Shenzhen Basic Research Program, China (Grant No. JCYJ20160429184552717).Received Date:16 April 2018
Accepted Date:12 July 2018
Published Online:05 October 2018
Abstract:Microfluidic is of great significance for biomedical research and chemical engineering. The mixing of liquids is an essential and necessary procedure for the sample preparation. Due to the low Reynolds number, laminar flow is dominant in a microfluidic channel and it is difficult to mix the fluids in the microchannel quickly and effectively. To improve the mixing efficiency of the liquids in microfluidic channels, we develop an acoustic mixer based on single microbubble oscillation. By designing the cylinder structure on the bottom surface, when the fluid flows through cylinder structure with a diameter of 40 m, the microbubble can be generated by the surface tension of the liquid. The device is fabricated by using standard soft lithography and the replica moulding technique, ensuring the stability and repeatability of the mixing. A piezoelectric transducer (PZT) with a resonant frequency of 165 kHz is attached to the polydimethylsiloxane microfluidic device on the glass substrate by ultrasound coupling gel. When the microbubble is excited by the PZT at a resonant frequency of 165 kHz, microbubble oscillates immediately. To verify whether ultrasound can induce microbubble cavitation, a passive cavitation detection system is established. The results show that the higher harmonics can be detected, indicating that the stable cavitation occurs. The microstreaming induced by the oscillating microbubble disturbs the fluid dramatically, achieving the mixture of liquids. Particle image velocimetry method is utilized to characterize the microstreaming, and a pair of counter-rotating vortices in the microchannel is detected. Furthermore, to test the performance of the device, the deionized water and rhodamine B are injected into the Y-shape microchannel. Relative mixing index is used to quantitatively analyze the mixing performance by measuring the grayscale values of the optical images. The results indicate that with the increase of the input power, mixing time can be shortened correspondingly. When the input power is 14.76 W, the mixing process is ultrafast, within 37.5 ms the high mixing uniformity can be achieved to be 92.7%. With the advantages of simple design, high efficient and ultrafast mixing, and low power consumption, this oscillating microbubble-based acoustic micromixer may provide a powerful tool for various biochemical studies and applications.
Keywords: biomedical ultrasound/
single microbubble/
oscillation/
microstreaming
