柔性尖端耦合气泡的高稳定性增强型超声微流控结构

High stability enhanced ultrasonic microfluidic structure with flexible tip coupled bubbles

超声微流控技术是一种将高频超声激励耦合至微流控芯片的技术。针对常规超声微流控器件柔性尖端结构扰动效果差以及气泡易受热变形等问题,提出一种柔性尖端耦合气泡的增强型超声微流道结构,提高流场扰动效果以及结构稳定时长。首先,利用有限元分析方法对超声激励下柔性尖端、气泡、耦合三种结构的流场分布特性进行仿真,得到速度场稳态分布特性。然后,设计并制备三种结构的超声微流控芯片,利用2.8μm聚苯乙烯微球作为示踪粒子对流场扰动特性进行分析。此外,对贴壁气泡和耦合结构中气泡尺寸及生长速度进行分析。最后,利用人血红细胞(RBCs)对耦合结构的生物样本适用性进行验证。实验结果表明:相比于柔性尖端及贴壁气泡结构,耦合结构的流场扰动范围分别提高439.53%和133.48%;气泡生长速率可由14.4%降低至3.3%。本文提出的增强型超声微流控结构有望在微米尺度流场扰动及颗粒操控方面广泛应用。

Ultrasonic microfluidic technology is a technique that couples high-frequency ultrasonic excitation to microfluidic chips.To improve the issues of poor disturbance effects with flexible tip structures and the susceptibility of bubbles to thermal deformation,we propose an enhanced ultrasonic microchannel structure that couples flexible tips with bubbles aiming to improve the disturbance effects and the stability duration.Firstly,we used finite element analysis to simulate the flow field distribution characteristics of the flexible tip,the bubble,and the coupling structure and obtained the steady-state distribution characteristics of the velocity field.Next,we fabricated ultrasonic microfluidic chips based on these three structures,employing 2.8μm polystyrene microspheres as tracers to analyze the disturbance characteristics of the flow field.Additionally,we analyzed the bubble size and growth rate within the adhering bubbles and coupling structures.Finally,we verified the applicability of the coupling structure for biological samples using human red blood cells(RBCs).Experimental results indicated that,compared to the flexible tip and adhering bubble structures,the flow field disturbance range of the coupling structure increased by 439.53%and 133.48%,respectively;the bubble growth rate reduced from 14.4%to 3.3%.The enhanced ultrasonic microfluidic structure proposed in this study shows great potential for widespread applications in micro-scale flow field disturbance and particle manipulation.