基于狭缝超强局域模式的片上超声微流控系统特性及其应用研究

Acoustofluidic systems have shown unique advantages in performing manipulation of biological particles and sensing opaque liquid, which play a significant role in a variety of applications in biology, medicine and environment. Manipulation of micro objects with much smaller diameters, however, requires stronger acoustic confinement and higher intensities than can be provided by these diffraction-limited systems. Recently, we have demonstrated that there is a confined mode in a sub-wavelength slot between two plates immersed in an inviscid liquid that can be efficiently excited by a plane wave by introducing periodic grooves at the upper or lower side of individual plate. In this research, we will investigate the characteristics and application of acoustofluidics based on strong localized mode in a sub-wavelength slot. Firstly, the dispersion relation of the acoustic field in a sub-wavelength slot between two identical plates with three dimensional finite size will be theoretically analyzed. The force exerting on the sub-wavelength particle in slot will be analyzed. The influence of the properties of particle and liquid in slot on the resonant peak will also be analyzed. Then the acoustofluidic system based on slot structure will be manufacture by MEMS. At last, we will apply the system here to the manipulation of sub-wavelength micro/nanoparticles and sensing micro-fluid. We believe that the architecture proposal here will help to bridge the gap between acoustofluidics and nanotechnology.

片上超声微流控技术可在微尺度下非接触、无损伤地操控与传感生物微粒及非透明流体，在生物医学、环境检测等领域具有广阔的应用前景。然而，自由声场受声波分辨率和声场局域限制，无法操控与传感远小于波长的微粒和微量流体。最近申请人理论研究发现双板狭缝结构对声波具有超强限制能力，可在远小于波长狭缝中形成高度局域声场。本项目将探索该狭缝局域模式的声力和声传感特性，及其在微流控系统中的应用。具体内容为理论研究三维有限双板狭缝结构的声场特性，分析远小于波长微粒在含狭缝微腔体内的受力特征及运动形态，探索微粒和流体性质对狭缝局域声场的影响；基于微加工工艺制备含双板狭缝结构的超声微流控系统；实现对远小于波长微粒的操控和传感，对微量流体的传感与检测。本项目为揭示超强局域声场、流场、微粒与结构的耦合规律有重要价值，为发展新型超声微流控器件，实现对纳米微粒及微量流体的灵敏、高效的操控与传感奠定坚实的物理基础与技术支撑。

超声微流控技术可在微尺度下非接触、无损伤地操控与传感生物微粒及非透明流体，在生物医学、环境检测等领域具有广阔地应用前景。然而，受声波分辨率限制，自由声场无法操控与传感远小于波长的微粒与微量流体。本项目主要研究了双板狭缝结构超强局域模式的操控微粒与传感特性，具体探讨了狭缝声学参量、结构参量对超强局域模式的影响；研制了狭缝结构样品；研究了基于狭缝超强局域模式的高灵敏声学传感器和微纳颗粒操控，以及狭缝局域模式的微流体Rayleigh流动，并探讨了超振荡波束与声学超透镜的超分辨成像与微粒操控。研究发现构建狭缝结构的双板厚度、凸起周期、狭缝宽度等均影响狭缝模式，双板厚度越小，狭缝宽度越窄，局域模式越强；发现狭缝系统可用于对微量液体的声速和密度进行同时传感，且当液体声速和密度变化趋势相反时，该传感器灵敏度较高；利用该狭缝系统实现了对远小于波长微粒的捕获；发现狭缝反相耦合模式产生的强局域声场诱发了一种超快速类Rayleigh流，其与经典Rayleigh流的流场结构相似，但最大速度高4个数量级，且具有更小的涡旋尺寸，可以更精确地操控微量的运动；还发现超振荡波束可在远场实现超分辨成像与远小于波长微粒操控。该项目为片上声学微量流体高灵敏传感器、微纳米颗粒精确操控、微量流体操控等技术提供了全新的物理机制和系统的实验方案。