It has been experimentally demonstrated that droplets,as tiny as 2 μm in diameter,can be generated at rates as high as 20 kHz,with much lower flow rates than needed in the case of conventional flow focusing.The configuration for generating such small droplets consists of a capillary cross,with an exit orifice inserted into the disperse phase channel.With such a structure,the interface of two immiscible fluids is deformed to a shape like Taylor cone.Upon its formation,tiny droplets are issued from the cone tip.This method is found to be highly stable across the flow rate ratios of external to internal fluids,1～60.By manipulating capillary inner diameters,tip diameters and tip positions,as well as the flow ratio,one can effectively produce droplets in various sizes.%基于毛细管十字连接器构建了一种新型聚焦流微液滴发生器结构.相对于常规微流体聚焦流结构,在较低流量条件下,该结构能产生更小的液滴.实验数据表明,液滴尺寸最小到2 μm,液滴发生频率高达20kHz.在该液滴发生结构中,液滴产生和收集毛细管的端部经过激光加热拉尖后,伸入到分散相通道在十字连接器处的出口.在实验中观察到,在毛细管尖端前面.分散相形成了一个稳定的泰勒锥形状,其中心形成一个尖端;该尖端进入拉尖的毛细管内部少许,液滴顺着尖端发射出来.实验发现当连续相和分散相流量比为1～60时,该结构能够稳定地制备微液滴.通过调节毛细管内径、尖端直径、尖端位置以及流量比,能有效地控制液滴直径.
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