Experimental Research On Pulse Driving And Controlling Of Micro-fluids

Driving and controlling of micro-fluids in micro-nano-scale structures is one of the key technologies promoting the development of micro-system. Liquid micro-jetting and powder micro-feeding are the important research areas in driving and controlling of micro-fluids. At present, there are a lot of realization methods, but most of them have bottlenecks. For example, huge external drives, special properties requested for liquid, complex processing technology of micro-nozzel and so on, exist in liquid micro-jetting; low resolution and difficulty of precise delivery exist in powder micro-feeding. The technology of driving and controlling of micro-fluids with high resolution and broad applicability is an important topic worthy of study. Simultaneously, designing and fabrication of micro-nozzels and application researches should be done.There are some creative theories in pulse driving and controlling of micro-fluids. In this paper, the technology of pulse driving and controlling of micro-fluids was applied to liquid micro-jetting and powder micro-feeding, and the basic principle and implementation device were introduced. Experimental studies were carried out in accordance with conclusions of theoretical analysis. Then, the preparation of droplet microarray, powder microarray and combinatorial materials array was guided by the experimental results. Meanwhile, based on the thermal deformation principle of glass, the fabrication process of glass micro-nozzles suited to the technology of pulse driving and controlling of micro-fluids was studied. The research achievements are as follow:The theoretical analysis results of micro-flow characteristics under the pulse driving and controlling of micro-fluids were provided, and the system parameters related with micro-flow characteristics of fluids were qualitatively obtained by theoretical analysis. On the basis of theoretical analysis results, a series of basic experiments were projected to study how the system parameters affect the micro-flow characteristics of fluids. The experimental results showed:under the pulse driving and controlling of micro-fluids, the liquid digitized micro-jetting and powder digitized micro-feeding could achieve high resolution, good stability.The influence laws of the system parameters affecting the micro-flow characteristics of fluids were obtained by the the experimental data and could be provided as basis for the applications of the liquid digitized micro-jetting and powder digitized micro-feeding. Based on the thermal deformation principle of glass, the fabrication process of glass micro-nozzles suited to the technology of pulse driving and controlling of micro-fluids was studied. The prototype for forging glass micro-nozzles and microscopic measurement system for measuring structural parameters of glass micro-nozzles were designed. The glass micro-nozzles were fabricated by the forging and pulling process based on the thermal deformation principle of glass, which had the following advantages:simple production process, easy to operate, and low cost.Application studies of the technology of pulse driving and controlling of micro-fluids on powder feeding in the laser cladding, the preparation of biochip and combinatorial materials chip were preliminarily carried out, including the experimental preparation of droplet microarray, powder microarray and combinatorial materials array.Using the liquid digitized micro-jetting, the medium-density microarray with 4000spot/cm2 was accomplished. Experimental results showed that average diameter of spots was 100?m; separation distance of spots was 160±10?m; spots were homogeneous and round; coefficient of variation (CV) for diameters of spots was 4.61%.Using the powder digitized micro-feeding, the powder microarray was accomplished. Density of powder microarray was 350spot/cm2, and mean diameter of spots was about 200?m. The regularity of powder microarray was remarkable.By directly feeding the powder of raw materials, Y2O3:Eu3+ luminescence materials array was successfully prepared. The feasibility that the technology of pulse driving and controlling of micro-fluids could be applied to preparation of combinatorial materials chip had been proven.