Dual path trace distribution system and experimental study of micro fluid driving and control based on pulse
|School||Nanjing University of Technology and Engineering|
|Course||Mechanical Manufacturing and Automation|
|Keywords||pulse driving&controlling of micro-fluids technology micro-dispensing two-channel microarray|
In the fields of life science, electronics packaging, rapid manufacturing and so on, precise and parallel dispensing operations of liquid materials with different natures are generally required, and the amount of reagent has been decreased to nanoliter and even picoliter level. It is of great significance to carry out the research on the automatic micro dispensing technology with small volume, high speed operating and wide applicability.As that non-contact dispensing method has the advantages of quantitative accuracy and good repeatability, it is the main development direction of dispensing technology currently. However, there are some deficiencies in the non-contact dispensing technologies, such as that the thermal driving type may affect the activity of the biological sample and the sprinklers in the displacement piezoelectric drive technology are not easy to disassemble, clean and maintain. The pulse driving&controlling of micro-fluids technology has advantages of high resolution of dispensing liquids, simple structure and wide applicability. A dual channel micro dispensing system based on pulse driving&controlling technology of micro-fluids was developed and basic experiments and application experiments were carried out. The research achievements were as follows:A dual channel micro-dispensing system consisting of a droplet generator, precision worktable, nozzle clamping and adjusting devices and control systems was developed. Among them, the droplet generator was the key device to realize micro dispensing with functions of regulating pressure of the liquid in micro-nozzle, fluid drive-control and clamping of micro-nozzle. Motion control, waveform, micro-arrays, graphics and other parameters were sent to the lower machine through PC interface and serial communication of the control system, and the lower system which the soft kernel of Nios II built-in FPGA was used as CPU could generate dual channel drive random waveform and drive two stepper motors, thus parallel, graphical, high precise and automatic micro-dispensing were realized.Basic experiments of micro dispensing were conducted using gycerol solution as dispensing liquid based on this system. The influences of the system parameters (including the driving voltage, the drive frequency, the inner diameter of the micro nozzle, viscosity of liquid, and the dispensing distance) on the dispensing amount and dispensing stability were researched. Dispensing liquid viscosity could be reach38mPa·s, dispensing volume could be reduced to picoliter level. The relative standard deviation (RSD) of the dispensing volume was less than1.74%under the conditions that the driving voltage was20V-80V, so the dispensing was stable. These results were basis for selecting experiment methods and system parameters.The research for the micro-lens array preparation was conducted based on this system. The UV-curable adhesive was jetted in drop-on-demand motion on the glass substrate coated with the hydrophobic film, and a15×15micro-lens array was obtained after the UV irradiation. The RSD of the diameter was0.64%, non-uniformity of the focal length was1.7%. A clear real image of the micro-lens array was obtained. The experiment process and results indicated that the system for the prearation of the micro-lens array had many advantages such as the simple fabrication process, low cost, higher precision, better material applicability and so on.The research on a phosphate buffer array solution with a pH gradient was conducted. Different ratios of Na2HPO4solution and KH2PO4solution were dispensed for mixing-reaction experiment, and a phosphate buffer arrays solution with a pH gradient was prepared on the ceramic substrate. Results showed that the RSD (n=9) of spots diameter of the prepared pH gradient arrays was0.8%, and the spots reacted fully, and also had uniform colors and significantly changed gradients. Results showed that parallelly dispensing with higher dispensing precision could be realized by this system, and solutions with different concentrations and ratios could be prepared by the adjusting the ratio of the reagents, and then meet the demand of automation, parallel and micro-dispensing.