Design Of Micro-Droplet Detection And Counting System With Optical Fiber

Droplet microfluidic technology is developed to realize the generation,manipulation and application of droplets on microfluidic chips in recent years.It is widely used in many fields,such as analytical chemistry,cells research and drug synthesis.Micro-droplets are reactors for processes of biochemical reaction,reagent mixing and particle synthesis.Therefore,it's important to count droplets whether to control the number of droplets to achieve the ratio of reactants,or to realize high-throughput analysis of droplets during the experiment.In order to realize the automatic counting of micro-droplets,a micro-droplet detection and counting system with optical fiber was designed in the paper.The main work and innovation of the paper are as follows:1.A micro-droplet detection and counting system with optical fiber was proposed and designed.On the microfluidic chip,the core of the receiving fiber is precisely aligned with the micro channel at the detecting area.The detecting and counting functions are realized according to the change of the light intensity when the droplet passes through the detecting area.Optical fiber arrays make the system easy to integrate and can detect multiple channels simultaneously.2.The design and simulation of the optical detection unit were completed.TracePro was used to simulate the optical path.The influence of beam collimation,droplet size,droplet refractive index and distance from receiving fiber to chip on the change of optical intensity caused by droplet passing through the detection area was discussed.The corresponding solutions are proposed for the characteristics of the signals under different detection conditions.The simulation results provide a basis for the overall design of the system.3.The design and debugging of the detection system hardware and software were completed.The hardware circuit includes a processing module of optical source modulation signal,a processing module of detection signal and a hardware control module,which can realize the processing of the droplet signal under different detection conditions.The software program includes epigynous computer software and hypogynous computer software,which realizes the human-computer interaction control and display of the counting result.4.The simulation experiment was completed and the actual droplet counting experiment was carried out after the experimental system has been built.The experimental results show that the system can process single-pulse signals and double-pulse signals under different detection conditions.The system can detect and count droplets with a radius of 10 ?m.What's more,the frequency that can be detected ranges from the low frequency to 7 KHz.The system satisfies the design goal of real-time detection and counting of high-throughput droplets on microfluidic chips.