Design Of Fluorescence Based Digital Droplet Sorting System

The digital fluorescent droplet sorting system which has the ability to analyze single droplet and the features of high accuracy and absolute quantification is based on the digital microfluidic chip and can sort the fluorescent and non-fluorescent particles which contained by droplet.Digital fluorescent droplet sorting system is ideal for the sorting of fluorescent labeled tumor cells,protein and bacterial for early diagnosis of the disease and microbial culture.Based on the research of digital microfluidic fluorescent droplet sorting system,a complete experimental platform is built to verify the feasibility of the sorting principle.In this paper,the principles of digital microfluidic and fluorescence detection are summarized and analyzed.The mechanism of the electrowetting-on-dielectric(EWOD)which effects on droplet contact angle and the manipulation of droplets are researched.On this basis,according to the need of sorting,the electrode array pattern and the material of each layer of chip are determined.The processing technology is designed according to the device structure,and the production of the device is completed using micro-nano processing technology.The hardware of the droplet sorting system is designed mainly to realize the droplet sorting,including the design and implementation of the fluorescence detection module,the signal modulation module,the electrode driving module and the control module.The development of related software includes the development of master control software running on μC/OS-Ⅲoperating system platform and the software used to generate drive signal source.Finally,an experiment platform is built based on the designed droplet sorting system.First,the droplet driving experiment is carried out to verify the realization of the automatic dispensing and transporting function of the system,and the optimal driving voltage,driving speed and driving droplet concentration range are explored.Then,the electric signals of the sorting process are collected in parallel and the different wave-forms corresponding to the different types of droplets are matched,and the theory of dynamic fluorescence threshold is proposed.Finally,the sorting experiment was carried out using the droplets having a concentration of 0.01mg/ml fluorescent particles and O.Olmg/ml mix particles,and the non-fluorescent droplets and fluorescent droplets were separated successfully by comparing the droplet images with the electric signal waveforms,and the feasibility of the system was verified.