Detection,Counting and Controlling of Microdroplet Using Image Processing and Control Techniques

Author:Faisal Mehmood

Supervisor:yin bao qun


Degree Year:2019





Droplet Microfluidics is a branch of microfluidics that has attracted great attention in recent years because of its interdisciplinary nature and has wide applications in various field especially in biomedical applications.It revolutionizes many different operations on droplets,such as,controlling the droplet,counting and detection of droplets to replace complicated experiments in chemical laboratory by employing integrated and miniaturized systems.However,microfluidic systems have encountered many challenges,one of which is to detect as well as to control the movement of micro droplet accurately and efficiently inside the micro channel.Many researchers succeeded in controlling the size of droplet through flow rates but only few have introduced efficient methods for droplet detection and counting.Hence few efforts have been devoted for this issueFor the first time we have introduced an effective and efficient system to resolve these issues automatically using control strategies.The contribution of this dissertation can be divided into two phases or techniques.In the first part we have successfully detected as well as counted the droplet inside the microfluidic channel.This is the first report in which we have presented an automatic system based on image processing algorithm for detection and counting of the droplets.This image processing algorithm is based on temporal differencing-based motion detection algorithm for continuous flowing droplet detection and counting.To account the intensity characteristics of droplet images,there are actually two steps performed by this specific algorithm.First of all,motion detection is carried out for all the droplets in every single frame.After that,complete droplet counting is performed based upon the detected moving droplet counts in each frame.A comprehensive discussion regarding this operation is presented in the report.Also,the overall system was tested to generate droplet of phosphate-buffered Saline and 8%polyethylene glycol diacrylate pre-polymer droplet.The results depicted that our algorithm is capable of detecting the droplets as well as counting them with lowest statistical errors.In the second part we have develop an overall system to control droplet movement inside microfluidic channel using fuzzy logic controller,image processing algorithm and micro-valves installed within microfluidic channel.Microvalves are one of the most significant control component in a microfluidic system,that are utilized to control the timing,position as well as rate of flow for generation of droplet in a microfluidic system.An additional desirable characteristic of designing a micro valve is the fact that it should be inexpensive,convenient to manufacture,includes a small footprint,can certainly function as the external valve going inside the channel as well as also can easily be integrated with complicated microfluidic network.The performance of two different controllers,PID and FLC,have been compared for this work.After careful consideration and concluding outputs,FLC has been selected and implemented.The fuzzy logic controller has been designed with fuzzy rule matrix and membership function providing an automatic technique for adjusting flow rates using syringe pumps.As soon as the desired droplet position of droplet is achieved,the controller closes that particular valve at the current position of droplet.Moreover,an image processing algorithm,based on greedy algorithm,is designed for tracking the droplet movement inside microfluidic channel.This algorithm helps in feedback input parameters to the controller,for example,the current location of droplet,error(distance between desired and current position of droplet in the microfluidic channel)and change in error(distance covered by the droplet from initial position desired position).On the basis of these parameters controller makes decision of changing the flow rates and to close a particular valve for precise position control.A COMSOL based study is primed for device structure by means of droplet generation and controlling the droplet through fitted valves.