Key Technology And Experimental Research For Digital Microfluidic Chip

At present, the digital microfluidic chip has had a certain application in the field ofbiology, chemistry and medicine, especially electrowetting on dielectric based digitalmicrofluidics, it has the atvantage of simple structure, convenient control, smallvolume,less reagent consumption, configurable, parallel processing and easy toautomate.So it has great application prospect in every field experiment. This paper mainresearch the electrowetting on dielectric based digital microfluidics respectively from thebasic theory of dielectric wetting technology, computer simulation and experimentalcomparison and analysis. The main contents includes:(1) By comparing the change of surface tension method, it is concluded the advantageof electrowetting on dielectric in droplets driven.Then theoretical basis of electrowetting ondielectric is introduced,the related formula is deduced and improved, drive the advantagesof the droplets, and the theoretical basis of dielectric wetting method, is introduced to therelevant formula derivation and improvement, finally we expound and analysis the fourbasic operations of the droplet(2)We use Comsol software to do some modeling and simulation of digitalmicrofluidic chip, discuss the voltage distribution, discuss the impacts of thickness ofdielectric layer on the voltage distribution and the effect of contact Angle along with thechanges of the applied voltage. We establish the droplet movement and split model, dosimulation to get each, discuss the influence of the style of electrode, electrode size anddistance between the on droplet movement. According to the simulation results of dropletmotion process, we get the best chip parameters: electrode side length to1mm, the lowersubstrate spacing of0.1mm to0.3mm, thickness of dielectric layer is1microns.(3)Design the overall structure and the electrode array, introduce production process,electrode layer uses laser engraving technology, dielectric layer uses vapor depositiontechnology, hydrophobic layer uses plasma surface treatment technology, zero electrodeselects ITO conductive glass. Exploit control circuit based on89C51, control dc voltage oneach electrode by photoelectric coupling switch.(4) Set up the experimental platform for research the influence of various parameterson the droplet movement, complete the droplet movement experiment, comparison and analysis the result of the experiment, get the following conclusion: droplet contact angledecreases with the increase of the applied voltage, and in a certain voltage reach saturatedcontact Angle; with the increase of thickness of dielectric layer, droplet contact Angledecreased slower; Different electrode style’s influence on the droplet movement is not big,fork tooth shape electrode droplets moving effect is better; the thicher dielectric layerthickness is, the greater minimum applied voltage the droplet requires for.(5) Because of the limitation of chip processing technology and the experimentalconditions, the measurement of droplet contact angle is not accurate, also can’t complete thedroplet generation, split and merge experiment, there are many deficiencies and needs to beimproved.