Digital Microfluidic Electrochemical Detection Platform For Building And Explore In Heavy Metal Detection

Digital Microfluidics,abbreviated as DMF,is a technology which manipulates droplets,in parallel with channel droplet technology.In DMF,electric fields are applied on electrodes which were previously fabricated with evaporation,sputtering or wet-etching.Theoretically,surface tension of a droplet between the dielectric layer and the liquid on top of it was modified.Also,the movement of individual droplets on dielectric surfaces were controlled to achieve the generation,splitting and transportaiton.By integrating microcontroller,personal computer and other feedback software and hardware technique,intelligent DMF realized manuvre of droplets with human intelligence.As a result,autonomous operation of droplet generation,dispensing,transport,fusion and positioning was accomplished.Recently,DMF emerged as a mature technology and demonstrated broad application potential,and eventually it will make unqiue contribution in chemistry,biology and medicine.In this thesis,firstly,intelligent DMF system for lab use,with hardware,functions,droplet manipulation mechanism,expert controller module and software interface were addressed.Secondly,spincoating was adopted for manufacture of low-cost digital chips.Also,the fabrication recipie of low-cost,high-perforance chips were investigated and the droplet actuation mechanism was studied.Finally,preliminary application of DMF system in integrated electrochemical detection of heavy metal ions were conducted.The major work in this thesis includes:1.A low-cost,high-performance composite insulation layer for digital microfluidic chips was obtained.In this recipe,CEP/p-d PMMA were used as double insulation layer.The resultant chip displayed a wide operation voltage from 30V-350V.Importantly,our deposition method does not rely on expensive instrument and the total cost was 1%of those in pervious reports only.2.Analysis was made on the actuation force exerted on droplets on our composite-layer-insulated DMF chip.From the results,it can be found that the superior performance comes from the negiligible portion of EWOD force and the dominant part of DEP force in the overall electromechanical force on droplts.3.PECVD was used to deposit Si02 insulation layer with a thickness of 800 nm.Magnetron sputtering was applied to deposit electrochemical sensing microelectrodes in platinum.After that,the sensing electrodes were addressed with oxidized graphene.Also,this electrode was used to test Pb2+with cyclic voltammetry.At-0.421 V,0.02mmol/LPb2+was detected.