Parylene C Deposited Vacuum-driven PDMS Microfluidic Chip For Digital PCR And Immunodetection

The digital PCR(dPCR)technology is wellknown as the third generation of PCR technology.The microfluidic chip technology provides an excellent platform for the application of dPCR.Among all the dPCR microfluidic chips,the self-priming compartmentalization(SPC)dPCR microfluidic chip developed by our research group not only can achieve DNA absolute quantification as other commercial instruments do,but also can achieve sample introduction without the need for external power sources.It provieds a simple and portable method for dPCR and has a wide application prospect.This paper developed a kind of vacuum self-maintaining dPCR microfluidic chip by depositing a layer of Parylene C membrane on the outside of the chip,and showed the holding time of the vacuum-driven power of the chip could be greatly extended to 30 days.This method totally solved the problems of the former SPC dPCR microfluidic chip of being hard to maintain the vacuum-driven power of the chip at atmospheric pressure.Furthermore,a Parylene C deposited vacuum-driven polydimethylsiloxane(PDMS)pump was developed and applied to a protein detection microfluidic chip as a power source.The main innovative developments include:1?A SPC microfluidic chip suited for the dPCR analysis has been developed.A glass coverslip is used as a waterproof layer.Channels that contain water are also designed around each sample panel to prevent the solvent(water)from evaporating during dPCR process.The statistics principle of dPCR is explored based on Poisson distribution,and the dynamic range and precision of the method have been explored.This dPCR chip allows three samples to be amplified simultaneously.In addition,since the reaction chambers and the channels have the same height,which makes the mold to be made much easier.It was shown that the template DNA solutions diluted to concentrations of 10 copies/?L can be measured quantitatively on the dPCR microfluidic chip.2?A novel method for making Parylene C coated vacuum self-maintaining dPCR PDMS microfluidic chip is for the first time presented,which prolongs the storage time of the SPC chips.And the mechanism of the vacuum-driven capability of PDMS microfluidic chips has been studied.Since Parylene C membrane has characteristics of transparent,compact and low permeability to gases,the reactions and results detections on the chip would not be affected.Furthermore,the evacuation process and Parylene C coating process can be carried out during the same time,the operation is quite easy.This new method prolongs greatly the storage life of the vacuum-driven PDMS microfluidic chips from one day to more than thirty days,and these chips still have the capacity of doing dPCR analysis.This performance would make SPC micro fluidic chips be widely accepted in point-of-care diagnosis.3?Some vacuum-driven pumps are made by depositing Parylene C membranes on the surfaces of PDMS blocks,and such pumps have been applied to the protein detection microfluidic chips to offer the driven power for test solution introduction and for reaction channels' washing.Using the characteristics of proteins adsorption of PDMS and Poly-l-ysine(PLL),the protein detection microfluidic chips are made of PDMS and PLL coated glass slides.These protein detection microfluidic chips making use of the principle of immunoassay,have been made and been successfully applied to the semi-quantitative detection of methamphetamine(MET)and procalcitonin(PCT).