Study On The Miniature C⁴D Microfluidic Chip Detecting System And Its Applicationm In Cd²⁺ Detection

With the rapid development of modern industry，environmental contamination threatis increasing. In the large area around of local manufacturing，there are a lot ofpollutions, which contain a large number of heavy mental contamination, especiallythe manufacturing enterprises of metallurgy, electronics, leather, and so on. Theheavy mental contamination is very serious dangerous when they accumulate in thebody of organism through food chain. To meet the needs of environmental protectionand huaman health, it is essential of quantitative detection of heavy mentalcontamination.At present, universal detecting methods of heavy mental in national standards, such asAtomic Absorption Spectroscopy(AAS), Atomic Fluorescence Spectroscopy(AFS),Inductively coupled plasma mass spectrometry（ICP-MS）and anodic strippingvoltammetry(ASV),et al, are all dependent on sophisticated instruments and largelaboratory to complete detection, which device used are high consumption, big size,and expensive. More critical, these device are complex when run and operated, needhigher condition when used, can not use for field detection in simple conditions, sothey can’t meet the actual demand of rapid, on-spot, real-time, online water testing.So it is very necessary to develop portable testing device of heave mental in water,which characterise as high degree of automation, less reagent consumption and easyoperation and maintenance.Microfluidic chip analysis also known as Lab-on-chip, is one of the latest new frontierin the field of analytical chemistry, and it is proposed on the basis of Miniaturizedtotal analysis systems by analyzed scientists in1990s. Relying on MEMS processingtechnology and biotechnology, we can build a micro labs platform on a small chip.This kind of technique has perfect prospect in the field of analytical chemistry andbiochemical test because it is characterized as integrated, automatic, high-throughputand low consumption, which integrate all functions including sample, reaction,separation, and test. But traditional C4D microfuidic chip technology has four defects:difficult injection technology of samples, professional and expensive productiontechnology of chips, not universal of chip interfaces, unstable signals for quantitativedetection. All of these defects above-mentioned hinder the entrance to the status oflarge scale applications.In this study, we build an automatic testing method of heavy mental ion Cd2+in water with MEMS processing technology, biotechnology and microfluidic chip technology.Seven sections of the study are done:（1）Laser etching and quick printing ofmicrofluidic chip made of polymethylmethacrylate(PMMA)（.2）Enlarging the size ofarea and tunnel of traditional microfluidic chip in order to reduce the manufacturingdifficulty, to shorten the cycle, to increasing the successful ratio, and to meet thetesting demand of mg/L.（3）Modifying the reactive tunnel of microfluidic chip withepoxy and polyamide to form double layers of electrophoresis, using for separation ofsamples.（4）Designing the size of the interface identical with common medicalinjector, replacing the traditional high pressure electric injection with compatiblemanual or automatic injection, increasing the portability and reliability of themicrofluidic chip.（5）Designing the signal transduction pathways wireless, changingthe microfluidic chip becoming disposable materials, pluging and replacing at anytime（.6）Improving the detecting electrode of the microfluidic chip, strengthening thesignals to2～3times（.7）Completing the design and manufacture of high voltage DCmodule for electrophoresis and microfluidic pump module for multi-channel injection.In this study, we selected a detecting method of Cd2+in water with microfluidic chipfrom four kinds of traditional electrophoretic separation systems, such as EDTA, PAN,Cadion-Triton100, and MES-L-His and determine Cadion-Triton100as thebackground buffer.For Cd2+, Na+, Cl-, and SO42-which linear range is0.5～20mmol/L, the quantitativedetection can be complete simultaneously within20minutes, and the minimal testinglimitation of Cd2+is0.05mmol/when pH is equal10. The total volume of the deviceincluding C4D microfluidic chip testing system and power is less than20cm×20cm×28cm. Miniature high voltage DC output is0～30000V，0.5mA（Max）and the fine tuning is5V. The moderate flow rate of miniature microfluidic pumpwith four dependent channels is0.1～5ml/min.In this study, we have completed preliminary design of the microfluidic chip using fortesting water quality, built a simple, easy to use, and economic microfluidic chipdetecting system. The cost is about25,000yuan,which is only the1/10～1/40ofcurrent applied equipment, and the testing result is accurate and reliable. So it isachieved the purpose of experimental design.