Key Techniques Of Multi-layer Composite Structure Microfluidic Chip

Microfluidic chip integrates micro-channel, micro detection cell, micro-sensingelectrodes integrated on one small chip. It has many advantages, such as strongportability, wide range of applications and low costs. Amperometric detection is animportant method in the field of electrochemical detection. It also has advantages ofhigh sensitivity, simple equipment, and easy to be integrated with other parts ofdetection system. This paper promotes a multi-layer composite structure microfluidicchip amperometric detection system based on PCB technology. We integratemicrofluidic chip with amperometric detection circuit to achieve the amperometricdetection function as well as to improve the system integration degrees, to reducesystem size and to make the application easy to carry and use.This article introduces the theories of microfluidic chip electrophoresis,electro-osmosis and amperometric detection. We put forward a new kind of microfluidicchip amperometric detection system. The system consists of two parts, one part iscomposite structure microfluidic chip, by the PCB substrate, PDMS middle layer,PMMA layer, the mechanical seal cover composition; the other part is amperometricdetection hardware circuit, by constant potential device circuit, signal conditioningcircuit, microprocessor chip circuit and so on. The two parts are integrated togetherthrough PCB technology. The entire test platform size is15cm7cm. Compared with thetraditional amperometric detection system, the size of platform is significantly reduced.This paper studies the key technologies in the process of composite structuremicrofluidic chip production. The key technologies include the use of PCB fabricationin making micro-electrodes and the drive electrodes, to achieve the detection electrodeintegration, and through the latter part of the electrode modification, we get threeelectrode testing system. Another one is using casting method to produce PDMSintermediate layer to improve the flatness of the PCB surface shortcoming. Through thePDMS layer surface modification we improve the hydrophilic properties of PDMS. Weuse a laser burning method to make micro-channel and micro-liquid storage in PMMAlayer. The method of chip encapsulation is mechanical pressing and we test the sealingperformance. We use electrochemical workstation to detect Pb(NO3)2oxidation-reduction reaction by cyclic voltammetry. Then we use Pb(NO3)2solventsystem to verify the correctness of three-electrode system on the chip, and find Pb2+oxidation peak potential values. At last we prove this microfluidic chip amperometricdetection system can be applied to the detection of heavy metals in water application.