Heavy Metal Ions μTAS Chip Based On Micromixer

The micro total analysis system（μTAS） based on micro electro mechanical system（MEMS）technology is multidisciplinary product of microelectronics, electrochemistry, analytical chemistry and so on. μTASis cur Rently becoming the Research hotspot due to its g Reat application prospect in the futu Re. Nonetheless, the Re is still some problems of μTAS chip for heavy metal ions detection, such as p Ret Reatment efficiency is poor and multilayer chip bonding. These problems led to the chip integration is unable to satisfy the portability and Real-time detection. In this paper, th Ree-dimensional horseshoe chaotic mixer was proposed to improve the p Ret Reatment efficiency; spindle shaped extraction column structu Re was design to Reduce horizontal and vertical proliferation band broadening; the flow-through testing cell and amperometric detection sensor with an inner filling pools we Re design to to improve the detection stability; novel bonding methods based on Polymethyl Methacrylate（PMMA） materials we Re proposed to achieve multi-layer μTAS chip assembled. Manufactu Re the heavy metal μTAS chip by utilize the above design and assembly process, then verified the chip performance by uses multiple testing methods.A novel 3D Horseshoe map was proposed, utilized the “vertical folding” to aviod the “overflow” problem during 2D horseshoe transformation. This operationnot only Reduce the fluid loss, but also make flow mo Re complex due to the Repeatedly changing of move di Rection. Then a microscale fluid mixing model was established based on fluid dynamics equations and multi-component material diffusion equation.Using this model to Research the performance of the chaotic micromixer, the Results showed that: the optimized 3D micromixer can nearly achieve the uniform mixing（σ<0.05）, when mixing distance is 12 mm and Re=10.Compa Red to the “squeeze-back” horseshoe mixer（Re=10, σ>0.2）, the mixing effect has been significantly improved.A new heavy metal μTAS chip structu Re was proposed based on micromixer. The sample was p Ret Reat by using th Ree-dimensional horseshoe mixer, in order to meet the selective adsorption condition of solid phase extraction column. The integration column structu Re was combined with modified sorbent to achieve separation and enrichment of heavy metal ions. The Ag/Ag Cl Refe Rence electrode with fluid-filled pool based on flow-through detector cell was design to ensu Re the stability of amperometric detection. The chip was consists of four layers substrates, the overall dimensions of 70 mm × 40 mm × 14 mm. In addition to the p Ressu Re injection device and electrochemical workstation, the enti Re testing process without any other external devices, the integration of μTAS chip has been significantly improved.A miscible organic solvent soaked bonding method was proposed to assemble multilayer PMMA chip with complex structu Re. The chloroform and ethanol we Re mixed in accordance with a certain proportion to achieve the chip sealing. The composition of the solution, soak time and other parameters we Re adjusted to ensu Re the structural integrity. The bonding st Rength was 267.5N/cm² while the deformation was only 7.26%, when soaked bonding condition: Vchloroform: Vethanol=1: 10, t=10min, T=40°C. A fumigation organic solvent bonding method was proposed to assemble μTAS chip with functional modules. Use polyimide tape as a mask to protect microstructu Re from chloroform vapor. The bonding st Rength was 61N/cm² while the deformation was 9.5%, when fumigation bonding condition: t=40s, T=65°C.A micromixer chip for sample p Ret Reatment, a solid phase extraction chip for separation and a amperometric sensor chip for heavy metal ions detection we Re assembly to identified working conditions of μTAS chip. Finally, the Hg²⁺, Pb²⁺ and Cr³⁺ solution we Re used as analog sample to test the μTAS performance. The detection limit of Hg²⁺ was 20μg/L,（n=5, standard deviation of 3%）. When the Re we Re interfering ions(Cr³⁺=1.0×10-6mol/L), the chip can still achieve accurate detection of Pb²⁺（1mg/L）. The indicators we Re meet criteria of Integrated Wastewater Discharge Standard（GB8978-1996）.