Microfluidic Chip For The Detection Of Organophosphorus Pesticides

In recent years, organophosphorus compounds, such as methyl parathion, because of high toxicity and low environmental persistence, are widely used in agricultural industry as an alternative to organochlorine chemicals. The use of organophosphorus compounds is from pesticides to the fungicide, herbicides, and rodenticides and so on. As a result, the groundwater, surface water resources and the soil are polluted. And its residues in food case serious threat to the human health. So it has a crucial role for human health and ecological balance to develop fast, reliable, sensitive and practical method for detection the organophosphorus compounds. Conventional methods for detection of the organophosphorus compounds require tedious sample pretreatment, high cost, largh and expensive equipment and professional people, so is not suitable for filed detection. PDMS microfluidic chip has the benefit of low sample volume, short detection time and simple equipment, so it is widely used in biology and chemistry.In this paper, a PDMS microfluidic chip integrated with organophosphorus hydrolyses, optical fibers and microchannel has successfully been fabricated for detecting the organophosphorus compounds. A large number of SU-8 pillars are fabricated in the channel by photolithography for adsorbing the enzyme and the principle of the device is based on the absorbance detection of the enzymatic product. The experiment result shows good linear relationship between absorbance and the concentration of organophosphorus solutions in the range of 10-6～10-4 mol/L (the correlation coefficient is 0.99). A novel method to bind the enzyme to the microfluidic is presented in this paper, which has advantages such as maintaining good enzyme activity, simple fabrication process and easy integration into portable device. An experiment platform is also fulfilled in this paper and we have done the experiment for large volume of the organophosphorus compounds. The hydrolysis by enzyme both in solution and fixed on Ni-NTA resin has been detected with different buffer solutions. Besides, we also studied the PDMS microfluidic fabrication process. We studied the SU-8 mold fabrication process, PDMS curing conditions, PDMS surface modification and different bonding methods between PDMS and the substrate.