| Since the first microfluidic paper-based analytical devices(?PADs)was introduced by Whitesides and co-workers in 2007,the fabrication of microfluidic analytical devices using paper as substrate have emerged a hotspot of research.Due to the abundant available advantages of PADs,low-cost,environmentally friendly,biocompatible and degradable,it has great potential applications in fields such as environment monitoring,food safety control,medical diagnostics.However,there are still many deficiencies in PADs.Therefore,this thesis proposes several more convenient and stable fabricating methods for PADs,which are dedicated to solving these problems,such as the low accuracy of colorimetric detection based on light reflection due to the narrow linear range,the low resolution of the hydrophilic and hydrophobic boundary of PADs fabricated by the common methods,and the detection results of PADs are not intuitive,as well as the complicated patterning process of colorimetric detection of PADs.The main work of this research includes the following aspects:(1)The patterned PADs were fabricated rapidly by ultraviolet-curing screen-printing method,and had been developed to environmental monitoring to perform the quantitative analysis of copper,iron and nickel ions in water.Compared with the traditional method,there was no significant difference between the limits of detection,but the results showed the 10 times expansion of linearity range by light transmission analysis,creating high accuracy.In addition,in the research of the interference study and the analysis of environmental samples,results showed the good specificity,indicating the reliability of the method proposed in this study.(2)Since the flow speed of the solution directly affects the speed of the detection process and the detection effect when the analysis was conducted on the PADs.Therefore,we proposed a new fabrication method of PADs,by combining the patterned mask and the ultraviolet-curing screen-printing method,the PADs with higher printing resolution,strong liquid absorption capacity,and liquid spreading efficiency were fabricated.By pasting the patterned mask on the paper substrate,it not only achieved the production of a variety of patterned PADs using only one single printing plate,improved the utilization of the printing plate,but improved the printing resolution of the PADs.In addition,the hydrophobic boundary on the PADs can effectively prevent the leakage of common organic solutions.(3)The PADs fabricated by mask-assisted ultraviolet-curing screen-printing method had been developed to the field of food quality control.The distance-based and the angle-based PADs were used for the determination of the chloride ion in milk,the results could be directlyread out without any external devices,which simplified the operational process and improved the user-friendliness.Among them,the distance-based PADs were designed with a transparent rule,the quantitative detection of chloride ions could be achieved by measuring the diameter of the colorimetric detection area.While qualitative and semi-quantitative detection of the chloride ion could be achieved by rotating the pointer on the angle-based PADs to determine whether the concentration exceeds 0.14% or not.(4)By adjusting the performance of charge and wettability of the paper,the PADs without hydrophobic boundaries were fabricated,and the patterned and dot matrix detection results were conducted with the using of bioactive ink pens,which simplified the prefabrication of PADs,and further improved the convenience and user-friendliness of paper-based analysis.This method could not only achieve "on-demand writing" to meet the requirements of different kinds of detection,but also achieved large-scale fabrication and automated detection of PADs by assisting with the desktop plotter,it could apply to single-step detection,simultaneous detection of different analytes and multi-step analysis like sandwich enzyme-linked immunoassay(ELISA). |
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