The Study On Fabrication And Application Of Microfluidic Paper-based Device By Using A Laser Printer

The burst development of microfluidic paper-based analytical devices(?PADs)has become an inaugural event since its first introduction in 2007 by Whitesides et al.Comparing with traditional microfluidic chips,?PADs combine the characteristics of microfluidic technology and paper materials.As a new type of detection platform,?PADs has great commercial application prospects in medical health,life science,environmental monitoring,food safety and other fields,as they are low cost,easy preparation,light and practical,less sample consumption,power-free fluid transport,disposable,and easy degradation in the environment etc.Since then,it have emerged a large number of some approaches,mainly including photolithography,wax printing,inkjet printing,screen printing,plasma,cutting,have been developed for the fabrication of ?PADs.However,these methods still feature limitations to their application in general labs.For example,these methods often involve special chemical reagents(such as SU-8,AKD,etc.),special metal masks,and expensive equipment(such as laser cutting machine or wax printer).Some methods face other problems such as ink compatibility problems and,low channel resolution.In this paper,developing a new preparation of ?PADs by using an unmodified office laser printer.We illustrated the mechanism,optimized the conditions,and defined the resolution of the proposed method.To demonstrate the practicability of the proposed method,a ?PADs that is based on multi-element colorimetric analysis and a dual-mode(colorimetric and electrochemical analysis)?PADs were developed.The specific contents are as follows:(1)Fabrication and characterization of ?PADs based on laser printerWe have developed a simple,fast and high-resolution fabrication method of ?PADs using an office laser printer.The method involves two steps,First,the designed microfluidic channel is printed on the filter paper by an office laser printer;then,the printed filter paper is placed in an oven at 170 ? for 90 min.We investigated the hydrophobic properties of the ?PADs from a microscopic and macroscopic perspective.From a macro point of view,we studied the surface contact angle before and after the heat treatment and the shape of the toner on the surface of the filter paper.From the micro of view,we explored the hydrophobicity mechanism of toner through thermogravimetric(TGA)and evolved gas analysis mass spectrometry(EGA-MS).At a heat treatment temperature of 170?,the optimum heat treatment time is 90 min.The anti-folding and bending properties were studied by kneading and folding.After optimization of experimental conditions,the correlation between the designed widths and the actual widths of the microchannels were obtained with the minimum actual width of the channel at 347±40 ?m.(2)Multi-channel detection platform for ?PADs based on laser printerUnder the optimum conditions,fabricating a ?PADs,and a multi-channel detection platform is constructed by combining the most widely used colorimetric detection method.This detection platform has the advantages of low cost,easy availability,light and practical,one-time use,a high degree of visualization,and fast analysis.In this experiment,four heavy metal ions such as Fe(III),Ni(II),Cu(II)and Cr(VI)were simultaneously detected by colorimetry.Firstly,the color reagents for detecting ions were modified in the pretreatment area and detection area of ?PADs,and then dried naturally at room temperature for 5 minutes at each time.Then the mixed standard solution of four ions was added to the sample dropping area,and the color reaction took place at each detection site.A color photograph is taken by using a smart phone and analyzed by the image processing software ImageJ,and the color intensity is linearly related to the logarithm of the heavy metal ion concentration.The ?PADs prepared by the method successfully realized the quantitative detection of heavy metal ions.(3)Dual-mode detection platform for ?PADs based on laser printerThe MWCNTs/Au/paper working electrode was prepared by electrodepositing gold on the surface of copper plate paper by ion sputtering,then modifying MWCNTs on the surface of Au/paper electrode and heating and drying.A dual-mode colorimetric-electrochemical ?PADs detection platform was prepared to detect heavy metal chromium(VI)and bisphenol A,respectively.The linear sweep voltammetry(LSV)was used to detect bisphenol A,and there was a good linear relationship between oxidation peak and bisphenol A concentration.The detection range was 0.5 mg/L~20 mg/L,and the detection limit was 0.16 mg/L.Finally,the simultaneous determination of heavy metal chromium(VI)and bisphenol A in plastic samples was successfully realized.