Fabricação de dispositivos microfluídicos a base de papel utilizando materiais de baixo custo

Abstract

Over the past six years, paper-based microfluidic devices (PADs), manufactured by applying hydrophilic materials on hydrophobic paper, have emerged as a promising platform for point-of-care diagnostics in developing countries, where the availability of resources is limited. These devices have attractive features such as low cost, ease of use, low consumption of reagents and sample, portability, and disposability. This work describes an alternative method for fabricating PADs by using low cost materials. In order to make the hydrophobic barriers on the chromatography paper, rubber/wood stamps and a mixture of polydimethylsiloxane (PDMS)/hexane have been used. The desired standards for PADs, drawn using graphic software, were made in rubber/wood stamps, whose were used to mark the paper with PDMS/hexane. In order to determine the resolution of the proposed method, the widths of hydrophobic barriers and the widths of hydrophilic channels were studied in the range of 200-1400 m and 1600-2200 m, respectively. The smallest hydrophobic barrier was obtained with 948 ± 112 m (n=9), that resulted from a line with nominal width of 200 m. The smallest width obtained for the hydrophilic channel was 721 ± 111 m (n=9), which originated from a channel with nominal of 1600 m. The PADs were tested in the colorimetric determination of bovine serum albumin (BSA). In this study the concentration range of the calibration curve varied from 0 to 50 mg mL-1, and the limit of detection (LD) was 7.2 mg mL-1. Moreover, PADs were fabricated with electrochemical detection, with working, reference, and auxiliary electrodes made by hand using 5B graphite pencil. The performance of these devices was evaluated by cyclic voltammetry (CV) of K3[Fe(CN)6] as model compound, and by the amperometric determination of acetaminophen in pharmaceutical formulations. For this, a calibration curve was constructed with concentrations of acetaminophen ranging between 100 and 800 mol L-1. The obtained coefficient of determination (R2) was 0.9977, and the limit of detection (LD) and limit of quantification (LQ) were determined as 6.52 mol L-1 and 21.72 mol L-1, respectively.