Cotton fiber-based assay with time-based microfluidic absorption sampling for point-of-care applications.

Time-based microfluidic absorption sampling was proposed using cotton fiber-based device made in swab stick. The assay was optimized and compared with conventional pipetted drop sampling using the same device. Reagents were integrated into cotton fiber device for assessing concentration of analytes by the colorimetric detection method through time-based absorption sampling microfluidic system. All assay parameters were first optimized using conventional pipette-based drop sampling. The color intensity is linear in the relevant concentration range of the analytes. The LOD are 0.189 mM for glucose and 6.56 μM for nitrite, respectively. These values are better than conventional drop sampling. The fiber-containing swab itself functions as sampling, assay and calibration device. Microfluidic cotton fiber-based assay device was fabricated and can determine analyte concentration in artificial salivary samples, colorimetrically, by time-based absorption sampling without the need of complex equipments.