Sensitive and reliable paper-based glucose sensing mechanisms with smartphone readout using the L*a*b* color space

Abstract

Paper-based assay platforms play an important role among rapid test methods. It is essential to combine these promising platforms with smartphones which make on-site analysis possible without using external image processors. In this study, the performance of paper-based glucose assay methods was investigated by using the L*a*b* color space as the quantitative measurement. For this purpose, two glucose assay methods, namely quinone and iodine, were compared in terms of linearity, limit of detection (LOD) and reliability. A lower LOD and higher sensitivity were obtained by the quinone method while the iodine method may lead to large indeterminate errors due to the formation of non-uniform color distribution. Moreover, color measurement strategies were tested by using both computer software and mobile applications. For this purpose, scanned images were processed on a computer and the results were compared with smartphone based color measurements. The lowest LOD value of 0.38 mM glucose was obtained with the mobile application running on an Android operating system. Finally, glucose assay was performed on sour cherry nectar and honey and the results were compared with the spectrophotometric glucose assay. Using smartphones and the L*a*b* color space appears to be promising for reliable paper-based sensing as they are totally portable.