A smartphone-based colorimetric sensing platform for detection of blood viscosity and hemoglobin

Blood diseases pose a significant threat to human health. Currently, the diagnosis of most blood diseases relies on large-scale professional instruments that require skilled operators in hospitals or commercial laboratories, thereby limiting access to diagnosis in underdeveloped and remote areas. In this study, we propose an innovative smartphone-based colorimetric sensing platform that integrates microfluidic devices based on fluid viscosity and flow characteristics. This platform enables the mixing of two fluids with disparate viscosities at the detection cell by employing microfluidic channels, resulting in discernible alterations in fluid color. It utilizes the ambient light sensor (ALS) of a smartphone to accurately measure the transmittance of the sample under examination, while an Android-based application is employed for result analysis. By altering the fluid composition, respective measurements of two crucial hematology indicators in blood, viscosity and hemoglobin concentration, can be achieved. Moreover, this portable sensor exhibits consistent detection values with those obtained from the state-ofthe-art equipment considered as the gold standard and demonstrates a detection limit comparable to it. The presented colorimetric sensing platform offers several advantages of portability, cost-effectiveness, and userfriendly operation, thus rendering it a valuable tool for early diagnosis of a variety of blood diseases, particularly in underserved regions with limited healthcare resources.