A low-cost compact blood enzyme analyzer based on optical sensing for point-of-care liver function testing

Serum alanine aminotransferase (ALT) is the most sensitive indicator of liver function; therefore, in clinical practice, its detection has diagnostic significance. However, hepatotoxicity monitoring is constrained in resource-limited areas due to the high cost and expensive equipment. This article describes a low-cost, compact blood enzyme analyzer (BEA) for point-of-care (PoC) liver function testing that uses reflection photometry to quantitate the colorimetric enzyme assay results. Moreover, the analyzer incorporates rapid and constant 37 °C temperature control to ensure that human serum enzymes remain active. The BEA was used to evaluate ALT in 50 whole blood samples using PoC photochemical test strips. The test results showed a linear correlation coefficient of 0.9749 compared with a clinical-specific biochemical analyzer and coefficients of variation (CV)% less than 5%. It has a low detection limit of 3.62 U L^-1 and a wide detection range of 4-480 U L^-1. In addition, the BEA enables smartphone access to the Internet of Medical Things (IoMT) via Bluetooth to facilitate active chronic disease management or remote diagnosis in PoC settings. Therefore, the BEA is a promising system for health management using the IoMT.