A novel, low-cost paper-based liver function point-of-care system

As one of the important means of quantitative evaluation of liver injury, biochemical analyzer is a conventional testing method. However, it has not been widely used in low - middle - income countries (LMICs) due to the limited personnel, lack of funding and complicated environmental problems. How to acquire the information of liver injury quickly with simple and efficient method providing powerful support for clinical decision-making is still a challenge for LMICs. To solve this problem, we designed a novel and easy-to-use point of care system for liver injury. This system consists of a detection device which is based on a two-photon macro photochemical sensor and a paper-based test card with a built-in system for blood cell filtration. The two-photon structure is used to reduce the overall volume and cost of the system, it makes up for the inter-station errors introduced during the instrument assembly process. The blood cell filtration system reduces the operational complexity, and the blood can be filtered, react and change color directly on the test card. The detection device obtains the continuous light reflection signal of the paper-based test card and quantifies the signal to complete the quantitative test of liver damage indexes. We simulated the national environment of LMICs to evaluate the performance of the system: under the environment of 35℃ and 90% relative humidity, 40 Heparin whole blood, the correlation R2 between our system and MindrayBS350s was greater than 0.95. Both of the Randox Quality Control level 2 and level 3 repeatability CV were less than 7.5%. The results show that the system is not only small in size, low in cost and simple in operation, its measurement performance and stability meet the clinical requirements of high temperature and high humidity environment, and so it can be used in LMICs for primary liver function screening and liver disease progression assessment.