Edema detection using absorption spectroscopy for early diagnosis of preeclampsia

Abstract Preeclampsia is a hypertensive disorder of pregnancy and a leading cause of maternal mortality and perinatal deaths worldwide. It reduces perfusion in multiple organs, with main symptoms being elevated blood pressure and proteinuria, often accompanied by peripheral subcutaneous fluid retention. This work presents the development of a portable measuring device for early detection of preeclampsia by monitoring blood pressure and subcutaneous fluid retention. The device integrates two optical sensor systems: PPG (photoplethysmography) for blood pressure and diffuse reflectance for fluid detection. Measurements are performed at 570 nm and 970 nm to distinguish between tissue and fluid contents. The sensor system was validated using a silicone finger phantom that mimics tissue absorption (0.4 mm −1 at 570 nm). A 0.5 mm change in liquid layer thickness was detected. A NaCl solution was introduced at a depth of 1.3 mm as the simulated fluid. The device also includes Bluetooth Classic for wireless data transfer to a smartphone app, facilitating monitoring during pregnancy. This portable solution offers a promising approach for early detection of preeclampsia by measuring hypertension and edema formation.