Digital microfluidic platform for automated detection of human chorionic gonadotropin

Determinations of Human chorionic gonadotropin (HCG) are important for diagnosis and monitoring of pregnancy, pregnancy-related diseases and several types of cancers. As a step toward decentralized diagnostic systems, we introduce a format of particle-based immunoassays relying on digital microfluidics (DMF) and magnetic forces to separate and resuspend HCG antibody-coated paramagnetic particles. On this basis, we developed DMF diagnostic platform for automated HCG detection and realized droplet operations at 20 Hz. Using this platform, 10–50 µg/mL of HCG was detected by chemiluminescence method and the linear relationship between HCG concentrations and chemiluminescence signals was obtained. To solve the biofouling problem, we use pluronic additives in reagent droplets. The effect of different additive concentrations on droplet actuation was tested. The DMF immunoassays only take 20 min to finish the whole sample detection process. We propose that the new technique has great potential for eventual use in a fast, low-waste, and inexpensive instrument for the quantitative analysis of proteins and small molecules in low sample volumes.