Lamb wave-based blood coagulation test

•Using a Lamb wave device, acoustic streaming of fluorescent particles suspended in citrated plasma is induced in a droplet.•The viscosity of the sample droplet increases due to blood coagulation, so that the acoustic streaming velocity decreases.•The acoustic streaming of particles finally stops at the “coagulation time (CT)”.•With increasing calcium concentration, CT decreases drastically due to improved blood coagulation.•Prothrombin time measured by the Lamb wave device was highly correlated with that of commercial instrument.