Abstract: A system to measure the flow rate of a liquid in a microfluidic circuit. The system includes a vessel that is partially filled with the liquid, a gaseous ceiling above the vessel and a pressure regulator to maintain the pressure of the gas in the gaseous ceiling at a predetermined value P1. A capillary pipe to extract the liquid from the vessel and to output the liquid at a pressure P2 lower than P1. A first inlet of the pressure sensor is connected to the gaseous ceiling, a second inlet of the pressure sensor is connected to the capillary pipe, and the outlet of the pressure sensor outputs a signal as a function of the pressure difference (P1?P2), which is a measurement representing the flow rate of pressurized P2 liquid supplied to the microfluidic circuit.

Abstract: A micro-structured substrate to support a liquid sample having a lower face and an upper face. At least one surface cavity of volume V0 opening onto the upper face and forming a zone for analyzing the liquid sample. A first groove having a first volume V1, positioned around each surface cavity and opening onto the upper face thereof. The substrate also includes at least one second groove opening onto the upper face thereof and positioned around the first groove. The sum of the volumes of the second grooves is equal to V2. The volume V1+V2 is greater than or equal to 0.05 V0, preferably 0.1 V0. An analysis assembly including the substrate and the use thereof is also contemplated herein.