A device for taking a sample of liquid by capillarity, including a channel for flow of the liquid delimited by two internal walls of the device between which a channel bottom extends, the distance separating the two internal walls decreasing in the direction of the channel bottom, the channel extending between a first collecting end, open onto outside of the device and configured to receive the liquid, and a second end, to enable the liquid to flow by capillarity along the channel bottom from the first end towards the second end. The channel includes, at the second end, a blocking structure to block the flow of liquid in the channel from the first end towards the second end.