A method for sampling a bodily fluid from a test subject, and a sampling system

A sampling system for sampling bodily fluid from the skin of a test subject, wherein the sampling system comprises:

• a fluid pump;
• a microneedle assembly
• a conduit connecting the fluid pump to the microneedle assembly the microneedle assembly comprises:
• a housing comprising a fluid port connected to the fluid pump via the conduit;
• a microneedle array in fluid communication with the fluid port wherein the microneedle array is formed on a substrate and comprises a plurality of microneedles extending from a first side of the substrate, each microneedle having a proximal end connected to the first side of the substrate and a distal end, wherein the distal end has a bevel, and wherein each needle has a hole extending from its proximal end to its distal end, and wherein each hole extends into a corresponding hole of the substrate, wherein the plurality of the microneedles provides a fluid path from the distal end to the fluid port;
• a rim extending around the microneedle array wherein the rim is aimed to define a sealing between the surrounding atmosphere and an interior of the housing when the rim is in contact with the skin of the test subject;
• a control unit configured to control the fluid pump and comprising a pressure sensor arranged to measure the pressure in the flow path through the conduit wherein the control unit
• upon placing the rim of the microneedle assembly in contact with the skin of the test subject, thereby sealing the interior of the housing from the surrounding atmosphere, is configured to:
• a) apply a negative penetration pressure by means of the pump to the fluid port and thereby to the interior of the housing, wherein the negative penetration pressure is maintained during a penetration time, whereby the plurality of microneedles penetrates the skin of the test subject;
• b) increase the pressure in the volume, lift-off, wherein the plurality of microneedles are removed from the skin during a lift-off time wherein the interior of the housing is at least at the atmospheric pressure;
• and
• d) apply a negative extraction pressure with the pump during an extraction time, whereby the bodily fluid released from the skin flows towards the fluid port and is collected in a sample volume