US-20260123865-A1 - A METHOD FOR SAMPLING A BODILY FLUID FROM A TEST SUBJECT, AND A SAMPLING SYSTEM

US20260123865A1US 20260123865 A1US20260123865 A1US 20260123865A1US-20260123865-A1

Abstract

The present invention relates to a method for sampling a bodily fluid from the skin of a test subject by means of a sampling system The method comprises the steps of a) 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; b) applying 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; c) 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) applying 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 The present invention also relates to a sampling system.

Inventors

Markus Renlund
Pelle Rangsten

Assignees

ASCILION AB

Dates

Publication Date: 20260507
Application Date: 20231013
Priority Date: 20221013

Claims (12)

1 . A method for sampling a bodily fluid from the skin of a test subject by means of a sampling system, 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; wherein the method comprises the steps of: a) 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; b) applying 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; c) 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) applying 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.
2 . A method according to claim 1 , wherein the negative penetration pressure is in the interval from −30 kPa to −45 kPa.
3 . A method according to claim 1 , wherein the penetration time is in the interval from 10 s to 60 s.
4 . A method according to claim 1 , wherein the negative extraction pressure is in the interval from −10 kPa to −30 kPA.
5 . A method according to claim 1 , wherein the negative extraction pressure is in the interval from −20 kPa to −30 kPa.
6 . A method according to claim 1 , wherein step d) further comprises a step d1 of decreasing the pressure in the volume during lift-off to the negative extraction pressure at a pressure difference speed smaller than 1 kPa/s.
7 . 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
8 . A sampling system according to claim 7 , wherein the negative penetration pressure is in the interval from −30 kPa to −45 kPa.
9 . A sampling system according to claim 7 , wherein the penetration time is in the interval from 10 s to 60 s.
10 . A sampling system according to claim 7 , wherein the negative extraction pressure is in the interval from −10 kPa to −30 kPA.
11 . A sampling system according to claim 7 , wherein the negative extraction pressure is in the interval from −20 kPa to −30 kPa.
12 . A sampling system according to claim 7 , wherein step d) further comprises a step d1 of decreasing the pressure in the volume during lift-off to the negative extraction pressure at a pressure difference speed smaller than 1 kPa/s.

Description

TECHNICAL FIELD The present disclosure generally relates to the field of sampling a fluid from test subject and more specifically to the field of sampling a bodily fluid with a microneedle array. BACKGROUND In modern analysis of test subjects such as for example human objects or animals there is a large interest in analyzing different bodily fluids and mixtures thereof. Traditionally, for a diabetes patient that wants to test the blood sugar level a lancet were used to penetrate the skin and extract a small amount of blood through the opening in the skin and then subject the test strip to the blood coming out of the skin were the lancet entered the skin. In recent years, a large interest has emerged in sampling other bodily fluids that are possible to extract from the skin of the test subject without causing damage to the skin and pain to the test subject. A common problem associated with sampling of bodily fluids is that the volume of bodily fluid is rather small and troublesome to extract in an efficient way. Some attempts have been performed to efficiently extract a bodily fluid from a test subject by introducing a local edema, which is used for sampling of the bodily fluid. This is for example disclosed in US20200315502. This method is both painful and provides a long lasting discoloring of the skin. It is therefore of great interest if an alternative method could be identified. Therefore, it is of great interest to provide a method for sampling of a bodily fluid that is able to efficiently extract the bodily fluid without introducing a local edema and still being effective. SUMMARY An object of the present disclosure is to provide a sampling method which seeks to mitigate, alleviate, or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination and to provide an improved sampling method. A further object of the present disclosure is to provide an improved sampling system. This object is obtained by a method for sampling a bodily fluid from the skin of a test subject by means of a sampling system, 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; wherein the method comprises the steps of a) 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; b) applying 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; c) 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) applying 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. The object is also obtained by 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