US-12622615-B2 - Interstitial fluid sampling device

Abstract

A device for extracting an interstitial fluid sample from the skin of a mammal subject is disclosed. The device comprises at least one micro-needle comprising a tip portion configured to be inserted into the skin of the mammal subject, and a passage configured to transport the interstitial fluid from the skin to a retaining material arranged in a channel of a body of the device. The retaining material is fluidically connected to the passage and configured to absorb and store the interstitial fluid sample transported by the passage. A holder configured to receive such a device is also disclosed.

Inventors

• Niclas Roxhed
• Federico RIBET
• Göran Stemme

Assignees

• BONSENS AB

Dates

Publication Date

20260512

Application Date

20210122

Priority Date

20200123

Claims (19)

1. 1 . A device for extracting an interstitial fluid sample from the skin of a mammal subject, comprising: at least one micro-needle comprising a tip portion, an end portion with a notch, and a passage, wherein the tip portion is configured to be inserted into the skin of the mammal subject, and wherein the passage is configured to transport the interstitial fluid sample, extracted from the skin by the at least one micro-needle, away from the tip portion; a body configured to support the at least one micro-needle; and a retaining material arranged in a channel of the body; wherein the retaining material is fluidically connected to the passage and configured to absorb and store the interstitial fluid sample transported by the passage, and wherein the retaining material abuts the end portion of the at least one micro-needle by being received in the notch to at least partly overlap a liquid meniscus formed by the filling of the passage with the interstitial fluid sample.
2. 2 . The device according to claim 1 , wherein the at least one micro-needle protrudes from the body such that the tip portion penetrates the skin in response to the body being placed on the skin.
3. 3 . The device according to claim 1 , wherein the passage at least partly extends into the retaining material.
4. 4 . The device according to claim 1 , wherein the retaining material is a porous material.
5. 5 . The device according to claim 1 , wherein the device is configured to allow removal of the retaining material.
6. 6 . The device according to claim 1 , further comprising a fill level indicator for indicating when the interstitial fluid sample stored in the retaining material reaches a predetermined volume.
7. 7 . The device according to claim 6 , wherein the fill level indicator comprises a substance configured to change a colour of the interstitial fluid sample, and wherein the body comprises a window indicating a progress of the coloured interstitial fluid sample along the channel.
8. 8 . The device according to claim 6 , wherein the fill level indicator comprises a sensor or detector configured to determine the fill level of the interstitial fluid sample in the retaining material.
9. 9 . The device according to claim 6 , wherein the predetermined volume is 10 μl or less.
10. 10 . The device according to claim 1 , wherein a tip radius of the tip portion is 50 μm or less, and wherein the micro-needle protrudes 2000 μm or less from the body.
11. 11 . The device according to claim 1 , wherein the passage is formed by a trench extending along at least a part of the micro-needle.
12. 12 . The device according to claim 11 , wherein the trench comprises a hydrophilic structure for facilitating capillary transport of the interstitial fluid sample.
13. 13 . A holder for a device for extracting an interstitial fluid sample from the skin of a mammal subject, the device including the structure of claim 1 , wherein the holder comprises a rim portion configured to be placed on the skin and to at least partially encircle the at least one micro-needle when said at least one micro-needle is inserted in the skin, and wherein the rim portion is further configured to exert a pressure on portions of the skin adjacent to the at least one micro-needle to facilitate extraction of the interstitial fluid sample from the skin.
14. 14 . The holder according to claim 13 , further comprising a resilient member configured to push the at least one micro-needle towards the skin when the rim portion is placed on the skin.
15. 15 . The holder according to claim 13 , further comprising an attachment means for securing the holder to the skin.
16. 16 . A method for sampling an interstitial fluid sample from the skin of a mammal subject, the method comprising: inserting at least one micro-needle comprising a tip portion, an end portion with a notch, and a passage into the skin of the mammal subject, transporting the interstitial fluid sample through the passage away from the tip portion, absorbing and storing the interstitial fluid sample at a retaining material comprising a porous matrix, wherein the retaining material abuts the end portion of the at least one micro- needle by being received in the notch at least partly overlapping a liquid meniscus formed by the filling of the passage with the interstitial fluid sample, and analysing the interstitial fluid sample to measure or detect the presence of one or more analytes/markers.
17. 17 . A device for extracting an interstitial fluid sample from the skin of a mammal subject, comprising: at least one micro-needle comprising a tip portion and a passage, wherein the tip portion is configured to be inserted into the skin of the mammal subject, and wherein the passage is configured to transport the interstitial fluid sample, extracted from the skin by the at least one micro-needle, away from the tip portion; a body configured to support the at least one micro-needle; a retaining material arranged in a channel of the body; and a fill level indicator for indicating when the interstitial fluid sample stored in the retaining material reaches a predetermined volume; wherein the retaining material is fluidically connected to the passage and configured to absorb and store the interstitial fluid sample transported by the passage, and wherein the retaining material abuts an end portion of the at least one micro-needle by being received in a notch of the end portion to at least partly overlap a liquid meniscus formed by the filling of the passage with the interstitial fluid sample.
18. 18 . The device according to claim 17 , wherein the fill level indicator comprises a substance configured to change a colour of the interstitial fluid sample, and wherein the body comprises a window indicating a progress of the coloured interstitial fluid sample along the channel.
19. 19 . The device according to claim 17 , wherein the fill level indicator comprises a sensor or detector configured to determine the fill level of the interstitial fluid sample in the retaining material.

Description

TECHNICAL FIELD The present disclosure generally relates to the field of sampling of interstitial fluid, and in particular to techniques for extracting an interstitial fluid sample from the skin of a mammal subject. BACKGROUND To access information on the health of a patent beyond assessment of the symptoms, analyses of bodily samples need to be performed. Assessment of the concentration or presence of specific analytes in the body is an important aspect of medical practice for patient monitoring and disease diagnostics. Such an assessment allows for doctors and nurses to acquire information, either qualitative or quantitative, on the status of a patient and take medical decision based on thereon. Depending on the disease or the condition to be assessed, different bodily matrices may be used, including tissue (for example via biopsy) and different fluids (both liquids and gases). Generally, it is common to use blood as a measurement matrix for a large variety of analytes, such as glucose, cholesterol, medical drugs, and the like. However, blood extraction is associated with invasive and painful methods, whether done via finger pricking or intravenously. Being able to monitor substances without the pain and discomfort associated with the blood sampling would therefore represent an improvement towards a more patient-centred healthcare. An emerging matrix for less invasive monitoring is the interstitial fluid (ISF), which has shown a good correlation with blood values for several analytes (such as glucose) and can be extracted from within the skin. ISF is a liquid present between tissue cells of the body, outside the cells themselves and the blood vessels. The composition of the ISF is known to be rather similar to that of blood plasma. In addition to water it may comprise salts, glucose, small proteins, lipids, amino acids, fatty acids, hormones, neurotransmitter, and other small biomolecules. The similarity is understood to be due to a molecular exchange between the blood in capillary vessels and the interstitial space occurring by diffusion, hydrostatic pressure, osmotic pressure, active transporters, and transcytosis across the capillary endothelium. Because of this similarity with blood plasma, ISF is gaining a growing interest as a monitoring matrix. Examples of current methods for ISF sampling involve the use of hollow microneedles that are inserted intradermally, and wherein an ISF flow is induced into the needles by vacuum suction. However, such techniques are relatively complex to use and associated with several drawbacks relating to e.g. incompatibility with current analytical standards in the clinics and difficulties ensuring a well-controlled and repeatable sampling volume. Thus, there is a need for improved sampling techniques in general, and for an improved device for extracting ISF samples in particular. SUMMARY It would be advantageous to achieve a technique overcoming or alleviating at least some of the above-mentioned drawbacks. In particular it would be desirable to enable an improved device for extracting an ISF sample from the skin of a mammal subject. To better address one or more of these concerns, a device and a holder having the features defined in the independent claims are provided. Preferable embodiments are defined in the dependent claims. Hence, according to a first aspect, a device for extracting an ISF sample from the skin of a mammal subject is provided, comprising at least one micro-needle having a tip portion and a passage, wherein the tip portion is configured to be inserted into the skin of the mammal subject, and wherein the passage is configured to transport the ISF sample, extracted from the skin by the at least one micro-needle, away from the tip portion. The device further comprises a body configured to support the at least one micro-needle, and a retaining material arranged in a channel of the body. The retaining material is fluidically connected to the passage and configured to absorb and store the ISF sample transported by the passage. According to a second aspect, a holder is provided, which is configured to receive a device according to the first aspect. The holder may also in some examples be referred to as a casing, a pressure generating means or an inserter. The holder comprises a rim portion configured to be placed on the skin and to at least partially encircle the at least one micro-needle when the at least one micro-needle is inserted in the skin. Further, the rim portion is configured to exert a pressure on portions of the skin adjacent to the at least one micro-needle to facilitate extraction of the ISF sample from the skin. The above device and holder may further be used in a method in which the at least one micro-needle is inserted into the skin of the mammal subject and the ISF sample is extracted to the retaining material, in which the ISF sample is absorbed and stored. The extraction may be facilitated by the application of a pressure on portions of