A MICRONEEDLE AND A FLUID CHANNEL SYSTEM FOR COLLECTING FLUID

Abstract

Microneedle (100, 200, 300, 720) comprising an elongated body (110, 210, 310) extending along a longitudinal axis from a top end to a bottom end on a substrate (300, 710), where the elongated body comprises an upper portion (120, 220, 320) and a lower portion (130, 230, 330). The lower portion (130, 230, 330) comprises an internal capillary bore hole (260, 730) extending into the substrate (300, 710). The upper portion (120, 220, 320) of the elongated body (110, 210, 310) has a semi-enclosed internal void space (140, 240) formed by at least three body sides whereof two body sides join at a sharp edge and a third body side is provided with an opening slit (150, 250, 350) extending from the lower portion (130, 230, 330) of the elongated body (110, 210, 310) to the upper end of the third body side. The top end of the elongated body (110, 210, 310) is configured as a bevel to create a sharp tip at the top of said edge, said bevel extending to the third body side. The semi-enclosed internal void space (140, 240) of the upper portion opening to the internal capillary bore hole of the bottom end of the elongated body (110, 210, 310), and the bottom end of the elongated body is connected to the substrate (300, 710).

Claims

1. A microneedle provided on a substrate, comprising: an elongated body extending along a longitudinal axis from a top end to a bottom end on the substrate, wherein: the elongated body comprises an upper portion and a lower portion; the lower portion of the elongated body comprises an internal capillary bore hole extending into the substrate; the upper portion of the elongated body has a semi-enclosed internal void space formed by at least three body sides whereof two body sides join at a sharp edge and a third body side is provided with an opening slit extending from the lower portion of the elongated body to the upper end of the third body side; the top end of the elongated body is configured as a bevel to create a sharp tip at the top of said edge, said bevel extending to the third body side; the semi-enclosed internal void space of the upper portion of the elongated body opening to the internal capillary bore hole of the bottom end of the elongated body; and the bottom end of the elongated body is connected to the substrate.

2. A microneedle according to claim 1, wherein the opening slit is positioned at the centre of a flat body side.

3. A microneedle according to claim 1, wherein at least one surface extending from the semi-enclosed internal void space to the third body side is curved.

4. A microneedle according to claim 3, wherein at least a part of all surfaces extending from the semi-enclosed internal void space to the third body side are curved.

5. A microneedle according to claim 1, wherein the elongated body comprises three body sides.

6. A microneedle according to claim 5, wherein the two body sides joined at a sharp edge are joined to a third body side through curved surfaces.

7. A microneedle according to claim 1, further comprising ridges that extends on an outer surface of the microneedle, where the ridges extends in a direction that is perpendicular to the longitudinal axis.

8. A microneedle according to claim 1, wherein the upper portion is having a first cross-sectional area, and the lower portion is having a second cross-sectional area, wherein the second cross-sectional area is larger than the first cross sectional area.

9. A microneedle according to claim 1, further comprising a dividing plane dividing the upper portion and the lower portion, wherein at least a part of the dividing plane is not in parallel with the substrate plane.

10. A microneedle according to claim 9, wherein the dividing plane between the upper portion and the lower portion is parallel with the bevel.

11. A microneedle according to claim 1, further comprising a curved portion connecting the elongated portion with the substrate.

12. A fluid channel system for transporting fluid from a plurality of inlets to a fluid collection area via a fluid channel, the fluid channel system comprising the fluid collection area and at least one sector, wherein each sector comprises a first section and a second section, wherein in each sector the first section comprises at least two inlet channels each connecting an inlet and the second section, wherein in each sector the second section connects the at least two inlet channels of the first section and the fluid collection area via a connective channel, wherein in each sector the at least two inlet channels merge into the connective channel; wherein each sector comprises at least one first droplet formation structure between the at least two inlets channels, wherein the at least one first droplet formation structure is arranged to collect fluid by reducing the fluid interface area to air and enlarge the fluid interface area to the channel wall via channel wall geometry, moving from one inlet channel towards another inlet channel than the one inlet channel; each connective channel comprises a second droplet formation structure, wherein the second droplet formation structure is arranged at the end of the connective channel providing an outlet to the fluid collection area and the second droplet formation structure is arranged to collect fluid moving from at least one connective channel; and wherein the fluid channel is defined at least by the at least two inlet channels and the at least one connective channel.

13. A fluid channel system according to claim 12, wherein the at least one first droplet formation structure is arranged to release collected fluid towards the connective channel.

14. A fluid channel system according to claim 12, comprising at least two sectors.

15. A fluid channel system according to claim 12, wherein each first section connects at least three inlets to the fluid collection area via the connective channel.

16. A fluid channel system according to claim 12, wherein each first droplet formation structure between each two inlet channels comprises two adjacent curved walls joined at an angle of less than 180°, such as less than 120°, 90°, 45°, 30°, 15° or 10°.

17. A fluid channel system according to claim 12, wherein each second droplet formation structure comprises two adjacent curved walls joined at an angle of less than 180°, such as less than 120°, 90°, 45°, 30°, 15° or 10°.

18. A fluid channel system according to claim 12, wherein each inlet channel comprises a first inlet channel part connecting the inlet and the first droplet formation structure, wherein the first inlet channel part geometry comprise at least two adjacent walls joined at an angle of less than 180°, wherein the inlet channel part longitudinally connects to the inlet.

19. A fluid channel system according to claim 12, wherein the cross-sectional area of the connective channel decreases from the inlets to the fluid collection area.

20. A fluid channel system according to claim 12, wherein the fluid collection area comprises an exit port, wherein the exit port is arranged to allow extraction of fluid collected in the fluid collection area.

21. A fluid channel system according to claim 12, wherein at least a part of a channel has a hydrophilic interior surface.

22. A chip for collecting fluid via at least one microneedle, comprising: at least one microneedle comprising an elongated body extending along a longitudinal axis from a top end to a bottom end and integrally formed on a first side of a substrate, wherein: the elongated body comprises an upper portion and a lower portion; the lower portion of the elongated body comprises an internal capillary bore hole extending into the substrate; the upper portion of the elongated body has a semi-enclosed internal void space formed by at least three body sides whereof two body sides join at a sharp edge and a third body side is provided with an opening slit extending from the lower portion of the elongated body to the upper end of the third body side; the top end of the elongated body is configured as a bevel to create a sharp tip at the top of said edge, said bevel extending to the third body side; the semi-enclosed internal void space of the upper portion of the elongated body opening to the internal capillary bore hole of the bottom end of the elongated body; and the bottom end of the elongated body is connected to the substrate, wherein each proximal end is integrally formed with the substrate and each capillary bore hole is in fluid communication with an inlet of a fluid channel system according to claim 12, on a second side of the substrate, wherein the chip is arranged to, upon a microneedle brought in contact with fluid, passively transport said fluid though said microneedle and the fluid channel system to a fluid collection area.

23. A method of fabricating a chip comprising at least one microneedle and a fluid channel according to claim 22 using a micro electro mechanical system fabrication process, the method comprising: growing a sacrificial oxide layer on a silicon wafer substrate; masking the sacrificial oxide layer with a patterned photoresist; removing the sacrificial oxide layer according to the patterned photoresist; etching the silicon wafer according to the pattern of the removed sacrificial oxide layer using a deep reactive ion etching method; removing the remaining sacrificial oxide layer by using an etchant.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0157] A more thorough understanding of the abovementioned and other features and advantages of the present invention will be evident from the following detailed description of embodiments with reference to the enclosed drawings, on which:

[0158] FIG. 1 is a schematic perspective view of a microneedle.

[0159] FIG. 2a is a microneedle shown from above according to an embodiment.

[0160] FIG. 2b is a microneedle shown from above according to an embodiment.

[0161] FIG. 2c is a microneedle shown from above according to an embodiment.

[0162] FIG. 2d is a microneedle shown from above according to an embodiment.

[0163] FIG. 2e is a microneedle shown from above according to an embodiment.

[0164] FIG. 2f is a cross-section of a microneedle according to an embodiment.

[0165] FIG. 3a is a schematic perspective view of a microneedle.

[0166] FIG. 3b is a schematic perspective view of a microneedle.

[0167] FIG. 3c is a schematic perspective view of a microneedle.

[0168] FIG. 4 is a schematic view of a fluid channel system shown from above.

[0169] FIG. 5 is a schematic view of a fluid channel system shown from above according to an embodiment.

[0170] FIG. 6a is a schematic view of a fluid channel system shown from above according to an embodiment.

[0171] FIG. 6b is a schematic perspective view of a part of a fluid channel system according to an embodiment.

[0172] FIG. 7 is a cross-sectional view of a schematic chip.

[0173] FIG. 8 is a schematic illustration of a method of fabricating a chip.

DETAILED DESCRIPTION

[0174] The present invention is based on the insights disclosed. When examined carefully it's clear that there is a need of an improved design of the microneedles and/or fluid channel systems in the prior art for sampling of bodily fluids.

[0175] FIG. 1 is a schematic perspective view of a microneedle 100 according to an embodiment of the present invention having an elongated body 110 extending along a longitudinal axis from a top end to a bottom end. The elongated body comprises a upper portion 120 and a lower portion 130. The upper portion 120 of the elongated body 110 has a semi-enclosed internal void space 140 formed by three body sides whereof two body sides join at a sharp edge and a third body side is provided with an opening slit 150 extending from the lower portion 130 of the elongated body 110 to the upper end of the third body side. The top end of the elongated body 110 is configured as a bevel to create a sharp tip at the top of the edge, the bevel extends to the third body side. The semi-enclosed internal void space 140 of the upper portion 120 of the elongated body 110 is opening to an internal capillary bore hole of the bottom end 130 of the elongated body 110. The internal capillary bore hole of the lower portion 130 of the elongated body 110 extends through the microneedle 100 and may also extend into a substrate to which the microneedle 100 may be provided on.

[0176] FIG. 2a is a top-view along the longitudinal axis of a microneedle 200 according to an embodiment. The microneedle 200 has a semi-enclosed internal void space 240 formed by three body sides whereof two body sides join at a sharp edge and a third body side is provided with an opening slit 250. The semi-enclosed internal void space 240 of the upper portion of the elongated body is here illustrated as having a triangular cross-section and the opening slit 250 is positioned at the centre of a flat body side. The opening slit 250 shown has a width that is smaller than the width of the internal void space 240.

[0177] FIG. 2b is a top-view along the longitudinal axis of a microneedle 200 according to an embodiment. The microneedle 200 has a semi-enclosed internal void space 240 formed by three body sides whereof two body sides join at a sharp edge and a third body side is provided with an opening slit 250. The semi-enclosed internal void space 240 of the upper portion of the elongated body is here illustrated as having a triangular cross-section and the opening slit 250. The opening slit 250 shown has a width that is larger than the width of the internal void space 240.

[0178] FIG. 2c is a top-view along the longitudinal axis of a microneedle 200 according to an embodiment. The microneedle 200 has a semi-enclosed internal void space 240 formed by three body sides whereof two body sides join at a sharp edge and a third body side is provided with an opening slit 250. The semi-enclosed internal void space 240 of the upper portion of the elongated body is here illustrated as having a triangular cross-section and the opening slit 250. In the present figure, the lower portion 230 can be seen as the upper portion 220 is having a first cross-sectional area, and the lower portion 230 is having a second cross-sectional area, wherein the second cross-sectional area is larger than the first cross sectional area. By this, the lower portion 230 may extend outside the upper portion 220. In the present figure, the lower portion 230 extend outside the upper portion 220 in an even manner.

[0179] FIG. 2d is a top-view along the longitudinal axis of a microneedle 200 according to an embodiment. The microneedle 200 has a semi-enclosed internal void space 240 formed by three body sides whereof two body sides join at a sharp edge and a third body side is provided with an opening slit 250. The semi-enclosed internal void space 240 of the upper portion of the elongated body is here illustrated as having a triangular cross-section and the opening slit 250. In the present figure, the lower portion 230 can be seen as the upper portion 220 is having a first cross-sectional area, and the lower portion 230 is having a second cross-sectional area, wherein the second cross-sectional area is larger than the first cross sectional area. By this, the lower portion 230 may extend outside the upper portion 220. In the present figure, the lower portion 230 extend outside the upper portion 220 on the third body side.

[0180] FIG. 2e is a top-view along the longitudinal axis of a microneedle 200 according to an embodiment. The microneedle 200 has a semi-enclosed internal void space 240 formed by three body sides whereof two body sides join at a sharp edge, a third body side is provided with an opening slit 250, and two body sides are joined to the third body side through curved surfaces. The semi-enclosed internal void space 240 of the upper portion of the elongated body is here illustrated as having a triangular cross-section and the opening slit 250.

[0181] In the present figure, the surfaces extending from the semi-enclosed internal void space 240 to the third body side are curved. In other examples, only a part of all surfaces, or a part of at least one surface, extending from the semi-enclosed internal void space 240 to the third body side are curved.

[0182] In the present figure, the lower portion 230 can be seen as the upper portion 220 is having a first cross-sectional area, and the lower portion 230 is having a second cross-sectional area, wherein the second cross-sectional area is larger than the first cross sectional area. By this, the lower portion 230 may extend outside the upper portion 220. In the present figure, the lower portion 230 extend outside the upper portion 220 in an even manner. The sides of the lower portion 230 are here joined through curved surfaces. In other examples, at least one or a plurality of the joints may be made through curved surfaces, while other may be joint at sharp edges.

[0183] Other shapes of the internal void space than the illustrated ones having a triangular cross-section are possible, such as for example the capillary bore hole may have a cross-section comprising multiple sharp corners and edges along the internal walls, thereby resulting in a cross-section in the form of for example a multiple pointed star polygon, a ring of flower petals, a MEMS comb drive structure, saw-tooth structures, a hypocycloid shape, an astroid shape, a bicorn shape, or a tricuspoid shape.

[0184] FIG. 2f is a cross-section of a microneedle 200 shown along the longitudinal axis of a microneedle 200 according to an embodiment. The illustrated microneedle 200 has a capillary bore hole 260 with a circular cross-sectional shape. The semi-enclosed internal void space may also have a circular shape.

[0185] The internal edges may also be edges with convex or concave shapes or straight shapes, corners with sharp angles and corners with blunt angles as well as rounded corners are also possible.

[0186] The walls of the internal void space and/or capillary bore hole may also comprise hydrophilic surfaces to enhance the fluid flow in the space or hole.

[0187] FIG. 3a is a schematic perspective view of a microneedle 300 provided on a substrate according to an embodiment of the present invention having an elongated body 310 extending along a longitudinal axis from a top end to a bottom end. The elongated body comprises a upper portion 320 and a lower portion 330. The upper portion 320 of the elongated body 310 has a semi-enclosed internal void space 340 formed by three body sides whereof two body sides join at a sharp edge and a third body side is provided with an opening slit 350 extending from the lower portion 330 of the elongated body 310 to the upper end of the third body side. The top end of the elongated body 310 is configured as a bevel to create a sharp tip at the top of the edge, the bevel extends to the third body side. The semi-enclosed internal void space 340 of the upper portion 320 of the elongated body 310 is opening to an internal capillary bore hole of the bottom end 330 of the elongated body 310. The internal capillary bore hole of the lower portion 330 of the elongated body 310 extends through the microneedle 300 and may also extend into a substrate to which the microneedle 300 is provided on.

[0188] FIG. 3b is a schematic perspective view of a microneedle 300 provided on a substrate according to an embodiment of the present invention having an elongated body 310 extending along a longitudinal axis from a top end to a bottom end. The elongated body comprises a upper portion 320 and a lower portion 330. The upper portion 320 of the elongated body 310 has a semi-enclosed internal void space 340 formed by three body sides whereof two body sides join at a sharp edge and a third body side is provided with an opening slit 350 extending from the lower portion 330 of the elongated body 310 to the upper end of the third body side. The top end of the elongated body 310 is configured as a bevel to create a sharp tip at the top of the edge, the bevel extends to the third body side. The semi-enclosed internal void space 340 of the upper portion 320 of the elongated body 310 is opening to an internal capillary bore hole of the bottom end 330 of the elongated body 310. The internal capillary bore hole of the lower portion 330 of the elongated body 310 extends through the microneedle 300 and may also extend into a substrate to which the microneedle 300 is provided on. In the present figure, the lower portion 330 can be seen as the upper portion 320 is having a first cross-sectional area, and the lower portion 330 is having a second cross-sectional area, wherein the second cross-sectional area is larger than the first cross sectional area. By this, the lower portion 330 may extend outside the upper portion 320. In the present figure, the lower portion 330 extend outside the upper portion 320 on the third body side.

[0189] FIG. 3c is a schematic perspective view of a microneedle 300 provided on a substrate according to an embodiment of the present invention having an elongated body 310 extending along a longitudinal axis from a top end to a bottom end. The elongated body comprises a upper portion 320 and a lower portion 330. The upper portion 320 of the elongated body 310 has a semi-enclosed internal void space 340 formed by three body sides whereof two body sides join at a sharp edge and a third body side is provided with an opening slit 350 extending from the lower portion 330 of the elongated body 310 to the upper end of the third body side. The two body sides are further joined to the third body side through curved surfaces, and the surfaces extending from the semi-enclosed internal void space to the third body side are curved. The top end of the elongated body 310 is configured as a bevel to create a sharp tip at the top of the edge, the bevel extends to the third body side. The semi-enclosed internal void space 340 of the upper portion 320 of the elongated body 310 is opening to an internal capillary bore hole of the bottom end 330 of the elongated body 310. The internal capillary bore hole of the lower portion 330 of the elongated body 310 extends through the microneedle 300 and may also extend into a substrate to which the microneedle 300 is be provided on.

[0190] In the present figure, the lower portion 330 can be seen as the upper portion 220 is having a first cross-sectional area, and the lower portion 330 is having a second cross-sectional area, wherein the second cross-sectional area is larger than the first cross sectional area. By this, the lower portion 330 may extend outside the upper portion 320. In the present figure, the lower portion 330 extend outside the upper portion 320 on the third body side. The upper portion 320 and the lower portion 330 are divided by a dividing plane. In the figure at least a part of the dividing plane is not in parallel with the substrate plane. In other examples, the dividing plane may also be essentially in parallel with the substrate, the dividing plane may also be parallel with the bevel of the microneedle.

[0191] In the present figure, the bevel extending to the third body side connects with the third body side with an angled portion. The angled portion may for example be approximately be in parallel with the substrate. The bevel extending to the third body side may also connect with the third body side with a curved portion.

[0192] In additional examples, the elongated body can be connected with the substrate with a curved portion.

[0193] In additional examples, the microneedle can also comprise ridges that extends on an outer surface of the microneedle. The ridges may extend in a direction that is perpendicular to the longitudinal axis of the microneedle. In additional embodiments, the ridges may extend in a direction that is in parallel with the longitudinal axis of the microneedle. In additional embodiments, the ridges may be arranged as a spiral extending with the longitudinal axis of the microneedle.

[0194] The opening slit may for an example be located at the centre of a body side, such as a flat body side. The opening slit may also be located at an off-set from the centre of a body side.

[0195] At least one surface, or at least a part of all surfaces, extending from the semi-enclosed internal void space to the third body side may be curved. In some examples, at least one or even all surfaces extending from the semi-enclosed internal void space to the third body side may be connected through curved surface sides.

[0196] The elongated body may comprise three body sides, as illustrated. The elongated body may also be realised with more sides, for example four sides or five sides. Additional examples with even more sides are possible, these more sides may be evenly spaces or asymmetrically spaced. For example, an elongated body having an even number of sides where every other side is longer than the others are possible.

[0197] Two body sides of the elongated body may be joined at a sharp edge, while both body sides joint at the sharp edge is joined to a third body side through curved surfaces. The body sides joint at the sharp edge may also be joined to a third body side and a fourth body side, respectively, through curved surfaces.

[0198] The microneedle may comprise ridges that extends on an outer surface of the elongated body, where the ridges extends in a direction that is perpendicular to the longitudinal axis.

[0199] In illustrations comprising a plurality of sectors, the references may be located at corresponding places in varying sectors.

[0200] In additional examples, the one or plurality of microneedles and/or the first substrate may comprise silicon. The one or plurality of microneedles and/or the first substrate may also comprise a majority of silicon, or be made of silicon.

[0201] In additional examples, at least one or two sides of the semi-enclosed internal void space of the upper portion and at least one side of the internal capillary bore hole of the bottom end of the elongated body may form a continuous surface. In other examples, all sides of the semi-enclosed internal void space of the upper portion may form respective continuous surfaces with sides of the internal capillary bore hole of the bottom end of the elongated body.

[0202] In additional examples, the capillary bore hole of the bottom end of the elongated body may merge continuously with the internal void space of the upper portion of the elongated body on at least one side. The capillary bore hole of the bottom end of the elongated body may also merge continuously with the internal void space of the upper portion of the elongated body on at least two adjacent sides.

[0203] In additional examples, the opening between the internal void space of the upper portion and the internal capillary bore hole of the bottom end may have an area equal or similar to the area of the internal capillary bore hole. The opening between the internal void space of the upper portion and the internal capillary bore hole of the bottom end may also be aligned with the internal capillary bore hole.

[0204] In additional examples, the semi-enclosed internal void space of the upper portion may be a continuation of the internal capillary bore hole of the bottom end. The internal capillary bore hole may also extend essentially straight through the substrate. The size of the internal capillary bore hole on one side of the substrate may be of the same size of the internal capillary bore hole on the opposite side of the substrate. The size of the internal capillary bore hole on one side of the substrate may also be within 1%, 5%, 10%, 25%, 50%, or 100% of the size of the internal capillary bore hole on the opposite side of the substrate. The size may be a diameter, but may also be a cross sectional area.

[0205] In additional examples, the cross sectional area of the internal capillary bore hole may increase linearly while extending through the substrate. The sides of the internal capillary bore hole may also be straight or straight while extending through the substrate.

[0206] In additional examples, the internal capillary bore hole may form an edge on a boundary with the substrate on a side opposite of the microneedle.

[0207] In additional examples, the cross section of the internal capillary bore hole may be triangular, square, drop shaped, star shaped, or circular.

[0208] FIG. 4 is a schematic view of a fluid channel system 400 shown from above according to an embodiment. The fluid channel system 400 is arranged for transporting fluid from a plurality of inlets 442 to a fluid collection area 410 via a fluid channel. The fluid channel system 400 illustrated comprise one sector 430, where the sector 430 comprises a first section 440 and a second section 450.

[0209] In the sector 430 the first section 440 comprises five inlet channels 441, each inlet channel 441 connecting an inlet 442 and the second section 450. In the sector 430 the second section 450 connects the five inlet channels 441 of the first section 440 and the fluid collection area 410 via a connective channel 451. In the sector 430 the five inlet channels 441 merge into the connective channel 451.

[0210] The sector 430 comprises four first droplet formation structures 431 between each of the five inlets channels 441. The four first droplet formation structures 431 are arranged to collect fluid by reducing the fluid interface area to air and enlarge the fluid interface area to the channel wall via channel wall geometry, moving from one inlet channel towards another inlet channel than the one inlet channel.

[0211] The connective channel 451 comprises a second droplet formation structure 432. The second droplet formation structure 432 is arranged at the end of the connective channel 451 providing an outlet to the fluid collection area 410 and the second droplet formation structure 432 is arranged to collect fluid moving from the connective channel 451.

[0212] FIG. 5 is a schematic view of a fluid channel system 500 shown from above according to an embodiment. The fluid channel system 500 is arranged for transporting fluid from a plurality of inlets to a fluid collection area 510 via a fluid channel. The fluid channel system 500 comprise at least one sector, where each sector comprises a first section 540 and a second section 550.

[0213] In each sector the first section 540 comprises at least two inlet channels 541, each inlet channel 541 connecting an inlet and the second section 550. In each sector the second section 550 connects the at least two inlet channels 541 of the first section 540 and the fluid collection area 510 via a connective channel 551. In each sector the at least two inlet channels 541 merge into the connective channel 551.

[0214] Each sector comprises at least one first droplet formation structure 531 between the at least two inlets channels 541. The at least one first droplet formation structure 531 is arranged to collect fluid by reducing the fluid interface area to air and enlarge the fluid interface area to the channel wall via channel wall geometry, moving from one inlet channel towards another inlet channel than the one inlet channel.

[0215] Each connective channel 551 comprises a second droplet formation structure 532. The second droplet formation structure 532 is arranged at the end of the connective channel 551 providing an outlet to the fluid collection area 510 and the second droplet formation structure 532 is arranged to collect fluid moving from at least one connective channel 551.

[0216] The fluid channel has at least two inlet channels 541 and at least one connective channel 551. In the present figure, there are ten sectors. Each sector is provided with five inlet channels 541, four first droplet formation structures 531 and one connective channel 551.

[0217] FIG. 6a is a schematic view of a fluid channel system 600 shown from above according to an embodiment. The fluid channel system 600 is arranged for transporting fluid from a plurality of inlets 642 to a fluid collection area 610 via a fluid channel. The fluid channel system 600 comprise at least one sector, where each sector comprises a first section 640 and a second section 650.

[0218] In each sector the first section 640 comprises at least two inlet channels 641, each inlet channel 641 connecting an inlet 642 and the second section 650. In each sector the second section 650 connects the at least two inlet channels 641 of the first section 640 and the fluid collection area 610 via a connective channel 651. In each sector the at least two inlet channels 641 merge into the connective channel 651.

[0219] Each sector comprises at least one first droplet formation structure 631 between the at least two inlets channels 641. The at least one first droplet formation structure 631 is arranged to collect fluid by reducing the fluid interface area to air and enlarge the fluid interface area to the channel wall via channel wall geometry, moving from one inlet channel towards another inlet channel than the one inlet channel.

[0220] Each connective channel 651 comprises a second droplet formation structure. The second droplet formation structure is arranged at the end of the connective channel 651 providing an outlet to the fluid collection area 610 and the second droplet formation structure is arranged to collect fluid moving from at least one connective channel 651.

[0221] The fluid channel has at least two inlet channels 641 and at least one connective channel 651. In the present figure, there are ten sectors. Each sector is provided with five inlet channels 641, four first droplet formation structures 631 and one connective channel 651.

[0222] FIG. 6b is a part of a schematic view of a fluid channel system 600 shown in perspective according to an embodiment that is similar to the one presents in FIG. 6a.

[0223] The channel system may further have at least one first droplet formation structure that can be arranged to release collected fluid towards the connective channel.

[0224] Further, the channel system may be arranged so that the at least one first droplet formation structure is arranged to release collected fluid towards the connective channel via a meeting structure. The meeting structure may for example be a channel wall extruded from a wall of the connective channel towards the droplet formation structure. The channel wall may be with a curvature or without a curvature.

[0225] The channel system may comprise one, two, at least two, at least three, a plurality, or any suitable number of sectors, such as five, six, seven, eight, nine or ten. Designs having even more sectors are also possible.

[0226] The first section may also connect three or more inlets to the fluid collection area via the connective channel. Each sector may in turn comprise a plurality of first sections, wherein each one of the plurality of first sections similar to the first section. The first droplet formation structures for each two inlet channels may also be arranged to comprise two adjacent curved walls joined at an angle of less than 180°, such as less than 120°, 90°, 45°, 30°, 15° or 10°.

[0227] The first droplet formation structure may also comprise a surface treated region on at least part of the wall of the fluid channel between the at least two inlets, wherein the surface treated region is arranged to direct fluid to the fluid collection area.

[0228] The second droplet formation structure may further comprise two adjacent curved walls joined at an angle of less than 180°, such as less than 120°, 90°, 45°, 30°, 15° or 10°. The second droplet formation structure may also comprise a surface treated region at the wall of the second channel arranged to retain fluid flowing towards the fluid collection area. The second droplet formation structure may further comprise a chemical substance arranged to interact with collected fluid and limit undesired reactions, such as citrate interacting with blood. The chemical substance to interact with collected fluid may be comprised in a surface layer at the second droplet formation structure.

[0229] The inlet channel may further comprise a first inlet channel part connecting the inlet and the first droplet formation structure, wherein the first inlet channel part geometry comprise at least two adjacent walls joined at an angle of less than 180°, wherein the inlet channel part longitudinally connects to the inlet. The inlet channel may also comprise a first inlet channel part connecting the inlet and the first droplet formation structure, wherein the first inlet channel part geometry comprise at least two adjacent walls joined at an angle of less than 180°, wherein the inlet channel part longitudinally connects to the inlet. The inlet may for example be a part of a bore hole or an upstream connective channel.

[0230] The cross-sectional area of the connective channel may decrease from the inlets to the fluid collection area. To decrease the cross-sectional area of connective channel, the depth of the connective channel may decrease from the inlets to the fluid collection area, and/or the width of the connective channel may decrease from the inlets to the fluid collection area. The connective channel may also have a tapered channel geometry decreasing in cross-sectional area from the substrate backside inlets to the fluid collection area.

[0231] The fluid collection area further may be arranged to comprise an exit port, wherein the exit port is arranged to allow extraction of fluid collected in the fluid collection area.

[0232] At least a part of a channel or channel wall in the channel system may have a hydrophilic interior surface. The part of the channel or channel wall having a hydrophilic interior surface may be a part of any one inlet channel, any one connective channel, a plurality of the inlet channels, a plurality of the connective channels, all of the inlet channels, all of the connective channels. The part may further be a part of one sector, a plurality of sectors or all sectors. Similarly, the part may further be a part of one section, a plurality of sections or all sections. The part may be a part of a collection area, a plurality of collections areas or all collection areas. For example, at least one side of a channel may have a hydrophilic interior surface, at least one side of a channel through the fluid channel system may have a hydrophilic interior surface, and/or at least two adjacent walls of the cross-sectional channel walls of a channel may have a hydrophilic surface.

[0233] The fluid channel system may further comprise a lid attached to the substrate having the channel system. The lid may be arranged to operate as a cover over the fluidic system. The lid or cover may cover the backside of the substrate, thus covering the fluidic system, except above the exit port. The lid or cover may also comprise a high-energy surface material. The lid or cover may for example be glass. The lid or cover may for example be attached to the substrate by bonding or gluing. The lid or cover may also comprise a high-energy material covering at least a part of the fluid channel system. The lid or cover may for example comprise a hydrophobic material that may be treated to be hydrophilic on parts of the surface, such as the surface covering the fluid channel system. The hydrophobic material may for example be a plastic and the hydrophilic treatment may for example be a surface treatment or the addition of a hydrophilic material.

[0234] FIG. 7 is a cross-sectional view of a schematic chip 700 for collecting fluid via at least one microneedle. The present figure is illustrated with a plurality of microneedles.

[0235] The chip 700 has microneedles according to any herein disclosed embodiment integrally formed on a first side of a common substrate 710. Each proximal end of the microneedles 720 is integrally formed with the substrate 710 and each capillary bore hole 730 is in fluid communication with an inlet 740 of a fluid channel system 750 according to any herein disclosed embodiment on a second side of the substrate 710.

[0236] The chip 700 is arranged to, upon a microneedle 720 brought in contact with fluid, passively transport said fluid though said microneedle 720 and the fluid channel system 750 to a fluid collection area.

[0237] FIG. 8 is a schematic illustration of a method of fabricating a chip comprising at least one microneedle according to any herein disclosed embodiment and a fluid channel according to any herein disclosed embodiment using a micro electro mechanical system fabrication process 800.

[0238] The fabrication process illustrated comprises the steps of growing 810 a sacrificial oxide layer on a silicon wafer substrate, masking 820 the sacrificial oxide layer with a patterned photoresist, removing 830 the sacrificial oxide layer according to the patterned photoresist, etching 840 the silicon wafer according to the pattern of the removed sacrificial oxide layer using a deep reactive ion etching method, and removing 850 the remaining sacrificial oxide layer by using an etchant.

[0239] The etchant used to remove the sacrificial oxide layer may for example be a liquid etchant, a plasma etchant, or a combination thereof. A liquid etchant may for example comprise hydrofluoric acid or a buffered oxide etch.

[0240] Thereby a microneedle, a channel system, a chip, and a fabrication process allowing fluid in contact with the microneedle to more easily reach the internal capillary bore hole, thereby allowing an increased amount of fluid to be transported through the microneedle and a channel system for transporting the fluid, an improved solution for sampling of bodily fluids may be provided.

[0241] While specific embodiments have been described, the skilled person will understand that various modifications and alterations are conceivable within the scope as defined in the appended claims.