Microfluid system and method for production thereof
The invention generally concerns a microfluidic system having a support body provided with a lancing member and a semi-open microchannel, for the capillary transport of a sample fluid from a receiving site to a target site. In order to obtain a higher aspect ratio the support body is coated with a build-up layer which laterally defines the microchannel in the upper region.
1 . A microfluidic system for collecting body fluids, the system Comprising:
a support body comprising a lancing member;
a semi-open microchannel, located on the support body such that the microchannel assists in the capillary transport of a fluid from a receiving site to a target site; and
a build-up layer coated on the support body for the fluid transport which laterally defines the microchannel in the upper region.
2 . The system according to claim 1 , wherein the microchannel has a lower cross-sectional region that is etched into the support body and an overlying upper cross-sectional region formed in the build-up layer.
3 . The system according to claim 1 , wherein the build-up layer laterally delimits the microchannel over its entire depth.
4 . The system according to claim 1 , wherein the build-up layer consists of a thick film photoresist.
5 . The system according to claim 1 , wherein the build-up layer is photostructured in order to form or increase the height of the microchannel.
6 . The system according to claim 1 , wherein the build-up layer has a layer thickness of more than 50 μm.
7 . The system according to claim 6 , wherein the thickness of the build-up layer is 200 to 500 μm.
8 . The system according to claim 1 , wherein the microchannel has several partial cross-sections etched down into the support body by successive etching steps starting from one surface of the support body.
9 . The system according to claim 8 , wherein the partial cross-sections are formed by photochemical mask etching.
10 . The system according to claim 1 , wherein a aspect ratio depth to width of the microchannel is larger than 0.5.
11 . The system according to claim 1 , wherein the microchannel has an inner width in the range of 50 to 500 μm.
12 . The system according to claim 1 , wherein the microchannel has an undercut in the region of its longitudinal edges formed by underetching.
13 . The system according to claim 1 , wherein the support body consists of an isotropically etchable material.
14 . The system according to claim 1 , wherein the support body has a flat shaped part consisting of metal.
15 . The system according to claim 14 , wherein the support body formed from a flat material has a thickness of 100 to 450 μm.
16 . The system according to claim 1 , wherein the build-up layer has an additional substance or composition which increases the hydrophilicity.
17 . The system according to claim 1 , wherein the wettability of a wall of the microchannel is increased by a chemical surface treatment.
18 . The system according to claim 1 , wherein the lancing member is formed by etching or punching and is positioned outside the microchannel.
19 . A method of manufacturing a microfluidic system to collect a body fluid, the method comprising:
providing a support body having a lancing member; and
applying a photoresist layer to the support body to form a semi-open microchannel that transports body fluid from a receiving site to a target site.
20 . The method according to claim 19 , wherein the photoresist is sprayed or knife coated onto the support body as a thick film or is applied by dip coating.
21 . The method according to claim 19 , wherein the process of forming the microchannel comprises the steps of:
photochemically etching a first photoresist layer;
removing the first photoresist layer;
applying a second photoresist layer and its photostructured in order to increase the height of the microchannel.