Gas chromatograph, column and manufacturing method

Abstract

The present invention relates to a column 140 for a gas chromatograph. The column 140 of the present invention is a 3D column having a carrier part 142 with a plurality of channels 143, a plurality of first and second connecting passages 1461, 1462, each connecting two adjacent first openings 1431 or second openings 1432, and first and second covers 1441, 1442 coupled to the carrier part 142, thereby providing a three-dimensional continuous flow path. Alternatively, the column may have a carrier part with a continuous planar flow path defined by open channels formed in the carrier part, a cover part attached to the carrier part with a plurality of filling holes arranged along the open channels, and a sealing member for sealing the filling holes. The present invention also relates to a manufacturing method.

Description

[Technical Field]

[0001] The present invention relates to a gas chromatograph for detecting volatile organic compounds in an analyte, and to a column for a gas chromatograph and a method for making such a column. [Background technology]

[0002] A gas chromatography system typically includes a column and a detector for identifying the various components in an analyte. The analyte passes along the length of the column, which is coated with a layer employed as a stationary phase, and is separated into its components due to their differential interactions with the stationary phase. The detector measures the amount of separated components exiting the column as a function of time.

[0003] Generally, a column is defined by a continuous flow path with a length and diameter. To load a column with a stationary phase, the column is filled with PDMS dissolved in a solvent containing the active component, such as hexane or pentane, and distributed by capillary action. The solvent must then be released as a gas to allow the active component to form the stationary phase. US 8,123,841 discloses a microcolumn with a serpentine geometry, with a limited ratio of channel spacing to column diameter, which facilitates coating the column with the stationary phase.

[0004] To increase the resolution of a gas chromatograph, the column length must be increased and, preferably, the diameter must be reduced to facilitate separation. However, a long column length and a relatively small diameter make it difficult to release the solvent as a gas when the stationary phase material is installed in the column. Therefore, increasing the column length without significantly increasing the thermal mass is always limited by the packing characteristics, particularly the release of the solvent as a gas from the column. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to propose a gas chromatograph column concept which allows for an increase in column length whilst providing good packing characteristics, in particular a homogeneous distribution of the stationary phase along the column length. [Means for solving the problem]

[0006] In a first aspect of the present invention, a gas chromatographic column for detecting volatile organic compounds in an analyte is provided. In particular, a gas chromatographic column according to the first aspect of the present invention is provided.

[0007] In a first alternative of the first aspect, a column is equipped with a stationary phase and configured to receive an analyte and separate volatile organic compounds in the analyte. The column is a 3D column having a carrier part having a plurality of channels, each extending from a first opening to an opposite second opening, a first cover coupled to the carrier part, and a second cover coupled to the carrier part, wherein the first cover has several first connecting passages, each connecting two adjacent first openings, and the second cover has several second connecting passages, each connecting two adjacent openings, and a three-dimensional continuous flow path is provided by the plurality of channels connected by the first and second connecting passages. The 3D column according to the present invention defines a column having a flow path with a planar extension and further an extension perpendicular to the planar extension. Thus, the column is defined by three parts: a carrier part, a first cover, and a second cover. The carrier part is provided with a plurality of channels, wherein the total length of the column is defined by the sum of the plurality of channels and the plurality of first and second connecting passages. As a result, a carrier having a channel extending from a first opening to a second opening offers excellent packing characteristics due to the short flow distance and can be easily equipped with a stationary phase. Furthermore, the three-dimensional flow path defined by multiple channels interconnected by first and second connecting passages allows for increased column length without significantly increasing thermal mass. Compared to planar columns, thermal mass remains relatively low while increasing column length. In contrast to the present invention, only serpentine column designs are known in the prior art, which increase column length while maintaining low thermal mass. It should be understood that avoiding increased thermal mass is important for ensuring uniform heating, shorter heating times, and less power consumption. The mobile phase carries the analyte through the column in a transport direction. In a 3D column, the transport direction is not linear, but defines the analyte's path through the column with a planar component and a component perpendicular to the planar component.

[0008] In a second alternative of the first embodiment, the column includes a carrier portion having a continuous planar flow path defined by open channels, particularly etched, formed in the carrier portion; a cover portion attached to the carrier portion having a plurality of fill holes arranged along the open channels; and a sealing member sealingly covering the fill holes. The column is thus a planar column, also referred to as a 2D column having a flow path with only planar extensions. The dispersed fill holes reduce the distance the solvent must traverse. Distributing the fill holes along the open channels in this manner facilitates solvent degassing, even for column lengths of 5 m or more and small diameters of 100 μm to 500 μm or less. The mobile phase carries the analytes through the column in a transport direction. In a serpentine-shaped 2D column, the transport direction is not linear but defines the path of the analytes through the column along a serpentine-shaped flow path with only planar components.

[0009] Preferably, the gas chromatograph is a micro gas chromatograph. Micro gas chromatography is performed on a micro gas chromatograph for increased portability, reduced power consumption, and increased analytical speed. In this regard, the term "micro gas chromatograph" refers herein to any portable version of a gas chromatograph that includes one or more microfabricated components. In particular, in micro gas chromatographs, column lengths are typically in the range of 1 m to 5 m, and column diameters are typically in the range of 100 μm to 500 μm. Therefore, the use of the column according to the present invention in a micro gas chromatograph is particularly advantageous. A micro gas chromatograph should be understood as a gas chromatograph having at least one microscale component.

[0010] Preferably, the first connecting passage is at least partially defined in the first cover, and the second connecting passage is at least partially defined in the second cover. In other words, the first cover at least partially includes the first connecting passage, and the second cover at least partially includes the second connecting passage. By defining the connecting passage in each of the first and second covers, the length of the flow path, and therefore the entire column, can be changed by changing the respective covers.

[0011] Preferably, the channels are aligned parallel to one another, each having a similar axial length. Parallel alignment of the channels allows for a more compact column design and reduces thermal mass. The uniform channel lengths simplify the coupling of the first and second covers. It should be understood that the first channel defining the inlet of the flow channel and the last channel defining the outlet of the flow channel may have a different axial length than the other channels. Preferably, the first free opening of the first or second opening defines the inlet end of the three-dimensional continuous flow channel, and the second free opening of the first or second opening defines the outlet end of the three-dimensional continuous flow channel. This allows the inlet and outlet ends to be integrated into a compact configuration of the channels within the carrier. It should be understood that the inlet and outlet ends may have various orientations.

[0012] Furthermore, it is preferred that the first cover forms the base and that the channels extend perpendicular to the first cover, thus providing a compact arrangement while allowing for more flexible design of the carrier component to take into account various connection types and space limitations.

[0013] Preferably, the column has at least one heater associated with at least one of the first cover and the second cover, which may be required to facilitate interaction of analytes, including volatile organic compounds, with the stationary phase.

[0014] According to a preferred embodiment, the first cover has a first cover surface, and the column has a first heater thermally connected to the first cover surface, the first heater extending along the first cover surface. Furthermore, the second cover has a second cover surface, and the column preferably has a second heater thermally connected to the second cover surface and extending along the second cover surface. It should be understood that the first heater preferably extends over the entire first cover surface, thereby providing a uniform heat distribution along the first cover surface. Furthermore, the second heater preferably extends over the entire second cover surface, thereby providing a uniform heat distribution over the entire second cover surface. Therefore, the interaction between the analyte and the stationary phase is further increased due to the uniform heat distribution.

[0015] Preferably, the channels are evenly distributed in the carrier portion, with each channel spaced at least a first distance from a first adjacent channel in a first direction perpendicular to the axial direction and at least a second distance from a second adjacent channel in a second direction perpendicular to the axial direction. In this regard, the even distribution of channels results in a uniform wall thickness that allows for uniform heat distribution. Therefore, the even distribution of channels results in more uniform heat distribution within the carrier portion.

[0016] Preferably, each channel has a cross-section defined by a first length extending in a first direction and a second length extending in a second direction, where the first distance is defined by the first length and the second distance is defined by the sin(60°) of the second length. This provides a hexagonal packing arrangement, allowing for the densest lattice packing of channels with circular cross-sections. This allows for increased column length while maintaining thermal mass compared to lower packing densities.

[0017] Preferably, the first cover and second cover are attached to the carrier part by one, several or all of the following attachment means: adhesive, seal ring, optical contact bond (e.g., An-sprengen), contact bond and PDMS thin film, which provides a fluid tide and heat resistant attachment means.

[0018] According to another preferred embodiment, the channel is defined by an inner wall extending in the transport direction and a surface-enhancing structure extending from the inner wall in a direction different from the transport direction, thereby increasing the flow resistance within the channel, generating turbulence and increasing the interaction between the stationary phase and the analyte. The surface-enhancing structure also provides an increased surface with the stationary phase and promotes increased interaction between the stationary phase and the analyte.

[0019] More preferably, the surface-enlarging structure comprises one or both of a plurality of protrusions extending from the inner wall and a plurality of cavities extending into the inner wall, the protrusions on the one hand and the cavities on the other hand providing suitable means for providing an enlarged surface area of ​​the column, resulting in increased interaction between the analyte and the stationary phase.

[0020] Preferably, the plurality of protrusions or cavities are equally spaced in the transport direction, so that the interaction between the stationary phase and the analyte is increased by the even spacing of the protrusions or cavities.

[0021] Furthermore, it is preferred that the plurality of protrusions or cavities extend perpendicular to the transport direction from the inner wall. Thus, the manufacture of the cavities or protrusions is simplified by drawing perpendicular to the transport direction since the inner wall defining the flow channel extends in the transport direction. Thus, the protrusions or cavities extend perpendicular to the inner wall.

[0022] Preferentially, the plurality of protrusions or cavities comprises a first plurality of protrusions or cavities arranged in a first row along the inner wall and a second plurality of protrusions or cavities arranged in a second row along the inner wall. Preferably, the first row is arranged opposite the second row. Arranging the plurality of protrusions or cavities in a row simplifies the manufacturing process.

[0023] Furthermore, the first plurality of protrusions or cavities are preferably offset in the transport direction from the second plurality of protrusions or cavities. This allows for increased density of the protrusions or cavities without the first plurality of protrusions interfering with the second plurality of protrusions and blocking the flow path. In this regard, increasing the density of the protrusions should be understood as decreasing the distance between two adjacent protrusions or cavities.

[0024] According to another preferred embodiment of the present invention, the sealing member comprises one, more or all of the following: - filling holes at least partially with non-gas-releasing sealant; - a wafer, which is a silicon wafer tightly attached to a cover part; - a wafer that is a glass plate or glass wafer tightly attached to a cover part; or - Foil tightly attached to the cover. In this way, a suitable means is provided for closing the packing holes after application of the stationary phase, including outgassing of the solvent through the packing holes.

[0025] In a second aspect of the present invention, a gas chromatograph for detecting volatile organic compounds in an analyte is presented.

[0026] The gas chromatograph has an injector for injecting an analyte, an inlet for receiving a flow of carrier gas as a mobile phase for carrying the analyte in a transport direction, a column having a stationary phase and configured to receive the analyte and separate volatile organic compounds in the analyte, and a gas detector configured to detect the volatile organic compounds separated by the column, the column being formed according to the first or second variant of the first aspect of the present invention.

[0027] According to the first alternative, the column is defined by three parts: a carrier section, a first cover, and a second cover. The carrier section is provided with multiple channels, where the total length of the column is defined by the sum of the multiple channels and the multiple first and second connecting passages. As a result, a carrier section with channels extending from the first opening to the second opening can easily be equipped with a stationary phase, provides excellent packing characteristics due to short flow distances, and enables outgassing. Outgassing is the release of gas dissolved or absorbed in a solvent, such as by sublimation or evaporation. Furthermore, the three-dimensional flow path defined by the multiple channels interconnected by the first and second connecting passages allows the column length to be increased without significantly increasing the thermal mass. Compared to planar columns, the column length is increased, but the thermal mass remains relatively low. In contrast to the present invention, the prior art only knows serpentine-shaped column designs, which increase the column length while maintaining a low thermal mass.

[0028] In a second alternative, the column comprises a carrier part having a continuous planar flow path defined by open channels formed in the carrier part, particularly etched, a cover part attached to the carrier part having a plurality of fill holes arranged along the open channels, and a sealing member sealingly closing the fill holes.

[0029] In a third aspect of the present invention, a method for manufacturing a column for a gas chromatograph is provided, the method comprising: - providing a carrier portion, a first cover and a second cover; - forming at least a portion of a continuous flow path in a carrier portion, the continuous flow path in the carrier portion being defined in part by a plurality of channels in the carrier portion; - applying a stationary phase to at least a portion of the flow path; - coupling a first cover to the carrier part, wherein each channel has a first opening, and the first cover has a plurality of corresponding first connecting passages, each connecting two adjacent first openings; - coupling a second cover to the carrier part, each channel having a second opening opposite the first opening, the second cover having a plurality of corresponding second connecting passages each connecting two adjacent second openings, and a three-dimensional continuous flow path provided by the plurality of channels connected by the first and second connecting passages.

[0030] By providing such a carrier part, forming a plurality of channels in the carrier part, and bonding first and second covers to said carrier part, this method has the same advantages and preferred embodiments as described with respect to the second aspect of the invention.

[0031] Preferably, the stationary phase is applied to the flow path partially defined by the multiple channels before the first cover and / or the second cover are bonded to the carrier part. Therefore, when coating the column with the stationary phase, the flow distance is significantly reduced and optimized packing characteristics are provided. As a result, the stationary phase can be applied more uniformly and quickly to the flow path defined by the channels.

[0032] The columns, particularly the continuous flow paths, are preferably formed at least in part by subtractive manufacturing processes, which in this application refers to controlled machining and material removal processes starting from a solid block, bar, or rod of plastic, metal, or other material that is shaped by removing material by cutting, boring, drilling, particularly laser drilling, grinding, and chemical material removal, particularly etching.

[0033] Preferably, the step of forming at least a part of the continuous flow path in the carrier part comprises: depositing or thermally growing an oxide layer on a carrier part, the carrier part being formed by an unpatterned silicon wafer; spin-coating a layer of photoresist onto the carrier part; photolithographically exposing the coated carrier to a pattern of intense light that defines the lateral dimensions of the plurality of channels to structure the oxide layer, thereby forming a hard mask that partially covers the carrier portion; Etching the carrier part, in particular reactive ion etching, in order to remove areas of the carrier part not covered by the hard mask and to form a plurality of channels.

[0034] Deposition of the oxide layer is preferably performed by physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD), or plasma-enhanced chemical vapor deposition (PECVD). Physical vapor deposition (PVD), also known as physical vapor transport (PVT), describes a variety of vacuum deposition methods that can be used to produce thin films and coatings on substrates such as metals, ceramics, glasses, and polymers. PVD is characterized by a process in which a material transitions from a condensed phase to a gas phase and then returns to the thin-film condensed phase. Chemical vapor deposition (CVD) is a vacuum deposition method used to produce high-quality, high-performance solid materials. Plasma-enhanced chemical vapor deposition (PECVD) is a chemical vapor deposition method used to deposit thin films on substrates from a gaseous state (vapor) to a solid state. The process involves chemical reactions that occur after the generation of a plasma of reactive gases. The channel structure is formed by photolithography, which includes at least spin-coating, exposure, and etching steps. Photolithography is a general term used for the technique of using light to create finely patterned thin films of a suitable material on substrates such as silicon wafers and protect selected areas of the film. Exposure to light causes a chemical change, and parts of the photoresist are removed by a special solution called a "developer," similar to a photographic developer. Positive photoresist, the most common type, dissolves in the developer when exposed to light, while negative photoresist dissolves in the unexposed areas. In etching, a liquid ("wet") or plasma ("dry") chemical agent removes the top layer of the substrate in areas not protected by photoresist. One suitable method is so-called reactive ion etching (RIE).

[0035] The etching time preferably determines the depth of the channel. Preferably, the oxide layer has a thickness of typically 1 μm. Furthermore, it is preferred that the resist layer has a thickness of typically 0.5 μm.

[0036] Preferably, forming at least a portion of the continuous flow path in the carrier portion includes forming a surface-enlarging structure extending from the inner wall in a direction different from the transport direction, thereby increasing the flow resistance in the channel, generating turbulence and increasing the interaction between the stationary phase and the analyte. The surface-enlarging structure also provides an increased surface area with the stationary phase, facilitating increased interaction between the stationary phase and the analyte.

[0037] In a fourth aspect of the present invention, an alternative method for manufacturing a column for a gas chromatograph is presented, the method comprising: - providing an unpatterned carrier portion; - etching an open channel in the carrier part; - attaching a cover portion to a carrier portion having a plurality of fill holes disposed along an open channel; - filling the open channel with a solvent containing an active ingredient through the filling holes; - outgassing the solvent through the filling holes to allow the active component to form a stationary phase; - sealing the fill hole with a seal member, thereby forming a continuous planar flow path.

[0038] Etching the open channel preferably includes the steps described for forming the channel, in particular RIE etching is a suitable etching process.

[0039] It should be understood that the gas chromatograph according to claim 1, the column according to claim 12 and the methods according to claims 13 and 16 have similar and / or identical preferred embodiments, in particular as defined in the dependent claims.

[0040] It is to be understood that a preferred embodiment of the invention can be any combination of the dependent claims or the above embodiments with the respective independent claim.

[0041] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. [Brief explanation of the drawings]

[0042] [Figure 1] 1 is a schematic diagram of a gas chromatography system according to a first embodiment. [Figure 2a] 1 is a schematic side view of a column for separating volatile organic compounds in an analyte according to a first embodiment. [Figure 2b] Schematic top view of the column according to FIG. 2a. [Figure 3] Schematic representation of the channel design and arrangement of the column according to Figures 2a and 2b. [Figure 4] Schematic diagram of a channel with the surface-enhancing structure of the column according to Figures 2a and 2b. [Figure 5] FIG. 10 is an exploded view of a column according to a second embodiment. [Figure 6a] FIG. 6 is a top view of an upper wafer with multiple top covers for the columns shown in FIG. 5. [Figure 6b] Detail of the top wafer shown in Figure 6a. [Figure 7a] FIG. 6 is a top view of a central wafer with multiple carrier portions for the columns shown in FIG. 5. [Figure 7b] Detail of the central wafer shown in Figure 7a. [Figure 8a] Top view of the bottom wafer with multiple top covers for the columns shown in Figure 5. [Figure 8b] Detail of the bottom wafer shown in Figure 8a. [Figure 9a] FIG. 10 is a schematic top view of a column according to a third embodiment. [Figure 9b] FIG. 10 is a side view of a column according to the third embodiment during the manufacturing process. [Figure 9c] FIG. 4 is a side view of a column according to a second embodiment in a manufacturing process using the sealing member according to the first embodiment. [Figure 9d] FIG. 10 is a side view of the column according to the second embodiment in a manufacturing process using the sealing member according to the second embodiment. [Figure 10] 5 is a flow chart showing a method for manufacturing the column according to FIGS. 1 to 8b; [Figure 11] 11 is a flow chart illustrating some steps of the method according to FIG. 10; [Figure 12] 9a to 9d, a flow chart illustrating a method for manufacturing the column according to FIGS. 9a to 9d. DETAILED DESCRIPTION OF THE INVENTION

[0043] 1 shows a gas chromatography system 1000 for detecting volatile organic compounds. The gas chromatography system 1000 includes a fluid container 170 that supplies a carrier gas 310, and a gas chromatograph 100 that is coupled to the fluid container 170 to receive the carrier gas 310. The gas chromatography system 1000 further includes a control unit 180. The fluid container 170 is preferably a high-pressure fluid container.

[0044] Gas chromatograph 100 has an inlet 110 for injecting analytes 320 including volatile organic compounds, and a preconcentrator 120 for receiving, concentrating, and desorbing analytes 320. Preconcentrator 120 has an injection port 121 coupled to inlet 110.

[0045] Analyte 320 is transported from inlet 110 to preconcentrator 120 in transport direction T. Preconcentrator 120 preferably includes a preconcentrator heater 122 controlled by control unit 180.

[0046] In the illustrated embodiment, the inlet 110 is an injector configured to inject accelerated analytes into the preconcentrator 120. The drive inlet 130 receives the accelerated flow of mobile phase 310 provided by pressurized hydrogen 310 and is coupled to a fluid reservoir 170 for injecting the mobile phase 310 into the flow path of the analytes 320 after they exit the preconcentrator 120 via a first conduit 131 or before they enter the preconcentrator 120 via a second conduit 132.

[0047] The gas chromatograph 100 also includes a column 140 with a stationary phase 141. The column 140 is configured to receive pre-concentrated analytes 320 carried by a mobile phase 310. The column 140 further includes a column heater 149 controlled by a control unit 180. The analytes 320 passing through the column 140 are separated within the column 140 due to their differential interactions with the stationary phase 141. The gas chromatograph 100 also includes a detector 150 disposed downstream of the column 140, the detector 150 configured to detect or identify volatile organic compounds separated by the column 140 over time based on the rate at which the volatile organic compounds pass through the column 140. The detector 150 is in signal communication with the control unit 180 and is configured to provide data regarding the detected volatile organic compounds, particularly data regarding transit time. The carrier gas 310 and analytes 320 streams are ultimately exhausted via an exhaust port 160.

[0048] 2a and 2b show a more detailed schematic of the column 140, with FIG. 2a showing a side view of the column and FIG. 2b showing a top view of the column.

[0049] As described with reference to FIG. 1 , the column 140 includes a stationary phase 141. The column 140 is configured as a 3D column and includes a carrier portion 142 having a plurality of channels 143. Each channel 143 extends from a first opening 1431 to an opposite second opening 1432. The column 140 further includes a first cover 1441 coupled to the carrier portion 143 and a second cover 1442 coupled to the carrier portion 143. The first cover 1431 includes a plurality of first connecting passages 1461, and the second cover 1442 includes a plurality of second connecting passages 1462. Each of the first connecting passages 1461 is configured to fluidly connect two adjacent first openings 1431. Each of the second fluid passages 1462 is configured to fluidly connect two adjacent second openings 1432. Thus, a three-dimensional continuous flow path is provided defined by the inner walls 145 provided by the channels 143 and corresponding connecting passages 1461 , 1462 , where the inner walls 145 are provided with the stationary phase 141 .

[0050] The channels 143 are preferably aligned parallel to one another. As particularly shown in FIG. 2b, second connecting passages 1462 connect each channel 143 in a zigzag pattern in a top view. A first free opening 14311 selected from the first openings 1431 or the second openings 1432 defines an inlet end 1471 of the continuous flow path 147. A second free opening 14312 selected from the first openings 1431 or the second openings 1432 defines an outlet end 1472 of the continuous flow path 147.

[0051] The first cover 1441 has a first cover surface 1441a, and the column 140 has a first heater 1491 associated with the first cover surface 1441a. The first heater 1491 is thermally connected to the first cover surface 1441a and extends along the first cover surface 1441a. Preferably, the second cover 1442 has a second cover surface 1441a, and the column 140 has a second heater 1492 associated with the second cover 1442. The second heater 1492 is thermally connected to the second cover surface 1442a and extends along the second cover surface 1442a.

[0052] As shown in Figure 2a, the channels 143 are arranged in parallel alignment, and as shown in Figure 2b, the channels 143 are evenly distributed in a serpentine pattern within the carrier part 142. However, other arrangements of the channels, including connecting passages, are possible.

[0053] The first cover 1441 is adhered to the carrier part 142 by a first adhesive means 1481, for example an adhesive, a seal ring, an optical contact bond or a thin PDMS film. Correspondingly, the second cover 1442 is adhered to the carrier part 142 by a second adhesive means 1482, for example an adhesive, a seal ring, an optical contact bond or a thin PDMS film. The inner wall 145 comprising the stationary phase 141 and defining the continuous flow path 147 preferably has a plurality of first receiving spaces 1451 arranged adjacent to the first opening 1431 and configured to at least partially receive the adhesive means, thereby enabling a fluid-tight connection with the first cover 1441.

[0054] 3 shows the design and arrangement of the channels 143 in more detail. The evenly distributed channels 143 are spaced apart from one another by a first distance Px in a first direction x, which extends perpendicular to the axial direction A along which the channels 143 extend. Furthermore, each channel 143 is spaced apart from at least a second adjacent channel in a second direction y perpendicular to the axial direction A and in the first direction x by a second distance Py.

[0055] In the illustrated embodiment, each channel 143 has a circular cross-section Q. However, other configurations of the cross-section Q are possible and may be beneficial in terms of reducing drag or increasing the surface area. The cross-section Q is defined by a first length Lx extending in a first direction x and a second length Ly extending in a second direction y. The first distance Px is defined by the first length Lx, and the second distance Py is defined by the sin(60°) of the second length Ly. Thus, a tightly packed channel 143 is provided, resulting in an increased column length of the continuous flow path 147. The channels 143 extend parallel to each other in the axial direction A. The channels 143 extend at an angle α relative to the extent of the first cover 144, which defines the bottom cover. Preferably, all columns 143 have the same length H in the axial direction A and therefore extend to the second cover 1442, which is the top plate, at the same angle relative to the first cover 1441. The angle α is preferably 90°, ensuring a space-saving arrangement. In Figure 3, the channel 143 has a circular cross section. However, other cross sections, for example defined by a polygonal cross section, are beneficial in order to provide a surface-enlarging structure.

[0056] FIG. 4 shows a cross-sectional view of a flow path 147 defined by the cross section of the channel 143. The inner wall 145 of the channel 143 preferably has a plurality of first surface-enlarging structures 1453 arranged in a first row 14531 and a plurality of second surface-enlarging structures 1454 arranged in a second row 14541 opposite the first surface-enlarging structures 1454. The presence of the first and second surface-enlarging structures 1453, 1454 increases the surface area with the stationary phase 141 and therefore increases the interaction of the analyte 320 (compared to FIG. 1 ) without significantly increasing the thermal mass of the column 140. In the embodiment shown in FIG. 4 , the first and second surface-enlarging structures 1453, 1454 are formed as protrusions projecting from the inner wall 145 into the flow path 147 perpendicular to the transport direction T. The first surface-enlarging structure 1453 is positioned offset from the second surface-enlarging structure 1454. The inner wall 145 preferably has a drag-reducing structure 1455.

[0057] 5 shows a second embodiment of the column 140, which differs from the first embodiment only in the dimensions of the flow path 147 formed by a plurality of channels 143 interconnected by a plurality of first connecting passages 1461 provided in the first cover 1441, which is the bottom cover, and a plurality of second connecting passages 1462 provided in the second cover 1442, which is the top cover. The inlet end 1471 of the continuous flow path 147 is partially defined by a first free opening and extends through the top cover 1442. The outlet end 1472 of the continuous flow path 147 is partially defined by a second free opening and also extends through the top cover 1442. To avoid repetition, reference is made to the detailed description of FIGS. 2a and 2b.

[0058] FIG. 6a shows the upper wafer 442 including a plurality of second covers 1442.1, 1442.2, 1442.3, 1442.4, where only four of the plurality of second covers are indicated by reference numerals. FIG. 6b shows section A1 shown in FIG. 6a in more detail. A plurality of second connecting passages 1462 are shown, where only a single second connecting passage 1462 is indicated by reference numeral. Each of the second connecting passages 1462 is configured to connect two adjacent channels 143 (see FIG. 7b).

[0059] FIG. 7a shows a central wafer 420 including a plurality of carrier portions 142.1, 142.2, 142.3, and 142.4, where only four of the plurality of carrier portions 142.1, 142.2, 142.3, and 142.4 are labeled with reference numerals. FIG. 7b shows section A2 shown in FIG. 7a in more detail. A plurality of channels 143 are shown, where only a single channel 143 is labeled with reference numerals. Each channel 143 is connected to at least one adjacent channel by a second connecting passage 1462 and a first connecting passage 1461 (see FIGS. 6b and 8b).

[0060] FIG. 8a shows a bottom wafer 441 including a plurality of first covers 1441.1, 1441.2, 1441.3, 1441.4, where only four of the plurality of first covers are labeled. FIG. 8b shows section A3 shown in FIG. 8a in more detail. A plurality of first connecting passages 1462 are shown, where only a single first connecting passage 1461 is labeled. Each first connecting passage 1461 is configured to connect two adjacent channels 143 (see FIG. 7b).

[0061] The top wafer 442, the central wafer 420 and the bottom wafer 441 are each manufactured by the steps shown in FIG. 11, and then the single central part 142, the first cover 1421 and the second cover 1422 can be separated from the respective wafers 240, 441, 442.

[0062] 9a-9d show a third embodiment of a column 240 having a carrier portion 242 with a continuous planar flow path 247. The continuous planar flow path 247 is defined by an open channel 2471 formed, particularly an etched channel, in the carrier portion 242. The open channel 2471 is equipped with a stationary phase 241. The column 240 further includes a cover portion 244 attached to the carrier portion 242 and a plurality of fill holes 2441 arranged along the open channel 2471.

[0063] As shown in Figure 9b, flow channel 247 is equipped with stationary phase 241 by filling solvent 2411 containing active component 2412 in open channel 2471 through filling holes 2441. Outgassing of solvent 2411 is allowed through filling holes 2441 as shown in Figure 9b. By outgassing solvent 2411, stationary phase 241 is formed with active component 2412 (see Figures 9c and 9d).

[0064] 9c and 9d, column 240 further includes a seal member 2412 that seals fill hole 2441. In FIG. 9c, seal member 2412 is preferably a non-outgassing sealant 2413 that is at least partially received in fill hole 2441.

[0065] 9d, the seal member 2412 is a wafer 2414 that is sealingly attached to the cover piece 244. The wafer may be formed at least partially or entirely from silicon or glass or foil and may be hermetically attached to the cover piece 244.

[0066] FIG. 10 shows a method 2000 for manufacturing a column 140 for a gas chromatograph 100, which includes, in a first step 2100, providing a carrier portion 142 and forming at least a portion of a continuous flow path 147 in the carrier portion 142, the continuous flow path 147 in the carrier portion being partially defined by a plurality of channels 143 formed in the carrier portion 142.

[0067] In a third step 2300, which is preferably performed following the second step 2200, a stationary phase 141 is applied to at least a part of the flow path 147, in particular to the plurality of channels 143. In a fourth step 2400, the method comprises bonding a first cover 1441 to the carrier part 142, each channel 143 having a first opening 1431, the first cover 1441 having a plurality of corresponding first connecting passages 1461, each connecting two adjacent first openings 1431.

[0068] In a fourth step 2400, the method 2000 includes coupling a second cover 1442 to the carrier part 142, each channel 143 having a first opening 1431 and an opposite second opening 1432. The second cover 1442 has a plurality of corresponding second connecting passages 1462, each connecting two adjacent second openings 1432. By performing this method 2000, a column 140 is provided having a three-dimensional continuous flow path 147, where the flow path 147 is defined by a plurality of channels 143 connected by first and second connecting passages 1461, 1462. Preferably, a stationary phase 141 is also applied to the first and second connecting passages 1461, 1462 in a third step 2300.

[0069] FIG. 11 shows a flowchart of the second step 2200, including preferred substeps. Forming at least a portion of the continuous flow path in the carrier portion includes, in a first substep 2210, depositing or thermally growing an oxide layer on the carrier portion 142, where the carrier portion 142 is formed by an unpatterned silicon wafer, such as the central wafer 240 shown in FIG. 7a. In a second substep 2220, a resist layer is spin-coated on the carrier portion. In a third substep 2230, a lithography mask having a pattern defining the lateral dimensions of the plurality of channels structuring the oxide layer is exposed, thereby forming a hard mask that partially covers the carrier portion 142. In a fourth substep 2240, the carrier portion 142 is etched, whereby areas of the carrier portion 142 not covered by the hard mask are removed to form the plurality of channels 143.

[0070] FIG. 12 illustrates an alternative method 3000 for fabricating the column 240 shown in FIGS. 9a-9d. This method involves providing an unpatterned carrier portion 242 in a first step 3100. In a second step 3200, open channels 1471 are etched into the carrier portion 242. A suitable etching method is RIE etching. In a third step 3300, a cover portion 244 having a plurality of fill holes 2441 arranged along the open channels 2471 is attached to the carrier portion 242. In a fourth step 3400, a solvent 2411 containing an active component 2412 is filled into the open channels 2471 through the fill holes 2441, followed by outgassing of the solvent 2411 through the fill holes 2441, allowing the active component 2412 to form the stationary phase 241. In a fifth step, the fill holes 2441 are sealed with a seal member 2442, thereby forming a continuous planar flow path 247.

[0071] The distance that the solvent 2411 must overcome is reduced by the distributed packing holes 2441. Thus, having packing holes 2441 distributed along the open channel 2471 facilitates outgassing of the solvent 2411 even for long column lengths exceeding 5 m and small diameters in the range of 100 μm to 500 μm or less.

[0072] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

[0073] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

[0074] A single unit or device may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0075] Any reference signs in the claims should not be construed as limiting the scope.

[0076] The present invention relates to a gas chromatograph column. The present invention is a 3D column including a carrier part having a plurality of channels, a plurality of first and second connecting passages each connecting two adjacent first or second openings, and a first and second cover coupled to the carrier part, thereby providing a three-dimensional continuous flow path. Alternatively, the column may include a carrier part having a continuous planar flow path defined by open channels formed in the carrier part, a cover part attached to the carrier part having a plurality of filling holes arranged along the open channels, and a sealing member for sealing the filling holes. The present invention also relates to a manufacturing method.

Claims

1. 1. A column for a gas chromatograph for detecting volatile organic compounds, comprising: the column includes a stationary phase and is configured to receive an analyte and separate the volatile organic compounds in the analyte; the column is a 3D column having a carrier part having a plurality of channels each extending from a first opening to an opposite second opening, a plurality of first connecting passages each connecting two adjacent first openings, a plurality of second connecting passages each connecting two adjacent second openings, a first cover coupled to the carrier part, and a second cover coupled to the carrier part, thereby providing a three-dimensional continuous flow path surrounded by the carrier part, the first cover, and the second cover; or The column comprises a carrier portion having a continuous planar flow path defined by an open channel formed in the carrier portion, and a cover portion attached to the carrier portion, the cover portion having a plurality of filling holes arranged along the open channel and a sealing member that seals the filling holes.

2. 2. The column of claim 1, wherein the first connecting passage is at least partially defined in the first cover and the second connecting passage is at least partially defined in the second cover.

3. 3. The column of claim 1 or 2, wherein the channels are aligned parallel to one another and each have a similar axial length.

4. 4. The column according to claim 1, wherein a first free opening of the first opening or the second opening defines an inlet end of the three-dimensional continuous flow path, and a second free opening of the first opening or the second opening defines an outlet end of the three-dimensional continuous flow path.

5. the first cover has a first cover surface, the column has a first heater thermally connected to the first cover surface and extending along the first cover surface; the second cover has a second cover surface, and the column has a second heater thermally connected to the second cover surface and extending along the second cover surface; A column according to any one of claims 1 to 4.

6. 6. A column according to claim 3, wherein the channels are evenly distributed in the carrier portion, and each channel is spaced apart from at least a first adjacent channel by a first distance in a first direction perpendicular to the axial direction, and spaced apart from at least a second adjacent channel by a second distance in a second direction perpendicular to the axial direction and the first direction.

7. 7. The column of claim 6, wherein each channel has a cross-section defined by a first length extending in the first direction and a second length extending in the second direction, the first distance being defined by the first length and the second distance being defined by sin(60°) of the second length.

8. 8. The column of claim 1, wherein one, more than one, or all of the plurality of channels are defined by an inner wall extending in a transport direction and have a surface-enlarging structure extending from the inner wall in a direction different from the transport direction.

9. The surface-enlarging structure is a plurality of protrusions extending from the interior wall; or a plurality of cavities extending into said interior wall; 9. The column of claim 8, comprising one or both of:

10. 10. The column of claim 9, wherein the plurality of protrusions or cavities comprises a first plurality of protrusions or cavities arranged in a first row along the inner wall and a second plurality of protrusions or cavities arranged in a second row along the inner wall.

11. The sealing member is a non-outgassing sealant at least partially received in said fill hole; a wafer, the wafer being a silicon wafer or a glass wafer, hermetically attached to the cover portion; a foil sealingly attached to said cover portion; 2. The column of claim 1, wherein one, more than one, or all of:

12. 1. A gas chromatograph for detecting volatile organic compounds in an analyte, comprising: an injector for injecting the analyte; a drive inlet for receiving a flow of carrier gas that serves as a mobile phase for carrying said analyte in a transport direction; a column comprising a stationary phase and configured to receive the analyte and separate the volatile organic compounds in the analyte; a gas detector configured to detect the volatile organic compounds separated by the column; 12. A gas chromatograph comprising: a column according to claim 1;

13. A method for manufacturing a gas chromatograph column, comprising: providing a carrier portion, a first cover and a second cover; forming at least a portion of a continuous flow path in the carrier portion, the continuous flow path in the carrier portion being defined in part by a plurality of channels formed in the carrier portion; applying a stationary phase to at least a portion of the continuous flow path; coupling a first cover to the carrier part, wherein each of the channels has a first opening, and the first cover has a plurality of corresponding first connecting passages, each connecting two adjacent first openings; and a step of connecting a second cover to the carrier portion, wherein each of the channels has a second opening opposite the first opening, the second cover has a plurality of corresponding second connecting passages each connecting two adjacent second openings, and a three-dimensional continuous flow path is provided by the plurality of channels connected by the first connecting passages and the second connecting passages.

14. 14. The method of claim 13, wherein the stationary phase is applied to the flow path partially defined by the plurality of channels before the first cover and / or the second cover are bonded to the carrier part.

15. forming at least a portion of a continuous flow path in the carrier portion, depositing or thermally growing an oxide layer on the carrier part, the carrier part being formed by an unpatterned silicon wafer; spin-coating a photoresist layer onto the carrier portion; forming a hard mask partially covering the carrier portion by structuring the oxide layer by photolithography by exposing the coated carrier to a pattern of intense light that defines the lateral dimensions of the plurality of channels; etching the carrier portion to remove areas of the carrier portion not covered by the hard mask to form the plurality of channels; 15. The method of claim 13 or 14, comprising:

16. A method for manufacturing a gas chromatograph column, comprising: providing an unpatterned carrier portion; etching an open channel in the carrier portion; attaching a cover portion to the carrier portion, the cover portion having a plurality of fill holes disposed along the open channel; filling the open channel with a solvent containing an active ingredient through the filling hole; outgassing the solvent through the filling holes to form a stationary phase of the active ingredient; and sealing the fill hole with a seal member to form a continuous planar flow channel (247).

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