OEHMAN PER OVE (SE)
| SE9800462A | ||||
| DE4110653A1 | 1992-01-23 |
| 1. | A method of producing a calorimeterassociated detector related to a measuring cell, wherein said detector is a thermal element, characterised in that said detector is formed on an electrically nonconductive base structure ; in that a part of said base structure intended to form said detector is comprised of one or more surface regions having a topographical structure; in that at least the surface region or surface regions exhibiting said topographical structure is/are covered with a first electrically conductive metal layer which is intended to form said thermal element ; in that said first metal layer is applied to the surface structure at an angle of incidence other than 90; and in that the topographical surface structure and/or configuration on which an electrically conductive layer has been thus applied provides the function of one or more thermal elements. |
| 2. | A method according to Claim 1, characterised in that said thermal element is a Bolometer. |
| 3. | A method according to Claim 1, characterised in that the surface region or surface regions of said topographical structure is/are coated with a second electrically conductive metal layer ; in that said first metal layer is applied to the surface structure at a first angle of incidence other than 90lu : in that said second metal layer is applied to said surface structure at a second angle of incidence other than 900 and different to said first angle, and in that said first and said second metal layers are caused to overlap each other within discrete surface parts of said detector. |
| 4. | A method according to Claim 3, characterised in that said first metal layer and said second metal layer are comprised of metals which provide the function of a thermocouple at said discrete surface parts of said detector. |
| 5. | A method according to Claim 1,2 or 3, characterised in that said detector is produced on a limited surface region ; and in that electric conductors and/or electric circuits and/or electronic circuits are formed on said limited surface region in the same way. |
| 6. | A method according to Claim 5, characterised in that said base unit is produced by a topographical shaping operation, such as a moulding, pressing or embossing operation, against a die or mould that exhibits a complementary topographical structure ; in that at least a part of said mould corresponding to said detector is produced by an electrode plating process or like process against a model that includes a topographical structure adapted with respect to said detector ; in that said model is produced by micromechanically working a substrate, such as a silicon substrate ; and in that the topographical structure and/or the configuration of said model is chosen to correspond to desired detectorassociated surface parts, electric conductors, and/or electric and/or electronic circuits. |
| 7. | A method according to Claim 5, characterised in that said base unit is produced by a shaping operation, such as a moulding, pressing or embossing operation, against a die or mould that has a complementary topographical structure ; in that at least a part of said mould corresponding to said detector is produced by micromechanically working a substrate, such as a silicon substrate; and in that the topographical structure and/or the configuration of said substrate is complementary with respect to desired detectorassociated surface parts, electric conductor paths, and/or electric and/or electronic circuits. |
| 8. | A method according to Claim 1, in which the measuring cell is formed from a first and a second part which together define a cavity, characterised in that said base unit is applied to a surface part on the inside of said first cell part. |
| 9. | A method according to Claim 1, in which said measuring cell is formed by a first and a second part which together define a cavity, characterised in that said base part is comprised of a part integral with said first cell part ; and in that said detectorassociated surface parts form a part of the inner surface of said cavity. |
| 10. | A method according to Claim 1,3,8 or 9, characterised in that the cavity associated surface sections are coated at the same time as detectorassociated surface parts, and with the same metal. |
| 11. | A method according to Claim 1 or 3, characterised in that said topographical structure is adapted to provide requisite connection pads belonging to said detector, electric conductors, and/or electric and/or electronic circuits. |
| 12. | A method according to Claim 8 or 9, characterised in that electric conductors and/or electric and/or electronic circuits are formed in said second cell part. |
| 13. | A method according to Claim 3, characterised in that the topographical structure belonging to said detectorassociated surface part includes a number of socalled conductive ridges; in that said conductive ridges have a first side surface, a second side surface, and an upper surface; in that a socalled conductive surface is located between two adjacent conductive ridges; in that said first angle is adapted so that said first side surface and at least a part of said upper surface of respective conductive ridges, and at least a part of said intermediate conductive surfaces are coated by said first metal layer ; in that said second angle is adapted so that said second side surface and at least a part of said upper surface of respective conductive ridges, and at least a part of said intermediate conductive surfaces, are coated with said second metal layer ; in that said first and second angles are adapted so that said second metal layers overlap and form an electric contact with said first metal layer on the upper surface of respective conductive ridges and on the intermediate conductive surfaces, such that said metal layers form a series of electrically interconnected junctions between said first and said second metal layers. |
| 14. | A method according to Claim 13, characterised in that said detector associated surface parts are positioned so that heat generated will activate said upper surface of respective conductive ridges, and such that said intermediate conductive surfaces will be shaded from said generated heat. |
| 15. | A method according to Claim 13, characterised by electrically insulating surface sections formed between said conductive ridges, with said intermediate conductive surfaces, and surrounding surface sections belonging to said base unit. |
| 16. | A method according to Claim 15, characterised in that said electric insulation is achieved by positioning socalled insulating ridges with adjacently located socalled insulating surfaces relative to each other and relative to said conductive ridges and also relative to said first and said second angles, such as to exclude a coating of both said first and said second metal layers on said insulating surfaces. |
| 17. | A method according to Claim 13, characterised in that said conductive ridges are given a configuration which forms nnumber of conductive ridges designated column 1, column 2 and so on up to column"n", wherein respective columns include mnumber of conductive ridges designated ridge 1, ridge 2 and so on up to ridge"m", wherein"m"may be different in respective columns; in that the first ridge in each column, with the exception of the"n"th column, and the"m"th ridge in each column with the exception of the last column, form interconnecting ridge, wherein the"m"th ridge in each column, with the exception of the last column, is connected electrically to the first ridge of the next following column ; and in that the resultant junctions between said first and said second metal layers belonging to all conductive ridges in all columns form said series of electrically interconnected junctions. |
| 18. | A method according to Claim 17, characterised in that the electrical interconnection between an"m"th ridge in a column and a ridge 1 in an adjacent column is achieved by forming an electrically conductive surface section between said adjacent columns: and in that said conductive surface section is connected electrically to interconnecting ridges belonging to said adjacent columns but is insulated electrically in other respects from said adjacent columns. |
| 19. | A method according to Claim 13, characterised in that the series of conductive ridges forms a seriesconnected thermocouple; in that the intermediate layer on a first or a second side surface of a first conductive ridge, or a conductive surface adjacent to said first conductive ridge, in said series of conductive ridges, forms a first thermocouple connecting electrode ; and in that a first or a second side surface of a last conductive ridge or a conductive surface adjacent said last conductive ridge in said series of conductive ridges forms a second thermocouple connecting electrode. |
| 20. | A method according to Claim 13, characterised in that said upper surface of respective conductive ridges is covered with a heat absorbing or heat generating layer. |
| 21. | A method according to Claim 20, characterised in that said heat absorbing or heat generating layer is comprised of enzymes or some corresponding substance. |
| 22. | A method according to Claim 13, characterised in that said first metal layer differs from said second metal layer : and in that a thermoelectric effect is obtained between said first and said second layers. |
| 23. | A method according to Claim 22, characterised in that said two metal layers are comprised of gold covering chromium. |
| 24. | A method according to Claim 1, characterised in that said first cell part includes a surface section intended for two or more different detectors. |
| 25. | A method according to Claim 1 or 21, characterised in that said second part has a surface section intended for two or more detectors. |
| 26. | A calorimeterassociated detector that includes a measuring cell that defines a cavity which is adapted to enclose a medium to be measured or evaluated, wherein the surface, or parts of the surface, that form wallparts within said measuring cell or cavity is/are covered with one or more different metal layers, and wherein said detector is a thermal element, characterised in that said detector is formed on an electrically nonconductive base structure; in that a part of said base structure intended to form said detector is comprised of one or more surface regions having a topographical structure ; in that at least the surface region or surface regions exhibiting said topographical structure is/are covered with a first electrically conductive metal layer which is intended to form said thermal element ; in that said first metal layer is applied to surface structures at an angle other than 90L ; and in that the topographical surface structure and/or configuration provided with such an electrically conductive layer provides the function of one or more thermal elements. |
| 27. | A detector according to Claim 26, characterised in that said thermal element is formed as seriesconnected resistances and function as a Bolometer. |
| 28. | A detector according to Claim 26 characterised in that the a surface region or surface regions of said topographical structure is/are coated with a second electrically conductive metal layer ; in that said first metal layer has been applied to surface structures at a first angle of incidence other than 902 ; in that said second metal layer has been applied to said surface structures at a second angle other than 90and different to said first angle of incidence, wherewith said first and said second metal layers mutually overlap within discrete detectorassociated surface parts. |
| 29. | A detector according to Claim 28, characterised in that said first and said second metal layers are comprised of metals which provide the function of a thermocouple at said discrete detectorassociated surface parts. |
| 30. | A detector according to Claim 26,27 or 28, characterised in that said detector is formed within a limited surface area ; and in that electrical conductors and/or electrical circuits and/or electronic circuits have been provided in said limited surface area in the same way. |
| 31. | A detector according to Claim 30, characterised in that said base structure has been produced by a topographically shaping process, such as a moulding, pressing or embossing process against a die or mould that has a complementary topographic structure; in that at least a part of said die or mould that corresponds to said detector is produced by electroplating or like process on a model having a topographic structure adapted to said detector; in that said model is produced by micromechanically working a substrate, such as a silicon substrate; and in that the topographic structure and/or the configuration of said model is chosen to correspond to desired detectorassociated surface parts, electric conductor paths, and/or electrical and/or electronic circuits. |
| 32. | A detector according to Claim 30 ! characterised in that said base structure has been produced by a shaping operation, such as a moulding, pressing or embossing operation, against a die or mould that has a complementary topographic structure or configuration ; in that at least a part of said die or mould that corresponds to said detector is produced by micromechanically working a substrate, such as a silicon substrate : and in that the topographical structure and/or the die or mould for said substrate is complementary in relation to desired detector associated surface parts, electric conductor paths, and/or electrical and/or electronic circuits. |
| 33. | A detector according to Claim 30, where a measuring cell is comprised of a first and a second part that are intended to mutually coact to form a cavity, characterised in that said base structure is applied to a surface section of said first cell part. |
| 34. | A detector according to Claim 26, wherein said measuring cell is comprised of a first and a second part which are intended to coact mutually to form a cavity, characterised in that said base structure forms an integral part of said first cell part : and in that said detectorassociated surface parts form an integral part of the inner surface of said cavity. |
| 35. | A detector according to Claim 33 or 34, characterised in that the cavity associated surface sections are coated at the same time as the detectorassociated surface parts, and with the same metal. |
| 36. | A detector according to Claim 26, characterised in that said topographical structure is adapted to provide requisite connection pads belonging to said detector, electric conductor paths, and/or electric and/or electronic circuits. |
| 37. | A detector according to Claim 33 or 34, characterised in that electric conductor paths and/or electric and/or electronic circuits are formed in said second cell part. |
| 38. | A detector according to Claim 28, characterised in that said topographical structure belonging to said detectorassociated surface part includes a number of socalled conductive ridges; in that said conductive ridges have a first side surface, a second side surface and an upper surface ; in that an intermediate socalled conductive surface is located between mutually adjacent conductive ridges; in that said first angle is adapted so that said first side surface and at least a part of said upper surface of respective conductive ridges, and at least a part of said intermediate conductive surface, is coated with said first metal layer ; in that said second angle is adapted so that said second side surface and at least a part of said upper surface of respective conductive ridges, and at least a part of said intermediate conductive surface, is coated with said second metal layer: in that said first and said second angles are adapted so that said second metal layers will overlap and provide electric contact with said first metal layer on said upper surface of respective conductive ridges and on said intermediate conductive surfaces, such that said metal layers form a series of electrically interconnected junctions between said first and said second metal layers. |
| 39. | A detector according to Claim 38, characterised in that said detector associated surface parts are positioned so that heat that is generated will activate said upper surface of respective conductive ridges and such that said intermediate conductive surfaces will be shaded from said generated heat. |
| 40. | A detector according to Claim 38, characterised in that electrically insulated surface sections are formed between said conductive ridges, with said intermediate conductive surfaces, and surrounding surface sections of said base structure. |
| 41. | A detector according to Claim 40, characterised in that said electrical insulation can be achieved by positioning socalled insulating ridges having adjacent socalled insulating surfaces relative to each other and relative to said conductive ridges and also relative to said first and said second angle such as to exclude application of both said first and said second metal layers on said insulating surfaces. |
| 42. | A detector according to Claim 38, characterised in that said conductive ridges are configured to form nnumber of columns of conductive ridges, said columns being designated here as column 1, column 2 and so on up to column"n", and where respective columns include mnumber of conductive ridges, where said ridges are designated ridge 1, ridge 2 and so on up to ridge"m", where"m"can be different for respective columns; in that the first ridge in each column, with the exception of the"n"th column and the"m"th ridge within each column, with the exception of the last column, form interconnecting ridges, where the"m"th ridge in each column, with the exception of the last column, is connected electrically with the first ridge of the next following column ; and in that the resultant junctions between said first and said second metal layers belonging to all conductive ridges in all columns form said series of electrically interconnected junctions. |
| 43. | A detector according to Claim 42, characterised in that adjacent columns include therebetween an electrically conductive surface section ; in that said electrical interconnection between an"m"th ridge of a column and a first ridge in an adjacent column is effected through said conductive surface section ; and in that said conductive surface section is connected electrically with interconnecting ridges belonging to adjacent columns but electrically insulated from said adjacent columns in other respects. |
| 44. | A detector according to Claim 38, characterised in that the series of conducting ridges forms a seriesconnected thermocouple : in that the metal layer and a first or a second side surface of a first conducting ridge or a conductive surface adjacent said first conductive ridge in said series of conductive ridges forms a first thermocoupleconnecting electrode ; and in that a first or a second side surface of a last conductive ridge or a conductive surface adjacent said last conductive ridge in said series of conductive ridges forms a second thermocouple connecting electrode. |
| 45. | A detector according to Claim 38, characterised in that the upper surface of respective conductive ridges is covered with an heatabsorbing and/or heat generating layer. |
| 46. | A detector according to Claim 45, characterised in that said heat absorbing and/or heatgenerating layer is a catalytic layer, such as a layer of enzymes or corresponding substances. |
| 47. | A detector according to Claim 28, characterised in that the first metal layer differs from the second metal layer, such as to obtain a thermoelectric effect between said first and said second metal layers. |
| 48. | A detector according to Claim 47, characterised in that said two metal layers are comprised of gold covering chromium. |
| 49. | A detector according to Claim 26, characterised in that said first cell part includes a surface section intended for two or more detectors. |
| 50. | A detector according to Claim 26 or Claim 49, characterised in that said second cell part includes a surface section intended for one or more detectors. |
Calorimeters are used to determine different endothermic and/or exothermic reactions, among other things.
In view of the small differences between these types of reactions, in general only exothermic or heat emitting reactions will be included in the following description.
More specifically, the present invention relates to a method of producing a calorimeter-related detector that has properties similar to the properties of thermocouples.
The present invention also relates to a detector comprised of a number of interconnected thermocouples or thermal elements produced in accordance with the method.
DESCRIPTION OF THE BACKGROUND ART A number of calorimeters that can be used to evaluate and determine heat changes in endothermic reactions are known to the art.
Also known are calorimeters that can be used to evaluate and determine heat changes in exothermic reactions.
By way of example of the present state of the art in this context, it can be mentioned that it is known to establish the course taken by and/or the total value of developed energy conversions.
It is also known that the concentration of a chosen element in liquid or gaseous form can be determined with the aid of a calorimeter.
When wishing to determine the concentration of a specific molecule, such as molecule present in the blood of a human being, there can be used an enzyme which is adapted to the molecule concerned and which will function to split the molecule while emitting heat.
In this respect, the heat generated is in relation to the value of said concentration, and when an enzyme is used as a molecule-splitting catalyst the concentration of the molecule can be determined time after time.
Thus, in this application, the same detector and calorimeter can be used at different measuring occasions.
Applications are also known in which an antibody, such as a protein, hormone, is taken up by an antigen (receptor) and heat is generated. The antibody concentration can therewith be determined by established the value of the heat generated.
It will noted in the case of this latter application that when antibodies can only be taken up once, antibody concentrations can only be determined once.
Such equipment thus requires the antigens to be changed between each measuring occasion.
Different types of thermal elements are used to evaluate the heat generated in both of the aforesaid assaying methods.
Also known to the art are so-called kinetic measuring processes in which a medium to be measured has an established sample concentration and in which the time variation of the reaction is measured.
This is normally a rectilinear function.
It is also known in this respect to use Bolometers as thermal elements with which received thermal radiation results in a change in resistance due to a variation in temperature, and where a number of series-coupled resistance changes are utilised to obtain accurate measuring results.
With respect to the general features of the present invention, it should also be mentioned that it is known to produce small mechanical structures by means of so- called micromechanical or microtechnological methods, where mechanical components are formed on and in a substrate, such as a silicon chip for instance, with the aid of different techniques.
The publication"Combustible Calorimeter Produced With 3D-Micro Technology", by Tsing Cheng, Landis & Gyr Corporation, Central Research and Development Lab., CH-6301 Zug, Switzerland, illustrates how a compact three-dimensional thermopile can be formed by microtechnological methods.
The substrate used in this case is a silicon disc or chip coated with a layer of Si- nitride (SiN), which provides effective heat conductivity and effective electric insulation (Fig. 5a). A grating or a number of ridges is/are formed on this surface (Fig. 5b). The grating is coated with metal layers so as to form two different electrical conductors at two different oblique angles (Fig. 5c), therewith forming a plurality of mutually sequential junctions from the one conductor to the other. This results in a stack of thermocouples.
The publication also discloses the possibility of constructing the three-dimensional structure (Fig. 5b) from polyimide.
Also relevant in the present context is a paper published in conjunction with a national conference"Micro Structure Workshop 1996"held in Uppsala, Sweden, March 26-27,1996, by Olle Larsson, Industrial Microelectronics Center (IMC), Stockholm, Sweden, entitled"Polymeric Microstructures and Replication Techniques", which describes how micromechanically produced models can be replicated by first producing a model that corresponds exactly to-the desired copy or replica with the aid of a micromechanical process, and then producing from the model a mould or matrix which is complementary to said model and the desired copy or replia, and thereafter producing several copies or replias with the aid of the mould. A number of ways of carrying out this procedure are described.
Prior publications"Photonics and the Environment", March 1996, illustrates and describes a detector in the form of a Bolometer, and prior publication 0-7803-4412- X/98 § 10.00 (c) 1998 IEEE describes"A Silicon IR-source and CO2-Chamber for CO2 Measurements". Both of these publications contribute towards a better understanding of the fundamental principles of the present invention.
SUMMARY OF THE INVENTION TECHNICAL PROBLEMS When taking into consideration the technical deliberations that a person skilled in this particular art must make in order to provide a solution to one or more technical problems that he/she encounters, it will be seen that on the one hand it is necessary initially to realise the measures and/or the sequence of measures that must be undertaken to this end, and on the other hand to realise which means is/are required to solve one or more of said problems. On this basis, it will be evident that the technical problems listed below are highly relevant to the development of the present invention.
When considering the present state of the art as described above, it will be evident that with respect to a method of producing a calorimeter-related detector which is comprised of a thermal element, it will be seen that a problem resides in realising
the measures that need to be taken to mass-produce such a detector in a simple and cost-effective manner, and also in realising how these measures can be implemented.
Another technical problem is one of realising how a detector and the electrically conductive paths and/or other electric and/or electronic components belonging to said detector can be produced within a limited surface region.
Another technical problem is one of realising how a topographic structure produced with high precision in, for instance, a silicon substrate either directly or through the medium of complementary means and representing or corresponding to a detector and/or a conductor path and/or electric, and/or electronic components can be transferred to form in plastic material a topographical structure whilst retaining the necessary precision, and then coating the topographical replica with one or more metal layers in a manner known per se so as to form said detector and also, when required, conductor paths, electric and/or electronic components and circuits, and when applicable connection pads.
Another technical problem is one of realising how a detector that has the form of a thermal element and that has been produced in accordance with the present invention shall be positioned and how the topographical pattern shall be formed in the plastic material and also of realising the conditions required to coat the topographical pattern with one or more metal layers and the type of metals that shall be chosen so as to allow exposure and/or reaction of solely the hot solder points or the like and not the cold solder points or the like, to the by-passing medium used for measuring purposes, such as a liquid, gas or gas mixture.
Another technical problem is one of realising what is required to insulte or isolate an integrated thermal element on a metal surface on an electrically insulated body or body part from the remainder of the surface without needing to employ lithographic methods to this end.
Another technical problem is one of realising how different ridges belonging to the topographical pattern or three-dimensional structure can be readily positioned in relation to one another so as to provide a series-coupling of thermal elements that are orientated in rows and columns and therewith provide a very compact detector surface that has a high density of thermal elements, regardless of whether the thermal elements are thermocouples or Bolometers.
Another technical problem is one of realising how the columns and/or rows of ridges shall be interconnected electrically when so required, and electrically isolated from one another when so required, by configuring the topographical structure and by choosing the metal layers and the method of their application in accordance herewith.
Another technical problem is one of realising how the topographical structure shall be formed within the measuring cell so as to provide the requisite connecting electrodes for an integrated detector, in addition to the thermal element.
Another technical problem is one of realising how solely the so-called hot solder points or the like can be adapted to absorb a heat-generating reaction developed thereon.
A related technical problem in this regard, particularly when a detector is adapted to detect low heat generation, is one of realising how the hot solder points or the like shall be covered by a heat-generating and heat-absorbing layer while the cold solder points or the like are allowed to remain intact.
Still another technical problem is one of realising which type of metals shall be used when coating, e. g., the inner wall parts of the first cell-part so as to achieve the intended function of said first part and the intended change in resistance or thermoelectric effect of the thermal elements formed.
With a starting point from a detector that includes a measuring cell, another technical problem is one of realising the conditions necessary for mass-producing said integrated/measuring cell in a simple and cost-effective manner.
With a starting point from an earlier known thermocouple-forming topographical structure, another technical problem is one of realising the conditions that are required for a similar topographical structure to form a portion of the first part of the measuring cell, and also to realise the advantages that are afforded hereby.
Another technical problem is one of realising the cost and production advantages that are afforded when one part of a two-part detector and a part of the detector surface-section may be produced by shaping the same, such as moulding, pressing or embossing, against a die or mould that has a topographical surface section complementary to the topography required for the thermal element, where at least that part of the die or mould which corresponds to the detector is produced by electroplating or likewise treatment of a model of a surface section of the detector, where said model is produced by micromechanically working a substrate, such as a silicon substrate.
Another technical problem is one of realising the production advantages and cost advantages that are afforded by shaping, such as moulding, pressing or embossing, a part of a two-part detector cell and a part of a surface section of the detector against a complementary model of the detector-associated surface section.
Another technical problem is one of realising the metrological advantages that are afforded by giving the topographical structure a square, or essentially square, extension.
It will be seen that in the case of such an extension, a technical problem is one of providing conditions which enable a plurality of columns of ridges with series- connected thermal elements to be interconnected to form a single series of interconnected thermal elements, particularly thermocouples.
SOLUTION With a starting point from a calorimeter-related detector comprised of a thermal element, there is proposed in accordance with the present invention with the intention of solving one or more of the aforesaid problems a method and a detector that are characterised in that the detector shall be formed on a base unit, that the part of the base unit that is intended to form the detector is comprised of one or more surface regions that is/are shaped to provide a topographical structure, that at least this surface region or the surface regions is/are coated at least with a first electrically conductive metal layer which is intended to form the thermal element via the topographical structure.
According to proposed embodiments that lie within the scope of the present invention, the thermal element may comprise a Bolometer or a row of thermocouples.
In this latter application, it is proposed that a first metal layer is applied at a first angle other than 90C, and that a second metal layer is applied at another angle other than 90D and different from said first angle, and that the topographical structure and/or said configuration including said electrically conductive coatings functions/function as one or more thermocouples by virtue of the first and the second metal layer or coating overlapping each other within discrete surface parts of the detector.
According to one embodiment of the invention, the detector is produced on a limited surface region, and electrical conductor paths and/or electric circuits and/or electronic circuits are produced in the same way adjacent the limited surface region.
With the intention of enabling the topographical structure to be produced with sufficient precision, it is proposed in accordance with the invention that the base structure of the detector is produced by shaping, such as moulding, pressing or
embossing, said base structure against a mould or die that has a complementary topographical structure, and that at least one part of the die or mould, i. e. that part which corresponds to the surface section of said detector, is produced by electroplating or likewise treating a model that has a topographical configuration adapted for said detector, and that said model is produced by micromechanically working a substrate, such as a silicon substrate.
Alternatively, the topographical structure can be produced with sufficient precision by shaping, e. g. moulding, pressing or embossing, the base structure against a mould or die that has said complementary topographical structure, and by producing at least a part of said mould or die, i. e. that part which corresponds to the surface section of said detector, by micromechanically working a substrate, such as a silicon substrate.
In those instances when a detector and a measuring cell formed as a cavity is comprised of first and second parts that are able to form said cavity when appropriately brought together, it is proposed in accordance with the invention that the base structure is applied as a unit separate from the first cell part.
According to the present invention, it is particularly beneficial for the base structure to form an integral part of the first cell part, and for the detector-associated surface parts to form a part of the inner surface of said cavity.
In such cases, the cavity-associated surface sections can be coated at the same time as the detector-associated surface parts are coated, and with the same metal coatings.
According to one embodiment of the invention, the topographical structure may be adapted to provide requisite detector connection pads, and also electric conductor paths and/or electric circuits and/or electronic circuits.
Electric conductor paths and/or electric and/or electronic circuits may also be formed in the second cell part.
According to one embodiment of the invention, the topographical part of the detector may comprise a number of so-called conductive ridges that have a first side surface, a second side surface and an upper surface, and to provide a so- called conductive surface in between respective mutually adjacent ridges.
According to the invention, the detector-associated base structure is coated with a layer of a first metal at a first angle relative to said base structure, and with a layer of a second metal at a second angle relative to said base structure, wherein the first angle is adapted so that the first side surface and at least a part of the upper surface of respective conductive ridges and at least a part of the intermediate conductive surfaces will be coated with the layer of said first metal, and wherein said second angle is adapted so that the second side surface and at least a part of the upper surface of respective conductive ridges and at least a part of the intermediate conductive surfaces will be coated with a layer of said second metal.
According to one embodiment, the first and the second angles are adapted relative to one another such that the layer of said second metal will overlap and be in electrical contact with the layer of said first metal solely on the upper surface of respective conductive ridges and on the intermediate conductive surfaces, such that the metal layers will form a series of electrically interconnected junctions between the first and the second metals.
It is also proposed in accordance with the present invention that the metal layers in the integrated part shall be electrically isolated from the metal layers within surrounding surface sections of the base structure.
Requisite electrical insulation, or isolation, between the conductive ridges and surrounding metal layers is achieved in accordance with the present invention with the aid of so-called insulating ridges that have associated so-called insulating surfaces that are positioned relative to one another and relative to said conductive ridges and also relative to said first and said second angle such that said insulating surfaces will be devoid of said first and said second metals.
With the intention of providing a series of thermocouples positioned in rows and columns, it is proposed in accordance with the invention that the conductive ridges will be given a configuration in which they form n-number of columns, these columns being designated column 1, column 2, etc., up to column"n", and where the number of conductive ridges in each column is"m", said columns being designated ridge 1, ridge 2 to ridge"m", where"m"may be different in respect of reach column.
In order to enable the ridges of respective columns to be coupled together, it is proposed in accordance with the invention that the first ridge in each column, with the exception of the"n"th column, and the"m"th ridge in each column, with the exception of the last column, form interconnection ridges, where the"m"th ridge in each column, with the exception of the last column, is electrically connected together with the first ridge of the next following column, whereby the junctions between the first and the second metal layers of all conductive ridges within all columns form said series of electrically interconnected junctions.
Thus, the junctions between the first and second metal layers of all conductive ridges in all columns will form a common series of electrically interconnected junctions.
According to the present invention, the electrical interconnection between an"m"th ridge in one column and a first ridge in an adjacent column is achieved by virtue of forming an electrically conductive surface section between the adjacent columns and connecting this conductive surface section to mutually interconnected ridges of adjacent columns while electrically insulating or isolating said conductive surface section from said adjacent columns in other respects.
With the intention of providing connection electrodes for the thus formed thermocouple, it is proposed in accordance with the invention that the aforesaid series of conductive ridges form the series-connected thermocouple, that the metal coating or layer on a first or a second side surface of a first conductive ridge, or a
conductive surface adjacent said first conductive ridge in said series of conductive ridges, forms a first connection electrode on the thermocouple, and that a first or a second side surface of a last conductive ridge, or an adjacent conductive surface of said last conductive ridge in said series of conductive ridges forms a second connection electrode on said thermocouple.
It is also proposed in accordance with the present invention that the upper surface of respective conductive ridges is covered with a heat-generating and/or a heat- absorbing layer.
More specifically, it is proposed in accordance with the present invention that the heat-absorbent layer may comprise a layer of enzymes or some corresponding substance.
In order to achieve a good thermoelectric effect in the junction of the metal chosen for the first metal layer to the metal chosen for the second metal layer, the first metal shall differ from the second metal. It is also proposed in accordance with the invention that the two metals are gold covering chromium, which together provide a thermoelectric effect.
The present invention also relates to a detector that has the properties possessed by a detector produced in accordance with the aforementioned method. The method and a detector constructed in accordance with the method offer a solution to all of the technical problems recited in the introduction.
ADVANTAGES Those advantages primarily afforded by an inventive method and a detector constructed in accordance with said method reside in the ability of manufacturing a calorimeter-related detector of a nature that is especially adapted for the purpose in question and that can be produced in a simple and cost-effective manner.
According to the invention, a detector that includes a very large number of series- connected thermal elements can be produced in large volumes and with great precision. This enables detectors integrated in a calorimeter to be mass-produced, said detector being highly sensitive as a result of the large number of series- connected thermal elements.
The necessary detector model is produced with high precision by micromechanically working, e. g.. a silicon base structure and the model transferred to a die or mould used in the mass production of gas cell base structures, for instance in a plastic material.
The advantages afforded by a method and/or a detector according to the present invention are applicable with respect to production, enabled by simple high precision manufacture, and with regard to cost by enabling the mass production of sensitive and effectively aligned detectors that are especially adapted with respect to their application.
The primary characteristic features of an inventive method are set forth in the characterising clause of the following Claim 1, while the primary characteristic features of an inventive detector are set forth in the characterising clause of the followingClaim 26.
BRIEF DESCRIPTION OF THE DRAWINGS A method and a calorimeter-related detector having features characteristic of the present invention will now be described in more detail by way of example, with reference to the accompanying drawings, in which Figure 1 is a highly simplified, schematic illustration of a calorimeter- related detector built-up on a plate or base structure and including a two-part detector whose one part is shown over a bottom part to which the detector is fastened and which is
adapted according to the specifications given in accordance with the present invention in other respects ; Figure 2 is a schematic, side view of a portion of a first part of the detector according to Figure 1 ; Figure 3 is a schematic, somewhat enlarged side view of an inventive detector ; Figure 4 illustrates a detector according to Figure 3 that includes two layers of different metals which form a number of series- connected thermal elements in the form of thermocouples ; Figure 5 is a highly simplified and schematic illustration of a possible conductor path, electric and/or electronic circuits, and connection pads that can be formed in accordance with the invention; Figures 6a and 6b are schematic side views that illustrate how a detector- adapted base structure can be formed from a die or mould and a model ; Figure 7 illustrates a discrete detector applied to a part belonging to a measuring cell ; Figure 8 is a simplified illustration in side view that shows how a detector can be aligned or positioned; Figure 9 illustrates schematically and from above how a detector can be isolated electrically from a surrounding metal layer : Figure 10 is a schematic side view showing how a detector can be isolated electrically from a surrounding metal layer ;
Figure 11 illustrates schematically and from above a detector that includes a plurality of columns of conductive ridges, and shows the columns interconnected electrically', Figure 12 illustrates schematically and from above a detector according to Figure 11 with which the columns are interconnected electrically by means of electrically conductive surface sections ; Figure 13 illustrates schematically and from above how conductive and insulating ridges co-act to form a detector that may include a plurality of columns of conductive ridges; Figure 14 illustrates schematically and in side view how conductive ridges can be adapted to absorb generated heat ; and Figure 15 is a highly simplified, schematic illustration of a measuring cell where the inner surfaces of the measuring cell cavity have been provided with a number of detectors.
DESCRIPTION OF EMBODIMENTS AT PRESENT PREFERRED The invention relates to a method of, inter alia, producing a calorimeter-associated detector. The invention provides a high degree of freedom with regard to positioning of the detector as a separate unit or as a unit that is integral with calorimeter components, such as the measuring cell.
The method has been described earlier under the heading"SOLUTION"and is described more succinctly in the following method Claims.
Consequently, the following description deals mainly with the calorimeter-adapted detector.
Figure 1 thus illustrates, among other things, a calorimeter-related detector 3, which is adapted to co-act with a sensor 1.
The illustrated sensor 1 includes a measuring cell 2 in which there is defined a cavity 21 that includes openings 21A, 21A'and/or openings 21 B through which a volume of medium"G"intended for measuring purposes and being in a liquid or gaseous state, can enter and leave said cavity.
The detector 3 has connected thereto one or more electric circuits or electronic circuits 1 b which function to evaluate the intensity of the heat received in or generated in the detector 3 and to evaluate the properties of and/or the concentration of the medium"G"on the basis of the intensity of said heat, among other things.
The measuring cell 2 is normally constructed with the aid of a plurality of mechanical parts.
As will be seen from Figure 1, the measuring cell 2 is comprised of a combination of a first part or component 2A and a second part or component 2B, of which at least the part 2A is made of a plastic material and has been formed by some sort of moulding or pressing process or by embossment against a die or mould, such as to enable the interior of the measuring cell to be given an adapted interior shape, i. e. in the interior of the cavity 21. In the illustrated case, the second part 2B may consist in a flat plate B or a base structure where the detector 3 can be formed on a surface 31".
The detector 3 is shown as a discrete component in Figure 1.
It will be apparent from the following description that components can be integrated either with the part 2A or in the surface of the base structure B.
In the Figure 2 embodiment, the surface of the detector 3 or at least parts of the surface of said detector is/are usually coated with two different metal layers M1, M2
that consist of a selected first metal in a first layer M1, and a selected second metal in a second layer M1.
In the case of one application of this kind, the detector 3 is usually mounted completely within the measuring cell 2.
It is important that the detector 3 is aligned in the best possible way to obtain a sufficiently good measuring signal. It is also important that the detector 3 is sufficiently sensitive to the generated heat to be detected.
It is also known to use thermal elements in the form of temperature dependent resistance elements, such as Bolometers, or thermoelectric elements or thermocouples. The sensitivity of these elements is usually enhanced, by connecting several such elements in series.
The following description is concentrated, to a large extent, on the measures required to construct a detector 3 in the form of a number of series-connected thermocouples.
Those skilled in this art will realise that the following proposals can be modified appropriately to provide series-connected resistance paths for a Bolometer.
According to the invention, at least the detector 3 constitutes a part of a surface 2B.
This surface may consist in an outer part within the wall parts of the cavity 21 with connection lines drawn down towards the supporting base B in connection with the detector 3 of the Figure 1 illustration, where requisite connecting pads are formed.
Figure 3 shows, in accordance with the present invention, that the detector 3 is formed specifically as a discrete unit on a body having the form of an underlying or base surface 31 or a part of a larger underlying supporting base surface B. In this case, that part of the underlying support surface 31 that forms the actual detector 3 is comprised of one or more surface regions 3a formed topographically in a plastic element.
At least the surface region or regions 3a is/are coated with a first and a second electrically conductive metal layer M1, M2, these layers being intended to form a thermocouple in accordance with Figure 4.
Those persons skilled in this particular art will realise that a Bolometer requires only a first electrically conductive metal layer on the topographically formed surface region.
In this case, the topographic structure shall form from the electrically conductive layer a loop whose electrical resistance varies with temperature. It is also possible to form a first and a second loop by means of a topographic structure, where the first loop is allowed to be exposed to generated heat and where the second loop is remote or distanced from said generated heat as a result of the topographic structure, therewith enabling compensation to be made for variations in background temperature.
In order to obtain a chosen conductive pattern, an electric and/or an electronic circuit and/or electric or electronic components, there is required a well-developed topographic configuration on the chosen surface region of the plastic element, and a particular metal coating application.
All persons skilled in this particular field are capable of creating a topographic pattern on an electrically insulating plate that will provide a desired printed circuit or the like subsequent to applying a metal layer or layers thereto.
It will be understood that in the illustrated case, the first metal layer M1 is applied to the surface region 3a concerned at a first angle"b"other than 90D or the normal, and that the second metal layer M2 is applied at a second angle'c"other than 90 X and differing from the first angle"b". These angles"b"and"c"normally lie in one and the same plane.
The topographic structure and/or the form 3a provided with electrically conductive coatings provides the function of one or more several thermocouples, by virtue of the first and the second metal layers M1, M2 being allowed to overlap within discrete surface parts of the detector.
Figure 5 shows the possibility of producing the detector 3 on a restricted surface region and to produce requisite electric circuitry 3'and/or electric and/or electronic circuits 3"and requisite connection pads 3"'within this restricted surface region in the same way as that described above, i. e. by coating a topographic structure with one or more metal layers from different angles.
As illustrated in Figure 6a, it is proposed in accordance with the invention that the underlying support surface 31 is produced by shaping, such as moulding, pressing or embossing, against a die or mould 31', where at least a part of the mould corresponding to the detector 3, according to Figure 6b, is produced by electroplating a model 31"of the detector 3, said model 31"being produced by micromechanically working a substrate, such as a silicon substrate, where the topographic structure and/or configuration of the model 31"is chosen to correspond to desired surface parts of the detector, electric conductor paths and/or electric and/or electronic circuits.
Alternatively, the base unit 31 shown in Figure 6a can be produced by shaping, such as moulding, pressing or embossing, said unit against a die or mould 31', where at least a part of the mould corresponds to the detector 3 produced by micromechanically working a substrate, such as a silicon substrate, where the topographical structure and/or configuration of the substrate 31'is complementarily dependent on desired detector-associated surface parts, electric conductor paths and/or electrical and/or electronic circuits.
Figure 7 shows that the base unit 31 may consist of a discrete of separate component and applied to the first part 2A and/or the second part 2B.
However, the most favourable embodiment for integrating the detector 3 in said cavity is that shown in Figure 3, where a base unit 31 is allowed to form an integral part of the first cell-part 2A, and where the detector-associated surface parts are an integral part of the surface belonging to said cavity 21.
Regardless of whether the base unit 31 is a discrete component in accordance with Figure 7 or an integral part of the first part 2A and/or the second part 2B, it is possible to coat the cavity-associated surface sections and the detector-associated surface parts at one and the same time, preferably with the same metals.
The present invention also enables the topographic structure to be adapted to provide the requisite connection pads 3"'belonging to said detector 3, electric conductor paths 3', and/or electric and/or electronic circuits 3".
Alternatively, the electrical conductor paths 3'and/or the electrical and/or the electronic circuits 3"can be formed in the second part 2B.
According to the present invention, the detector 3 may comprise an integral part of the first part 2A, illustrated in Figure 3, or the second part 2B. The person skilled in this art will understand how the present method shall be applied when the formed detector 3 does not constitute an integral part of the first cell-part 2A.
It is particularly convenient to provide the base unit or support 21 with a number of conductive ridges 5,5', 5". Each of these conductive ridges has a first side surface 5a, a second side surface 5b and an upper surface 5c. An intermediate surface 6, designated here a conductive surface, is located between two mutually adjacent conductive ridges 5,5'.
It should perhaps be mentioned that the expression"conductive ridges"may be somewhat misleading, since the topographic structure has the form of a greatly reduced"skyscraper structure", i. e. the structure is comprised of a plurality of narrow rods where the rods in one row (or column) may be slightly offset laterally
with respect to the rods in adjacent alternate rows and with different rods of different heights.
As previously described with reference to Figures 3 and 4, the electrically non- conductive base unit 31 is coated with the first metal M1 at a first angle"b"in relation to the detector surface, and with the second metal M2 at-a second angle"c" relative to said detector surface.
The first angle"b"shall be adapted so that the first side surface 5a and at least a part of the upper surface 5c of respective conductive ridges 5,5', 5", and at least a part of the intermediate conductive surfaces 6 will be coated with the first metal layer M1, and the second angel"c"shall be adapted so that the second side surface 5b and at least a part of the upper surface 5c of respective conductive ridges 5,5', 5", and at least a part of the intermediate conductive surfaces 6 will be coated with the second metal layer M2, in accordance with Figure 4.
The first and the second angles"b","c"shall be adapted so that the second metal layer overlaps the first metal layer M1 on the upper surface 5c of respective conductive ridges 5,5'and on the intermediate conductive surfaces 6,6'so as to form an electric contact with M12, M21, and so that the metal layers M1, M2 will form a series of electrically coupled ridges or transitions M12, M12', M21, M21' between the first and the second metals.
As evident from Figure 4, this results in a series of thermal elements, where the number of series-connected thermal elements corresponds to the number of ridges.
In order to obtain an electrically functioning detector 3, it is necessary for all thermal elements to be insulated electrically from surrounding metal layers, i. e. that the metal layers M1, M2 in the detector-associated surface are electrically isolated at 71 from the metal layers M1 R, M2R on the surrounding surface.
As illustrated in Figure 8, it is proposed in accordance with the present invention that the integrated part is aligned relative to the angle of incidence"a"of the incident light 4 by positioning the detector 3 in relation to incident heat rays 4, such
that said rays 4 will activate the upper surface 5c of respective conductive ridges, and such that the intermediate conductive surfaces 6 will lie in the shade of the conductive ridges with respect to incident heat rays 4.
As will be seen from Figures 9 and 10, electric isolation, or insulation, 71, between the detector 3 and surrounding metal layers M1 R, M2R is achieved with the aid of insulating ridges 81 with adjacent insulating surfaces 91 belonging to the integrated part are so positioned relative to each other and relative to the conductive ridges 5, 5', 5"and relative to the first and to the second angle"b","c"that both the first metal coating and the second metal coating will be absent on the insulated surfaces 71.
Figures 9 and 10 also show how a column of ridges is constructed. It is desirable to obtain a large number of series-coupled transitions from one metal to the other metal, in order to enhance the resolution, or sensitivity, of the detector 3. If it is necessary to increase the number of series-connected transitions, the detector surface will obtain a pronounced oblong shape. For reasons of measuring technology, however, it is desirable for the detector surface to have an essentially square shape.
Accordingly, it is proposed in accordance with the invention that the conductive ridges have a configuration which comprises a number of columns of mutually parallel conductive ridges, as shown in Figure 11, where the number of columns is "n", here designated column 1 (k1), column 2 (k2), and so on to column"n" (kn) where the number of conductive ridges in respective columns is"m", here designated ridge 1 (a1), ridge 2 (a2) and so on up to ridge"m" (am) and where"m" may be different for respective columns.
In order for the ridges in respective columns to form a coherent series of junctions, it is proposed in accordance with the invention that the"m"th ridge"am"of each column, with the exception of the last column"kn", is coupled electrically 51 to the first ridge"a1"of the next following column.
In this way, the transitions between the first and the second metals belonging to all conductive ridges within all columns form a common series of electrically coupled junctions.
Figure 12 illustrates an embodiment in which the electric interconnection 51 between two ridges of two mutually adjacent columns k1, k2 can-be effected by forming an electrically conductive surface section 51'as said interconnection.
Figure 13 illustrates that an essentially square thermocouple can be constructed by combining electrically conductive ridges a1, a2 with insulating ridges 81.
It is also suggested in accordance with the present invention that the series of electrically conductive ridges form the series-connected thermocouples, where the metal layer on a first or on a second side surface of a first conductive ridge k1, a1. or a conductive surface adjacent said first conductive ridge, in the series of conductive ridges forms a first connection electrode 53 on the series-connected thermocouple, and that a first or a second side surface of a last conductive ridge kn, am, or a conductive surface adjacent said last conductive ridge, in the series of conductive ridges, forms a second connection electrode 54 on the series-connected thermocouple.
Figure 14 is intended to show in particular that when the detector 3 is adapted to detect generated heat, the upper surface 5c of a respective conductive ridge may be covered with a heat-absorbing or a heat-generating layer 55.
This is done so that the hot solder points constituting measuring points in the thermocouple shall absorb the greatest possible part of the thermal energy present.
The cold solder points, i. e. the conductive surfaces between the conductive ridges, shall not be subjected to heat generation.
According to one preferred embodiment of the invention, the heat-absorbing layer 55 may be comprised of a layer of enzymes or some corresponding substance.
The two metals M1, M2 used shall be appropriate with respect to their thermoelectric properties. Thus, the first M1 shall differ from the second metal M2 and the metals shall provide a thermoelectric effect in coaction with one another.
According to one preferred embodiment, the two metals are gold and chromium respectively, where chromium is the first, innermost metal M1, and gold is the second metal M2.
It will also be understood that a measuring cell can be provided or allocated with a plurality of detectors, within the concept of the invention. This possibility is illustrated in Figure 15, in which the first part 2A includes integrally two or more different detectors 31,32, and/or by providing the second part 2B or further second parts with one or more detectors 33,34.
It is pointed out that with the intention of facilitating an understanding of the invention, the devices and apparatus illustrated have been greatly enlarged and greatly simplified. In practical applications, the cavity in a measuring cell will have dimensions in the regions of millimetres or a centimetre, whilst the detector and its ridges will have dimensions in the micrometer range. However, the present invention is not restricted to specific sizes of the components and said components may have any desired dimensions, in accordance with the requirements that prevail in respect of a particular application.
It will be understood that the invention is not restricted to the aforedescribed and illustrated exemplifying embodiments thereof, and that modifications can be made within the concept of the invention as illustrated in the following Claims.