BE1027365B1 - Sensor for measuring a content of an element in a fluid and / or a change of such content in a fluid - Google Patents

Abstract

Sensor (1) for measuring a content and / or a change of such content of an element in a fluid with a component (2) which has or exist a receiving portion (21) in the form of one or more solid bodies made of a material that readily takes up and releases the element in question and of which one or more dimensions (B, D, L) increase or decrease depending on whether an amount of such element is received or released by the recording portion (21) and a measuring portion ( 22) which measures the change of one or more dimensions (B, D, L) of the recording portion (21).

Description

* BE2019 / 5378 Sensor for measuring a content of an element in an Eluidum and / or a change of such content in an Eluidum. | 5 | The present invention relates to a sensor for | the measurement of a content of an element in a fluid {and / or a change of such content in a fluid, 9 Without limiting the invention thereto, the invention relates to a sensor incorporating an oxygen sensor # for measurement of a oxygen content and / or a change of such oxygen content in a fluid is or 9 oo A hydrogen sensor For just measurements of a # 15 hydrogen content and / or a change in salmon hydrogen content in a fluid. However, the invention may also relate to sensors that measure levels of other elements and / or changes in levels of other elements, wherein the levels or changes in levels can relate to individual elements or to a combination of such elements.

In the following text, many features of the invention are set forth with reference to sensors that are oxygen sensors, but the techniques applied may also be applied by analogy to sensors for measuring levels and / or changes in levels of other elements.

/ BE2019 / 5378; However, in some cases information will be provided | that can be important for an application in a sensor | which is of a different type than an oxygen sensor, wherein according to the invention all other features of the | The oxygen sensor can also be used on the sensor concerned. 9 Oxygen sensors are typically used with 9 combustion engines of vehicles with a # 18 engine management system FOR measuring the oxygen content and / or a change in the oxygen content in the exhaust gases of an exhaust system of such a vehicle, for example to evaluate and possibly evaluate the effectiveness of combustion. to adjust the ratio between the injected fuel and air or, for example, to check the effectiveness of a catalytic converter in the exhaust system. It is also not excluded, however, to use the sensor according to the invention for other purposes. Many oxygen sensors are already known in the prior art, but they have a number of drawbacks.

The first type of known and widespread oxygen sensors uses zirconium oxide and sen Nernst cell. An electrochemical reaction is hereby established, whereby the difference between the oxygen content in the fluid to be measured, for example in a flow of Exhaust gases, and the oxygen content in a reference

: fluid, for example in the airflow of outside air that is supplied to the motor, generates a potential, [This potential therefore indicates how big the difference in | 5 oxygen is pleasant between the two fluids: a disadvantage of these known oxygen sensors is that they have a | have a fairly high tendency to fail due to thermal shock.

Yet another drawback of these known oxygen sensors is that they are quite large in size. An additional drawback of these known oxygen sensors is that the processes that take place in them are complicated. Yet another known and widespread type of oxygen sensors are the resistive type oxygen sensors which use so-called "mixed oxides" or metal oxides. Len big drawback. Of these known oxygen sensors, the conditions in which they are usually applied, such as in an exhaust system, are very extreme, which leads to unreliable electrical contacts and thus to an unreliable operation of the oxygen sensor in question. Another drawback of this type of known oxygen sensors is that their operation is not linear, so that a change in the oxygen content cannot be read directly but requires additional processing.

* BE2019 / 5378 An additional disadvantage of this type of known oxygen sensors is that they are not broadband sensors, so that it is impossible to determine an oxygen content with them. The present invention therefore aims at a solution; to deal with the aforementioned and / or other problems, | More specifically, it is an object of the invention to provide a sensor, 9 in particular an oxygen sensor or hydrogen sensor, but not necessarily such a sensor, which can be of very small design.

Yet another object of the invention consists in realizing a sensor in which the electrical or electronic parts are completely isolated from the fluid in which the relevant content or the change of the relevant content is to be measured.

Such fluid may be, for example, a flow of exhaust gases.

Yet another object of the invention is to provide a sensor that functions essentially in a linear fashion.

To this end, the present invention relates to a sensor for measuring a signal level of an element in a fluid and / or a change of such content in a fluid, the sensor comprising an electronic component comprising at least the following parts: - a recording part below the form of one or more solid bodies consisting of or consisting of a material that readily absorbs and releases the element in question and of which one or more dimensions increases or increases or decreases or decreases as an amount of suction element is cogenomized through the recording portion or 9 is issued; and, | - a substantially planar substrate having a 9 plurality therein that induces the change of one or more 9 dimensions of the recording portion; {wherein the recording part is tightly connected to the measuring part but is electrically isolated from the 9 mooring part, A great advantage of such a sensor according to the invention is first and foremost that the sensor and in particular the aforementioned component thereof can be made very small. with the techniques available from electronics.

Another great advantage of a sensor according to the invention is that a completely different method is used to determine the content of a relevant element such as oxygen and / or a change in that content than is the case with the known sensors.

More specifically, it is the intention to measure the change of one or more dimensions of a recording part upon absorption and removal of the element concerned, for example oxygen.

A first advantage of this is that the change in dimension of the recording portion can be directly and linearly related to a change in absorption or release of the particular element, such as oxygen, into or from the recording portion.

© BE2019 / 5378 Another advantage of this measurement technique is that the effects of the relevant dimension change or dimension changes can be measured without exposing the | measuring circuit on the respective fluid is necessary. | Another additional advantage of this proposed method 9 for determining the content and / or a change in the content of the element concerned is that there are many | various measuring techniques can be used. The measuring portion is described as part of the substrate because the epitaxially formed layer is usually considered to be associated with the substrate. The whole is then flat. Also in this condition the wafer is normally delivered. Only after this layer is a topography created. The measurement structure is made use of the epitazial layer, either by implantation as usual with a silicon substrate or by etching as usual with other materials such as GaN, Sit and the like.

in a preferred embodiment of a sensor according to the invention, the sensor comprises a conversion portion capable of generating a signal Le, wherein the change of one or more dimensions of the recording portion is in particular converted into a signal, preferably an optical or electrical signal that changes as a function of the content of the element concerned and / or the change in a content of the element in question present. 36 Such a converting portion can take many forms and can consist, for example, of means converting a voltage, current,

An electrical layer or any other {physical quantity generated by the measurement part, can {convert into a signal according to the content present | of the element concerned, for example the oxygen content, and / or according to an existing | change of such content. With the insight to better demonstrate the characteristics of the invention, below are by way of example without any limiting character some preferred embodiments of a sensor, with characteristics applicable to a sensor. oxygen sensor, as on other sensors, according to the invention described with reference to the accompanying figures, in which:

figure 1 schematically represents, in perspective, a disassembled version of a sensor according to the invention; figure Z shows on a larger scale in perspective the connection of parts of the sensor to a wiring frame; fiquur 3 schematically shows in section and on a larger scale a possible embodiment of an electronic component forming part of a sensor according to the invention :;

Figures 4 and 5 schematically represent two possible embodiments of a measuring part of a sensor according to the invention in plan view and to an even larger scale: Figures 5 to 7 in an analogous manner to that shown in Figure

3 show possible alternative embodiments of the electronic component forming part of a sensor according to the invention; and,

Figures 8 and 9% schematically illustrate in cross section how other embodiments of a sensor according to the invention can be realized with other measuring techniques. | Figure 1 shows a sensor 1 according to the invention 9 in a disassembled state, which is for example an oxygen sensor 1, 9 This sensor 1 contains an electronic component 2 which constitutes the essence of the sensor 1, possible embodiments of which are illustrated. in Figures 3 and 5 to 7 and which will be discussed in further detail.

This electronic component 2 is not shown in figure 1 because of its small reception. However, it is schematically illustrated with reference to figure 1 that the sensor 1 is provided with a housing 3 in which the electronic component 2 is housed. It is of course the intention that the core of the sensor 1, which is formed by the aforementioned electronic components 23 component 2, is as well shielded as possible to withstand the extreme conditions of heat, usually 600 ° C to 700 ° C and above, pressure and any aggressive chemical substances that may be present in the fluid in which the content or change of such content should be measured,

The housing 3 comprises a head 4 in the form of a cylindrical sleeve 4 with an open end 5 and a closed end 6, 5 The walls of the head 4, in particular the cylindrical wall | 7, as well as the bottom 8 at the closed end 5 of the 9 cylindrical sleeve 4, are perforated and thus F provided with perforations 9. The housing 3 further comprises a tube 10 on which the head 4 is arranged at the end 11. at the end 12, the tube 10 is provided with a flange 13.

The housing 3 of the oxygen sensor 1 further includes an elongated sleeve 14 disposed in the tube 10 and containing the electronic component 2, which is not shown in Figure 1.

It is intended here that a recording portion of the oxygen sensor 1 extends into the head 4 in order to be able to be exposed to a gas or fluid flowing through the perforations 9 in the head 4 in order to thus determine the element to be measured, such as for example oxygen. , to be able to receive in or release back from the receiving part of the sensor |, depending on whether the relevant gas is rich or poor in the relevant element, such as for example oxygen or hydrogen,

The elongated sleeve 14 is protected by a shield 15 consisting of two semi-cylindrical portions 16 and | 17 together surrounding the elongated sleeve 14, | The semi-cylindrical portions 16 and 17 may, for example, be made of magnesium oxide or of a | sealing glass, such as a = borosilicate glass or a: aluminosilicate glass, id. In figure 2 it is further shown that portions 18 of the electronic component 2 are preferably electrically connected to a nickel-plated copper wiring frame 19 by means of platinum wire connectors 20.

Here, both the parts 18 of the electronic component 2 and the wiring frame 19 can be held in an LCP container, where LCP stands for "Liquid Crystal Polymer".

In order to obtain a good seal of the oxygen sensor 1, polyphenylene sulphide refinishing or the so-called "PPS over molding" can be applied. Another possibility consists in realizing the electrical connections by direct shrinking or welding and then applying a seal, preferably a seal based on one or more fluorocarbon elastomers.

Fiquur 3 shows a first possible embodiment of an electronic component 2 forming part of a sensor 1, for example an oxygen sensor 1, according to the invention. This electronic component 2 first and foremost contains a 9 5 absorption portion, which in this case is an oxygen absorption portion 9 21 and which in this case is formed by one solid-state | Body 21 consisting of a material which readily absorbs and releases oxygen 9, in other embodiments, the recording portion 21 or 9 may analogously be a hydrogen absorption portion 21 and so on. Furthermore, the material is intended to be such that one or more multiple dimensions of the recording portion 21 increases or increases or decreases or decreases depending on whether the relevant measuring element, for example oxygen or hydrogen, is absorbed or released by the recording site 21,

according to the invention, for this purpose, this oxygen uptake portion 21 is preferably made of platinum (Pt) in case the sensor 1 serves to take in or release oxygen or palladium (Pd) in the case the sensor 1 serves to store hydrogen. to take or to deliver, which are materials that typically meet the aforementioned conditions in solid form.

The electronic component 2 further comprises a measuring portion 22 which measures the change of one or more dimensions of the recording site 217, for example the oxygen absorption portion 21, as a result of absorption or release of the element concerned, for example oxygen, og. This measurement portion 22 can take many forms. , as further; 3 will be discussed. ; The electronic component Z is preferably manufactured | with the techniques known from electronics. : 10 This is also the case in the examples shown in the | Figures. Here, the most portion 22 is disposed on a substantially planar substrate 23, which is typically a 153 silicon sulfate, for example. By substantially flat is meant essentially flat, but with possibly small variations in height or thickness, whereby a certain topography of a few microns as a result of any etching processes applied is always considered to be substantially flat. Furthermore, the electronic component 2 is provided with a heating element 24 surrounding the measuring portion 22.

The heating element 24 is typically a tungsten or platinum heating element 24, Platinum is preferred to use fewer different materials and it can be connected directly by ultrasonic welding, so-called "wire bonding".

| To avoid corrosion, over the measuring section 22 and over | the heating element 24 has a passivation layer 25 applied. 9> This passivation layer 25 typically consists of aluminum oxide 9 or silicon nitride. 9 The recording portion 21 is disposed on a portion 26 of 9 the passivation layer 25 and is thus separated from the | 10 measurement site 22 by means of the passivation layer 25. The recording site 21 in this example is one solid body which is designed as a beam-shaped and / or plate-shaped element 38, but in other embodiments this may not necessarily be the case, as further will still be described.

By making the receiving portion 21 elongated and thus having a width B and thickness D which are relatively small with respect to the length, the force build-up in the longitudinal direction will be much greater than in the width direction and the thickness direction and / or the change in the dimensions of the recording site 21 mainly take place in the longitudinal direction,

In such a case, it is evident to measure this change or these changes along the longitudinal direction with the measuring part 27 when the relevant element to be measured, for example oxygen, is taken up or released by the recording part 21,

: in a possible embodiment of a sensor 1 according to the invention, the measuring portion 22 may contain, for example, a portion 27 consisting of a | semiconductor material with piezo resistive and / or piezo | 5 electrical properties. 9 In this case, the semiconductor material preferably extends 9 over a portion 27 with dimensions, in this case a width B 'and a length L', which correspond zubstantially with the dimensions, the width B and the length L, of the oxygen absorption portion 21 in order to create a change in the resistivity tensor c Le in the piezo-resistive semiconductor material corresponding to the expansion or contraction in the adjacent material 28, which in this case is formed by the portion 26 of the passivation layer 25, under the influence of the expansion or shrinkage of the recording portion 21 by receiving or releasing the relevant element to be measured, such as, for example, oxygen.

It is clear that such a change of the resistivity tensor can be easily measured by additional means by, for example, passing an electric current through the semiconductor material and measuring the voltage or vice versa by applying an electric voltage across the semiconductor material and the resulting electric current cp Le measure. A haliconductor material suitable for these purposes can be, for example, gallium nitride (GaN), but it can be mixed with other semiconductor materials such as silicon, indium nitride (InN}, aluminum nitride (AIN, silicon

{45 BE2019 / 5378 carbide or carborundum {810}, diamond and / or zinc oxide (Zn0}), is certainly also possible, and the use of other materials is of course also not possible | excluded from the invention. 9 Another important aspect of the invention consists of: decoupling part 29 of the substantially planar substrate 23 at 9 location from essential elements of the electronic component 2, such as the recording part 21, the measuring part # 22 and the heating element 24. of the remaining portion 30 of the substantially planar substrate

23. This is achieved in the example shown in Figure 3 by making the portion 295 of the substantially flat substrate 23 at the location of the aforementioned essential elements 21, 22 and Zi of the electronic component 2 substantially thinned to form a kind of membrane. 31. A thinned construction of the aforementioned portion 29 can be realized reasonably easily by etching away the relevant portions of the substantially planar substrate 23.

A thin embodiment of the aforementioned part 25 of the substantially flat substrate 23 has the advantage that the dimensional change or dimensional changes of the recording part 21 can or can continue better, while the substantially flat substrate 23 also has a smaller mass there, so that it is more has greater resistance to thermal shock.

Other and additional ways to increase the resistance to thermal shock can be the | substantially flat substrate 23 to be manufactured from a material having a relatively low volumetric # & heat capacity, and relatively low coefficient of thermal expansion and a relatively high thermal conductivity. Figures 4 and 5 show how to measure the measuring portion Z2 of the sensor. 1 can be given a special shape which is very suitable for measuring the deformations or stresses caused by the absorption or delivery of the relevant element to be measured, such as, for example, oxygen, through the recording part 21. In these embodiments, the fertilizer part 22 contains a portion 32 having a structure consisting of at least a pair of interlinked structures 33 and 34 resembling Halipiates and interconnected in opposite directions.

A Hall plate is a structure that measures the magnetic field using the Hall effect. The structures 33 and 34 are each similar to such Hall 23 plate in the sense that they are each also formed by a square, insulated structure 33 and 34 with electrical contacts to the four nook points, electrical contacts U1, V1, XL and Yi, respectively. and electrical contacts UZ, V2, X2 and Y2.

3 The electrical contacts extend in the diagonal directions RR ', 58 "and TT' of the square structures 33 and 34, | 3 Here the electrical contacts X1 and Y1, as well as the electrical contacts XZ and YZ, lie on opposite sides. 9 vertices of the square structures 33 and 34 defining the direction RR 'of a first diagonal of each square 9 structure 33 and 34.

9 The structures 33 and 34 are, as already mentioned above, connected to each other in reverse by being disposed such that these first diagonal directions RR 'of each structure 33 and 34 extend in line with each other and by the electrical contacts X1 and X2 of the structures 33 and 34 are electrically interconnected, or, as is the case in Levens in Figure 4, in that the electrical contacts X1 and X2 form a single electrical contact. Similarly, the electrical contacts U1 and VI, as well as the electrical contacts U2 and V2, on the other opposite vertices of the square structures 33 and 34, The electrical contacts U1 and Vi of the structure 33 extend along its diagonal direction SS 'and the electrical contacts UZ and V2 of the structure 34 extend according to its diagonal direction TT '. From the foregoing, it follows that the diagonal directions SS' and TT 'extend parallel to each other.

LB BE2019 / 5378 The electrical contacts U1 and U2 are both on one {same side of the common diagonal direction | RR 'and the electrical contacts V1 and V2 are both on the other side of the common diagonal direction 9. Above each of the structures 33 and 34, a portion, 9 and the portions 35 and 38, respectively, of the receiving portion 21 is arranged. 9 9 Each such part 35 and 36 of the receiving part 21 consists in this case of a series 37 of beam-shaped and / or plate-shaped elements 38 which are elongated and uniform and which are parallel to each other in their longitudinal direction and at equal distance E from each other. are drawn up. Other embodiments in which the elongate elements 38 are not of beam-shaped or plate-shaped design are of course not excluded from the invention.

Also embodiments in which a series 37 of elements 38 is used, in which the elements 38 are not parallel to each other and / or in which the elements 38 are not designed uniformly, are not excluded from the invention.

The beam-shaped and / or plate-shaped, elongated elements 38 of each square structure 33 or 34 extend in a direction PP, respectively direction 90 °. Here each of the directions PP and 00 "is parallel to a pair of opposite sides of the square structure concerned 33 or 34,

La BE2019 / 5378 Furthermore, the elements 38 of the two structures 33; and 34 are expressed with their length L according to the concerned | directions PP "and QQ ', which are respectively located right on top of each other, 9 To measure a change of the element in question, such as for example oxygen, received by the F receiving portion 21 in the elongated elements 38, it is intended. that across a pair of opposite electrical # 12 contacts of the structure 33, more specifically the pair of opposite electrical contacts Xi and Y1 in the case of Figure 4 and the pair of opposite electrical contacts U1 and Vl in the case of Figure 5, an electrical voltage difference AV is being constructed.

This electrical voltage difference AV can be, for example, a positive electrical voltage difference AV between an electrical contact with an electrical potential of 0 Volt and an electrical contact with an electrical potential of V + Volt. In the same way, an equal electrical voltage difference AV is applied across a corresponding pair of opposite electrical contacts of the structure 34, more specifically across the pair of opposite electrical contacts Xd and YZ in the case of Figure 4 and across the pair of opposite electrical contacts UZ and V2. in the case of figure 5. The measurement is then made by measuring the resulting electrical voltage between the pairs or one of the pairs

; cresisting electrical contacts of the square, structures 33 and 34,: In the case of figure 4, this measurement is therefore done between the | & pair of electrical contacts Ul and Vl of the structure 33 9 and / or the pair of electrical contacts U2 and V2 of the F structure 34, 9 In the case of Figure 5: the measurement between the There | 10 electrical contacts X1 and Y1 of the structure 33 and / o the 9 pair of electrical contacts X2 and YZ of the structure 34. In the absence of mechanical stresses and any other effects that could affect the electron currents in the structures 33 and 34, in short, in a neutral state, it can be assumed that the electron currents will flow through the semiconductor material in question from the electrical contacts with positive potential V + Volt to the electrical contacts with zero potential 0 Volt, in the direction indicated by the arrows ESI and ESZ. in what follows, more explanation is provided of the operating principle behind the structure of the measuring portion 22-22 of the sensor 1, which is shown in Figures 4 and

5. The arrangements of figures à and 5 work differently depending on whether for the square structures 33 and 34 semiconductor materials with pronounced piezo-resistive properties, such as, for example, silicon (Sij, are used, or when materials are used for this purpose BE2019 / 5378). mainly piezorelectric effects occur, such as, for example, gallium nitride (GaN). 9 When materials with mainly piezo- 9 resistive effects are used, a change in the mechanical stress (cf extension or shortening) in accordance with a certain direction in the semiconductor causes material for a change 9 of the charge carrier mobility that is different in the direction of the applied mechanical stress (or 0 elongation or shortening) compared to the charge carrier mobility in the direction perpendicular thereto.

For example, the square structures 33 and 34 shown in Figures and D which form the actual measuring portion 22 can be made of a semiconductor material with pronounced piezo-resistive property such as a p-silicon, while the beam-shaped and / or plate-shaped, elongated elements 38 forming the oxygen uptake portion 21 can be made, for example, from platinum.

In such a case, incorporation of the relevant element to be measured, for example oxygen incorporation, into the platinum elements 38 provides a tensile stress in the longitudinal direction LI of these elongated elements 38, both in the elements 38 themselves and in the underlying silicon of the square structures. 33 and Gé.

The local electron conduction decreases in the direction PP "or 209" of the elongated elements 38.

9 In this way the electron currents are deflected away from the | elongated elements 38, or, in other words, the electrons tend to move perpendicular to the elongated | elements 38, 9 This results in electron flows more or less according to | directions indicated by the arrows ES1 'and ES2 ° in 9 dotted lines in figures 4 and 5.

16 These electron currents ES1 "and ES2" deviate in line with the aforementioned principle from the originally diagonal direction RR ", SS GE TT? directed electron currents ES1 and ESZ and this in the direction of the corresponding electrical contacts, either the electrical contacts U1 and U2 in the case of figure 4, or the electrical contacts X1 and X2 in the case of figure 5.

The electrical contacts involved, ie the electrical contacts UL and U2 in the case of Figure 4 and the electrical contacts Xi and X2 in the case of Figure 5, can be regarded as negative sensor points NS, while the opposite electrical contacts, ie, the electrical contacts V1 and V2 in the case of Figure 4 and the electrical contacts Y1 and Y2 in the case of Figure 5 can be considered as positive sensor elements PS, However, when materials are used for the structures 33 and 34 which mainly have piezorelectric effects, then the operation is slightly different and a change of mechanical tension causes one

9 change in electron density in the # semiconductor material in question. | This is due to the fact that the semiconductor material of the structures 33 and 34 and the | Quenching isolation material have different piszoelectric constants. 9 For example, when gallium nitride: (GaN} is used as the semiconductor material for the manufacture of structures 33 and 34 9 12 and when Al {Ga) N is used for the above classification as material, then when the element to be measured is included , for example upon oxygen absorption, in the elongated platinum-made elements 38, a mechanical tensile stress, as well as under these segments 38. This mechanical tensile stress creates additional charge carriers under the elements 38, whereby the conductivity under the elements 38 increases. tendency to deflect towards the elements 38, which is just the opposite of what happened in the case described above,

When using such materials with predominantly piezoelectric effects, the arrows ES1 ° and E52 'tend to the opposite side of the respective diagonal direction RR', SS 'or TT' than shown in Figures 4 and 5 and the positive sensor poles. PS and negative sensor poles NS must be swapped accordingly in such a case,

| Nevertheless, the relative deflection of the electron currents in each of the cases can be measured through the respective electrical contacts which are perpendicular to the directions ES1L and ESZ of the electron currents in the neutral state. {It is only the interpretation of the measured | voltage differences between the positive sensor poles PS and 9 the negative sensor poles NS, which must be inverted according to the material used 9 10 in order to # crend them according to an amount of oxygen or other element to be measured or a change in the amount of oxygen or other The element to be moored which is incorporated in or delivered by the elongated elements 38. Structures 33 or 34 are of the same shape as Hall plates and are therefore each individually sensitive to the magnetic field via the Hall effect.

However, by inversely connecting structures 33 and 34 as described, the magnetic field, as well as thermal gradients, process imperfections, and a multitude of other effects are excluded from the output signal.

In order to manufacture an above-described electronic component 2 for a sensor 1, for example an oxygen sensor 1, according to the invention, it is possible, for example, to proceed by performing the following steps according to a method in accordance with the invention.

Starting from the substantially flat substrate 23, it is first possible by means of the epitaxial growth technique (epitaxial growth ”) a layer of gallium nitride or: silicon carbide on The substantially flat substrate | 5 which forms the measuring portion 22. 9 In a next step, this deposited layer | be transformed into the Correct structure or shape, for example in accordance with the structure shown in figure 4, After that, a passivation layer 25, consisting for example of aluminum oxide, can be deposited a first time, for example by applying so-called "atomic layer deposition" or ALD. . Openings can then be formed in this passivation layer 25 by etching for making electrical contacts.

in a next step, platinum is deposited, for example by applying a micro-technological process, the so-called lift-off process, in which a tantalum / platinum adhesion layer can be applied. This platinum layer ultimately forms the internal electrical interconnections, the recording part as well as the contact surfaces with which external electrical contact is made. A subsequent step may consist in re-deposition of a vassivation layer, which for instance consists of new aluminum oxide, whereby for instance the so-called "atomic layer deposition" or ALD is applied again.

Afterwards, etching is preferably used to open 9 bonding flags for making electrical contacts and to improve the structure of the oxygen-receiving portion. 21 to achieve, | Until then, the groove 3% or the recess 40 in the substantially square substrate 23 can be realized by etching 9 again, preferably using a deep reactive ion etching technique. 9 10 9 It is clear that with the aforementioned implementation techniques a sensor 1, such as for example an oxygen sensor 1, can be realized which is extremely small, which opens the way for its use in all kinds of applications with small dimensions, but also in fuel cells, engines. and so on, Figure 6 shows another embodiment of an electronic component 2 of a sensor 1 according to the invention, wherein the receiving portion 21 is redesigned as a series 37 of beam-shaped and / or plate-shaped elements 38 which are elongated and uniform and which are arranged parallel to each other along their longitudinal direction and equidistant E from each other.

However, as already mentioned, the recording site 21 can be designed according to the invention in many other ways, whereby other shapes, different relative positions, angles and distances can be used.

The measuring portion 22 is located below the recording portion 2 and separated from it by means of a passivation layer 25,

| The substantially planar substrate 23 also has a portion 23 at the location of essential elements of the electronic component 2, such as the recording portion 21, the measuring portion 22 and to a lesser extent the heating element 24, which is again decoupled from the remaining portion 30 of the the substantial portion of substrate 23, 9 However, in this embodiment, the aforementioned portion is | 29 of the substantially flat substrate is not made thinned, as was the case in the previous embodiment, in the case of Figure 6 the decoupling is realized by means of a groove 39 which surrounds the aforementioned portion 29 at the location of the essential elements. 21, 22 and to a lesser extent 24 of the electronic component 2.

In this case, the groove 39 in particular extends below the heating element 24,

Suck groove 39 can be re-realized by etching away the relevant portions of the substantially square substrate 23,

Figure 7 shows yet another embodiment of an electronic component 2 for a sensor 1, such as, for example, an oxygen sensor 1, according to the invention, which can be regarded as a combination of the embodiments shown in Figures 3 and 5,

Indeed, in the embodiment of Fig. 7, the recording part 21 has been re-realized as in Fig. 6

| a is a series 37 of parallel beam-shaped elements 38, | consisting for example of platinum and which are arranged on the passivation layer 25 at a distance 9 E from each other, 9 3 On the other hand, the portion 29 of the substantially flat substrate 23 is decoupled from the remaining portion 31 of the substantially flat surface 23 by the substantially flat substrate 23. much thinner, just as in the embodiment of Figure 3, in which there is an etched recess 40 under the portion 29. In Figure 8 an additional electronic component 2 for a sensor 1 according to the invention is shown, this time the measuring portion 22 contains a desite having a structure that forms an optical waveguide 41 (optical waveguide ") and wherein the length of the optical waveguide d1 is a measure of the quantity of the element to be measured.

This optical waveguide 41 is provided under the recording portion 21 and is separated from the recording portion 21 by a passivation layer 25. The waveguide 41 is made, for example, of silicon oxide, # 5. Furthermore, the optical waveguide 41 is provided on a waveguide coating 42 which is, for example, of tungsten. is fabricated and provided between the waveguide 41 and the substantially planar substrate 23, but many other techniques can be used to realize such optical waveguide 41,

The passivation layer 25 may, for example, consist of silicon nitride {SiN} and the substantially planar substrate 23 is | typically a silicon substrate. # 5 Further, in the embodiment of Figure 8, as in the cases of Figures 3 and 7, a recess 40 of the substantially planar substrate is etched away to form a thinned portion 29 of the substantially planar substrate 23 9b location of the essential elements 21 and 22 of the sensor 1, which can serve as a kind of membrane 31, In figure 9 a sensor Ì or more specifically its electronic component 2 is shown, in this case the measuring part 22 being capacitive. comprises means 43 with which a deformation of the recording portion 21 due to absorption or release of the relevant element to be measured, such as oxygen, can be measured.

Figure 10 shows yet another embodiment of a sensor 28 L1 or more specifically its electronic component 2, in which case the measuring part 22 comprises optical measuring means 44 with which a deformation, for example a deflection, of the recording part 21 due to recording or release. of the relevant element to be measured, such as oxygen, can be absorbed.

An advantage of all the aforementioned techniques to form a sensor L according to the invention is that such sensor 1 can also function without problems as broadband sensor 1,

# 30 BE2019 / 5378

; The invention is in no way limited to the sensors 1 according to the invention described by way of example and illustrated with reference to the figures. but this sensor 1 is possible

: be accomplished in other ways without going beyond it

: 5 to enter the scope of the invention.

Claims (1)

AL BE2019 / 5378 Conclusions | ds Sensor {1} for measuring a content of sen 9 5 element in a fluid and / or a change of such 9 content in a fluid, characterized in that the F sensor {1} comprises a component {2} that contains at least contains the 9 following parts: {- an absorption site {21} in the form of one or 9 id several solid bodies that consists or consist # of a material that easily absorbs and releases the element concerned and of which one or more dimensions {B , D, L) increases or increases or decreases or decreases as an amount of such element is received or released by the recording portion {21}; and, - a substantially planar substrate containing a measuring section (22) therein that measures the change of one or more dimensions (B, D, L) of the recording section {21}; wherein the recording section (21) is tightly connected to the measuring section (22) but is electrically isolated from the measuring section (22). 2. Sensor {1} according to claim 1, characterized in that the sensor {1} is an oxygen sensor (1} for measuring an oxygen content and / or a change of such oxygen content in a fluid or a hydrogen sensor for measuring a hydrogen content and / or a change of such hydrogen content in a fluid, wherein the absorption part (21) is an oxygen absorption part (213, or a hydrogen absorption part as the case may be. 9 5 3. Sensor {1} according to claim 1, characterized in that 9 the sensor {1} contains a converting part which is on stake F to generate a signal, the change of one or more dimensions of the recording part {21} # being more particularly converted into a signal, preferably LG an optical or electrical signal , which changes to L function of the content of the element in question and / or the change in a content of the element in question present. 4, Sensor {13 according to claim 1 or 2, characterized in that the oxygen uptake portion (21) is formed by one or more solid bodies made of platinum (Pt) OE from a semimetal alloy. Sensor (1) according to one or more of the preceding claims, characterized in that the one or more solid bodies are in the form of a beam-shaped and / or plate-shaped element (383 or in a series (37) of such beam-shaped and / or or plate-shaped elements (36) which are elongated and which are arranged next to each other in their longitudinal direction {L} and at a distance from each other, 6. Sensor (1) according to one or more of the preceding claims, characterized in that the component (2 ) of the sensor {1} comprises the following parts: | 33 BE2019 / 5378 - one or more heating elements (243 surrounding the measuring part (22); 9 - a passivation layer (25) placed over the measuring part (22) and the one or more heating elements (24): 5; 9 - the recording part {21} which is arranged on a 9 part (26) of the passivation layer {25} and which is separated from the measuring part {22} by means of the passivation layer {25}. Sensor {1} according to claim 6, characterized in that a part {23} of the substantially planar substrate {23} is uncoupled from the remaining part at the location of essential elements (21, 22, 24) of the component (2) {30} of the substantially planar substrate {23} by means of a groove {35} that encircles the aforementioned portion {29} at the location of essential elements (21, 22, 24) of the component {2} or through the front end portion (29, 34) of the substantially flat substrate (23) to be fed substantially thinned, 8. Sensor {1} according to claim 7, characterized in that the groove (39) in the substantially flat substrate is 1235 or just substantially thinned portion (29, 31) of the substantially planar substrate (23) is made by etching away the respective portions of the substantially planar substrate (23). 3, Sensor {1} according to one or more of the preceding claims, characterized in that the measuring part (22) has one or more of the following TE BE2019 / 5378 | semiconductor materials contains: - gallium nitride {GaN}: - indium nitride (InN}: - aluminum nitride {AlNi; - silicon {S1}; 9 - silicon carbice or carborundum (SiC); | - diamond: and / or, - zinc oxide {ZnO}. Sensor (1) according to one or more of the preceding claims, characterized in that the measurement site (22) contains a part (27) consisting of a semiconductor material with piezo-resistive properties, the semiconductor material extending over a part (27). ) with dimensions (B ', L') substantially corresponding to the dimensions (B, L) of the recording portion (21) in order to induce a change in the resistivity tensor in the piezo-resistive semiconductor material that coincides with the expansion or contraction in the adjacent material under the influence of the expansion or contraction of the receiving portion (21) by receiving or releasing the respective element, Sensor {1} according to one or more of the preceding claims, characterized in that the meat part (22) contains a part (72) with a structure consisting of at least one pair of interconnected square structures resembling Hall plates. (33, 34} with electrical contacts (U1, V1, X1, Y1, U2, V2, XZ, YE} and dis are connected inversely to each other in that the structures (33, 34) are positioned such that first diagonal directions (ER) extend in line with each other and that: a pair of electrical contacts (A1, X2) thereof: are electrically interconnected, with a portion (35, 9, 36) above each | 5 of the square structures (33, 34}). of the receiving portion (21) it is arranged that F consists of a series (37) of elements {38} arranged next to each other at a distance (E) from each other and 9 whereby the elements (38) of these two rows (373) | 10 extend with their length (L) in directions (PP, QQ) that are perpendicular or post-perpendicular to each other, 12. Sensor (1) according to one or more of the preceding claims, characterized in that the measuring part {22) comprises a part with a structure that forms an optical waveguide {41} which lies beneath the recording part {21 } is provided and separated from it by a passivation layer {25} and wherein the length of the optical waveguide (41) is a measure of the amount of the element to be measured present. 13. Sensor (1) according to one or more of the preceding claims, characterized in that the measuring part {22} contains capacitive means {43}, which allows deformation of the recording part {21} due to absorption or release of the relevant element to be measured. to be measured. Sensor (1) according to one or more of the preceding claims, characterized in that the measuring section (22) contains optical fertilizers (44) with which an ae 36: BE2019 / 5378; deformation, for example a deflection, of the recording site {21} by recording or releasing the | the element to be measured can be measured, Sensor {1} according to one or more of the preceding: conclusions, characterized in that the sensor {1} is a: broadband sensor {1}. | Sensor {1} according to one or more of the preceding claims, characterized in that the sensor (1) has one or more vassivation layers (25) of | aluminum oxide or silicon nitride,