WO2016189231A1

WO2016189231A1 - Detector and associated manufacturing method

Info

Publication number: WO2016189231A1
Application number: PCT/FR2016/051192
Authority: WO
Inventors: Pierre MOUSSEAU; Pierre-Yves JOUAN; Christophe PLOT; Alain Sarda; Axel FERREC; Nadine ALLANIC; Rémi DETERRE
Original assignee: Centre National De La Recherche Scientifique; Universite De Nantes
Priority date: 2015-05-22
Filing date: 2016-05-19
Publication date: 2016-12-01
Also published as: FR3036484A1; FR3036484B1

Abstract

The invention relates to a detector (10) comprising a housing (12) defining a tubular recess (14) open at one end of said housing (12) wherein a substrate (20) made of electrically and thermally insulating material and having a thermal conduction coefficient lower than the thermal conduction coefficient of the housing (12) is arranged, at least one first pair of pins (28) made of an electrically conductive material being inserted into the substrate (20) and having first ends (30) which are flush with an outer surface (32) of said substrate (20), said first ends of said first pair (28) being connected by a first resistive element in which the impedance varies with a first physical parameter.

Description

DETECTOR AND METHOD OF MANUFACTURING THE SAME

The invention relates to a sensor sensitive, for example, to a variation in temperature and / or pressure and a polymer manufacturing mold comprising such a detector.

During the operations of developing polymer parts in a mold, it is necessary to know in real time the temperature and pressure conditions prevailing in the mold as close to the polymer "paste" in transformation. In fact, knowledge of the production parameters, such as temperature and pressure makes it possible to control and monitor the production of the polymer material and, if necessary, to adjust the conditions for producing the polymer that is being formed. .

For this, many sensors are available but are limited by the particular conditions of temperature and pressure inside the mold and the lack of sensitivity of these commercial sensors.

The known sensors or detectors can be classified into two large families. The first relates to intrusive detectors, that is to say opening into the interior of the mold and non-intrusive detectors, that is to say not opening through the mold. These detectors may be of the thermocouple type, with RTD denoting the acronym for resistance temperature detector or thermistor.

The non-intrusive sensors currently used are mainly thermocouple sensors. It is for example known from WO2014104077 to house three thermocouple junctions in a block of material integrated in a housing. These junctions are successively arranged one above the other. The outer surface of the housing is intended to come flush with the inner surface of a mold. This type of sensor allows temperature detection or heat flow inside the mold but remains imprecise because the junctions Thermocouples are not closer to the material. This type of sensor has a response time quite high due to the thermal inertia due to the housing and the block of material and does not measure a small amount of heat flow. The same difficulties arise in document US2008170600A1.

Among the so-called open-ended sensors, sensors are known that use thin layers in order to have information that is as close to the material as possible.

The resistances deposited in thin layers make it possible to obtain a precise and localized temperature measurement. Lichtenwalner et al. [D.J. Lichtenwalner et al. Sensors and Actuators A 135 (2007) 593-597] have developed a sensor concept capable of evaluating several different physical quantities, namely temperature and stress. This is made possible by the integration of elements made from two materials: platinum and nickel-chromium. However, the connection of thin layers with copper son to be able to recover the electrical signal is at the origin of many malfunction (short circuit, bad contact, oxidation, ...).

It is known from US4245500 to integrate in a solid medium a sensor consisting of two superimposed thermoelectric elements that allow the measurement of a temperature difference between them. These elements are integrated in a capsule that has a thermal conductivity identical to that of the medium. The sensitive elements are metal alloys (Chromel and Alumel) and relatively large thicknesses and of the order of one millimeter implying a high response time. Sensor sensitivity also remains low, similar to that of conventional thermocouples.

The invention aims in particular to provide a simple, effective and economical solution to the problems of the prior art described above.

For this purpose, it proposes a detector sensitive to a variation of temperature, comprising a housing defining a tubular cavity open at one end of said housing in which is arranged a support of electrically and thermally insulating material and having a coefficient of thermal conduction lower than the coefficient of thermal conduction of the housing, at least a first pair of pins made of electrically conductive material being housed in the support and having first ends which are flush with an outer face of said support, said ends of said first pair of pins being connected by a first resistive element whose impedance varies with the temperature.

The configuration of the detector or sensor according to the invention makes it possible to have at least one first element sensitive to the surface of a support. This support can be integrated so that its outer surface is flush with the inner face of a mold. The sensor according to the invention, which could be considered as intrusive since the sensitive element is intended to be arranged in the mold, can in practice be considered as a non-intrusive sensor because of the very small thickness of the sensitive element intended to be arranged in the mold. The direct contact of the resistive element with the medium makes it possible to reduce the reaction time of the whole measurement acquisition chain and makes it possible to increase considerably the sensitivity of the detector with respect to non-emerging sensitive element detectors. According to the invention, the resistive element is not housed in a cavity, intended to protect the resistive element, as in some documents of the prior art.

The sealing integration of the pins in a support makes it possible to avoid material leaks in the support. The use of a support having a low coefficient of thermal conduction and less than that of the housing makes it possible to limit the conduction of heat towards the housing.

The housing surrounding the support ensures a good mechanical strength to the support and pin assembly when it is integrated into the wall of a mold.

Said at least one resistive element preferably has a thickness less than 10 μητι, more preferably less than 2 μηη and even more preferably between 500 nm and 2 μιτι.

According to a particular embodiment of the invention, the device comprises a second pair of pins connected by a second resistive element whose impedance varies with a second physical parameter.

When the first physical parameter is different from the second physical parameter, the first physical parameter being for example the temperature and the second physical parameter being the pressure, it is thus possible with the first element to measure a temperature variation and with the second element of measure a variation of pressure. It is also possible with this device to decouple the influence of the first physical parameter on the measurement of the impedance of the second element which is a function of the second physical parameter and vice versa.

In this embodiment, the first element and the second element may be arranged on said face of the support so as to be substantially parallel to each other. This configuration makes it possible to have measurements by the first and second elements that are made in the same operating plane. This arrangement makes it possible to have a symmetry of the active face of the detector.

According to another possible embodiment of the invention, the first physical parameter and the second physical parameter are identical and the first element and the second element are carried by the external face of the support so that the first element is arranged according to the axis of the housing between the outer face of the support and the second element and separated from the second element by an insulating layer.

In this configuration, when the first and the second physical parameters are temperature, for example, it is possible with such an arrangement to measure a heat flux between the first element and the second element. The thickness of the insulating layer is determined in relation to the thickness of each of the first and second elements so as to have a significant and quantifiable difference in impedance. between said two first and second elements.

In a practical embodiment of this embodiment, the first resistive element and the second resistive element are each oriented in a given direction substantially perpendicular to the axis of the housing, which directions are perpendicular to each other. The overlap zone of the first and second elements can thus be considered as representative of the measurement point. The use of such an arrangement of the first and second elements makes it easier to pass the first and second pins in a small support, particularly small diameter when it is circular section.

An electrical protection layer preferably covers said at least first resistive element. The protective layer is preferably a passivation layer, made for example of silicon nitride or aluminum nitride. It also protects the first element of contact with oxygen, to prevent oxidation.

The protective layer preferably has a thickness of the order of a few hundred nanometers.

According to another characteristic of the invention, the housing comprises an internal shoulder on which the support is mounted in support. This shoulder is intended to allow a good mechanical support of the support on the shoulder of the housing which is it intended to be fixed on a wall of a mold.

The pins of said at least first pair are preferably of identical geometries and arranged symmetrically with respect to the axis of the housing. The pins may have a diameter less than one millimeter.

The tubular housing may have a cylindrical outer face provided with a thread for fixing it in an opening of a mold.

Said at least first element can be made in one of the following materials: a metallic material, an oxide in particular oxide nickel, a semiconductor material or a metal alloy.

Said at least a first pair of pins is made of a metallic material.

The pins of the first pair may include second ends opposite the first ends and connected to terminals of an electrical circuit so that the sensor forms one of the components of a Weatstone bridge electrical circuit. The electrical circuit can be connected to synchronous detection means.

The invention also relates to a mold for manufacturing polymer parts comprising a closed chamber intended to receive a polymer material and a wall of the chamber of which is traversed by at least one detector as described above, the external face of the detector located on the outside. side of the first ends of the pins being arranged to be flush with an inner surface of the enclosure.

The invention also relates to a method for producing a detector of the type described above, consisting of:

- provide a tubular housing,

provide a support of electrically and thermally insulating material and having a coefficient of thermal conduction coefficient lower than the coefficient of thermal conduction of the housing,

inserting a first pair of pins in the support so that the first ends of the pins are flush with an external surface of the support and brazing the pins in the support,

- fix the support in the housing by brazing,

depositing at least a first resistive element, whose impedance varies with a first physical parameter, on the outer surface of the support so as to connect said first two ends of the first pair of pins,

- Deposit an electrical protection layer over the first element and the outer surface of the support.

The deposition of said at least first element can be achieved by sputtering.

Other advantages and characteristics of the invention will appear on reading the following description given by way of nonlimiting example and with reference to the appended drawings in which:

- Figure 1 is a schematic sectional view of a detector according to the invention;

FIG. 2 is a schematic view from above of the detector of FIG. 1;

FIG. 3 is a schematic perspective view of a second embodiment of the invention;

FIG. 4 is a schematic view from above of the second embodiment of the invention;

- Figure 5 is a schematic top view of a detector according to a third embodiment of the invention;

FIGS. 6 and 7 are diagrammatic representations of two types of connection of the pins to a conductive element in a detector according to the invention;

FIG. 8 is a schematic view of the steps of the method for producing the detector of FIGS. 1 to 3;

FIG. 9 is a schematic view of the steps of the method for producing the detector of FIG. 4;

FIG. 10 is a schematic view of the steps of the method for producing the detector of FIG. 5;

- Figure 1 1 is a schematic view of a detection circuit Wheatstone bridge resistive circuit incorporating a detector according to the invention;

FIG. 12 is a diagrammatic view of a capacitive-capacitance Wheatstone bridge detection circuit incorporating a detector according to the invention;

FIG. 13 is a schematic representation of a Wheatstone bridge circuit comprising first and second resistive elements responsive to a temperature change;

FIG. 14 is a schematic representation of the integration of a detector according to the invention in a mold.

Reference is first made to FIG. 1 which represents a detector 10 according to the invention comprising a tubular housing 12, preferably of cylindrical shape, defining internally a cavity 14 between a first end 16 and a second end 18 and in which is mounted a support block 20 of electrically insulating material and preferably having a coefficient of thermal conduction lower than the coefficient of thermal conduction of the housing 12. The support block 20 has a cylindrical shape and comprises along the axis 47 a first end 22 and a second end 24 and is mounted from the first end 18 of the housing 12 so as to bear axially on an internal radial annular shoulder 26 of the housing 12. The support 20 houses a first pair of pins 28 made of an electrically conductive material. These first pins 28 each comprise a first end 30 flush with the outer surface 32 of the support 20, which itself is flush with the annular edge of the first end 18 of the cylindrical housing 12. The first pins 28 also each comprise a second end 34 opposite to the first end 30 and projecting from a face 35 of the so-called internal support 20 which is opposite to the outer face 32. It is understood that the term face / outer surface of the support designates the face / surface of the support which is the outside of the case. The support 20 is fully housed in the housing, when its outer / outer surface is flush with the annular edge of an end 18 of the housing, in this case the first end 18 of the housing as shown in FIGS.

As shown in Figures 1 and 2, chamfers 36 are formed at the outlets of the housing holes of the first pins 28 on the outer face 32. Similarly, chamfers 36 are formed on the support 20 and the housing 12 at the level of the first end 18 of the housing 12. These chamfered areas are intended to allow a solder, for example by soldering the housing 12 and the support 20 and the first pins 28 with the support 20. In this way, the parts fixing areas are not not formed protruding on the first face, that is to say the outer face 32 of the support 20, which allows easy polishing of the outer face 32 of the support 20 as will appear more clearly in relation to Figure 8 by example, describing a method of producing a detector according to the invention. The solders are made so as to withstand up to a temperature of the order of 300 ° C.

The first ends 30 of the first pins 28 are connected to one another by a first substantially straight resistive element 38 whose impedance varies with a first physical parameter (FIG. 2). This physical parameter can be, for example, temperature or pressure. FIGS. 3 and 4 show a second embodiment of a detector 39 according to the invention in which the support comprises a second pair of pins 40. The first pins 40 are connected to one another by a first element 38 whose impedance can vary with a first physical parameter as previously described and the second pins 40 are connected to each other by a second substantially rectilinear element 42 whose impedance varies with a second physical parameter. This second physical parameter can be temperature or pressure, for example.

In this second embodiment of the invention, the first physical parameter and the second physical parameter are different. The first physical parameter is chosen to match the temperature and the second physical parameter is chosen to match the pressure. In this way, a first element 38 makes it possible, by measuring its impedance, to determine the temperature of the physical environment in which it is immersed and a second element 42 makes it possible, by measuring its impedance, to determine the pressure of the physical environment. in which he is immersed. The use of two elements 38, 42 sensitive to two different physical parameters makes it possible to decouple the effects of the first physical parameter on the measurement of the impedance of the second element 42 responsive to the second physical parameter and vice versa.

In this embodiment, the first member 38 is substantially parallel to the second member 42. However, other orientations of the first member 38 relative to the second member 42 may be used.

FIG. 5 represents a third embodiment of a detector 43 according to the invention also comprising a first pair of pins 28 and a second pair of pins 40 and also a first element 44 of electrical connection of the first pins 28 and a second element The first element 44 is arranged between the outer face 32 of the support 12 and the second element 46, the first element 44 and the second element 46 being separated by an insulating layer whose thickness is chosen. so that the first 44 and second 46 elements, made of the same material, have a significant and quantifiable impedance difference thus making it possible to determine a heat flux value.

In this embodiment, the first resistive element 44 and the second resistive element 46 are substantially perpendicular to the axis 47 of the housing 12 (Figures 1 and 5). In addition, the first 44 and second 46 straight elements are substantially perpendicular to each other so as to have a central overlap area.

Although not shown with regard to the embodiments of FIGS. 3 to 5, bevels 36 may also be made as described with reference to FIG.

It is also understood that the sensor may comprise a number of pairs of pins greater than two as described with reference to FIGS. 3 to 5. It would thus be possible to make a detector comprising 3 or 4 pairs of pins, the limit of the number of pins being essentially a function of the external surface of the detector to arrange the resistive elements therein.

FIGS. 6 and 7 show two pin connection modes 48 to a resistive element 50. Thus, in a first mode, this connection can be made in such a way that the ends of the resistive element 48 are in direct contact with the resistive elements. first ends 34 of the pins 48 (Figure 6). In a second embodiment, this connection can be made in such a way that the ends of the resistive element 51 are in direct contact with an insulating layer 52 of a thickness of the order of a few micrometers, which insulating layer 52 covers the first ends 30 of the pins 48 (Figure 7). In this second mode, an insulating layer is interposed between the ends of the resistive element 51 and the first ends 30 of the pins 48.

Referring now to Figure 8 which shows schematically the steps of a method of producing the detector of Figures 1 and 2.

Firstly, the various constituent parts of the detector 10 are produced independently of one another. The support 20 is inserted into the housing 12 through the first end thereof until the support abuts on the inner annular shoulder of the housing 12, the outer face of the support then flush with the first annular edge of the housing 12. In a second step II, an operator brazes the support 20 on the housing 12, an insertion of the pins 28 in the tubular housing of the support 20 and a brazing of the first pins 28 in the support 20. The pins 28 are dimensioned and inserted into the support so that the first ends 30 of the pins 28 are flush with the outer face of the support and the second ends 34 of the pins 28 project from the inner face 35. In a third step III, a mask 54 is applied to the outer face of the support 20, this mask 54 comprising an opening of identical shape to the desired shape for the resistive element 38. The method consists in producing a deposit, of a metallic or semiconductor material sensitive to a given first physical parameter, by reactive cathode sputtering such as a plasma-enhanced chemical vapor deposition on the mask 54, which leads to the formation a resistive element 38 of corresponding shape to the opening of the mask 54. In a fourth step IV, the method consists in forming a passivation layer 56 above the resistive element 38 so as to form a protective barrier electrical component of the resistive element 38.

Note that when it is desired to make a connection between the pins 28 and the resistive element 38 of the capacitive type as shown in FIG. 7, an intermediate operation of deposition of an insulating layer 52 on the outer surface of the support is then performed. 20 before the application of a mask 54 and the vapor deposition of the resistive element.

FIG. 9 schematically represents the steps of a method for producing the detector of FIGS. 3 and 4. Firstly, the various constituent parts of the detector 39 are produced independently of each other, namely the first 28 and second 40 pins. , the support 20 comprising four holes of shapes adapted to receive by sliding the first 28 and 40 seconds pins, and the housing 12. In a second step II, an operator, after assembling the parts, proceeds to solder the first 28 and 40 seconds 40 pins 20 with the support 20 and the support 20 in the housing 12. In a third step III, a first mask 56 having a rectilinear elongated opening is arranged on the support 20. A first vapor phase deposition of a sensitive material is then performed. at the temperature on the mask 56 which leads to the formation on the support of a first resistive element 38 of identical shape to that of the open Opening the first mask 56. In a fourth step IV, a second mask 58 having a rectilinear elongate opening is provided on the support. The mask 58 is positioned on the support so that the rectilinear opening is substantially parallel to the first resistive element 38. It then proceeds to a sputtering deposition phase vapor on the second mask 58 of a pressure sensitive material which leads to the formation of a second resistive element 42 sensitive to the pressure on the support. Finally, in a fifth step V, an operator deposes a passivation layer 60 in a manner similar to that described with reference to FIG. 8.

FIG. 10 schematically represents the steps of a method for producing the detector 43 of FIG. 5. The steps I to V described are identical to those described with reference to FIG. 9. However, the method in relation with FIG. of the method of Figure 9 in that it comprises an intermediate step 11 ll. Also, the vapor phase vapor deposited material in steps III and IV are identical so that the first element 44 and the second element 46 both have sensitivity to the same physical parameter which is the temperature here. In addition, the first 62 and second 64 masks are shaped and positioned on the support so that the first 44 and second 46 resistive elements are perpendicular to each other.

Stage II 11 essentially consists in depositing an insulating layer 66 on the first resistive element 44, immediately after the first mask 62 has been removed. In this way, the second resistive element 46 is formed above the layer isolator 66 which thus separates the first resistive element 44 from the second resistive element 46.

When it is desired to make a point temperature measurement, it is desirable for the resistive element 38 to be in a semiconductor material, such as an oxide of nickel, magnesium or manganese whose resistivity varies exponentially with the temperature; which makes it possible to obtain a good accuracy of the temperature value. This type of resistive element can be used in the embodiments shown in Figures 1 and 4. The resistive element preferably has a length less than one centimeter. It would be possible with these materials to consider a quasi-punctual deposit of the resistive element. This type of material can be used in connection with a direct connection pins to the resistive element 50 as with reference to Figure 6 or by indirect connection through an insulating layer as described with reference to Figure 7.

When it is desired to make a so-called "integrated" measurement of temperature on a surface, it is desirable for the resistive element 38 to be in a conductive material whose resistivity varies linearly with the temperature such as, for example, nickel whose linearity up to At 200 ° C is remarkable, platinum or gold whose linearity is also good over a wide temperature range and has good thermal stability. It would also be possible to use copper but its thermal stability is lower. To obtain the desired sensitivity, the resistive element should have a longer length, that is to say greater than or equal to 1 centimeter. The resistive element may be in the form of a linear or circular coil.

To make a measurement of the pressure, it is possible to use metal alloys whose resistivity varies with a gauge factor. These metal alloys are for example: an alloy of nickel and copper, an alloy of nickel and chromium, an alloy of nickel, chromium, copper and iron or an alloy of platinum and tungsten. The length of the resistive element is preferably greater than or equal to 1 cm. It would also be possible to envisage deposits in the form of linear or circular coils over a greater length of the outer face of the support to increase the sensitivity of the detector thus formed.

When it is desired to measure a heat flow, it is possible to use metals whose resistivity varies linearly with temperature, such as nickel, platinum, gold or copper. This type of resistive element can be used in the embodiment shown in FIG. 5. The length of the resistive element 44, 46 is preferably greater than or equal to 1 cm. It would also be possible to envisage deposits in the form of linear or circular coils over a greater length of the outer face of the support to increase the sensitivity of the detector thus formed.

The passivation protective layer intended to serve as an electrical insulator is, for example, SiO 2, Si 3 N 4, Al 2 O 3 or AlN. The thickness is of the order of a few microns, typically between 1 and 4 μιτι.

FIG. 11 represents a Wheatstone bridge electrical circuit 68 comprising two known resistors Rx1 and R1, a precision variable resistor Rz and a direct voltage source 70 or in harmonic regime and a resistive element 50 according to FIG. The resistive element 50 is connected to the circuit 68 by its second ends 34 (Figures 1 1 and 6). The detector is arranged between the resistor R1 and the variable resistor Rx1. The voltage source is connected on one side between the resistors Rx1 and R1 and between the resistor Rz and the resistive element 50.

The circuit 68 also comprises synchronous detection means 72 intended to be used with a harmonic power supply.

Wheatstone bridge based electrical mounting is initially balanced with external variable resistance to the system. The variation of the impedance of the resistive element 38 with the temperature makes it possible to detect the event which induced this disturbance. The function of the Wheatstone bridge is to change the nature of the electrical signal, linearize it over a temperature range and amplify it. The combination of resistive mounting with synchronous detection allows signals to be separated at different frequencies to avoid measurement noise and to detect signals with smaller amplitudes.

A sensor in capacitive mounting as described with reference to Figure 7 can also be used in place of the resistive mounting detector (Figure 12).

In the case of the detector 39 shown in FIG. 4, comprising a first resistive element 38 sensitive to temperature and a second resistive pressure sensitive element 42, each resistive element 38, 42 can be connected to its own electrical Wheatstone bridge circuit. . In the case of the detector 43 shown in FIG. 5, it would be possible to use a Wheatstone bridge electrical circuit according to FIG. 13. This circuit is similar to that described with reference to FIG. However, the variable resistor is here replaced by the first resistive element 44. The second resistive element 46 here forms the fourth component of the Wheatstone bridge circuit. With this arrangement, it is thus possible to measure a flow of heat flowing between the first and second resistive elements.

FIG. 14 is a schematic perspective view of a portion of a mold 74 comprising two detectors 76 according to the invention which are fixed through a wall of the mold by means of a threading of the outer surface of the housing of each of the detectors screwed into a corresponding thread of an orifice of a wall of the mold. More precisely, the annular edge 18 and the outer face of the support of each detector 76 are flush with an inner face of the mold 74.

The housing can be made of titanium, the titanium pins and the alumina support.

In the embodiments shown in the figures, the first resistive element and / or the second resistive have a thickness of less than 10 μιτι, preferably less than 2 μιτι and more preferably between 500 nm and 2 μιτι.

Claims

1. A detector (10,39,43) comprising a housing (12) defining a tubular cavity (14) open at one end of said housing (12) in which a support (20) of electrically and thermally insulating material and having a thermal conduction lower than the thermal conduction coefficient of the housing (12), at least a first pair of pins (28) made of electrically conductive material being housed in the support (20) and having first ends (30) which are flush with an outer face (32) said carrier (20), said first ends of said first pair (28) being connected by a first resistive element (38) whose impedance varies with a first physical parameter.

2. Detector according to claim 1, characterized in that it comprises a second pair of pins (40) connected by a second resistive element (42) whose impedance varies with a second physical parameter.

3. Detector according to claim 2, characterized in that the first physical parameter is different from the second physical parameter, the first physical parameter being for example the temperature and the second physical parameter being the pressure.

4. Detector according to claim 2 or 3, characterized in that the first element (38) and the second element (42) are arranged on said face of the support (20) so as to be substantially parallel to each other .

5. Detector according to claim 2, characterized in that the first physical parameter and the second physical parameter are identical and in that the first element (44) and the second element (46) are carried by the outer face (32) of the support (20) so that the first element (44) is arranged along the axis (47) of the housing (12) between the outer face of the support (12) and the second element (46) and separated from the second element (46) by an insulating layer (66).

6. Detector according to claim 5, characterized in that the first resistive element (44) and the second resistive element (46) are each oriented in a given direction substantially perpendicular to the axis (47) of the housing (12), which directions being perpendicular to each other.

7. Detector according to one of claims 1 to 6, characterized in that an electrical protection layer (56) covers said at least first resistive element (38).

8. Detector according to claim 7, characterized in that the protective layer (56) is a passivation layer, made for example of silicon nitride or aluminum.

9. Detector according to claim 7 or 8, characterized in that the protective layer has a thickness of the order of a few hundred nanometers.

10. Detector according to one of the preceding claims, characterized in that said at least one first resistive element (50, 51) is connected either directly to the pins (48) or via an electrically insulating layer (52). .

1 1. Detector according to claim 10, characterized in that the insulating layer (52) has a thickness of the order of a few micrometers.

12. Detector according to one of the preceding claims, characterized in that the housing (12) comprises an inner shoulder (22) on which the support (20) is mounted in abutment.

13. Detector according to one of the preceding claims, characterized in that the pins (28) of said at least first pair of pins (28) are of identical geometries and arranged symmetrically with respect to the axis (47) of the housing (12).

14. Detector according to one of the preceding claims, characterized in that the tubular housing (12) has a cylindrical outer face provided with a thread for fixing it in an opening of a mold.

15. Detector according to one of the preceding claims, characterized in that said at least first element (38) is made of one of the following materials: a metal material, an oxide in particular nickel oxide, a semi material -conductor or a metal alloy.

16. Detector according to one of the preceding claims, characterized in that said at least a first pair of pins (28) is made of a metallic material.

17. Detector according to one of the preceding claims, characterized in that said at least first resistive element has a thickness of less than 10 μιτι, preferably less than 2 μιτι and advantageously between 500 nm and 2 μιτι.

18. Detection device comprising a detector according to one of the preceding claims, the pins (28) of the first pair of pins comprising second ends (34) opposite the first ends (30) and connected to terminals of a circuit so that the sensor forms one of the components of a Weatstone bridge electrical circuit.

19. Device according to claim 18, characterized in that the electrical circuit is connected to synchronous detection means.

20. Mold (74) for manufacturing polymer parts comprising a closed chamber intended to receive a polymer material and a wall of the chamber of which is traversed by at least one detector (76) according to one of the preceding claims 1 to 17. , the outer face of the detector located on the side of the first ends of the pins being arranged to be flush with an inner surface of the enclosure.

21. Process for producing a detector according to one of Claims 1 to 17, consisting of:

- provide a tubular housing (12),

- providing a support (20) of electrically and thermally insulating material and having a coefficient of thermal conduction coefficient lower than the coefficient of thermal conduction of the housing (12), inserting a first pair of pins (28) in the holder (20) so that first ends (30) of the pins (28) are flush with an outer surface (32) of the holder (20) and brazing the pins (28); ) in the support (20),

- fix the support (20) in the housing (12) by brazing,

depositing at least a first resistive element (38), whose impedance varies with a first physical parameter, on the outer surface of the support (20) so as to connect said two first ends of the first pair of pins (28),

depositing a layer (56) of electrical protection above the first element (38) and the outer surface of the support (20).

22. The method of claim 21, characterized in that the deposition of said at least first element is made by sputtering.