WO2017129695A1 - Printed sensor device for detecting media - Google Patents

Abstract

The invention relates to a printed sensor device for detecting media. The printed sensor device comprises a support substrate with a first surface, a second surface opposite the first surface, at least one printed finger electrode structure, and a printed detection layer, wherein the printed detection layer is pressed onto a printed finger electrode structure face facing away from the first surface of the support substrate, and the printed finger electrode structure is covered at least in some regions. The printed detection layer can be heated directly by the at least one printed finger electrode structure and/or indirectly by a printed heating layer on the second surface of the support substrate.

Description

 Description title

 Printed sensor device for detecting media

The invention relates to a printed sensor device for detecting media, in particular gases.

State of the art

Sensor devices, in particular gas sensors, find in particular a broad application in medical technology, environmental technology and automotive technology. To improve their performance, different technologies are used, for example metal oxide semiconductors (MOS). In this case, it is always necessary that during operation a corresponding gas sensor must be heated. For this purpose, an external and separately manufactured heating element is currently used. By different heating of the gas sensor, different gases can be detected or a functionality of a corresponding detection layer is restored by heating the gas sensor. In other words, by heating the detection layer, a detected gas can be desorbed.

For example, a gas sensor is based on Metal Oxide Semiconductor (MOS) technology for detecting different gases upon heating a detection layer. Heating up to start up a gas sensor is therefore essential. Further, by heating a gas sensor, an initial state of the gas sensor can be restored. By heating a gas sensor, in particular a detection layer, corresponding molecules or detected molecules are desorbed in particular by means of the gas sensor. Further, by heating, a recalibration may be performed, which is usually required after a certain number of measurements to ensure a measurement accuracy of a gas sensor. In this case, the thermal heating of the gas sensor, in particular of the detection layer, takes place by means of a heating element produced separately, for example a Peltier element.

Thus, a heating of a gas sensor is essential in order to take a gas sensor into operation as well as to optimize a measurement accuracy and secondly a lifetime. However, the attachment of a separate heating element has the following disadvantages in particular:

Since an external and separately produced heating element is not an integrally installed heating element within a sensor device, heat loss occurs and consequently an increased energy requirement; the attachment of an externally and separately manufactured heating element to a sensor device requires an additional process step after the provision or completion of a sensor device. Consequently, higher production costs arise; Further, between a heating element produced externally and separately and the detection layer, in particular, there is a substrate, resulting in a high heat loss. Furthermore, when using an external heating element only substrates can be used which have a very high thermal conductivity.

In other words, at present no heating element can be provided in a sensor device which can already be integrated into the sensor device during production of a sensor device.

In particular, conventional gas sensors producible by MOS technology include patterning a substrate by photolithography followed by physical vapor deposition (PVD) of a metal on the patterned structure with conductive electrodes. For the preparation of corresponding detection layers both as A heating layer requires two separate process steps. In particular, PVD methods can be used for depositing the detection layer and the heating layer.

To provide printed and flexible electronics or For electronic thin films, soluble nanomaterials (solution-processed nanomaterials) can be used. Nanomatics in aqueous solution enable the use of printing technologies, such as spray deposition or printing, such as inkjet printing, to deposit different layers. In particular, these technologies ensure high scalability and are applicable to various types of substrates and are particularly cost-effective.

However, for the deposition of a heating layer, currently only PVD methods or, as described above, external heating elements, for example Peltier elements, are used for heating corresponding components or layers of a sensor device. This means that printing techniques do not appear to be suitable for depositing a heating layer. Due to the limited scalability produced by PVD layers thus the advantages can not be fully exploited by means of printing technology, especially in terms of scalability.

It is thus desirable to provide particularly printed sensor devices having self-heating.

In other words, it is desirable to provide a heating element which can be produced by means of printing technology and whose dimensioning or structuring withstands high temperatures.

Aus - Ahmed Abdelhalim et al.- Metaphoric nanoparticles functionalizing carbon nanotube networks for gas sensing applications - IOP Publishing; Nanotechnoiogy 25 (2014) 055208 (1 Opp) - a gas sensor is known, which is operated by means of a Peltier element. Disclosure of the invention

The invention provides a printed sensor device for detecting media according to claim 1.

Preferred developments are the subject of the respective subclaims.

Advantages of the invention

Surprisingly, it has been found in the present invention that a printed finger-electrode structure also acts as a heating element at the same time by applying a corresponding voltage. Since the finger electrode structure described below can be produced by a printing method or spraying method, the printed sensor device described here is particularly cost-effective to manufacture and easily scalable. In other words, the sensor device described here does not require an external and separately produced heating element and can in particular heat itself based on the finger electrode structure.

According to a first aspect of the present invention, a printed sensor device for detecting media comprises a carrier substrate having a first surface and a second surface opposite the first surface. The carrier substrate may comprise different materials, for example plastic (polyimide), semiconductor materials (silicon / silicon dioxide), glass, wood, and / or a sintered material.

In other words, depending on the use of the printed sensor device described here, any carrier substrate can be used. Here, the term "printed sensor device" means a device that is functional in itself and by means of a pressure or

Spray method can be produced. That is, the below-described components or layers of the printed sensor device are integrally connected with each other. The term "integrally interconnected" is understood to mean lying connection, that in particular a non-destructive removal of a component of the printed sensor device is not possible.

The printed sensor device further comprises at least one printed interdigitated structure (IDES) structure. The printed finger-electrode structure may include, for example, gold, palladium, silver, aluminum or alloys of these materials. Furthermore, the printed finger electrode structure can comprise carbon nanotubes, for example silver nanoparticles (AgNPs) or silver nanowires (AgNWs), of the materials mentioned here, wherein these can be produced from soluble nanomaterials (solution-processed nanomaterials). Other conductive metallic materials are conceivable for the printed finger electrode structure.

In the present context, "interdigitated" is understood to mean electrodes which intermesh in particular in a comb-like manner, in which the electrodes are spaced from each other so that no short-circuit is produced, and the distance is determined in such a way that largely no parasitic capacitances occur during operation.

The printed sensor device further comprises a printed detection layer, which is printed on a side facing away from the first surface of the carrier substrate side of the printed finger electrode structure and the printed finger electrode structure covered at least partially. In other words, the printed finger electrode structure is disposed between the support substrate and the printed detection layer. For example, the comb-like interdigitated electrodes of the finger-electrode structure may be completely covered by the printed detection layer.

The printed detection layer can be indirectly heated by the at least one printed finger electrode structure directly and / or by a printed heating layer on the second surface of the carrier substrate. That is, the printed sensor device exclusively by the at least one printed finger electrode structure is directly heated. Furthermore, the printed detection layer can be indirectly heated by the printed heating layer on the second surface of the carrier substrate. That is, the printed detection layer is heatable independently from the printed finger electrode structure or through the printed heating layer. Furthermore, it is conceivable that the printed detection layer can be heated by a combination of the printed finger electrode structure and the printed heating layer.

According to a preferred weather formation, the printed finger electrode structure comprises at least two printed contact pads, wherein the printed detection layer can be heated by applying a voltage to the at least two printed contact pads. In particular, the finger electrode structure may comprise four printed contact pads. The at least two printed contact pads described here serve on the one hand to detect a changing resistance of the printed detection layer, wherein the changing resistance depends in particular on the medium to be measured and on an electrical conductivity of the printed detection layer. Further, the printed contact pads serve to apply the voltage required to heat the printed finger-electrode structure. The printed sensor device is suitable, for example, to detect ammonia (NH ₃ ), carbon dioxide (CO ₂ ), carbon monoxide (CO) and ethanol (C ₂ H ₆ O).

Thus, the printed finger electrode structure described herein may be particularly useful for improving the electrical conductivity of the printed detection layer and for heating the printed detection layer. Thus, no separate heating element is required to start up the printed sensor device, since self-heating by the finger electrode structure is possible. In other words, the printed finger-electrode structure described here is characterized by a dual function. According to a further preferred development, the carrier substrate has a thickness of 250 to 750 micrometers. For example, the carrier substrate may have a thickness of 500 microns. In particular, a flexible carrier substrate for the printed sensor device can be used.

Thus, a wide range of carrier substrates can be used, wherein the printed sensor device is functional in itself and can be imprinted or deposited on different carrier substrate materials. In particular, the carrier substrate may comprise a polyimide and have a thickness of, for example, 500 micrometers.

According to a further preferred development, the carrier substrate is designed to be flexible. Thus, the printed sensor device can in particular be arranged on very thin carrier substrates with a vertical extension of less than 500 micrometers.

According to a further preferred development, the printed finger electrode structure is lamellar, with electrodes of the printed finger electrode structure extending parallel to one another and the electrodes being at a distance from one another. In other words, the electrodes are arranged comb-like intermeshing with each other, wherein the electrodes have a distance from each other. In particular, very small printed finger electrode structures with an area of a few millimeters, for example 3 mm ² , can be provided.

According to a further preferred development, the distance between the electrodes is between 50 microns and 500 microns. For example, the distance between the electrodes may be 100 micrometers. In this way, a surface tension of the printed detection chip can be used in a simple manner, as a result of which the printed detection layer can be homogeneously printed or deposited on the at least one printed finger electrode structure. According to a further preferred development, the printed detection layer comprises carbon nanotubes with metallic nanoparticles. This provides a large surface-to-volume ratio.

According to a further preferred development, the printed heating layer comprises carbon nanotubes or silver nanowires, wherein the carbon nanotubes and silver nanowires can be deposited by means of spray technology. For example, an already established method for the printed detection layer can be used to provide the printed heating layer. Thus, the printed sensor device can in particular be produced cost-effectively, since no separate printing process or spraying process is required for printing on the heating layer.

Deposition of the printed detection layer and the printed heating layer may, for example, be performed by an automatic atomizing spray gun or atomizing spray nozzles. This makes it possible to provide very small printed sensor devices.

According to a further preferred development, the metallic nanoparticles comprise gold, platinum, chromium, palladium, aluminum or silver. In particular, these materials have good thermal conductivity.

According to a further preferred development, the carbon nanotubes and the metallic nanoparticles (NP1) can be printed by means of a spraying method and / or printing method. Thus, the printed heating layer and the printed detection layer can be inexpensively provided by using the same printing method or spraying method. In particular, particularly small printed sensor devices can be provided by the methods described here.

According to a further preferred development, the printed detection layer and / or the printed heating layer are transparent. In other words, those which are the printed detection layer and / or the printed heating layer may be translucent. The printed detection layer and / or the printed heating layer may be the same material. materials or different materials. For example, the printed sensor device described herein can be used in a variety of industrial applications.

Brief description of the drawings

Further features and advantages of the present invention are explained below with reference to embodiments with reference to the figures.

Show it:

Figure 1 is a schematic cross-sectional view of a printed sensor device according to a first embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of a printed sensor device according to a second embodiment of the present invention;

Figure 3 is a plan view of the printed sensor device according to the first and / or second embodiment of the present invention;

Figure 4 is a perspective view of a printed sensor device according to a third embodiment of the present invention; and

Figures 5-7 are graphs for demonstrating a functionality of the printed sensor device described herein according to the first, second and third embodiments.

Embodiments of the invention in the figures, like reference numerals designate the same or functionally identical elements. Figure 1 is a schematic cross-sectional view of a printed sensor device according to a first embodiment of the present invention.

In Fig. 1, reference numeral 10 denotes a printed sensor device for detecting media. The printed sensor device 10 comprises a carrier substrate 20 having a first surface 21 and a second surface 22 opposite to the first surface 21. Further, the printed sensor device 10 comprises a printed finger electrode structure 30 and a printed detection layer 40, the printed detection layer 40 being mounted on a first surface the surface 21 of the support substrate 20 side facing away from the printed finger electrode structure 30 is printed. The support substrate 20, the printed detection layer 40, and the intervening printed finger electrode structure 30 are in direct contact with each other and can not be separated non-destructively.

The printed finger electrode structure 30 may include, for example, gold, palladium, silver, aluminum, or alloys of these materials. Further, the printed finger electrode structure 30 may comprise silver nanoparticles (AgNPs) or silver nanowires (AgNWs) of the materials referred to herein.

The printed finger electrode structure 30 shown in FIG. 1 further comprises four printed contact pads K1, K2, K3, K4, wherein the four contact pads K1 to K4 are free from a material of the printed detection layer 40 and the printed detection layer 40 is applied by application a voltage at two of the four printed contact pads K1 to K4 of the printed finger electrode structure 30 is heatable.

In the embodiment shown in FIG. 1, the material of the carrier substrate can be selected freely; in particular, the carrier substrate can comprise glass, ceramic or wood. The printed sensor device 10 shown in FIG. 1 is functional in itself. Figure 2 is a schematic cross-sectional view of a printed sensor device according to a second embodiment of the present invention.

The printed sensor device 10 shown in FIG. 2 is based on the sensor device 10 shown in FIG. 1 with the difference that a printed heating layer 50 is arranged on the second surface 22 of the carrier substrate and by means of the printed heating layer 50 either the printed detection layer 40 and / or the printed finger electrode structure 30 is heatable.

Furthermore, it is conceivable that the printed sensor device 10 of FIG. 2 can be indirectly heated by a combination of the printed finger electrode structure 30 directly and by the printed heating layer 50 on the second surface 22 of the carrier substrate 20. The carrier substrate 20 shown in FIG. 2 comprises a material which has a good thermal thermal conductivity. In particular, the carrier substrate 20 has a thickness D1 (shown by the double arrow) of 250 microns to 750 microns.

FIG. 3 is a plan view of the printed sensor device according to the first and / or second embodiment of the present invention.

FIG. 3 shows a printed sensor device 10 with the printed finger electrode structure 30, wherein the printed finger electrode structure 30 comprises electrodes E1, E2 which are comb-like intermeshing and have a distance A1 (shown by the double arrow) from one another at the distance A1 ,

For example, as the carrier substrate 20, a silicon wafer of thermally grown silicon dioxide having a thickness of 200 nanometers can be provided. For example, the Interdigitated Electrode Structure (IDES) structure includes a 5 nanometer thick chromium layer to promote gold adherence to the silicon dioxide. The finger electrode structure 30 comprising gold has a thickness of, for example, 40 nanometers and is vapor-deposited on the silicon dioxide. The distance A1 between the electrodes E1, E2 of the finger electrode structure 30 is, for example, 100 micrometers. In particular, the printed detection layer 40 can be printed onto the finger electrode structure 30 by means of a spraying process in order to form a resistive network for, for example, gas detection. After forming the carbon nanotube NT1 with metallic nanoparticles NP1, the printed sensor device 10 can be put into operation by corresponding application of a voltage at the contact pads K1 to K4 or K1 to K2. The metallic nanoparticles NP1 include in particular gold, platinum, chromium, palladium, aluminum or silver.

In the printed sensor device 10 shown in FIG. 3, it is alternatively conceivable for the printed heating layer 50 (not shown) comprising the carbon nanotube NT1 ¹ or Siibernanowires to be printed on the second surface 22 of the carrier substrate 20.

Figure 4 is a perspective view of a printed sensor device according to a third embodiment of the present invention.

The printed sensor device 10 shown in FIG. 4 is indirectly heated exclusively by the printed heating layer 50 on the second surface 22 of the carrier substrate. Here, the same methods as for printing the detection layer 40 may be used to print the heating layer 50. The printed detection layer 40 and the printed finger electrode structure 30 may in particular comprise carbon nanotubes (NT1). The printed heating layer 50 may comprise carbon nanotube NT1 'or silver nanowires.

Figures 5, 6 and 7 are graphs for proving a functionality of the printed sensor device according to the first, second and third embodiments described herein. In the graphs of Figs. 5, 6 and 7, the time in minutes on the X-axis on the left Y-axis is the temperature in degrees Celsius and the right Y-axis is the voltage in volts.

As can be seen clearly from FIGS. 5, 6 and 7, the temperature (measurement curve) increases stepwise (see FIGS. 5 and 6) or interval (see FIG. 7) as a function of the applied or predetermined voltage (dashed line). In other words, the temperature increases as much as possible in proportion to the applied voltage at the contact pads K1 to K4 of the printed finger electrode structure 30 and / or printed heating layer 50.

Although the present invention has been described in terms of a printed sensor device, it will be understood that a plurality of printed sensor devices may be disposed on the carrier substrate.

Although the present invention has been described in terms of preferred embodiments, it is not limited thereto. In particular, the materials and topologies are only exemplary and are not limited to the illustrative examples.

Claims

claims A printed sensor device (10) for detecting media comprising: a support substrate (20) having a first surface (21) and a second surface (22) opposite the first surface (21); at least one printed finger electrode structure (30); a printed detection layer (40) printed on one side of the printed finger electrode structure (30) facing away from the first surface (21) of the carrier substrate and covering the printed finger electrode structure (30) at least in regions; and wherein the printed detection layer (40) is indirectly heatable by the at least one printed finger electrode structure (30) directly and / or by a printed heating layer (50) on the second surface (22) of the carrier substrate (20). 2. Printed sensor device (10) according to claim 1, wherein the printed finger electrodes comprise structure gold, palladium, silver, aluminum or alloys of these materials. 3. A printed sensor device (10) according to claim 1, wherein the printed finger electrode structure (30) comprises at least two printed contact pads (K1, K2, K3, K4), the printed detection layer being formed by applying a voltage to the at least two printed contact pads (K1, K2, K3, K4) is heated. 4. Printed sensor device (10) according to claim 1, wherein the carrier substrate (20) has a thickness (D1) of 250 to 750 microns. 5. A printed sensor device (10) according to claim 1, wherein the carrier substrate (20) is flexible. 6. A printed sensor device (10) according to claim 1,  wherein the printed finger electrode structure (30) is lamellar and electrodes (E1, E2) of the printed finger electrode structure (30) run parallel to each other and the electrodes (E1, E2) are spaced apart from each other (A1 ) exhibit. 7. Printed sensor device (10) according to claim 5,  wherein the distance (A1) between the electrodes (E1, E2) is between 50 microns and 500 microns. 8. A printed sensor device (10) according to claim 1,  wherein the printed detection layer (40) comprises carbon nanotubes (NT1) with metallic nanoparticles (NP1). 5  9. A printed sensor device (10) according to claim 1,  wherein the printed heating layer (50) comprises carbon nanotubes (ΝΤ1 ') or silver nanowires, wherein the carbon nanotubes and silicon nanowires are separable by spray technology. 0  10. A printed sensor device (10) according to claim 8,  wherein the metallic nanoparticles (NP1) comprise gold, platinum, chromium, palladium, aluminum or silver. 5 11. A printed sensor device (10) according to claim 8 or 9,  wherein the carbon nanotubes (NT1; NTT) and the metallic nanoparticles (NP1) are printable by a spraying process and / or printing process. 12. The printed sensor device (10) according to claim 1, wherein the printed detection layer (40) and / or the printed coating layer (50) are transparent.