Sensor and sensor system for detecting mechanically applied forces

Abstract

: The invention relates to a sensor for detecting mechanically applied forces, comprising a first electrode layer (1), a second electrode layer (2) and an intermediate layer (3) arranged between the first electrode layer (1) and the second electrode layer (2), wherein the first electrode layer (1) comprises at least two first electrodes (4) on the surface facing the intermediate layer (3), the second electrode layer (2) has at least four second electrodes (5) on the surface facing the intermediate layer (3), and the second electrode layer (2) has at least two third electrodes (6) on the surface facing away from the intermediate layer (3). The first electrodes (4) are arranged perpendicularly to the third electrodes (6) such that at least four overlap regions (7) are formed in an n / m matrix, where n corresponds to the number of first electrodes (4) and m to the number of third electrodes (6), and the third electrodes (6) are electrically connected to the second electrodes (5) via second connection openings (8) which are formed in the second electrode layer (2). Furthermore, the first electrodes (4) and the third electrodes (6) have a lower electrical resistance value than the second electrodes (5), wherein the intermediate layer (3) has a contacting opening (9) in each overlap region (7). In addition, contact can be established between the first electrode layer (1) and the second electrode layer (2) through the contacting opening (9).

Description

[0001] Dresden University of Technology

[0002] P149849PC00

[0003] Sensor and sensor system for detecting mechanical forces

[0004] The present invention relates to a sensor and a sensor system for detecting mechanical forces.

[0005] Due to the aging population, the demand for home and care robots is increasing. Tactile information is essential for safe interaction with humans. Tactile sensors enable robots to interact with information from their environment and significantly reduce the risk of injury when people interact with machines. Conventional sensors are usually rigidly constructed, which makes installation on uneven surfaces difficult and still carries the risk of damaging fragile objects. Therefore, flexible and stretchable tactile sensors are frequently used.

[0006] Soft, flexible, and stretchable tactile sensors can be installed on a variety of irregular surfaces and touch objects without causing damage. Several common transduction principles have been demonstrated for such sensors, including piezoresistive and piezocapacitive. However, piezoresistive sensors suffer from signal instability. Under prolonged pressure, the resistance tends to decrease further, resulting in inaccurate pressure measurement. Piezocapacitive sensors are more stable than piezoresistive sensors and can remain stable under prolonged pressure, but they place high demands on the measurement electronics. This means that users must pay a significant premium for the measurement electronics. Furthermore, both types of sensors are susceptible to environmental influences. Temperature and humidity affect the measurement results.Furthermore, nearby conductive objects and electromagnetic fields also affect the piezocapacitive sensor.

[0007] Human skin is covered with Meissner corpuscles, tiny pressure sensors that allow humans to sense the shape of objects through touch. Researchers are currently attempting to replicate this ability of human skin by combining multiple tactile sensors. Due to the large number of sensors, configuring a separate connection for each sensor to connect to the measurement electronics would make the setup extremely complex and require a large number of connection ports.

[0008] For this purpose, the circuits are arranged in a specific number of rows and columns. While the wires can be arranged in irregular lines if needed, a matrix arrangement is far more common as the chosen technical solution. Such array structures have a significant disadvantage: if the three sensors at the corners of a rectangle or square are pressed, a false active signal, namely a ghosting signal, is generated at the opposite corner.

[0009] This ghosting signal is also common on keyboards. To solve this problem, some high-quality keyboards have a diode added to each key. The diode prevents reverse current flow, thus eliminating the ghosting signal. However, adding a diode to each sensor would not only significantly increase costs, but stretchable diodes are also not currently widely available commercially. Therefore, it is not possible to use diodes to suppress ghosting signals from such a stretchable sensor array.

[0010] US 2023 / 0207227, for example, discloses a flexible switch that generates an electrical signal through contact between the electrodes when they are mechanically connected. This mechanical switching method significantly reduces the influence of environmental factors on the measurement results. However, a disadvantage is that ghosting signals cannot be prevented, and adapting the switch to different measurement tasks requires complex design modifications.

[0011] The present invention is therefore based on the objective of proposing a sensor or a sensor system that enables individual adaptation to the measurement conditions and also minimizes the occurrence of ghosting signals.

[0012] This problem is solved according to the invention by a sensor and a sensor system for detecting mechanical forces according to independent claim 1 and dependent claim 10. Advantageous embodiments and further developments are described in the dependent claims.

[0013] A sensor for detecting mechanical forces comprises a first electrode layer, a second electrode layer, and an intermediate layer arranged between the first and second electrode layers. The first electrode layer has at least two first electrodes on the surface facing the intermediate layer, and the second electrode layer has at least four second electrodes on the surface facing the intermediate layer and at least two third electrodes on the surface facing away from the intermediate layer. The first electrodes are arranged perpendicular to the third electrodes, resulting in at least four overlapping regions in an n / m matrix, where n corresponds to the number of first electrodes and m to the number of third electrodes.The third electrodes are electrically connected to the second electrodes via secondary connection openings formed in the second electrode layer. The first and third electrodes exhibit a lower electrical resistance than the second electrodes. Furthermore, the intermediate layer forms a contact opening in each overlap area, allowing contact between the first and second electrode layers.

[0014] Initially, the term "second electrodes" can simply refer to an additional electrical resistor. Furthermore, "contactable through the contact opening" means that the first and second electrode layers can be contacted through the contact opening. This means that the first and second electrodes can come into direct mechanical contact and thus be electrically contactable. Because a mechanical force allows the first electrode layer to connect to the second electrode layer, an electrically conductive connection is created, causing a change in the circuit's resistance. This change can be detected, allowing conclusions to be drawn about the acting mechanical force. Moreover, this layered structure makes it possible to manufacture the sensor in a simple and cost-effective manner.Furthermore, this sensor design is less susceptible to external environmental influences and therefore exhibits high reliability even under harsh environmental conditions. Additionally, this design effectively suppresses ghosting signals, thus improving detection precision. "Perpendicular" here refers to an angular range of between 80° and 100°, preferably between 85° and 95°, and most preferably exactly 90°.

[0015] Furthermore, the second electrodes can have a resistance value that is ten to one hundred times, preferably thirty to one hundred times, and particularly preferably fifty to one hundred times, the resistance value of the first and third electrodes. This large difference in resistance allows ghosting signals to be prevented even more effectively and reliably. Additionally, on the side of the first electrode layer facing away from the intermediate layer, a third electrode layer with at least two fourth electrodes can be arranged parallel to the third electrodes, the fourth electrodes being electrically connected to the first electrodes via first connecting openings in the first electrode layer.

[0016] By integrating an additional third electrode layer, which features a fourth electrode arranged parallel to the third electrodes, a rectified interface can be created without significantly increasing the electrical resistance. This simplifies the integration of the sensor into existing sensor systems.

[0017] Furthermore, a fourth electrode layer can be formed on the third electrodes, wherein a pressure amplifier, in particular a spherical or hemispherical pressure amplifier, can be formed in alignment with at least one contact opening. The pressure amplifier can be designed as a protrusion, so that mechanical forces originating from a flat surface can be detected more effectively. The protrusion or pressure amplifier amplifies the deformation of the second electrode layer.

[0018] Furthermore, the first and second connection ports can be filled with an electrically conductive polymer, in particular electrically conductive carbon nanoparticle-doped polydimethylsiloxane (PDMS). The use of electrically conductive carbon nanoparticle-doped PDMS significantly reduces the sensor's manufacturing costs. PDMS is also particularly suitable because its chemically inert properties and biocompatibility allow for use in a wide variety of technical applications. Its mechanical properties are also particularly well-suited for a flexible sensor.

[0019] Furthermore, the second electrode can have a first contact area located outside the overlap areas and a second contact area located within an overlap area, with each first contact area being electrically connected to a third electrode via a second connection opening. This allows for the creation of a 2D structure that ensures the detection of the mechanical force is not affected by the mechanical properties of the other electrode layers.

[0020] Furthermore, the first electrode layer, the intermediate layer, the second electrode layer, the third electrode layer, and the fourth electrode layer can all be made of a stretchable elastomer. By using elastomers, the sensor can be designed as a completely flexible and stretchable sensor.

[0021] Furthermore, the first, third, and / or fourth electrodes can be made of PDMS doped with electrically conductive carbon nanoparticles. This makes it possible to produce cost-effective, flexible electrodes that remain functional even under large elastic deformations.

[0022] Furthermore, the second electrodes can be made of electrically conductive carbon nanoparticle doped PDMS, so that different electrical resistance values ​​of the electrodes can be generated in a simple way.

[0023] A sensor system for detecting mechanical forces comprises at least one sensor with the properties described above, an inverted amplifier circuit, and a measuring device, wherein the inverted amplifier circuit is connected to the first electrodes or to the fourth electrodes, and wherein the measuring device is connected to the third electrodes to conduct electrical current across the electrodes.

[0024] An inverting amplifier provides a virtual ground that maintains a ground potential despite flowing electrical currents, thus effectively suppressing ghosting signals. Furthermore, this sensor system can be used particularly in the fields of human-machine interaction, robotics, and mechanical gripping.

[0025] Exemplary embodiments of the invention are illustrated in the drawings and are described below with reference to Figures 1-8 and the respective sub-figures. Recurring features are identified by identical reference numerals.

[0026] They show:

[0027] Fig. 1a is a schematic, perspective exploded view of a sensor for detecting mechanical forces;

[0028] Fig. lb a schematic, perspective under-view of a second electrode layer from Fig. 1a with second electrodes;

[0029] Fig. 2a shows a schematic, side view of a first electrode layer, an intermediate layer, a second electrode layer and a fourth electrode layer without mechanical force being applied;

[0030] Fig. 2b shows a schematic, side view of a first electrode layer, an intermediate layer, a second electrode layer and a fourth electrode layer under mechanical force;

[0031] Fig. 3a is a schematic drawing of an inverted amplifier circuit without mechanical force;

[0032] Fig. 3b is a schematic drawing of an inverted amplifier circuit with mechanical force application;

[0033] Fig. 4 shows a schematic, perspective view of a first electrode, a third electrode and a second electrode designed as an additional electrical resistor;

[0034] Fig. 5a is a schematic side view of Fig. 4 with a first mechanical force applied;

[0035] Fig. 5b a schematic side view of Fig. 4 with a second mechanical force applied; Fig. 6a a perspective schematic view of the layer structure of the sensor with a second electrode;

[0036] Fig. 6b is a schematic side view of Fig. 6a under the influence of a mechanical force;

[0037] Fig. 7 is a schematic side view of Fig. 2a under a planar mechanical load;

[0038] Fig. 8a is a schematic side view of Fig. 7 with a pressure amplifier and

[0039] Fig. 8b is a schematic side view of Fig. 8a under the influence of a mechanical force.

[0040] Figure 1a shows an embodiment of a sensor, schematically illustrating its individual layers. The sensor comprises a first electrode layer 1, on which, in this example, six first electrodes 4 are formed, all arranged parallel to one another. Fewer first electrodes 4 are also possible, but at least two must be present. An intermediate layer 3, comprising a plurality of contact openings 9, is arranged on the surface of the first electrode layer 1, on which the first electrodes 4 are formed. The contact openings 9 are spaced apart from one another and oriented towards the first electrodes 4. This means that each contact opening 9 is positioned such that it is located above a first electrode 4.The cross-section of the contact opening 9 can have any geometry, in particular circular, cross-shaped, rectangular, or square. Furthermore, the geometries of the contact openings 9 can differ from one another (in pairs). However, the geometries of the contact openings 9 can also all be identical.

[0041] Furthermore, a second electrode layer 2 is arranged above the intermediate layer 3, which has second electrodes 5 on the surface facing the intermediate layer 3. The second electrodes 5 are at least partially located in the area of ​​the contact opening 9. The first electrodes 4 and the second electrodes 5 are also spaced apart by the intermediate layer 3. The arrangement of the second electrodes 5 is also shown in Fig. 1b.

[0042] Furthermore, third electrodes 6 are arranged on the surface of the second electrode layer 2 facing away from the intermediate layer 3. In this embodiment, these third electrodes 6 have the same number as the first electrodes 4. The third electrodes 6 and the second electrodes 5 are electrically connected to each other via second connecting openings 8, which are arranged in the second electrode layer 2. Each second electrode 5 can be electrically connected to a third electrode 6 via a second connecting opening 8.

[0043] Furthermore, the third electrodes 6 extend in a direction offset by 90° to the direction of extension of the first electrodes 4. This means that the third electrodes 6 run perpendicular to the direction of extension of the first electrodes 4. As a result, the first electrodes 4 and the third electrodes 6 form overlapping regions 7 (see Figs. 2a and 3a). Here, "overlap region 7" means that in several areas, regions of the first electrodes 4 and the third electrodes 6 overlap perspectively. "Perspective overlap" means that the first electrodes 4 and the third electrodes 6 overlap in the overlapping regions 7 without any mechanical contact between them. Furthermore, the overlapping regions 7 are designed such that each overlapping region 7 encloses a contact opening 9.

[0044] Furthermore, the overlap regions 7 are formed in such a way that they are arranged in an n / m matrix. Here, n corresponds to the number of first electrodes 4 and m to the number of third electrodes 6. In this example, six first electrodes 4 and six third electrodes 6 are provided, resulting in a 6 / 6 matrix. This means there are a total of 36 overlap regions 7. This number of overlap regions 7 also determines the number of measuring points; that is, in this embodiment, there are 36 measuring points. Since, in this embodiment, a second electrode 5 is at least partially arranged in each region of each contact opening 9, and each overlap region 7 comprises each contact opening 9, the number of overlap regions 7, or the number of measuring points, corresponds to the number of second electrodes 5. This means that in this embodiment, there are 36 second electrodes 5.

[0045] Furthermore, a fourth electrode layer 13 is formed on the third electrodes 6, wherein pressure amplifiers 14 are formed on the surface of the fourth electrode layer. In this embodiment, the pressure amplifiers 14 are designed as hemispherical protrusions. Each protrusion is aligned with a contact opening 9, and the number of protrusions corresponds in particular to the number of measuring points, here 36.

[0046] In this embodiment, first connecting openings 12 are additionally provided in the first electrode layer 1. Each connecting opening 12 connects a first electrode 4 to a fourth electrode 11 arranged on a third electrode layer 10. The number of fourth electrodes 11 corresponds to the number of first electrodes 4.

[0047] Furthermore, the fourth electrodes 11 are arranged parallel to the second electrodes 5 and the third electrodes 6, so that the connection points of the third electrodes 6 and the fourth electrode 11 are aligned. Alternatively or additionally, the pressure intensifiers 14 can also be formed on the surface of the third electrode layer 10 facing away from the first electrode layer 1. If no third electrode layer 10 with fourth electrodes 11 is provided, the pressure intensifiers can also be formed on the surface of the first electrode layer 1 facing away from the intermediate layer 3.

[0048] Thus, the structure of the sensor in this embodiment can be described as follows: The sensor comprises eight individual layers. The first layer, from bottom to top, can be formed from a thin elastomer membrane (third electrode layer 10). The second layer is a stretchable, low-resistance conductive electrode (fourth electrode 11) made of polydimethylsiloxane (PDMS) doped with conductive carbon nanoparticles. The third layer is an elastomer (first electrode layer 1) with openings (first connection openings 12) filled with low-resistance conductive PDMS to electrically connect the fourth electrode 11 and the first electrode 4. The fourth layer consists of the stretchable, low-resistance conductive electrodes (first electrodes 4) oriented perpendicular to the second layer. The fifth layer is an elastomer (intermediate layer 3) with openings (contact openings 9).The sixth layer is an elastomer (second electrode layer 2) whose openings (second connection openings 8) are filled with low-resistance conductive PDMS and onto which high-resistance conductive PDMS electrodes (second electrodes 5) are printed. The seventh layer comprises the stretchable, low-resistance conductive electrodes (third electrodes 6). The eighth and uppermost layer comprises the elastomer (fourth electrode layer 13) with the pressure intensifiers 14. In this example, elastomers were used as the starting material for the layers, and doped and undoped PDMS were used to form the electrical connections. It is important that the first electrodes 4 and the third electrodes 6 have a lower electrical resistance than the second electrodes 5. The resistance of the first electrodes 4 and the third electrodes 6 is preferably 1–10 kΩ, whereas the resistance of the second electrodes 5 is preferably 100–1000 kΩ.This resistance value can be measured as the electrical resistance between two measuring points, which, in the embodiment shown in Figure 1a, each have a maximum distance along the longitudinal axis of one of the electrodes. Similarly, the resistance value of the second electrodes 5 is determined by arranging one of the measuring points at the thickenings of the respective electrode. The resistance value can also be understood as the specific resistance, which is given for the first electrodes 4 and the third electrodes 6 1-10'. 2 - 1-10' 4 Ohm-m is, for the second electrodes 5 preferably 1-10 1 - 1-10 ^Ohm-m.

[0049] Figure 2a shows a contact opening 9 in the intermediate layer 3, which, as described above, is formed in the overlap area 7 between the first electrode layer 1 with the first electrodes 4 and the second electrode layer 2 with the second electrodes 5, which are electrically connected to a third electrode 6 via a second connecting opening 8. In other words, a measuring point is shown here. In Figure 2b, a mechanical force is exerted on the second electrode layer 2, causing it to deform into the contact opening 9. Alternatively or additionally, a force can also be applied to the first electrode layer 1, causing it to deform into the contact opening 9. This brings the first electrodes 4 into contact with the second electrodes 5. As soon as the electrodes 4 and 5 come into contact, the circuit changes from open to closed.The resistance value read by a measuring device (not shown), e.g., a measuring microcontroller, changes from infinity to a valid, i.e., specifically finite, value. With a detection array of 36 measurement points, there are six electrode tracks in each row and column, representing the first electrodes 4 and the third electrodes 6. The measuring microcontroller applies an electrical input signal (active high) to row 1 and then sequentially reads the analog voltage values ​​in columns 1-6. The microcontroller then repeats the same steps for rows 2-6. Furthermore, the deformation of the second electrode layer 2 (or the first electrode layer 1) is elastic, so that as soon as the mechanical force no longer acts on the second electrode layer 2, the second electrode layer 2 returns to the initial state shown in Fig. 2a.

[0050] Figures 3a and 3b show how the problem of ghosting signals is solved by an inverting amplifier circuit. An inverting amplifier provides a virtual ground that maintains a ground potential despite the presence of electrical currents. When an input signal is applied to port R1, port R2 is the true ground, and ports Sp1 and Sp2 are the virtual ground, as shown in Fig. 3a. If the resistance at the measurement point is much higher than the resistance of the electrode tracks, the circuit can be simplified to that shown in Fig. 3b. In this case, when 1-1, 2-1, and 2-2 are printed, a circuit path is also formed from R1 through Sp1 and R2 to Sp2. However, since R2-port, Sp1-port, and Sp2-port are all at zero potential, and R1-port has a much lower resistance to Sp1-port than to Sp2-port, most of the current flows to Sp1-port. Sp2-port has no current input, therefore no ghosting signal is read.

[0051] Figure 4 shows another embodiment of the measuring point, in which the second electrode 5 is designed as an additional electrical resistor 18, which is printed as an additional layer of high-resistance, stretchable elastomers onto the third electrodes 6. This results in the contact openings 9 being partially filled. Figure 5a shows the embodiment described in Figure 4 under load (subjected to a mechanical force). When pressure is applied, the structure of the additional resistor 18 changes. With increasing pressure (Figure 5b), the central part of the resistor 18 becomes thinner. A reduction in the resistor thickness (corresponding to the wire length) leads to a reduction in the resistance value. Since the elastomer is very soft, it is compressed very thinly under high pressure, resulting in a very low resistance value and the failure of the anti-ghosting circuit.

[0052] For this reason, a further alternative embodiment of the measuring point or the second electrode 5 is shown in Fig. 6a. Here, the second electrode layer 2 is provided between the intermediate layer 3 and the first electrode layer 1, on which the second electrodes 5 form a second contact area 16 in the overlap area 7 and a first contact area 15 that lies outside the overlap area 7. In addition, the second electrode layer has a second connecting opening 8, which electrically connects the first electrodes 4 to the second contact area 16. In this embodiment, the two contact areas 16, 17 are circular and connected via a narrow rail or bridge. The value of this resistance, i.e., the resistance value of the second electrode 5, thus depends primarily on the narrow rail and is not influenced by pressure. This resistance value is only affected by strain.Under normal use (elongation < 100%), changes in resistance value have no effect on the anti-ghosting function because the deformation of the second contact area 16 is significantly reduced (see Fig. 6b). Fig. 6b also shows the fourth electrode layer 13. In this embodiment, the contact opening 9 causes deformation of the first electrodes 4, which are arranged on a first electrode layer 1 (not shown).

[0053] Fig. 7 shows the part of the sensor already depicted in Fig. 2a, but now under a planar mechanical load. This can be achieved, for example, by a flat surface 17. As can be seen in Fig. 7, in such a load scenario, sufficient deformation of the second electrode layer 2 is not achieved, so that the second electrodes 5 do not come into contact with the first electrodes 4. This means that, in this embodiment, the sensor would not detect the mechanical load. For this reason, an additional fourth electrode layer 13 with pressure amplifiers 14 (protrusions) can be provided (see Fig. 8a). The protrusion can, for example, be a stretchable, spherical segment-shaped elastomer above the measuring point, i.e., above the overlap area 7. Due to its stretchability, the protrusion also deforms under planar pressure and brings the second electrode 5 into contact with the first electrode 4 (see Fig. 8b).

[0054] The sensor shown in Fig. 1 can also be manufactured from a silicone film or an elastomer using conventional lamination processes, as described below by way of example. The silicone film is supplied by the manufacturer on a PET (polyethylene terephthalate) substrate as a roll up to 100 meters long. Two conductive elastomer inks based on carbon particles are used. One is highly conductive and the other has a high resistance. The individual manufacturing steps are described below.

[0055] Step 1 is the preparation of the lower layer of silicone film (third electrode layer 10) and the upper layer of silicone film (fourth electrode layer 13). The two silicone films are manually cut from a roll of silicone film using a paper cutter.

[0056] Step 2 consists of applying and positioning the laser-cut PET mask onto the lower and upper layers of silicone sheets.

[0057] Step 3 involves printing the fourth electrode 11 onto the third electrode layer 10 and the third electrode 6 onto the fourth electrode layer 13 using highly conductive stretchable elastomer ink via an automated film-drawing machine. After printing, the mask is removed and the electrodes are cured in an oven.

[0058] Step 4 is the preparation of the middle lower layer of silicone film (first electrode layer 1). The silicone film is manually cut from the roll using a paper cutter, and the first connection openings 12 are cut into it using a laser cutter. Step 5 consists of applying adhesive to the middle lower layer of silicone film (first electrode layer 1).

[0059] Step 6 is the lamination of the first electrode layer 1 and the third electrode layer 10 with the fourth electrodes 11 from step 3 printed on them. The laminated stack is left in an oven to cure the adhesive.

[0060] Step 7 consists of filling the first connection openings 12 of the first electrode layer 1 of the stack of step 6 with highly conductive stretchable elastomer ink and placing it in the oven to cure.

[0061] Step 8 consists of peeling off the PET carrier from the stack of step 7 and applying the laser-cut PET mask to the surface of the first electrode layer 1 facing away from the third electrode layer 10.

[0062] Step 9 involves printing the first electrodes 4 onto the surface of the first electrode layer 1 facing away from the third electrode layer using highly conductive, stretchable elastomer ink via an automated film-drawing device. After printing, the mask is removed and the electrodes are cured in an oven.

[0063] Step 10 is the preparation of the middle upper layer of silicone sheets (second electrode layer 2). The silicone sheet is manually cut from the roll using a paper cutter, and second connection openings 8 are cut into it using a laser cutter.

[0064] Step 11 consists of applying adhesive to the middle upper layer of silicone film (second electrode layer 2).

[0065] Step 12 is the lamination of the middle upper layer silicone film (second electrode layer 2) and the upper silicone film (fourth electrode layer 13) with printed third electrodes 6 of step 3.

[0066] Step 13 consists of filling the second connecting openings 8 of the middle upper silicone (second electrode layer 2) of the stack of step 12 with highly conductive stretchable elastomer ink and placing it in the oven to cure.

[0067] Step 14 consists of peeling off the PET carrier from the stack of step 13 and applying the laser-cut PET mask to the surface of the second electrode layer 2 facing away from the fourth electrode layer 13.

[0068] Step 15 involves printing the second electrodes 5 onto the surface of the second electrode layer 2 facing away from the fourth electrode layer 13 using high-resistance stretchable elastomer ink via an automated film-drawing device. After printing, the mask is removed and the electrodes are cured in an oven.

[0069] Step 16 is the preparation of the middle layer of silicone sheets (intermediate layer 3). The silicone sheet is manually cut from a roll using a paper cutter and contact openings 9 are cut into it using a laser cutter.

[0070] Step 17 consists of applying adhesive to the middle layer of silicone film (intermediate layer 3).

[0071] Step 18 is the lamination of the middle layer of silicone film (intermediate layer 3) and the stack from step 15.

[0072] Step 19 is the peeling off of the PET carrier of the middle layer of silicone films (intermediate layer 3) of the stack from step 18.

[0073] Step 20 consists of applying glue to the stack from step 19.

[0074] Step 21 is the lamination of the stack from step 9 and the stack from step 20.

[0075] Step 22 is the removal of the top PET carrier from the stack from step 21.

[0076] Step 23 involves printing the touch amplifiers (protrusions 14) on all measuring points. The uncrosslinked elastomer is manually dispensed into the top layer (fourth electrode layer 13) of the stack using a needle and cured in an oven. Automatic dispensing systems, screen printing, and pad printing can all replace manual dispensing.

[0077] Step 24 consists of cutting the stack into individual sensors using a laser.

[0078] Reference symbol list

[0079] 1 first electrode layer

[0080] 2 second electrode layer

[0081] 3 Intermediate layer

[0082] 4 first electrode

[0083] 5 second electrode

[0084] 6 third electrode

[0085] 7 Overlap area

[0086] 8 second connecting opening

[0087] 9 Contact opening

[0088] 10 third electrode layer

[0089] 11 fourth electrode

[0090] 12 first connecting opening

[0091] 13 fourth electrode layer

[0092] 14 pressure boosters

[0093] 15 first contact area

[0094] 16 second contact area

[0095] 17 flat surfaces

[0096] 18 additional electrical resistance

Claims

Technical University of Dresden P149849PC00 Patent claims 1. Sensor for detecting mechanical forces, comprising: a first electrode layer (1), a second electrode layer (2), and an intermediate layer (3) arranged between the first electrode layer (1) and the second electrode layer (2), wherein the first electrode layer (1) has at least two first electrodes (4) on the surface facing the intermediate layer (3), and the second electrode layer (2) has at least four second electrodes (5) on the surface facing the intermediate layer (3), and the second electrode layer (2) has at least two third electrodes (6) on the surface facing away from the intermediate layer (3), wherein the first electrodes (4) are arranged perpendicular to the third electrodes (6) such that at least four overlap regions (7) are formed in an n / m matrix, wherein n corresponds to the number of first electrodes (4) and m to the number of third electrodes (6), andwherein the third electrodes (6) are electrically connected to the second electrodes (5) via second connecting openings (8) formed in the second electrode layer (2), wherein the first electrodes (4) and the third electrodes (6) have a lower electrical resistance value than the second electrodes (5), wherein the intermediate layer (3) has a contact opening (9) in each overlap area (7), wherein, the first electrode layer (1) can be contacted with the second electrode layer (2) through the contact opening (9).

2. Sensor for detecting mechanical forces according to claim 1, characterized in that the second electrodes (5) have a resistance value that is ten to one hundred times, preferably thirty to one hundred times, particularly preferably fifty to one hundred times, the resistance value of the first electrodes (4) and third electrodes (6).

3. Sensor for detecting mechanical forces according to one of the preceding claims, characterized in that on the side of the first electrode layer (1) facing away from the intermediate layer (3) a third electrode layer (10) with at least two fourth electrodes (11) is arranged parallel to the third electrodes (6), wherein the fourth electrodes (11) are electrically connected to the first electrodes (4) via first connecting openings (12) in the first electrode layer (1).

4. Sensor for detecting mechanical forces according to one of the preceding claims, characterized in that a fourth electrode layer (13) is formed on the third electrodes (6), wherein a pressure amplifier (14), in particular a spherical or hemispherical pressure amplifier (14), is formed in alignment with at least one contact opening (9).

5. Sensor for detecting mechanical forces according to one of the preceding claims, characterized in that the first connecting openings (12) and the second connecting openings (8) are filled with an electrically conductive polymer, in particular electrically conductive carbon nanoparticle-doped polydimethylsiloxane, PDMS.

6. Sensor for detecting mechanical forces according to one of the preceding claims, characterized in that the second electrodes (5) have a first contact area (15) which is arranged outside the overlap areas (7) and a second contact area (16) which is arranged inside an overlap area (7), wherein each first contact area (15) is electrically connected to each third electrode (6) via a second connecting opening (8).

7. Sensor for detecting mechanical forces according to one of the preceding claims, characterized in that the first electrode layer (1) and / or the intermediate layer (3) and / or the second electrode layer (2) and / or the third electrode layer (10) and / or the fourth electrode layer (13) comprises a stretchable elastomer.

8. Sensor for detecting mechanical forces according to one of the preceding claims, characterized in that the first electrodes (4) and / or the third electrodes (6) and / or the fourth electrodes (11) are made of polydimethylsiloxane, PDMS, doped with electrically conductive carbon nanoparticles.

9. Sensor for detecting mechanical forces according to one of the preceding claims, characterized in that the second electrodes (5) are made of electrically conductive polydimethylsiloxane, PDMS.

10. Sensor system for detecting mechanical forces, comprising: at least one sensor according to one of claims 1-9, an inverted amplifier circuit and a measuring device, wherein the inverted amplifier circuit is applied to the first electrodes (4) or to the fourth electrodes (11), and wherein the measuring device is connected to the third electrodes (6) to conduct electrical current through the electrodes.

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