WO2022233390A1

WO2022233390A1 - Flexible acceleration sensor based on 2d materials and its use

Info

Publication number: WO2022233390A1
Application number: PCT/EP2021/061605
Authority: WO
Inventors: Borna RADATOVIC; Valentino JADRISKO
Original assignee: Nanoing J.D.O.O.
Priority date: 2021-05-03
Filing date: 2021-05-03
Publication date: 2022-11-10

Abstract

The present invention discloses an improved acceleration sensor based on 2D material and common proof mass in the form of an insulating layer (50). It comprises at least two-unit acceleration sensors (100, 100') with selected 2D materials (10, 10'), a pair of side electrodes (20, 21; 20', 21') with optionally deposed auxiliary surface electrodes (30, 31; 30', 31') and a capacitive electrode (40, 40'). An insulated layer (50) is larger than the area of the 2D material (10). The flexible substrate (60) carries all unit acceleration sensors. The strain gauge of the said unit-sensor is measured via resistivity R₁₀₀ between pair of side electrodes (20, 21), with optionally use of deposed auxiliary surface electrodes (30, 31), and using the capacitance measurement C₁₀₀ between the capacitive electrode (40) and conductive 2D material (10). In preferred embodiment, two equally aligned unit-sensors are used, and differential measurement is performed.

Description

FLEXIBLE ACCELERATION SENSOR BASED ON 2D MATERIALS AND ITS USE

DESCRIPTION

Technical Field

The present invention discloses an acceleration sensor based on two- dimensional (2D) materials and its use. From the nature of invention, the said invention belongs to the technical field of acceleration measurement where solid seismic mass is used. The distortion of 2D materials used for sensing acceleration significantly change their electric resistance. Said strain gauge factor of the used 2D material is well known in the related art. In one aspect of the invention, the change in capacitance between the selected 2D material and the electrodes formed oppositely to the said 2D material, with an insulated layer acting as the seismic mass sandwiched between, is also used for improved calculation of an acceleration to which the sensor is exposed. In addition to improved sensing, the invention enables application of accelerometers based on 2D materials for flexible and stretchable electronics.

Technical Problem

The main technical problem solved by the present invention can be regarded as an improved construction of the acceleration sensor based on extensive use of novel 2D materials. The disclosed acceleration sensor is based on two 2D materials with relatively high resistivity and significant gauge factor and where said sensor comprises at least two unit acceleration sensors that share a common insulator layer that serves as common proof mass, i.e. seismic mass. This setup enables, among other improvements, a differential measurement between the data used from unit acceleration sensors in order to estimate the acceleration more accurately and eliminate the thermal noise and other spurious signals such as parasitic mechanical vibrations generated within the sensor. Furthermore, the disclosed acceleration sensor is designed to be used together with the flexible substrate to which, at least, two unit acceleration sensors are mounted. This setup allows formation of continuous series of sensors deposited on the elongated flexible substrate. Such belt-like setup can be further mounted on flexible bodies, e.g., spheroids or similar bodies, to form the set of sensors in the form of NEMS (nanoelectromechanical system) for determination of the acceleration vector with improved accuracy and with the thickness which is of the nanometre scale.

State of the Art

The development of novel two dimensional materials with significant strain gauge factors propelled the field of NEMS accelerometers based on 2D materials. In the reference 1) it is quoted that layered two- dimensional (2D) materials possess outstanding electronic, optical, chemical and mechanical properties for a wide range of potential future nanoelectronic devices. Besides the carbon-based graphene, many other 2D materials are being investigated, like phosphorene, hexagonal boron nitride and transition metal dichalcogenides (TMDs), where later are used in the present invention. The large-area growth of these materials is now possible and their transfer to arbitrary substrates enable future volume production for commercial wafer-based applications. Furthermore, other techniques which differ from wafer- based applications are also disclosed.

1) Stefan Wagner, 2D MATERIALS FOR PIEZORESISTIVE STRAIN GAUGES AND MEMBRANE BASED NANOELECTROMECHANICAL SYSTEMS, dissertation; Faculty of Electrical Engineering and Information Technology of the Rheinisch-Westfalische Technische Hochschule Aachen; DE, on July 16, 2018. Source: https://d-nb.info/1181193214/34

The above cited reference is an excellent review of the current know how in the field of used 2D materials with the present invention. Reference 1) discloses only general principles used in the field without disclosing specific sensors architectures. 2) CN patent application published as CN111983257 for the invention AN ACCELERATION SENSOR BASED ON SUSPENDED TWO-DIMENSIONAL MATERIAL AND HETEROGENEOUS LAYER SUSPENDED MASS, filed in the name of jSIflSI.

The above cited reference teaches about an accelerometer with a proof mass attached to the suspended 2D material. In reference 2) the suspended two-dimensional material is selected from the following group: graphene (graphene), hexagonal boron nitride (hBN), molybdenum disulfide (M0S2), tungsten diselenide (WSe2), molybdenum diselenide (MoSe2), tungsten disulfide (WS2), platinum diselenide (PtSe2), molybdenum diselenide (MoTe2), tungsten diselenide (WTe2), vanadium diselenide (VSe2), chromium disulfide (CrS2), chromium diselenide (CrSe2), other transition metal dichalcogenides (TMDC), and black phosphorus (P). Furthermore, see paragraph [0034], reference 2 quotes that a typical acceleration sensor usually includes a suspended mass structure, which is displaced with the applied acceleration and which causes the resistance or capacitance of the sensing structure of the said acceleration sensor to change.

3) US patent US 10,228,387 for the invention TWO-DIMENSIONAL MATERIAL-BASED ACCELEROMETER, filed in the name of Kulite Semiconductor Products Inc.

Reference 3) discloses system and method for a two-dimensional material-based accelerometer. In one embodiment, an accelerometer comprises a substrate; a membrane suspended over an opening in the substrate to form a suspended membrane, wherein the membrane is composed of a two-dimensional material; a mass structure coupled to the suspended membrane; wherein the mass structure distorts the suspended membrane about a first axis in response to an applied acceleration providing a first and instantaneous change in a conductance of the suspended membrane, so that the applied acceleration along the first axis can be detected. Paragraph [0024] of reference 3) quotes that used two-dimensional materials may comprise a single atomic layer to several atomic layers, and in addition to graphene, materials such as molybdenum disulfide (M0S2), tungsten diselenide (WSe2) can be used.

4) CN patent application published as CN109507451 for the invention MOLYBDENUM DISULFIDE FILM BASED ACCELERATION SENSOR CHIP AND PROCESSING METHOD THEREOF, filed in the name of UNIV XI AN JIAOTONG.

Reference 4) teaches about M0S2 based acceleration sensors specifically designed in the form of the Wheatstone bridge that allows four M0S2resistors to be measured with only 4 contacts, said resistors are distributed evenly over the central proof mass.

5) International PCT patent application published as WO2017022577A1, for the invention STRAIN RESISTANCE ELEMENT, PRESSURE SENSOR, STRAIN GAUGE, ACCELERATION SENSOR, AND ANGULAR VELOCITY SENSOR, filed in the name of Murata Manufacturing Co.

Reference 5) discloses a standard NEMS construction of the pressure sensor, strain gauge, acceleration sensor or an angular velocity sensor. It uses a strain resistance film formed on a rigid surface of the SiCU substrate, wherein the strain resistance film is formed as a film of graphene or a transition metal dichalcogenide having a single atom layer thickness or a multi-atom layer thickness. The used NEMS geometry is rather generic.

6) CN patent application published as CN110531113 for the invention A PLANAR DIFFERENTIAL ACCELEROMETER DEVICE BASED ON GRAPHENE RESONATORS AND A PROCESSING METHOD THEREOF, filed in the name of Southeast University.

The technical problem solved in reference 6) is ability to overcome the problems and deficiencies in the prior art with the setup having two counterphase formed graphene resonators. 7) CN patent application published as CN109470886 for the invention MULTI-AXIS PAPER-BASED ACCELERATION SENSOR AND PREPARATION METHOD THEREOF, filed in the name of Jiangsu Jicui Micro Nano Automation System and Equipment Tech Research Institute Co Ltd.

Reference 7) teaches about the system of resonators formed as the U- shaped structure made of carbon film, i.e., highly oriented pyrolytic graphite, graphene or carbon nanotubes; with the proof mass attached on one end and packed in the form of a cube. The described system of resonators is capable to determine acceleration vector.

8) Tsai, M.-Y., Tarasov, A., Hesabi, Z. R., Taghinejad, H., Campbell, P. M., Joiner, C. A., ...Vogel, E. M. (2015). FLEXIBLE MoS₂ FIELD- EFFECT TRANSISTORS FOR GATE-TUNABLE PIEZORESISTIVE STRAIN SENSORS. ACS Applied Materials & Interfaces, 7(23), 12850-12855. doi:10.1021/acsami.5b02336.

Reference 8) teaches about flexible MoS₂ FETs. Atomically thin molybdenum disulfide is found to be a promising two-dimensional semiconductor for high-performance flexible electronics, sensors, transducers, and for the energy conversion systems. A piezoresistive strain sensing with flexible MoS₂ FETs made from highly uniform large- area films is demonstrated in the reference 8). In addition, the said reference discloses the way said FETs are made on flexible substrate.

Reference 8) is possibly the closest prior art document having in mind that the disclosed unit acceleration sensor, based on 2D material, resembles partially the architecture disclosed herein. Other prior art documents cited hereby are just the documents defining general state, e.g., use of metal dichalcogenides for accelerometers and without particular relevance for the claimed subject matter.

Summary of the Invention

The present invention discloses an acceleration sensor based on two dimensional materials with significant strain gauge factor. It comprises at least two unit acceleration sensors, where each unit acceleration sensor is composed of several layers described below.

• 2D material of the unit acceleration sensor is shaped as an identical elongated rectangle, with a pair of side electrodes formed around the opposite shortest sides of the said rectangle, with optionally deposed auxiliary surface electrodes situated close to the mentioned respective side electrodes. Such setup allows 2 or 4 contacts resistivity measurements of the said 2D material.

• A capacitive electrode of the unit acceleration sensor is geometrically shaped as the mentioned 2D material.

• An insulated layer of the unit acceleration sensor, which geometry is arbitrary, is significantly larger than the area of the 2D material used. The said insulated layer carries on its top side mentioned 2D material, side electrodes and optionally deposed auxiliary surface electrodes. On its bottom side, the capacitive electrode is positioned below the top positioned 2D material and forms a parallel plate capacitor with the said top 2D material.

• A flexible substrate of the unit acceleration sensor is formed below the capacitive electrode in a way to sandwich the said capacitive electrode between the said flexible substrate and the insulated layer.

• All components are encapsulated with encapsulation material that encloses said unit acceleration sensor.

• The strain gauge of the said unit sensor is determined by measuring resistivity between the pair of side electrodes, with optionally use of deposed auxiliary surface electrodes, and by using the capacitance measurement between the capacitive electrode and the conductive 2D material. The acceleration sensor, according to the invention, is formed in a way that insulated layer, which acts as a sensor proof mass is common to all unit acceleration sensors. The same flexible substrate carries all unit acceleration sensors. The acceleration data are calculated from the set of resistivity and/or capacitance data measured from all unit sensors according to the calibration model.

The suitable 2D materials for the acceleration sensor are selected from the group of metal dichalcogenides, with the thickness ranging from monolayer to a plurality of atomic layers. The most suitable metal dichalcogenides are molybdenum disulphide (M0S2) or platinum diselenide (PtSe2)· In the preferred embodiment, each unit acceleration sensor (100) has the same 2D material.

In yet another embodiment all centres of mass of all unit acceleration sensors are laying on the same line, where said centres of mass are equidistantly spaced one from another. In one variant, all unit acceleration sensors are aligned in the same direction. In yet another variant, the number of unit acceleration sensors are two and the acceleration data are obtained from the set of resistivity/capacitance data.

Use of the acceleration sensors are also disclosed. In one variant, all acceleration sensors share a common flexible substrate. In another variant the common flexible substrate is in the form of a belt. In one embodiment, one or more belts with sensors are arranged to follow couture of a centre body, and in yet another variant, the said centre body is a spheroid.

Description of Figures

Figure 1 shows a unit acceleration sensor construction in the side view. Figure 2 depicts the acceleration sensor's side view, which is composed of two unit acceleration sensors formed on the same flexible substrate, sharing the common insulated layer as a proof mass. Figure 3 shows the top view of acceleration sensor depicted on Figure 2. Figures 4A-4C shows the acceleration sensor formed form three unit acceleration sensors in various orientations, which are sharing the common insulated layer as a proof mass and that are mounted on the same flexible substrate.

Figure 5 depicts the use of multiple acceleration sensors, arranged on the belt-type flexible substrate, and mounted on the elastic spheroid.

Figure 6 depicts flowchart with the steps A-F of acceleration unit sensor formation.

Detailed Description of the Invention

The acceleration sensors based on solid seismic mass or proof mass are well known in the art, see the references l)-7) cited before. Novel materials, such as 2D materials, help to make acceleration sensors very small and to be packed as NEMS (nanoelectromechanical system). Therefore, the inner geometry plays the important role in forming the reliable acceleration sensor, especially if the sensor is formed on the elastic substrate, which is the case in this invention.

Figure 1 depicts, so-called, the unit acceleration sensor (100) used to form an acceleration sensor (101) according to the invention. The unit acceleration sensor (100) is formed on flexible substrate (60). This flexible substrate can be made as a polymer ribbon, where the suitable polymers are PC (polycarbonate), PDMS (polydimethylsiloxane), PC-PDMS (polycarbonate polydimethylsiloxane copolymer), PET (polyethylene terephthalate) or similar polymers used in NEMS. The flexible substrate (60) is significantly longer and wider than the unit acceleration sensor (100), as obvious from Figures 2, 3, 4A-4C and should be capable to carry plurality of unit acceleration sensors (100). The capacitive electrode (40) is formed over the flexible substrate (60). Said capacitive electrode (40) is formed from a conductive material by thermal evaporation or via sputtering in order to produce thin metal film. In case that some 2D material is used for forming the said electrode (40) instead of metal, a stamping transfer is employed and 2D material with high conductivity is used for the mentioned purpose, i.e., graphene. Thermal evaporation, sputtering and stamping transfer are well known techniques in the field.

The insulated layer (50) is formed over the capacitive electrode (40). Said insulated layer (50) is shared among two or more unit acceleration sensors (100, 100', ...), as depicted on Figure 2, and it is used as the proof mass for the mentioned unit acceleration sensors (100, 100', ...). The insulated layer (50) can be formed in various ways. If the insulator layer is made of polymer, then the insulated layer (50) is formed by dripping a polymer droplet with subsequent spin coating to form a polymer film. The suitable polymer and solvent is, for example, Polymethyl methacrylate (PMMA) and alcohol-water solvent mixture. If the insulated layer (50) is formed as a thin oxide-layer, e.g., A1₂0₃, then the Atomic Layer Deposition (ALD) or the sputtering method can be used. Finally, if non-conductive 2D material is used for the layer (50), i.e., hexagonal boron nitride (hBN) or calcium fluoride (CaF₂), a stamping transfer can be employed equally well. For the person skilled in the art is obvious that the thickness of proof mass formed as an insulated layer (50) should be chosen carefully to render unit acceleration sensor (100) operational and enough sensitive.

The core of the unit acceleration sensor (100) is carefully selected 2D material (10) that is formed over the said insulated layer (50) in the form of elongated rectangle, as depicted in Figure 1 and 3. In practice, the nano- and micro- scale 2D materials usually grow in triangular or hexagonal form. The consequence of that fact is that rectangles are formed only on rather bigger lateral scales. For smaller dimensions, it is necessary to use an etching process, a plasma cleaner, or a focused ion beam technique to shape the 2D material (10) according to the needs, i.e., to produce elongated-like rectangles, or other suitable geometries. Said 2D material (10) should be chosen to have a significant strain gauge factor. Suitable 2D materials are selected from the group of metal dichalcogenides, with the thickness ranging from monolayer to a plurality of atomic layers, preferably formed from molybdenum disulphide (M0S2) or platinum diselenide (PtSe2)· Said 2D material (10) is deployed over the insulator layer (50) by stamping transfer. Stamping transfer can be the PDMS Stamp Assisted Mechanical Exfoliation or, 2D material (10) can be formed on another substrate by any other convenient technique known in the related art and subsequently transferred to the insulator layer (50).. Molybdenum disulphide (M0S2) or platinum diselenide (PtSe2) is found to be an excellent choice having in mind comparably high resistivity that has some advantages in resistivity measuring by two contacts only vs. highly conductive 2D materials, e.g. graphene resistivity measurements with four contacts.

Finally, a pair of side electrodes (20, 21) is formed around the opposite shortest sides of the said 2D material (10) rectangle, with optionally deposed auxiliary surface electrodes (30, 31) situated close to the mentioned respective side electrodes (20, 21), allowing 2 or 4 contacts resistivity measurements of the said 2D material (10); as depicted on Figure 1. In case of metal electrodes, the Stencil lithography or the Electron beam lithography is used for forming electrodes. If 2D conductive material is used for the electrodes, such as graphene, stamping transfer can be used for the electrode formation over the selected 2D material (10). Once the electrode is formed over the 2D material (10), the sensor (100) encapsulation is performed by dripping the encapsulating polymer (70) over the top of the unit acceleration sensor (100). The whole preparation process is summarised on Figure 6, via steps A.-F.

The person skilled in the art will immediately recognise that the whole unit acceleration sensor can be formed to have thickness less than 100 pm, over the flexible substrate, which is thickest part of the device, rendering such sensor applicable everywhere. The construction of the mentioned unit acceleration sensor is very similar to those described in the reference 8) disclosing flexible M0S2 FET. However, the said invention goes broader that the mentioned teaching. The novel part of the said invention is the fact that an improved acceleration sensor (101) is based on 2D material and common proof mass in the form of an insulated layer (50), where it comprises at least two unit acceleration sensors (100, 100') with selected 2D materials (10, 10'), as depicted in Figure 2, and Figure 3. It should be remembered that a common proof mass in the form of insulated layer (50) enables various differential measurements in case of two unit acceleration sensors (100, 100') for elimination thermal noise and other spurious signals such as parasitic mechanical vibrations. Let us focus on the acceleration sensor (101) built solely with two unit acceleration sensors (100, 100'), depicted on Figures 2 and 3. Any change in acceleration in lateral direction, i.e., direction parallel with the flexible substrate (60) will certainly displace insulating layer (50) over the flexible substrate (60) in the same direction. Also, any change in acceleration in transversal direction, i.e., direction perpendicular to the flexible substrate (60) will displace insulating layer (50) far of the flexible substrate (60), or closer to the flexible substrate (60), depending on the acceleration direction and proof mass inertia, i.e. insulating layer (50) inertia.

For the lateral movement of the insulating layer (50), the selected 2D materials (10, 10'), as depicted in Figure 2, will record almost no change in resistivity (R₁₀₀, R'₁₀₀) and modest changes in capacitances (Cioo, C'₁₀₀) due to the slight change of geometrical factors that forms parallel plate capacitors 2D-material (10; 10') and capacitive electrode (40;40').

The resistivities are measured via two side electrodes (20, 21; 20', 21') respectively, or in the case where high conductivity 2D materials are used, such as graphene, with 4 contact technique where auxiliary surface electrodes (30, 31; 30', 31') are used as voltage electrodes and the mentioned side electrodes (20, 21; 20', 21') as current contacts. Capacitance ( Cioo , C ' ioo ) is measured between capacitive electrodes (40; 40') and the corresponding 2D materials (10; 10') acting as the parallel plate capacitors, with the insulated layer (50) acting as dielectric inserted between the plates. The side electrodes (20, 21; 20', 21') and the capacitive electrodes (40; 40') forms the contacts for measuring the said capacitances having in mind that the corresponding 2D materials (10, 10') are semiconductive or conductive and capable to redistribute the electrical charge over their surfaces. Capacitance can be measured by various techniques, with astonishing precision, see reference 9) below:

9) Rui Yang, Tupta, M. A., Marcoux, C., Andreucci, P., Duraffourg, L., & Feng, P. X.-L. (2015). Capacitance-voltage (C-V) characterization in very thin suspended silicon nanowires for NEMS-CMOS integration in 160nm Silicon-on-Insulator (SOI). 2015 IEEE 15th International Conference on Nanotechnology (IEEE-NANO). doi:10.1109/nano.2015.7388835 or via standard change in resonant frequencies of some driven oscillators where (Cioo, C'_IOO) determines capacitance in the RC constant of some oscillatory circuits.

For the transversal movement of the insulating layer (50), the selected 2D materials (10, 10'), as depicted in Figure 2, will record a significant change in their resistivities ( Rioo , R'IOO) and again modest changes in capacitances ( Cioo , C ' ioo ) due to the slight change of geometrical factors that forms capacitors due to the bending of the insulated layer (50). The advantages of the disclosed design depicted on Figures 2 and 3 is that the differential measurement of ( Rioo , R' ioo ; Cioo , C ' ioo ) is possible, which offers a better insight regarding the whole sensor (101) status and better noise cancelation / suppression. Certainly, the offset values can be previously recorded or balanced in a way that ( Rioo - R' ioo ) is set to 0 in case of no acceleration, and where any acceleration will gain the value of the said difference. Figures 4A-4C depicts further possibilities of the acceleration sensor (101) formation where three unit sensors (100, 100', 100") are used. Figure 4A shows the situation where common proof mass in the form of insulated layer (50) that is shared among all three sensors (100, 100', 100"), and which is aligned in the same direction with its centre of the mass laying on the same line. Such setup is sensitive as the setup disclosed on Figure 2.

However, the setups depicted on Figure 4B and 4C are different. It is obvious that these setups enable all the features previous explained for the two unit sensors, plus additional sensing of the acceleration vector which is not parallel with the elastic substrate (60). If one imagines the acceleration vector that is laying parallel to the insulated layer (50), see Figure 4, but which is inclined with some angle to the substrate (60), various readings will be recorded from three unit sensors. Unit sensors (100, 100") aligned with the insulated layer (50) will show different values that the unit sensor (100') aligned perpendicular to the said unit sensors (100, 100"). The same will occur for the case depicted via Figure 4C. So, the combination of two or more unit sensors (100, 100', ...), and possibility to have various alignments opens the whole new perspective for measuring the acceleration vector via moving the insulated layer (50) acting as the common proof mass / solid mass. The person skilled in the art will immediately recognize that various alignments of the unit sensors (100, 100', ...) helps to measure projection of the actual acceleration vector in the plane of the insulated layer (50) proof mass. It is known in the art that practical use of the acceleration sensor (101) composed form two or more unit acceleration sensors (100, 100', ...), requires calibration process before any use. The calibration process can be manual or machine supported and completely automatised.

The way the number of electrode contacts can be minimised is disclosed in reference 4) where four contacts are used to monitor four 2D unit sensor mounted on the same proof mass forming an acceleration sensor. Such wiring in the form of Wheatstone bridge is commonly used for minimising number of measuring contacts. The person skilled in the art will certainly employ one or more similar solutions for analysing the grid of 2D resistors in order to accurately read all the 2D sensors used.

The elastic substrate (60) has further advantages over the prior art teaching, where the acceleration sensors and the corresponding solid proof mass are usually formed over the rigid substrates. The elastic substrate (60) can be shaped arbitrary, for instance in the form of a belt; further attached to some centre body (90), i.e., as a spheroid as depicted in Figure 5. In the case of such setup, many acceleration sensors (101), composed form two- or three- unit acceleration sensors (100, 100', ...) are distributed over the centre body - that is used as a 3D acceleration sensing device.

It is obvious from the Figure 1 that any bending of the elastic substrate (60) will affect the whole unit acceleration sensor (100), however the values of (Rioo, Cioo) will remain constant in the absence of the acceleration. Once the acceleration is applied to the centre body (90) this body will be slightly deformed out of original position, inducing strain in elastic substrate (60), and plurality of the sensors (101) will record different values then in stationary condition when no acceleration is applied. For the spheroid depicted in Figure 5 it is essential to check the data of acceleration sensors (101) positioned on the opposite side of the said spheroid to establish the difference. Knowing the exact positions of all sensors (101) and measured data, it is very simple to establish the 3D acceleration vector applied to the elastic body, especially if the pre-calibrated sensors (101) are used. If the sensors (101) are not pre-calibrated, then the calibration of all sensors (101), fixed to the centre body (90), can be performed subsequently in accordance with the acceleration measurement.

Connecting all sensors (101) to the system and by applying machine learning optimizations it is possible to increase accuracy to an even greater extent. Centre body (90) in the form of a spheroid can be formed to be tick from 500 pm to several centimetres. Depending on the number of flexible substrate (60) used, a system may achieve desired accuracy within the theoretical limits imposed by the used 2D materials within the unit acceleration sensors (100).

Industrial Applicability

The present invention discloses a novel acceleration sensor based on two-dimensional (2D) materials, more particularly materials that are selected from the group of metal dichalcogenides, molybdenum disulphide (M0S2) or platinum diselenide (PtSe2)·The said acceleration sensor is formed over the flexible substrate and contains two or more unit acceleration sensor for improved accuracy. The industrial applicability of the mentioned sensors is obvious, mostly for flexible and bendable electronic circuits and devices.

Reference numbers

10 2D material

20, 21 side electrodes 30, 31 auxiliary surface electrodes 40 capacitive electrode 50 insulated layer 60 flexible substrate 70 encapsulation material 90 centre body 100 unit sensor

101 acceleration sensor

Claims

1. An acceleration sensor (101) based on two dimensional (2D) materials with significant strain gauge factor, which is comprising at least two unit acceleration sensors (100), where each unit acceleration sensor (100, 100', ...) has:

2D material (10) shaped as an identical elongated rectangle, with a pair of side electrodes (20, 21) which are formed around the opposite shortest sides of the said rectangle, with optionally deposed auxiliary surface electrodes (30, 31) situated close to the mentioned respective side electrodes (20, 21), allowing 2 or 4 contacts resistivity measurements of the said 2D material (10), a capacitive electrode (40) that is geometrically shaped as the mentioned 2D material (10), an insulated layer (50), which geometry is arbitrary, and which is significantly larger than the area of the 2D material (10) used, where the said insulated layer (50) carries on its top side before mentioned 2D material (10), side electrodes (20, 21) and optionally deposed auxiliary surface electrodes (30, 31) and, on its bottom side the capacitive electrode

(40) which is positioned below the top positioned 2D material (10) and forms a capacitor with the said top 2D material, a flexible substrate (60), that is formed below the capacitive electrode (40), in a way to sandwich the said capacitive electrode (40) between the said flexible substrate (60) and the insulated layer (50), where all components are encapsulated with encapsulation material (70) that encloses said unit sensor (100), and where the strain gauge of the said unit sensor (100) is measured by measuring resistivity Rioo between the pair of side electrodes (20, 21), with optionally use of deposed auxiliary surface electrodes (30, 31), and using the capacitance measurement Cioo between the capacitive electrode (40) and the conductive 2D material (10), characterised in that, the acceleration sensor (101) is formed in a way that insulated layer (50), which acts as a sensor (101) proof mass is common to all unit acceleration sensors (100, 100', ...), where the same flexible substrate (60) carries all unit acceleration sensors (100, 100', ...), and where the acceleration data are calculated from the set of data { ( Rioo , Cioo ) , (R'IOO, C ' ioo ) , — } measured from all unit sensors (100, 100', ...) according to the calibration model.

2 . The acceleration sensor (101) according to claim 1, where the suitable 2D materials are selected from the group of metal dichalcogenides, with the thickness ranging from monolayer to a plurality of atomic layers.

3. The acceleration sensor (101) according to the claim 2, where the most suitable metal dichalcogenides are molybdenum disulphide (MOS₂₎ or platinum diselenide (PtSe₂₎ .

4. The acceleration sensor (101) according to any of the preceding claims, where each unit acceleration sensor (100) has the same 2D material.

5. The acceleration sensor (101) according to any of the preceding claims, where all centres of mass of all unit acceleration sensors (100, 100', ...) are laying on the same line, and where said centres of mass are equidistantly spaced one from another.

6. The acceleration sensor (101) according to claim 5, where all unit acceleration sensors (100, 100', ...) are aligned in the same direction.

7. The acceleration sensor (101) according to claim 6, where the number of unit acceleration sensors (100, 100') are two and the acceleration data are obtained from the set of data { ( Rioo , Cioo ) , ( R' ioo , C' ioo ) } ·

8. Use of the acceleration sensors (101) according to any of the claims 1-6, where said sensors (101) share a common flexible substrate (60).

9. Use of the acceleration sensors (101) according to claim 8, where said sensors (101) share a common flexible substrate (60) in the form of a belt.

10. Use of the acceleration sensors (101) according to claim 9, where one or more belts with sensors (101) are arranged to follow couture of a centre body (90).

11. Use of the acceleration sensors (101) according to claim 10, where the said centre body (90) is a spheroid.