Device for measuring force on a complex surface

Abstract

The present description relates to a conformable force-measuring device, intended to be subjected simultaneously to compressive forces and bending forces, the device comprising sensors (11, 12) arranged on either side of a substrate (100), the sensors comprising an organic piezoelectric layer (120) arranged between a first electrode (110) and a second electrode (130), the sensors (11, 12) being arranged opposite each other, so as to form a bimorph (10), the sensors being connected to electrically conductive tracks (200) intended to be connected to measuring apparatuses, the organic piezoelectric layers (120) of the sensors (11, 12) being polarised and the sensors (11, 12) being intended to be electrically connected to the measuring apparatuses so as to cancel out either the compressive forces or the bending forces.

Claims

CLAIMS 1. Force measuring system comprising a conformable device intended to be subjected simultaneously to compressive forces and bending forces, the device comprising a substrate (100) having a first face (100a) and a second face (100b), at least one first sensor (11) arranged on the first face (100a) of the substrate (100) and at least one second sensor (12) arranged on the second face (100b) of the substrate (100), the sensors (11, 12) comprising an organic piezoelectric layer (120) arranged between a first electrode (110) and a second electrode (130), the sensors (11, 12) being arranged opposite one another, so as to form a bimorph (10), the system further comprising measuring devices electrically connected to the sensors (11, 12) to measure the signals of the sensors (11, 12) , the organic piezoelectric layers (120) of the sensors (11, 12) being polarized and the sensors (11,12) being electrically connected to the measuring devices so as to cancel either the compressive forces or the bending forces, and measure, respectively, either the bending forces or the compressive forces applied to the device, in which system:, - the polarization of the sensors (11, 12) is opposite, the sensors being connected to the measuring devices in opposite ways and the signals measured by the measuring devices are added, whereby the bending forces are canceled and the compressive forces are measured, or - the polarizations of the sensors (11, 12) are identical, the sensors being connected to the measuring devices in an identical manner and the signals measured by the devices measurement forces are added, whereby the bending forces are cancelled and the compression forces are measured, or - the polarizations of the sensors (11, 12) are opposite, the sensors being connected to the measuring devices in an identical manner and the signals measured by the measuring devices are subtracted, whereby the bending forces are canceled and the compression forces are measured, or - the polarizations of the sensors (11, 12) are identical, the sensors are connected to the measuring devices in opposite directions and the signals measured by the measuring devices are subtracted, whereby the bending forces are canceled and the compressive forces are measured.

2. System according to claim 1, wherein the sensors (11, 12) are covered by a stack successively comprising a first dielectric layer (140), a ground plane (150) and a second dielectric layer (160).

3. System according to one of the preceding claims, in which the ground plane is made of carbon and / or in which the first dielectric layer (140) and the second dielectric layer (160) are made of EDAG or PVDF.

4. System according to one of the preceding claims, in which the substrate (100) is a PEN or PI substrate.

5. System according to any one of the preceding claims, in which the substrate (100) comprises two support substrates (10: ., 102), for example made of TPU, assembled to each other by an adhesive element (103).

6. System according to any one of the preceding claims, in which the first face (100a) of the substrate (100) is covered by a first matrix of sensors and the second face (100b) of the substrate (100) is covered by a second matrix of sensors, the first matrix and the second matrix being arranged opposite each other.

7. System according to the preceding claim, in which, on the one hand, the first electrode (110) of each sensor (11) of the first matrix is ​​connected to an individual electrically conductive track (200) and, on the other hand, in which all the second electrodes (120) of the sensors (11) of the first matrix are connected to a common electrically conductive track (200) and in that, on the one hand, the first electrode (110) of each sensor (12) of the second matrix is ​​connected to an individual electrically conductive track (200) and, on the other hand, in that all the second electrodes (120) of the sensors (12) of the second matrix are connected to another common electrically conductive track (200).

8. Method for measuring compressive and flexural force, comprising the following steps: - provide a force measuring system as defined in one of the preceding claims, - simultaneously apply compressive and bending forces to the measuring device, - add or subtract the signals measured by the measuring devices, so as to cancel either the compressive forces or the bending forces, and thus measure, respectively, either the bending forces or the compressive forces applied to the device.

9. Method according to claim 8, wherein the device comprises a first matrix of sensors on the first face (100a) of the substrate (100) and a second matrix of sensors on the second face (100b) of the substrate (100), the first matrix and the second matrix being arranged opposite each other.

10. Method according to one of claims 8 to 9, wherein the sensor(s) (11) of the first face (100a) have a polarization opposite to the polarization of the sensor(s) (12) of the second face (100b), wherein the sensor(s) (11) of the first face (100a) are electrically connected to first charge amplifiers (301), the sensor(s) (12) of the second face (100b) are electrically connected to second charge amplifiers (302), the electrical connections to the first charge amplifiers (301) and the electrical connections to the second charge amplifiers (302) being opposite, the signals from the sensors being added to eliminate the signal of the bending forces and obtain the signal of the compression forces.

11. Method according to claims 8 to 10, in which, on the one hand, the first electrode (110) of each sensor (11) of the first matrix is ​​connected to an individual electrically conductive track (200), itself electrically connected to a charge amplifier, and, on the other hand, in which all the second electrodes (120) of the sensors (11) of the first matrix are connected to a common electrically conductive track (200), electrically connected to the ground of one of the measuring devices, and in which, on the one hand, the first electrode (110) of each sensor (12) of the second matrix is ​​connected to an individual electrically conductive track (200), itself electrically connected to a charge amplifier, and, on the other hand, in that all the second electrodes (120) of the sensors (12) of the second matrix are connected to a common electrically conductive track (200), electrically connected to the ground of one of the measuring devices.

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