CN-116358764-B - Triaxial MEMS force sensor with self-calibration function

CN116358764BCN 116358764 BCN116358764 BCN 116358764BCN-116358764-B

Abstract

The invention discloses a triaxial MEMS force sensor with a self-calibration function, which comprises a glass substrate, a fixed electrode on the upper surface of the glass substrate and a device layer suspended above the glass substrate. The fixed electrode on the upper surface of the glass substrate comprises a fixed interdigital aluminum electrode, a fixed metal electrode, an electrode connecting wire and a self-detection leading-out electrode. The device layer suspended above the glass substrate comprises a device anchor point, four L-shaped piezoelectric driving beams, an electrostatic attraction module, a sensitive driving table and a capacitive triaxial force sensor. The fixed metal electrode is correspondingly arranged with the central mass block of the capacitance type triaxial force sensor, and the electrostatic attraction module is arranged between the piezoelectric driving beam and the sensitive driving platform. The invention suppresses the problem of cross-axis crosstalk, realizes cross-axis and normal triaxial driving, realizes real-time detection of a cross-axis driving capacitor, and realizes switching of a force detection mode and a calibration mode by adjusting an electrostatic attraction module.

Inventors

DONG LINXI
HU MENGYI
Huang Yima
LIU CHAORAN
YANG WEIHUANG
YAN HAIXIA

Assignees

杭州电子科技大学

Dates

Publication Date: 20260512
Application Date: 20230215

Claims (9)

1. The triaxial MEMS force sensor with the self-calibration function is characterized by comprising a glass substrate, a fixed electrode on the upper surface of the glass substrate and a device layer suspended above the glass substrate; The fixed electrode on the upper surface of the glass substrate comprises a fixed interdigital aluminum electrode, a fixed metal electrode, an electrode connecting wire and a self-detection extraction electrode; The device layer suspended above the glass substrate comprises a device anchor point, four L-shaped piezoelectric driving beams, an electrostatic attraction module, a sensitive driving table and a capacitive triaxial force sensor; the fixed interdigital aluminum electrode is correspondingly arranged with the grid-type silicon electrode on the sensitive driving table, the tangential driving capacitor is detected in a differential mode through a variable area method, and a capacitance signal is led out along an electrode connecting line through a self-detection leading-out electrode; The fixed metal electrode is correspondingly arranged with a central mass block of the capacitive triaxial force sensor, the capacitance is detected through a variable-interval detection normal force, and a capacitance signal is led out along an electrode connecting line through a self-detection leading-out electrode; The static attraction fixed comb teeth are fixed on the static attraction anchor points, the static attraction movable comb teeth are connected with the sensitive driving table and positioned at the diagonal position of the sensitive driving table, move along with the sensitive driving table and correspond to the static attraction fixed comb teeth one by one, and the movable attraction block is connected with the sensitive driving table and corresponds to the attraction fixed island; The sensitive driving platform comprises a transverse sensitive unit and a longitudinal sensitive unit; The capacitive triaxial force sensor comprises a limiting block, a U-shaped beam, an inclined beam, a central mass block and a tangential force detection module, wherein the central mass block is connected with the sensitive driving platform through the U-shaped beam and the inclined beam; The capacitive triaxial force sensor tangential force detection module comprises a tangential force detection anchor point, tangential force detection movable comb teeth and tangential force detection fixed comb teeth, wherein the tangential force detection fixed comb teeth are fixed on the tangential force detection anchor point, eight groups of tangential force detection modules are symmetrically distributed around a central mass block, and two groups are arranged on each side.
2. The triaxial MEMS force sensor with self-calibration function according to claim 1, wherein the L-shaped piezoelectric driving beam comprises an L-shaped silicon beam, a driving lower electrode Pt covered on the L-shaped silicon beam, a piezoelectric material PZT covered on the driving lower electrode, and a distributed driving upper electrode Pt covered on the piezoelectric material PZT.
3. The triaxial MEMS force sensor with self-calibration function according to claim 2, wherein one end of each L-shaped piezoelectric driving beam is fixed on a device anchor point, and the other end is connected with a sensitive driving stage.
4. The triaxial MEMS force sensor with self-calibration function according to claim 1, wherein the electrode connection wires and the self-detection extraction electrodes are nineteen pairs in total; each fixed interdigital aluminum electrode is connected with two electrode connecting wires and two self-detection extraction electrodes, so that tangential driving capacitance signals are extracted; A fixed metal electrode is connected with an electrode connecting wire and a self-detection extraction electrode, so that signals of the normal force detection capacitor are extracted; Eight tangential force detection anchor points are connected with eight electrode connecting lines and eight self-detection extraction electrodes, so that signals of the tangential force detection module are extracted; the two electrostatic attraction anchor points are connected with the two electrode connecting wires and the two self-detection leading-out electrodes, so that electrostatic attraction is realized, and the detection mode of the force sensor is switched.
5. The triaxial MEMS force sensor with self-calibration function according to claim 1, wherein a distance between the movable actuation block and the fixed actuation island is smaller than a distance between the electrostatic actuation fixed comb teeth and the electrostatic actuation movable comb teeth.
6. The triaxial MEMS force sensor with self-calibration function according to claim 1, wherein four fixed interdigital aluminum electrodes are used, two fixed interdigital aluminum electrodes in the transverse direction are used as the lower electrode of the transverse driving detection capacitor, and two fixed interdigital aluminum electrodes in the longitudinal direction are used as the lower electrode of the longitudinal driving detection capacitor.
7. The triaxial MEMS force sensor with self-calibration function according to claim 1, wherein the limiting block is thinned by a central mass block, and is located below the U-shaped beam for overload protection during normal force detection, so as to prevent contact of a normal force detection electrode.
8. The triaxial MEMS force sensor with self-calibration function according to claim 1, wherein the lateral sensitive unit is composed of two lateral grid-type silicon electrodes, which are used as the upper electrode of the X-axis driving detection capacitor; the longitudinal sensitive unit consists of two longitudinal grid-type silicon electrodes which are used as an upper electrode of the Y-axis driving detection capacitor.
9. The triaxial MEMS force sensor with self-calibration function according to claim 1, wherein eight areas around the central mass block are connected with the same number of movable comb teeth for detecting tangential force and are in one-to-one correspondence with the fixed detection comb teeth for detecting tangential force, and a gap between the movable comb teeth for electrostatic attraction is larger than a gap between the fixed comb teeth for electrostatic attraction.

Description

Triaxial MEMS force sensor with self-calibration function Technical Field The invention belongs to the field of triaxial force sensors and MEMS self-calibration devices, and particularly relates to a triaxial MEMS force sensor with a self-calibration function. Background The three-axis force sensor can be used for detecting touch sense, is an important medium for the intelligent robot to sense human life, and plays a key role in the fields of medical care, robot industry, wearable devices and the like. The force sensor can be classified into a capacitive type, a piezoelectric type, a piezoresistive type, an electromagnetic type and an optical type according to the principle, wherein the capacitive sensor is widely used due to the advantages of high sensitivity, high resolution, good temperature stability and the like. In general, a capacitive sensor employing differential detection has higher sensitivity than a sensor employing non-differential detection, and differential detection capacitance can be classified into a tilting type capacitance, a gate type capacitance, and a comb type capacitance. The inclined capacitor changes in capacitance through changing the distance, the upper electrode is inclined when being subjected to external force, one corresponding capacitor is reduced, the other capacitor is increased, but the inclined capacitor is usually calculated through a complex integration algorithm at present, the grid type capacitor changes in capacitance through changing the area, the output linearity is higher, the comb type capacitor changes in capacitance through changing the area and the distance, and the comb electrode with specific distribution can reduce cross axis interference. The grid type capacitor and the comb type capacitor are simple in principle, have good performance and are widely applied. At present, the sensor performance is error due to environmental change, process design and other factors, and in order to ensure the accuracy of the measurement result, it is very important to calibrate the sensor regularly. Current calibration techniques require the sensor to be sent to a calibration drive station in the factory to simulate the sensor's operating conditions. However, in practical applications, it is not practical to solder the sensor to the PCB and detach it for calibration. In addition, most of the current researches are to provide calibration functions for the inertial sensor, and few calibration methods for the force sensor are available. Therefore, to save additional calibration costs, it is extremely important to integrate a real-time self-calibration structure for the sensor at the beginning of the design. In the calibration process, the driving table for simulating external excitation is an indispensable structure, and the driving table can be classified into electrostatic driving, electromagnetic driving, piezoelectric driving and the like according to principles. The electrostatic driving is mainly based on the principle of electrostatic force between capacitors, the principle is simple and easy to understand, but the problems of attraction effect, electrostatic plate touch effect and the like exist, the electromagnetic driving is based on the principle that an electrified wire is acted by ampere force in a uniform magnetic field, larger driving moment and offset can be generated, but the electromagnetic driving has the disadvantages of high energy consumption and easy heating, the piezoelectric driving is based on the principle of crystal piezoelectric effect, and when pressure is applied, the piezoelectric material generates deformation and offset, and the mode has the advantages of adjustable range, large-range output, low driving voltage and the like. Disclosure of Invention In order to overcome the defects in the background technology, the invention provides a triaxial MEMS (micro electro mechanical system) force sensor with a self-calibration function. The invention solves the technical problems by adopting the scheme that: a triaxial MEMS force sensor with self-calibration function comprises a glass substrate, a fixed electrode on the upper surface of the glass substrate and a device layer suspended above the glass substrate. The fixed electrode on the upper surface of the glass substrate comprises a fixed interdigital aluminum electrode, a fixed metal electrode, an electrode connecting wire and a self-detection extraction electrode. The device layer suspended above the glass substrate comprises a device anchor point, four L-shaped piezoelectric driving beams, an electrostatic attraction module, a sensitive driving platform and a capacitive triaxial force sensor. The number of the fixed interdigital aluminum electrodes is 4, the 2 transverse fixed interdigital aluminum electrodes are used as lower electrodes of the transverse driving detection capacitor, and the 2 longitudinal fixed interdigital aluminum electrodes are used as lower electrodes of the longitudinal d