High performance strain sensor - silicon based resonant strain sensor

If a worker wants to do something good, he must first sharpen his tools. In today's globalization, patents are not only a means of protection for innovation, but have become a weapon in the commercial battlefield. Mames Consulting has created a patent operation platform for MEMS, sensors and IoT, integrated intellectual property resources in the entire industry chain, and actively promoted the protection and effective use of intellectual property. A strain gauge, also known as a strain gauge, is a commonly used sensor that utilizes the piezoresistive properties of an elastic material (metal, alloy, semiconductor, or cermet) to detect the positive strain and shear strain of a structure under test. Widely used in structural health monitoring, covering applications such as civil engineering, machinery, aerospace, medical and wearable systems. Compared with the traditional strain gauge, the silicon-based resonant strain sensor has the characteristics of high sensitivity, small temperature drift, quasi-digital output, strong anti-interference ability, etc. It is a kind of high-performance strain sensor. Silicon-based resonant strain sensors generally use a double-ended fixed-end tuning fork (DETF) resonant sensor. A high quality factor (Q value) is obtained by connecting two double-ended fixed beams in parallel and inverting the vibration of the two beams to form a tuning fork structure. At present, the main problem of the silicon-based resonant strain sensor is that the silicon micro-mechanical structure is greatly affected by the air damping, and it is difficult to obtain a high Q value under normal pressure, and vacuum packaging must be used, and the currently mature micro-mechanical vacuum Packaging techniques typically require high temperature processes in excess of 400 degrees or require the use of low permeability packaging materials in combination with getters, which are less compatible with silicon based resonant strain sensing structures. An H-type resonant strain-sensitive structure is used in the high-precision resonant pressure sensor developed by Yokogawa Electric Corporation of Japan. The structure adopts a homogeneous H-beam, and the four arms of the H-beam are vibrated by electromagnetic driving, and the vibration frequency changes with stress by electromagnetic detection. Since the structure is a homogeneous silicon structure and there is no metal lead, vacuum encapsulation can be realized by a high temperature silicon epitaxial process. However, the structure must use electromagnetic driving and electromagnetic detection. When used as a strain sensor, the electromagnet is difficult to package. [Recommended Invention Patent] "Resonant Strain Sensor of Coupling Resonance" [Disclosure] In view of the above disadvantages of the prior art, the present invention provides a resonant strain sensor coupled with resonance to realize a high temperature process vacuum package High-Q, high-resolution, high-sensitivity, long-term stability, piezoresistive detection resonant strain sensor.

The three-dimensional schematic diagram of the structure of the coupled-type resonant strain sensor of the present invention comprises: two sensitive beams, the two ends of each sensitive beam are fixedly supported; the detecting beam is connected to the above two Root between sensitive beams. Among them, the sensitive beam works on the stress-sensitive transverse vibration mode, and the detection beam works on the longitudinal vibration mode with significant overall piezoresistive effect. The transverse vibration mode of the sensitive beam is approximately equal to the resonant frequency of the longitudinal vibration mode of the detection beam. The beam and the detecting beam form a coupling resonance, and the external driving causes the whole structure to vibrate at the coupled resonant frequency. The stress in the sensitive beam changes the resonant frequency of the sensitive beam, and the coupled resonant frequency of the entire structure changes accordingly, and the piezoresistive effect of the detecting beam is measured. By coupling the resonant frequency, the stress value can be measured and the strain calculated. The coupled resonant resonant strain sensor of the present invention can be made of a homogeneous silicon material, and does not need to be fabricated with metal leads, and is compatible with a high temperature vacuum packaging process. The resonant structure can be driven by electrostatic driving, electrothermal driving and electromagnetic driving. A variety of methods, using piezoresistive testing. Therefore, the resonant resonant strain sensor of the present invention has the advantages of high-temperature process vacuum packaging, high Q value, high resolution, high sensitivity, long-term stability, and the like, and has wide application prospects in the field of stress detection. [Related patents] "Resonant strain structure, strain sensor and preparation method based on range expansion"