Air-coupled capacitive micromachining ultrasonic transducer, preparation method and application

A technology of capacitive micromachining and ultrasonic transducers, which is applied in chemical instruments and methods, vacuum evaporation plating, fluids using vibration, etc., can solve problems such as slow detection speed, achieve easy matching, low acoustic impedance, and achieve phase The effect of deflection control

Active Publication Date: 2018-10-26
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] When the air-coupled ultrasonic probe is applied to the non-destructive testing inside the plate, it is gener

Method used

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  • Air-coupled capacitive micromachining ultrasonic transducer, preparation method and application
  • Air-coupled capacitive micromachining ultrasonic transducer, preparation method and application
  • Air-coupled capacitive micromachining ultrasonic transducer, preparation method and application

Examples

Experimental program
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Example Embodiment

[0047] Example 1

[0048] The purpose of the embodiments of the present invention is to provide a capacitive micro-ultrasonic transducer for ultrasonic nondestructive testing applied to air coupling. The transducer is composed of 16 array elements, and each element is composed of multiple sensitive elements, see figure 2 (A).

[0049] The structure of each sensitive element is composed of upper electrode 3, diaphragm 1, cavity 5, and substrate 2 from top to bottom (wherein, substrate 2 is also used as the bottom electrode), see figure 2 (B).

[0050] A cavity 5 is sandwiched between the diaphragm 1 and the substrate 2 to form a capacitor. A DC voltage is pre-loaded between the upper electrode 3 and the lower electrode 2, so that an electrostatic field is formed in the capacitor. The diaphragm 1 acts on the electric field force. Deformation occurs below, thereby forming a pre-tightening force in the diaphragm 1, and the diaphragm 1 is in a stable equilibrium state.

[0051] When a ca...

Example Embodiment

[0053] Example 2

[0054] Combine below figure 1 The solution in Example 1 is further introduced, as detailed in the following description:

[0055] The overall structure of the embodiment of the present invention is composed of two parts of the diaphragm 1 and the base 2. The diaphragm 1 is composed of an upper electrode 3 and a membrane 4.

[0056] In specific implementation, the thin film 4 may be a single crystal silicon thin film. It can also be set according to actual application needs, which is not limited in the embodiment of the present invention.

[0057] Among them, the material of the upper electrode 3 can be gold, aluminum, etc. In the embodiment of the present invention, a single crystal silicon film is used as a component of the diaphragm 1 and the ultrasonic receiving sensor.

[0058] The substrate 2 is composed of a cavity 5 and an insulating layer 6 together. The material of the insulating layer 6 is silicon dioxide, and the cavity 5 is formed by etching of doped l...

Example Embodiment

[0060] Example 3

[0061] See figure 2 (B), an embodiment of the present invention provides a method for preparing a hollow-coupled ultrasonic transducer, which corresponds to the hollow-coupled ultrasonic transducer in Examples 1 and 2, and the method includes:

[0062] The SOI wafer bonding technology used in the embodiment of the present invention is a bulk silicon process. This technology overcomes the disadvantages of using a sacrificial layer, and processes larger cell sizes through deep etching of the silicon base material, with high processing reliability. The process flow of the SOI wafer bonding process is as follows:

[0063] (A) Prepare a silicon substrate 2. The silicon substrate 2 uses doped low-resistance silicon, which can form a parallel plate capacitor with the top electrode;

[0064] (B) Reactive ion etching (RIE) or wet etching is used to etch the cavity 5 of the target depth at the required position, and the depth of the cavity 5 is 5 μm;

[0065] (C) An insulati...

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Abstract

The invention relates to an air-coupled capacitive micromachining ultrasonic transducer, a preparation method and application. A transducer array comprises 16 array elements; each array element is formed by multiple sensing units; each sensing unit is structurally formed by an upper electrode 1, a vibrating diaphragm 2, a cavity 3 and a base 5 sequentially from top to bottom; and each base is usedas a lower electrode. The working frequency of the designed transducer is 100kHz to 2MHz. The transducer array is manufactured based on an SOI bonding process; each vibrating diaphragm is made of monocrystalline silicon; each upper electrode is gold or aluminum; an insulating layer 4 is silicon dioxide or silicon nitride; and the array elements of the transducer are divided through etching the low-resistance-silicon bases to form grooves, so that the array with the multiple array elements is formed. According to the air-coupled ultrasonic transducer, an ultrasonic wave in a metal plate or a composite plate is excited through an air coupling manner and is used for nondestructively detecting internal defects of the plate. The transducer is matched with a phased array system, and pulse drivesignals of the array elements are delay-controlled, so that the phase-controlled deflection and the focusing of an acoustic beam are adjusted, and the freedom degree of detecting is increased.

Description

technical field [0001] The invention relates to the field of ultrasonic transducers, in particular to an air-coupled capacitive micro-processed ultrasonic transducer, a preparation method and an application. Background technique [0002] In recent years, ultrasonic testing technology has been widely used in the field of non-destructive testing. The relatively mature testing methods mainly use liquid immersion method or contact method using coupling agent to reduce the energy loss of ultrasonic in the air, but this limits its application. Non-contact ultrasonic non-destructive testing technology has the characteristics of non-contact, no need for water immersion or coupling agent, which makes up for this deficiency well, and is suitable for composite material testing, material property evaluation, food industry, etc. field. [0003] The non-contact detection method based on the air-coupled ultrasonic transducer can be used for the detection of metals, polymers or composite m...

Claims

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Application Information

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IPC IPC(8): B06B1/06C30B33/00C30B33/02C30B33/08C23C14/16
CPCB06B1/0629C23C14/16C30B33/005C30B33/02C30B33/08
Inventor 张慧李志郑冠儒刘玉振于露
Owner TIANJIN UNIV
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