Micro-electro-mechanical-systems based acoustic emission sensors
OwnerDidem OZEVIN, Hossain SABOONCHIinventors
Life of this patent
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Abstract
Acoustic emission (AE) microelectromechanical system (MEMS) transducers of the present disclosure utilize a spring-mass system and a capacitance-change transduction principle. The transducers include a dielectric layer between a fixed electrode and a moveable metal layer to reduce the stiction failure. The moveable metal layer may displace in a particular direction when interacting with elastic waves. Additionally, the moveable metal layer may be formed using an electroplating technique. In some embodiments, multiple spring-mass unit cells may be combined in parallel to increase the sensitivity of the transducer.
Claims27
A method of manufacturing acoustic emission (AE) transducers comprising:
- depositing a first insulating layer on a substrate, wherein the substrate comprises an n-type silicon wafer;
- depositing a second insulating layer on the first insulating layer;
- forming an electrode on the second insulating layer;
- depositing a third insulating layer on the electrode;
- forming a sacrificial layer on the third insulating layer;
- forming a metal component on the sacrificial layer;
- and
- removing the sacrificial layer, wherein the removing provides a separation between the metal component and the third insulating layer.
An apparatus comprising:
- a substrate comprising a wafer;
- a first insulating layer having a first side of the first insulating layer coupled to a side of the substrate, wherein the first insulating layer comprises the first side and a second side;
- a second insulating layer having a first side of the second insulating layer coupled to the second side of the first insulating layer, wherein the second insulating layer comprises the first side and a second side;
- a fixed electrode coupled to the second side of the second insulating layer;
- a third insulating layer covering the fixed electrode;
- and
- a metal spring connected to at least a portion of the third insulating layer, wherein the metal spring is configured to displace in at least one degree of freedom in response to an acoustic emission wave interacting with the apparatus.
An acoustic emission (AE) transducer comprising:
- a plurality of unit cells, wherein each unit cell comprises:
- a substrate comprising a wafer;
- a first insulating layer having a first side of the first insulating layer coupled to a side of the substrate, wherein the first insulating layer comprises the first side and a second side;
- a second insulating layer having a first side of the second insulating layer coupled to the second side of the first insulating layer, wherein the second insulating layer comprises the first side and a second side;
- a fixed electrode coupled to the second side of the second insulating layer;
- a third insulating layer covering the fixed electrode;
- and
- a metal spring connected to at least a portion of the third insulating layer, wherein the metal spring is configured to displace in at least one degree of freedom in response to an acoustic emission wave interacting with the AE transducer.
A method of measuring acoustic emission waves comprising:
- measuring a first capacitance value from a transducer, wherein the first capacitance value corresponds to a capacitance between a fixed electrode and a metal spring, wherein the fixed electrode is covered with an insulator, wherein the transducer includes an air gap between the insulator and the metal spring, and wherein the first capacitance value corresponds to the metal spring at a rest position;
- receiving, at the transducer, an acoustic emission wave, wherein the acoustic emission wave causes the metal spring to displace in at least one degree of freedom;
- measuring a second capacitance value from the transducer, wherein the second capacitance value corresponds to the metal spring at a displaced position;
- determining a capacitance change between the second capacitance value and the first capacitance value;
- and
- based on the capacitance change, determining a magnitude of the acoustic emission wave.
Dependencies are inferred from the claim text.