# US 8,770,031 B2 · Capacitive acoustic inspection apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,770,031 B2 - Document ID: US8770031B2 - Status: Granted - Kind: B2 - Application number: 11/839,118 - Filed: 2007-08-15 - Published: 2009-02-19 - Granted: 2014-07-08 - Earliest claimed: 2007-08-15 - Assignees: The Boeing Company - Applicants: Steven Kenneth Brady - Inventors: Steven Kenneth Brady - Web page: https://patentgrep.com/patent/US8770031B2 ## CPC - G01N 29/2406: {Electrostatic or capacitive probes, e.g. electret or cMUT-probes} - G01N 29/2412: {using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]; (investigating the presence of flaws using eddy currents G01N27/90, magnetostrictive transducers B06B1/08, measuring magnetostrictive properties G01R33/18)} - G01N 2291/0231: Composite or layered materials - G01N 2291/2694: Wings or other aircraft parts - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract A method and apparatus for non-destructive testing. An embodiment of the present disclosure provides a non-destructive inspection system comprising a capacitive acoustic transducer and a control unit connected to the capacitive transducer. ## Claims ### Claim 1 A non-destructive inspection system comprising: a transducer comprising a capacitor; and a control unit connected to the transducer and configured to charge the capacitor from a power source to cause an electric field to be produced by the capacitor, to send a command to cause an acoustic source to generate an acoustic wave in a test material, and to detect changes in the electric field after sending the command when the capacitor is positioned such that the electric field extends into the test material. ### Claim 2 (depends on 1) The non-destructive inspection system of claim 1, wherein the control unit is configured to isolate the capacitor from the power source after a charge has built up to a selected amount and while detecting the changes in the electric field after sending the command. ### Claim 3 (depends on 2) The non-destructive inspection system of claim 2, wherein the test material is not a part of the capacitor and the control unit is configured to detect the changes in the electric field generated by the capacitor in response to the acoustic wave propagating in the test material. ### Claim 4 (depends on 3) The non-destructive inspection system of claim 3, wherein the transducer generates the acoustic wave. ### Claim 5 (depends on 1) The non-destructive inspection system of claim 1, wherein the control unit comprises a switch connected to the capacitor and the power source. ### Claim 6 (depends on 5) The non-destructive inspection system of claim 5, wherein the switch is configured to apply power to the capacitor when in a closed state to charge the capacitor to generate the electric field and to isolate the capacitor from the power source when in an open state. ### Claim 7 (depends on 5) The non-destructive inspection system of claim 5, wherein the control unit comprises an oscilloscope. ### Claim 8 (depends on 5) The non-destructive inspection system of claim 5, wherein the transducer comprises the capacitor mounted in a housing. ### Claim 9 (depends on 8) The non-destructive inspection system of claim 8, wherein the housing further comprises the switch. ### Claim 10 (depends on 8) The non-destructive inspection system of claim 8, wherein the capacitor is a surface capacitor. ### Claim 11 (depends on 8) The non-destructive inspection system of claim 8, wherein the capacitor comprises a plurality of concentric rings. ### Claim 12 (depends on 8) The non-destructive inspection system of claim 8, wherein the capacitor has a serpentine structure with interlaced fingers. ### Claim 13 A method for testing a sample, the method comprising: supplying power to a capacitor to form a charged capacitor producing an electric field; positioning the capacitor such that the electric field extends into the sample; sending an acoustic wave into the sample; and detecting a response to the acoustic wave by detecting changes in the electric field produced by the charged capacitor in response to the acoustic wave in the sample. ### Claim 14 (depends on 13) The method of claim 13 further comprising: isolating the charged capacitor from the power to form an isolated charged capacitor. ### Claim 15 (depends on 14) The method of claim 14, wherein the isolating step comprises: isolating the charged capacitor from the power by opening a switch connecting the capacitor to a power source supplying the power to form the isolated charged capacitor. ### Claim 16 (depends on 13) The method of claim 13, wherein the sending step comprises: changing a voltage across the capacitor to generate the acoustic wave. ### Claim 17 (depends on 13) The method of claim 13 further comprising: displaying the response on a display device. ### Claim 18 (depends on 13) The method of claim 13 further comprising: displaying the response on an oscilloscope. ### Claim 19 (depends on 13) The method of claim 13, wherein the sample is one of a dielectric material, a composite material, or a conducting material. ### Claim 20 (depends on 13) The method of claim 13, wherein the capacitor is mounted in a housing.