Oceanographic sensor with in-situ cleaning and bio-fouling prevention system

• US 4,092,858 A
• Filed: 03/11/1977
• Issued: 06/06/1978
• Est. Priority Date: 11/26/1975
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Edgerton, Gene A.
• Primary Examiner(s): Ciarlante, Anthony V.
• Application Number:
  US05/776,578
• Time in Patent Office: 452 Days
• Field of Search: 73/170 A, 340/10, 134/1
• US Class Current: 73/170.29
• CPC Class Codes: G01V 1/38 specially adapted for water-covered areas G01V1/28 takes precedence

Abstract

An oceanographic sensor which allows in-situ bio-fouling prevention and/orleaning of foreign matter from its surface while simultaneously operating in a sensor mode. The sensor mode is fabricated from crystal substance and utilizes the piezoelectric electric effect. Sensing elements are fabricated on either the outside or inside, or both sides, of the core depending upon what measurements need to be taken. When the sensor is submerged and excited by an electrical potential, at or near resonance, the sensor core will vibrate and remove all foreign matter from its surface. The cleaning and bio-fouling prevention is done concurrently with oceanographic parameter measurements made by the sensor. Also, it should be noted that when the transducer is vibrated at or near its resonant frequency at a level below the cavitation threshold, the transducer and sensor system deters all bio-fouling from adhering to the sensor surface. Therefore, the oceanographic sensor device of this invention allows both in-situ cleaning of contaminants and a bio-fouling prevention system for use with submerged transducers.

Claims

1. An oceanographic sensor system having the capability of both self-cleaning and bio-fouling prevention simultaneously while operating in a sensor mode while submerged, for removal of foreign materials thereon and the prevention of fouling thereof, comprising:

a. a transducer substrate element of suitable crystal substance and shape operable to be vibrated at or near a resonant frequency at various energy levels;

b. a plurality of separate sensor means fabricated on surfaces of said transducer substrate element as an integral part thereof;

c. at least two of said sensor means being on opposite sides of said transducer element;

d. said sensor means being electrically connected to sensor readout means;

e. an electrical means for providing an alternating electrical potential to vibrate said transducer element while said sensor means is operating in a sensor mode;

means for connecting any of the sensor means on one side of the transducer element to one side of said electrical means and any of the conductive coatings on the opposite side of said transducer element to the opposite side of said power source for exciting the transducer substrate element to cause vibration thereof at desired frequencies to generate sonic energy which varies in energy intensity from levels which create acoustic streaming forces to intensities which cause cavitation forces to cause removal of any foreign fouling matter on the transducer element and integral sensor means by cavitation of the surrounding water and to prevent fouling due to marine organisms adhering to the sensor surface by acoustic streaming of water adjacent the surface thereof concurrently while oceanographic parameter measurements are being made by said sensor means.

2. A device as in claim 1 wherein said transducer substrate element is a piezoelectric transducer.

3. A device as in claim 1 wherein said transducer substrate element is a magnetostrictive transducer.

4. A device as in claim 1 wherein said transducer is in the shape of a hollow cylinder having sensor means on the inner and outer surfaces thereof.

5. A device as in claim 4 wherein sensor power and readout circuit means are connected across opposite ends of each of said separate sensor means fabricated on exterior surfaces of said transducer substrate element for measuring ocean current and other oceanographic phenomenon.

6. A device as in claim 4 wherein:

a. the interior surface of said hollow cylinder transducer has a single sensor means thereon and the exterior surface has a plurality of separate sensor means positioned about the exterior surface thereof;

b. vibration circuitry, sensor, power and readout circuitry being connected across opposite ends of each of the plurality of separate sensors means positioned about the exterior said surface for simultaneously cleaning, fouling prevention and measuring ocean current pehnomenon.

7. A device as in claim 1 wherein said transducer is made of natural quartz crystal.

8. A device as in claim 1 wherein said transducer is made of synthetic quartz crystal.

9. A device as in claim 1 wherein said transducer is made of barium titanate.

10. A device as in claim 1 wherein said transducer is made of ferroelectric crystal substances.

11. A device as in claim 1 wherein said sensor power and readout circuitry is connected across opposite ends of each of said plurality of sensor means for measuring various ocean characteristics.

12. A device as in claim 1 wherein said separate sensor means are non-corrosive metal films formed on the crystal substrate.

13. A drive as in claim 1 wherein said sensor means are semiconductor coatings.

14. A device as in claim 1 wherein said transducer is operable to be vibrated for cleaning and fouling prevention simultaneously while operating said sensor means for making oceanographic measurements.

15. A device as in claim 1 wherein said means for connecting the sensor means to said electrical means includes switching means which also operates to switch said transducer to electrical heating means.

16. A device as in claim 1 wherein said electrical means includes means for vibrating said transducer at various frequencies which vary from approximately 10 Khz to its resonant frequency at or below the cavitation threshold.

17. A method for self-cleaning oceanographic solid-state sensors in-situ for removal of fouling marine organisms and prevention of fouling thereof while submerged in a body of water and simultaneously operating in a sensing mode, comprising:

a. mounting sensing elements on surfaces of a trasducer substrate such that at least two of the sensing elements are mounted on opposite sides of the transducer substrate and are connected to sensor readout circuitry;

b. while operating in a sensing mode, electrically connecting said at least two sensing elements via switching means to an electrical source for electrically exciting said substrate to vibrate ultrasonically in water to generate sonic energy which varies in energy intensity from levels which create acoustic streaming forces to intensities which cause cavitation forces and thereby loosen and remove foreign and marine matter from the surface of the transducer substrate and the elements mounted thereon and prevent fouling marine organisms from adhering thereon by acoustic streaming of water adjacent the substrate surface.