Surface acoustic wave-based sensing and actuation of contamination

• US 10,600,438 B2
• Filed: 03/29/2019
• Issued: 03/24/2020
• Est. Priority Date: 04/18/2018
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Ramakrishnan, Narayanan
• Primary Examiner(s): Hindi, Nabil Z
• Application Number:
  US16/369,297
• Publication Number:
  US 20190325904A1
• Time in Patent Office: 361 Days
• Field of Search: 360 75, 360 71, 360 9712, 720671, 134184
• CPC Class Codes: G11B 5/6058 using piezoelectric means
• CPC Class Codes: G11B 5/6076 Detecting head-disk contact
• CPC Class Codes: G11B 5/6082 Design of the air bearing surface
• CPC Class Codes: H02N 2/08 using travelling waves , i.e. Rayleigh surface waves

Abstract

A method includes producing a first surface acoustic wave (SAW) on a magnetic head slider using a first interdigitated transducer (IDT), wherein the SAW has a first set of wave characteristics. The method also includes receiving the first SAW at a second IDT on the magnetic head slider. The method also includes analyzing the SAW for a second set of wave characteristics. The method also includes determining, based on the analyzing, that a substance having at least one characteristic is located in a path of the SAW on the magnetic head slider.

Claims

1. A method, comprising:

producing a first surface acoustic wave (SAW) on a magnetic head slider using a first interdigitated transducer (IDT), wherein the SAW has a first set of wave characteristics;

receiving the first SAW at a second IDT on the magnetic head slider;

analyzing the SAW for a second set of wave characteristics; and

determining, based on the analyzing, that a substance having at least one characteristic is located in a path of the SAW on the magnetic head slider.

2. The method of claim 1, further comprising:

producing a second SAW on the magnetic head slider using the first IDT, wherein the second SAW is configured to actuate the substance based on the at least one characteristic of the substance.

3. The method of claim 1, wherein the first set of wave characteristics includes:

a first amplitude, a first velocity, a first wavelength, a first phase, and a first direction of propagation.

4. The method of claim 1, wherein the second set of wave characteristics includes:

a time delay, a second amplitude, a second velocity, a second wavelength, a second phase, and a second direction of propagation.

5. The method of claim 1, wherein the first SAW is used for sensing the substance, and the second SAW is used for actuating the substance.

6. The method of claim 1, wherein the substance is a contaminant.

7. The method of claim 1, wherein the first SAW is produced on a trailing edge of the magnetic head slider.

8. A head slider apparatus for use in a hard-disk drive, comprising:

a controller in communication with a first interdigitated transducer (IDT) and a second IDT;

a leading edge, a trailing edge, and an air bearing surface;

the first IDT being located on the trailing edge and having a first interdigitated spacing configured to interface with a piezoelectric substrate to create a first surface acoustic wave (SAW) having an first wavelength and an first amplitude;

the second IDT configured to receive the first SAW created by the first interdigitated transducer, the received first SAW having a second wavelength and second amplitude; and

wherein the controller is configured to analyze the received first SAW by comparing the second wavelength to the first wavelength and the second amplitude to the first amplitude, to determine whether a contaminant is located on the trailing edge.

9. The head slider apparatus of claim 8, wherein if the controller determines that a contaminant is located on the trailing edge, then the controller is configured to cause the first IDT to interface with the piezoelectric substrate to create a second SAW, and wherein the second SAW is configured to actuate the contaminant.

10. The head slider apparatus of claim 9, wherein the second SAW is configured to actuate the contaminant by having a contact angle and power at a time of SAW incidence with the contaminant.

11. The head slider apparatus of claim 8, further comprising:

an acoustic reflector configured to reflect the first SAW from the first IDT to the second IDT.

12. The head slider apparatus of claim 8, wherein the first IDT and the second IDT are the same IDT.

13. The head slider apparatus of claim 8, wherein if the controller determines that a contaminant is located on the air bearing surface, then the controller is configured to cause the first IDT to interface with the piezoelectric substrate to create a second SAW, wherein the second SAW is configured to actuate the contaminant.

14. A head slider apparatus for use in a hard disk drive, comprising:

a controller in communication with a first interdigitated transducer (IDT) and a second IDT;

a leading edge, a trailing edge, and an air bearing surface;

the first IDT being located on the air bearing surface and having a first interdigitated spacing configured to interface with a piezoelectric substrate to create a first surface acoustic wave (SAW) having an first wavelength and an first amplitude;

the second IDT configured to receive the first SAW created by the first interdigitated transducer, the received first SAW having a second wavelength and second amplitude; and

wherein the controller is configured to analyze the received first SAW by comparing the second wavelength to the first wavelength and the second amplitude to the first amplitude, to determine whether a contaminant is located on the air bearing surface.

15. The head slider apparatus of claim 14, wherein if the controller determines that a contaminant is located on the air bearing surface, then the controller is configured to cause the first IDT to interface with the piezoelectric substrate to create a second SAW, wherein the second SAW is configured to actuate the contaminant.

16. A method, comprising:

receiving a first set of wave characteristics;

determining, based on the first set of wave characteristics, that a substance having at least one characteristic is located on a trailing edge surface of a magnetic head slider; and

producing a first surface acoustic wave (SAW) on the trailing edge surface of the magnetic head slider using a first interdigitated transducer (IDT), based on the first set of wave characteristics such that the substance is actuated.

17. The method of claim 16, wherein the first set of wave characteristics is received at the first IDT.

18. The method of claim 16, wherein the first SAW has a second set of wave characteristics, and wherein the first SAW is used for actuating the substance.

19. The method of claim 16, wherein a second SAW comprises the first set of wave characteristics, and wherein the second SAW is used for sensing the substance.

20. The method of claim 16, wherein the first set of wave characteristics includes:

a first amplitude, a first velocity, a first wavelength, a first phase, and a first direction of propagation.