Electromechanical transducer

• US 5,780,727 A
• Filed: 03/05/1997
• Issued: 07/14/1998
• Est. Priority Date: 09/12/1994
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Gimzewski, James K., Welland, Mark E., Schlittler, Rato R.
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): LARKIN, DANIEL SEAN
• Application Number:
  US08/793,788
• Time in Patent Office: 496 Days
• Field of Search: 73/105, 73/514.21, 73/514.22, 73/514.23, 73/514.34, 73/514.36, 73/514.37, 73/514.38, 250/306, 257/414-418
• US Class Current: 73/105
• CPC Class Codes: B82Y 35/00 Methods or apparatus for measurement or analysis of nanostructures
• CPC Class Codes: G01H 11/06 by electric means
• CPC Class Codes: G01K 5/72 with electric transmission means for final indication
• CPC Class Codes: G01L 1/16 using properties of piezoelectric devices
• CPC Class Codes: G01Q 20/04 Self-detecting probes, i.e. wherein the probe itself generates a signal representative of its position, e.g. piezoelectric gauge
• CPC Class Codes: G01Q 70/14 Particular materials
• CPC Class Codes: Y10S 977/721 On a silicon substrate
• CPC Class Codes: Y10S 977/837 Piezoelectric property of nanomaterial
• CPC Class Codes: Y10S 977/849 with scanning probe
• CPC Class Codes: Y10S 977/851 Particular movement or positioning of scanning tip
• CPC Class Codes: Y10S 977/863 Atomic force probe

Abstract

A field effect transistor and a piezoelectric sensor are positioned between layers of silicon and aluminum to function as a bimetallic electromechanical transducer. The transducer can be used in atomic force microscopy or as an actuator, a chemical sensor, or an oscillator.

Claims

1. Electromechanical transducer comprising;

at least one flexible element;

voltage generating means for responding to deflections of said flexible element; and

an amplifying circuit which with the voltage generating means is incorporated in said electromechanical transducer with said flexible element as a unitary structure, said amplifying circuit means having at least one field-effect transistor with a gate electrode operable by said voltage generating means for measuring deflections of said flexible element and having protection means against breakthrough voltage.

2. Electromechanical transducer in accordance with claim 1, wherein the voltage generating means comprises piezoelectric material.

3. Electromechanical transducer in accordance with claim 2, wherein the piezoelectric material has a multimorphous structure.

4. Electromechanical transducer in accordance with claim 1, wherein the flexible element further comprises at least two metallic layers, having different thermal expansion coefficients, with the voltage generating means and the amplifying circuit sandwiched therebetween.

5. Electromechanical transducer in accordance with claim 4, wherein the flexible element is covered by a chemically active or absorbing layer.

6. An electrical transducer comprising:

a first silicon flexible member;

a field effect transistor having gate, source, and drain electrodes formed in layers on said flexible member;

a piezoelectric material formed on the gate of the field effect transistor to sense flexing of the first flexible member;

a second aluminum flexible member with a different coefficient of expansion than the first flexible member, said second flexible member covering the piezoelectric material so that field effect transistor and the piezoelectric material are sandwiched between the first and second flexible elements to form an integral unit of the mentioned elements; and

leads extending from the cate, source, and drain electrodes for supplying electrical energy to the field effect transistor and sensing electrical responses of the field effect transistor to the flexing of the metallic elements.

7. The electrical transducer of claim 6 wherein said piezoelectric material has a multimorphous structure.

8. Electromechanical transducer comprising;

at least one flexible element covered by a chemically active or absorbing layer;

voltage generating means for responding to deflections of said flexible element;

an amplifying circuit which with the voltage generating means is incorporated in said electromechanical transducer with said flexible element as a unitary structure, said amplifying circuit means having at least one field-effect transistor with a gate electrode operable by said voltage generating means for measuring deflections of said flexible element; and

at least two metallic layers in said flexible element, said two metallic layers having different thermal expansion coefficients and having the voltage generating means and the amplifying circuit sandwiched therebetween.

9. Electromechanical transducer in accordance with claim 8, wherein the voltage generating means comprises piezoelectric material.

10. Electromechanical transducer in accordance with claim 9, wherein the piezoelectric material has a multimorphous structure.

11. Electromechanical transducer in accordance with claim 8, wherein the transistor further comprises protection means against break-through voltage.

12. An electrical transducer comprising:

a body of the electrical transducer;

a first flexible member extending out from the body of the electrical transducer;

a field effect transistor having gate source, and drain electrodes and an insulating layer between the gate, source, and drain electrodes formed in layers on said flexible member;

a piezoelectric material formed on the gate of the field effect transistor to sense flexing of the first flexible member, and

a second flexible member covering the piezoelectric material so that field effect transistor including the gate, drain, and source electrodes and the piezo electric material are sandwiched between the first and second flexible elements to form an integral cantilever unit of the mentioned elements that extends out from said body.

13. The electrical transducer of claim 12 wherein the first and second flexible members are metallic with different coefficients of thermal expansion to provide a bimetal effect to bend the cantilever unit in response to temperature changes to produce a voltage from the transducer.

14. The electrical transducer of claim 12 wherein one of said flexible members is silicon and the other is aluminum.

15. The electrical transducer of claim 13 including a chemically active or absorbing layer which generates heat over the second flexible member.

16. The electrical transducer of claim 12 wherein said electrical transducer is a microscope probe.