Mechanical deformation amount sensor

• US 20040012062A1
• Filed: 05/29/2003
• Published: 01/22/2004
• Est. Priority Date: 07/19/2002
• Status: Active Grant

• Current Assignee: Panasonic Electric Works Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Works Ltd (Panasonic Holdings Corporation)
• Inventors: Arakawa, Masao, Sakai, Jun, Miyajima, Hisakazu, Yabuta, Akira
• Granted Patent: US 6,848,320 B2
• Time in Patent Office: Days
• US Class Current: 257/419
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2203/0118 Cantilevers
• CPC Class Codes: B81B 2203/0127 Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
• CPC Class Codes: B81B 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00
• CPC Class Codes: B81B 3/0086 Electrical characteristics, e.g. reducing driving voltage, improving resistance to peak voltage
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G01L 9/0055 bonded on a diaphragm
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges
• CPC Class Codes: G01P 2015/0828 the mass being of the paddle type being suspended at one of its longitudinal ends
• CPC Class Codes: Y10S 977/956 Of mechanical property

Abstract

A mechanical deformation amount sensor includes a sensor structure which is formed by a semiconductor substrate or an insulating substrate and integrally includes a deformation portion deformable, when a physical quantity to be detected is applied to the sensor structure, due to the physical quantity and a support portion for supporting the deformation portion, a carbon nanotube resistance element which is provided on the deformation portion so as to be mechanically deformed in response to deformation of the deformation portion and a wiring pattern which is formed in a pattern on the sensor structure so as to be connected to the carbon nanotube resistance element. By applying a voltage to the carbon nanotube resistance element via the wiring pattern, a change of electrical conductivity of the carbon nanotube resistance element upon mechanical deformation of the carbon nanotube resistance element is fetched as an electrical signal.

Claims

1. A mechanical deformation amount sensor comprising:

a sensor structure which is formed by a semiconductor substrate or an insulating substrate and integrally includes a deformation portion deformable, when a physical quantity to be detected is applied to the sensor structure, due to the physical quantity and a support portion for supporting the deformation portion;

a carbon nanotube resistance element which is provided on the deformation portion so as to be mechanically deformed in response to deformation of the deformation portion; and

a wiring pattern which is formed in a pattern on the sensor structure so as to be connected to the carbon nanotube resistance element;

wherein a voltage is applied to the carbon nanotube resistance element via the wiring pattern such that a change of electrical conductivity of the carbon nanotube resistance element upon mechanical deformation of the carbon nanotube resistance element is fetched as an electrical signal.

2. The mechanical deformation amount sensor as claimed in claim 1, wherein the deformation portion is so formed as to be thinner than the support portion and is deformed so as to be deflected elastically when the physical quantity is applied to the sensor structure.

3. The mechanical deformation amount sensor as claimed in claim 1, wherein the sensor structure is a micro-electro-mechanical systems (MEMS) sensor chip formed by a silicon substrate.

4. The mechanical deformation amount sensor as claimed in claim 3, wherein the carbon nanotube resistance element is provided on the deformation portion through an insulating film.

5. The mechanical deformation amount sensor as claimed in claim 1, wherein the carbon nanotube resistance element is disposed such that a longitudinal direction of the carbon nanotube resistance element is orthogonal to a direction of deformation of the deformation portion.

6. The mechanical deformation amount sensor as claimed in claim 1, wherein the wiring pattern has, at its end portion connected to the carbon nanotube resistance element, a metal electrode such that each of opposite end portions of the carbon nanotube resistance element is covered by the metal electrode.

7. The mechanical deformation amount sensor as claimed in claim 1, wherein a surface of the carbon nanotube resistance element is covered by an insulating coating film.

8. The mechanical deformation amount sensor as claimed in claim 7, wherein the insulating coating film is a passivation film provided on a surface of the sensor structure.

9. The mechanical deformation amount sensor as claimed in claim 1, wherein a step portion is formed on the deformation portion and the carbon nanotube resistance element is provided on the deformation portion so as to stride over the step portion.

10. The mechanical deformation amount sensor as claimed in claim 1, wherein a reference resistance element is provided at a portion of the sensor structure other than the deformation portion and the reference resistance element and the carbon nanotube resistance element are connected to each other by the wiring pattern so as to form a bridge circuit.

11. The mechanical deformation amount sensor as claimed in claim 10, wherein the reference resistance element is formed by a carbon nanotube.

12. The mechanical deformation amount sensor as claimed in claim 1, wherein the carbon nanotube resistance element is formed by a single-wall carbon nanotube.

13. The mechanical deformation amount sensor as claimed in claim 12, wherein the carbon nanotube resistance element is formed by a plurality of the single-wall carbon nanotubes which are arranged side by side and are electrically connected to each other in parallel.

14. The mechanical deformation amount sensor as claimed in claim 1, which acts an acceleration sensor having an acceleration as the physical quantity to be detected;

wherein the sensor structure further includes a weight portion integrally coupled with the support portion by the deformation portion.

15. The mechanical deformation amount sensor as claimed in claim 1, which acts a pressure sensor having a fluid pressure as the physical quantity to be detected;

wherein in the sensor structure, the support portion is formed in a shape of a frame and the deformation portion is formed by a diaphragm occupying an inside space of the frame of the support portion such that the diaphragm bears the fluid pressure.

16. The mechanical deformation amount sensor as claimed in claim 15, wherein the carbon nanotube resistance element is provided at a peripheral edge portion of the diaphragm.