Quantum tunneling cantilever accelerometer

• US 4,638,669 A
• Filed: 05/07/1985
• Issued: 01/27/1987
• Est. Priority Date: 05/07/1985
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Chou, Stephen Y.
• Primary Examiner(s): Levy, Stewart J.
• Assistant Examiner(s): Chapman, Jr., John E.
• Application Number:
  US06/731,715
• Time in Patent Office: 630 Days
• Field of Search: 73/517 R, 73/862.64, 73/862.68
• US Class Current: 73/514.25
• CPC Class Codes: G01P 15/0894 by non-contact electron transfer, i.e. electron tunneling

Abstract

A highly sensitive accelerometer is disclosed in which the current is measured across a pair of electrodes resulting from voltage pulses from a pulse generator. The electrodes are located within a vacuum chamber. One of the electrodes is cantilevered and has its free end suspended over the other fixed electrode. The amount of current through the vacuum gap between the electrodes is determinative of acceleration since the current is an exponential function of the distance between the electrodes and the distance between the electrodes changes linearly with acceleration.

Claims

1. An accelerometer comprising;

a vacuum chamber;

an electrode fixed in position within said vacuum chamber;

a cantilevered electrode located within said vacuum chamber having a fixed end and a free end, the free end of said cantilevered electrode being aligned with and separated from said fixed electrode such that acceleration of said accelerometer causes the free end of said cantilevered electrode to move towards said fixed electrode;

means for providing a voltage pulse across said fixed electrode and said cantilevered electrode; and

means for measuring the current flow caused by said voltage pulse, the amount of acceleration being determinable from the current measurement.

2. The accelerometer of claim 1 wherein the current flow caused by said voltage pulse is substantially composed of tunneling current.

3. The accelerometer of claim 1 wherein said current measuring means comprises a pulse ammeter.

4. The accelerometer of claim 1 further comprising an insulation layer covering said fixed electrode so that said cantilevered electrode is prevented from touching said fixed electrode.

5. A highly sensitive accelerometer comprising;

a vacuum chamber;

an electrical insulation member located within said vacuum chamber;

an electrode fixed on said insulation member;

a cantilevered electrode having one end fixed on said insulation member and a free end suspended over said fixed electrode;

a pulse generator which provides a voltage pulse across said fixed electrode and said cantilevered electrode; and

means for measuring the current across the vacuum gap between said fixed electrode and said cantilevered electrode.

6. The accelerometer of claim 5 wherein the current flow caused by said voltage pulse is substantially composed of tunneling current.

7. The accelerometer of claim 5 wherein said current measuring means comprises a pulse ammeter.

8. The accelerometer of claim 5 further comprising an insulation layer covering said fixed electrode so that said cantilevered electrode is prevented from touching said fixed electrode.

9. A method for making highly sensitlive acceleration measurements comprising;

providing a vacuum chamber;

generating a voltage pulse across a pair of electrodes located within the vacuum chamber, one electrode in cantilever suspension over the other electrode such that the distance between said electrodes provides a measure of acceleration; and

measuring the current flow caused by said voltage pulse, said current measurement providing a measure of the distance between the electrodes and hence the acceleration.

10. The method of claim 9 wherein the current flow caused by said voltage pulse is substantially composed of tunneling current.