Micro-electromechanical capacitive strain sensor

• US 7,380,461 B2
• Filed: 03/09/2007
• Issued: 06/03/2008
• Est. Priority Date: 03/09/2006
• Status: Expired due to Fees

• Current Assignee: Suryakala Majeti
• Original Assignee: Suryakala Majeti
• Inventors: Majeti, Suryakala
• Primary Examiner(s): Lefkowitz; Edward
• Assistant Examiner(s): ROY, PUNAM P
• Application Number:
  US11/684,592
• Publication Number:
  US 20080034883A1
• Time in Patent Office: 452 Days
• Field of Search: 735/041.2, 7350414-50416, 737/77, 737/80, 257/417
• US Class Current: 73/780
• CPC Class Codes: G01B 7/22 using change in capacitance
• CPC Class Codes: G01L 1/148 using semiconductive material, e.g. silicon
• CPC Class Codes: Y10T 29/49103 Strain gauge making
• CPC Class Codes: Y10T 29/49147 Assembling terminal to base

Abstract

A micro-electromechanical capacitive strain sensor. The micro-electromechanical capacitive strain sensor comprises a first bent beam, a second bent beam, and a straight center beam. The first bent beam, second bent beam, and straight center beam are aligned in the X-axis with the straight center beam located between the first and second bent beams. The first bent beam, second bent beam, and straight center beam are disposed between two anchors. The two anchors are aligned in the Y-axis. The first bent beam is bent away from the center beam and the second bent beam is bent towards the center beam to provide a set of differential capacitors with respect to the center beam, wherein the center beam serves as a common reference with respect to the first and second bent beams.

Claims

1. A micro-electromechanical capacitive strain sensor, comprising:

first and second bent beams made of single crystal silicon;

a straight central beam made of single crystal silicon; and

first and second anchors, wherein said first and second beams and said straight central beam are disposed between said first and second anchors,

wherein said straight central beam, first and second bent beams and said anchors form an essentially planar structure, wherein the distance between said first and second anchors is between about 900 μ

m and 1,500 μ

m,

wherein each of said first and second bent beams define first and second opposite end rafter segments and a straight middle collar segment,

wherein said first bent beam is manufactured to be bent away from said center beam and said second bent beam is manufactured to be bent towards said center beam to provide a set of differential capacitors with respect to said center beam, wherein said center beam serves as a common reference with respect to said first and second bent beams such that when said first and second opposite ends of said first, second and center beams are displaced in opposite directions in the X-axis the first bent beam is deflected in the Y-axis direction towards the center beam thereby increasing capacitance and the second bent beam is deflected in the Y-axis direction away from said center beam thereby decreasing capacitance.

2. The micro-electromechanical capacitive strain sensor of claim 1 further comprising a plurality of three-beam structure units arranged in parallel, wherein each three-beam structure unit comprises first and second bent beams and a straight center beam.

3. A micro-electromechanical capacitive strain sensor, comprising:

a first bent beam, a second bent beam, and a straight center beam,

wherein said first, second and center beams are each made of silicon,

wherein said first, second and center beams each define first and second opposite ends,

wherein said central horizontal beam is located between said first and second bent beams,

wherein said first, second and center beams are aligned in the X-axis,

wherein said first, second and center beams do not touch each other,

wherein said first bent beam is bent away from said center beam and said second bent beam is bent towards said center beam to provide a set of differential capacitors with respect to said center beam, wherein said center beam serves as a common reference with respect to said first and second bent beams such that when said first and second opposite ends of said first, second and center beams are displaced in opposite directions in the X-axis the first bent beam is deflected in the Y-axis direction towards the center beam and the second bent beam is deflected in the Y-axis direction away from said center beam; and

a first longitudinal anchor and a second longitudinal anchor, wherein the first and second anchors are positioned in the Y-axis relative to said first and second bent beams, wherein the first anchor is connected to the first opposite ends of the first, second and center beams, and the second anchor is connected to the second opposite ends of the first, second and center beams,

wherein said first and second anchors are made of insulating material and thereby electrically isolate said first, second and center beams from each other.