Contact type micro piezoresistive shear-stress sensor

• US 6,877,385 B2
• Filed: 10/22/2001
• Issued: 04/12/2005
• Est. Priority Date: 11/16/2000
• Status: Expired due to Fees

• Current Assignee: National Science Council
• Original Assignee: National Science Council
• Inventors: Chen, Gin-Shin, Yang, Chung-Hsien, Ho, Jyh-Jier, Hsieh, Ming-Chun, Ju, Ming-Shanng, Ting, Shyh-Fann, Fang, Yean-Kuen
• Primary Examiner(s): NOORI, MAX H
• Application Number:
  US10/085,256
• Publication Number:
  US 20020174727A1
• Time in Patent Office: 1,268 Days
• Field of Search: 737/60, 737/77, 737/74, 737/81, 738/41
• US Class Current: 73/777
• CPC Class Codes: A61B 2562/028 Microscale sensors, e.g. electromechanical sensors [MEMS]
• CPC Class Codes: A61B 2562/12 Manufacturing methods specially adapted for producing sensors for in-vivo measurements
• CPC Class Codes: A61B 5/103 Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes A61B5/08 takes precedence; measuring aids for tailors A41H1/00; measuring instruments specially adapted for dentistry A61C19/04
• CPC Class Codes: G01L 1/18 using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material

Abstract

There is disclosed a semiconductor sensor for measuring the contact shear stress distribution between the socket of an above-knee (AK) prostheses and the soft tissue of an amputee'"'"'s stump. The sensor is fabricated by the micro-electro-mechanical system (MEMS) technology, and its main sensing part is 2-X shaped with a flange structure. The sensor is prepared by anisotropic wet etching of bulk silicon in KOH solution and a square flange above the sensing diaphragm is formed through surface micromachining of deposited SiO₂ thin film. This invention has the following characteristics: piezo-resistivity of the monolithic silicon will be utilized to convert shear deformation of the sensor into an electrical signal and a micro sensor which can measure the shear force vector acting on the sensing flange.

Claims

1. A contact-type micro piezoresistive shear-stress sensor comprising:

a) a silicon substrate;

b) a sensing diaphragm formed into etched cavities at preset locations on the silicon substrate and having a substantially square shape;

c) a flange framed by means of etching technology at the center of said sensing diaphragm;

d) two X-shaped piezoresistors implanted at the center of adjacent longitudinal sides of said sensing diaphragm between the respective side and the center of said sensing diaphragm; and

e) a protective membrane of semi-conductor protective material formed on said sensing diaphragm.

2. The contact-type micro piezoresistive sheer-stress sensor as defined in claim 1, wherein said flange is formed of the same material as said protective membrane.

3. The contact-type micro piezoresistive sheer-stress sensor as defined in claim 2, wherein said protective membrane and said flange are formed of SiO₂ or Si₃N₄.

4. The contact-type micro piezoresistive sheer-stress sensor as defined in claim 1, wherein said silicon substrate is formed of high doping semi-conductor piezoresistive material.

5. The contact-type micro piezoresistive sheer-stress sensor as defined in claim 3, wherein the formation of the flange comprises immersion in an etching agent at a concentration of HF:

H₂O of 1;

10, and preparation of the semi-conductor is according to the process of pattern etching for size and shape.