Method and apparatus for detection of contaminants in a fluid

• US 6,897,661 B2
• Filed: 12/05/2003
• Issued: 05/24/2005
• Est. Priority Date: 03/14/2003
• Status: Expired due to Term

• Current Assignee: American Sterilizer Company (Steris Corporation)
• Original Assignee: Steris Corporation
• Inventors: Allen, David, Centanni, Michael A.
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): He, Amy
• Application Number:
  US10/729,740
• Publication Number:
  US 20040178804A1
• Time in Patent Office: 536 Days
• Field of Search: 324691-698, 324/519, 324/439, 324/658, 324/686, 324/464
• US Class Current: 324/663
• CPC Class Codes: G01N 27/221 by investigating the dielectric properties using microwaves G01N22/00; measuring loss factors or dielectric constants per se G01R27/26
• CPC Class Codes: G01N 27/226 Construction of measuring vessels; Electrodes therefor
• CPC Class Codes: G01N 33/483 Physical analysis of biological material

Abstract

A contaminant detecting system for determining the presence of a miscible or immiscible contaminant in a fluid. The fluid acts as a dielectric between the plates of a capacitive sensing element. The measured capacitance value varies in accordance with the composition of the fluid, to indicate the presence or absence of the contaminant in the fluid.

Claims

1. A contaminant detecting system for determining the presence of a contaminant in a fluid used in a microbial decontamination process, comprising:

a capacitor having first and second conducting elements, said fluid being a dielectric therebetween, and being used to process an article in the microbial decontamination process;

sensing means responsive to a change in an electrical property of the capacitor, said change in the electrical property varying according to the presence of the contaminant in the fluid, said contaminant being removed from said article during the microbial decontamination process; and

control means for receiving a measured value from said sensing means indicative of the electrical property of the capacitor, said control means capable of detecting the presence of miscible and immiscible contaminants in the fluid, wherein said control means;

(a) determines the presence of a miscible contaminant in the fluid if the measured value deviates a predetemined amount from a threshold value, and

(b) determines the presence of an immiscible contaminant in the fluid if said measured value spikes from a base value during a predetermined time period.

2. A contaminant detecting system according to claim 1, wherein said sensing means includes a sensing circuit for sensing capacitance.

3. A contaminant detecting system according to claim 2, wherein said sensing circuit includes means for generating a digital value indicative of an input capacitance.

4. A contaminant detecting system according to claim 3, wherein said means for generating the digital value indicative of the input capacitance is selected from the group consisting of:

a charge-transfer capacitance sensor IC and a capacitance-to-digital-converter (CDC).

5. A contaminant detecting system according to claim 1, wherein said control means includes:

means for comparing said measured value with the threshold value to determine if the measured value deviates a predetermined amount from said threshold value.

6. A contaminant detecting system according to claim 1, wherein said miscible contaminant selected from the group consisting of:

blood, urine, and miscible soil.

7. A contaminant detecting system according to claim 1 wherein said immiscible contaminant selected from the group consisting of:

dirt, bone matter, skin, organ tissue, and immiscible soil.

8. A contaminant detecting system according to claim 1, wherein said microbial decontamination process is selected from the group consisting of:

a washing process, an antimicrobial treatment process and a rinsing process.

9. A method for determining the presence of a contaminant in a fluid used in a microbial decontamination process, comprising:

passing the fluid between a capacitor having first and second conducting elements, said fluid being a dielectric therebetween, and being used to process an article in the microbial decontamination process; and

determining a measured value indicative of an electrical property of the capacitor, said electrical property varying according to the presence of the contaminant in the fluid, said contaminant being removed from said article during the microbial decontamination process;

detecting the presence of a miscible contaminant in the fluid if the measured value deviates a predetermined amount from a threshold value, and

detecting the presence of an immiscible contaminant in the fluid if the measured value spikes from a base value during a predetermined time period.

10. A method according to claim 9, wherein said electrical property is capacitance.

11. A method according to claim 9, wherein said method further comprises:

comparing said measured value with the threshold value to determine whether the measured value deviates said predetermined amount from said threshold value.

12. A method according to claim 9, wherein said immiscible contaminant selected from the group consisting of:

dirt, bone matter, skin, organ tissue, and immiscible soil.

13. A method according to claim 9, wherein said miscible contaminant selected from the group consisting of:

blood, urine, and miscible soil.

14. A method according to claim 9, wherein said microbial decontamination process is selected from the group consisting of:

a washing process, an antimicrobial treatment process and a rinsing process.