AMORPHOUS IROX FILM PH SENSOR

• US 20110140703A1
• Filed: 10/25/2010
• Published: 06/16/2011
• Est. Priority Date: 02/13/2008
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Original Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Inventors: Chiao, Jung-Chih, Huang, Wen-Ding
• Granted Patent: US 8,552,730 B2
• Time in Patent Office: Days
• US Class Current: 324/438
• CPC Class Codes: C23C 28/345 with at least one oxide layer
• CPC Class Codes: G01N 27/403 Cells and electrode assemblies
• CPC Class Codes: G01N 27/4167 pH electrodes therefor G01N27/302, G01N27/36

Abstract

The present invention provides a pH sensing apparatus that includes a flexible polymer substrate, one or more amorphous iridium oxide film sensor electrodes disposed on the flexible polymer substrate, and a reference electrode corresponding to each amorphous iridium oxide film sensor electrode. Each reference electrode is disposed on the flexible polymer substrate in close proximity to the corresponding amorphous iridium oxide film sensor electrode. The amorphous iridium oxide film sensor electrodes provide a potential in reference to the reference electrodes that varies according to a pH of a substance contacting the amorphous iridium oxide film sensor electrodes and the reference electrodes.

Claims

1. A pH sensing apparatus comprising:

a flexible polymer substrate;

one or more amorphous iridium oxide film sensor electrodes disposed on the flexible polymer substrate;

a reference electrode corresponding to each amorphous iridium oxide film sensor electrode, wherein each reference electrode is disposed on the flexible polymer substrate in close proximity to the corresponding amorphous iridium oxide film sensor electrode;

a first electrical contact pad corresponding to each amorphous iridium oxide film sensor electrode, wherein each first electrical contact is disposed on the flexible polymer substrate and electrically connected to the corresponding amorphous iridium oxide sensor;

a second electrical contact pad corresponding to each reference electrode, where each second electrical contact pad is disposed on the flexible polymer substrate and electrically connected to the corresponding reference electrode; and

wherein the amorphous iridium oxide film sensor electrodes provide a potential in reference to the reference electrodes that varies according to a pH of a substance contacting the amorphous iridium oxide film sensor electrodes and the reference electrodes.

2. The apparatus as recited in claim 1, wherein:

the flexible polymer substrate is a Kapton polyimide flexible substrate;

the amorphous iridium oxide film sensor electrode comprises a chromium layer, a gold layer and an iridium oxide thin film; and

the reference electrode comprises a chromium layer, a platinum layer and a silver layer.

3. The apparatus as recited in claim 1, wherein the pH sensing apparatus is biocompatible and is integrated into a packing for a food to detect spoilage of the food.

4. The apparatus as recited in claim 1, wherein the pH sensing apparatus is biocompatible and is integrated into a bandage to detect whether or not a wound covered by the bandage is healing or becoming infected.

5. The apparatus as recited in claim 1, wherein the pH sensing apparatus is biocompatible and is integrated into an acid reflux detector.

6. The apparatus as recited in claim 1, further comprising a radio frequency identification device connected to the first and second electrical contact pads.

7. The apparatus as recited in claim 1, wherein the radio frequency identification device is a passive device or an active device.

20. The apparatus, device, bandage or system of claim 1, 15, 17, 18 or 19, further comprising a visual indicator attached to the pH sensing apparatus.

8. A method for fabrication one or more pH sensors comprising the steps of

depositing a chromium layer and a gold layer on a flexible polymer substrate to define a sensor electrode and a first electrical contact pad;

depositing a sacrificial layer on the first electrical contact pad and the flexible polymer substrate;

coating the sacrificial layer and the sensor electrode with an iridium oxide thin film;

heating the sensor electrode to form an amorphous iridium oxide sensor electrode;

removing the sacrificial layer;

depositing a chromium layer, a platinum layer and a silver layer on the flexible polymer substrate to define a reference electrode and a second electrical pad; and

electroplating the silver layer.

9. The method as recited in claim 8, wherein:

the flexible polymer substrate comprises a Kapton polyimide flexible substrate; and

the sacrificial layer comprises SU-8.

10. The method as recited in claim 8, further comprising the steps of applying a sacrificial layer of S1813 to the chromium, platinum and silver layers.

11. The method as recited in claim 8, wherein an electron-beam evaporator deposits the chromium layer, the gold layer, the chromium layer, the platinum layer and the silver layer.

12. The method as recited in claim 8, wherein:

the sacrificial layer and the sensor electrode are coated with the iridium oxide thin film by a dipcoating process; and

the heating step comprises at 150 degrees Celsius for at least 1 hour followed by a second heating step of 300 degrees Celsius for another 5 hours after the sacrificial layer is removed.

13. The method as recited in claim 12, wherein the second heating step is performing in an oven purged with inert gas starting at 25 degrees Celsius and increasing to 300 degrees Celsius in a period of 2 hours, and staying at 300 degrees Celsius for another 5 hours.

14. The method as recited in claim 8, wherein the step of depositing the sacrificial layer comprises the steps of:

depositing the sacrificial layer using a spin cycle;

heating the sacrificial layer at 65 degrees Celsius for 3 minutes and then 10 minutes at 95 degrees Celsius; and

developing and drying the sacrificial layer.

15. A device for detecting spoilage in a food, comprising:

a biocompatible pH sensing apparatus for physical contact with the food comprising;

a flexible polymer substrate,

one or more amorphous iridium oxide film sensor electrodes disposed on the flexible polymer substrate,

a reference electrode corresponding to each amorphous iridium oxide film sensor electrode, wherein each reference electrode is disposed on the flexible polymer substrate in close proximity to the corresponding amorphous iridium oxide film sensor electrode,

a first electrical contact pad corresponding to each amorphous iridium oxide film sensor electrode, wherein each first electrical contact is disposed on the flexible polymer substrate and electrically connected to the corresponding amorphous iridium oxide sensor,

a second electrical contact pad corresponding to each reference electrode, where each second electrical contact pad is disposed on the flexible polymer substrate and electrically connected to the corresponding reference electrode, and

wherein the amorphous iridium oxide film sensor electrodes provide a potential in reference to the reference electrodes that varies according to a pH of the food contacting the amorphous iridium oxide film sensor electrodes and the reference electrodes;

a passive radio frequency identification chip electrically connected to the first and second electrical contact pads; and

a tag antenna electrically connected to the passive radio frequency identification chip.

16. The device as recited in claim 15, wherein the device is integrated into a label.

17. A system for detecting spoilage in a food, comprising:

a biocompatible pH sensing apparatus in physical contact with the food comprising;

a flexible polymer substrate,

one or more amorphous iridium oxide film sensor electrodes disposed on the flexible polymer substrate,

a reference electrode corresponding to each amorphous iridium oxide film sensor electrode, wherein each reference electrode is disposed on the flexible polymer substrate in close proximity to the corresponding amorphous iridium oxide film sensor electrode,

a first electrical contact pad corresponding to each amorphous iridium oxide film sensor electrode, wherein each first electrical contact is disposed on the flexible polymer substrate and electrically connected to the corresponding amorphous iridium oxide sensor,

a second electrical contact pad corresponding to each reference electrode, where each second electrical contact pad is disposed on the flexible polymer substrate and electrically connected to the corresponding reference electrode, and

wherein the amorphous iridium oxide film sensor electrodes provide a potential in reference to the reference electrodes that varies according to a pH of the food contacting the amorphous iridium oxide film sensor electrodes and the reference electrodes;

a passive radio frequency identification chip electrically connected to the first and second electrical contact pads;

a tag antenna electrically connected to the passive radio frequency identification chip; and

a radio frequency identification reader comprising a computer connected to an antenna.

18. A bandage for detecting a condition of a wound, comprising:

a wound dressing material;

a biocompatible pH sensing apparatus attached to the wound dressing material for physical contact with the wound comprising;

a flexible polymer substrate,

one or more amorphous iridium oxide film sensor electrodes disposed on the flexible polymer substrate,

a reference electrode corresponding to each amorphous iridium oxide film sensor electrode, wherein each reference electrode is disposed on the flexible polymer substrate in close proximity to the corresponding amorphous iridium oxide film sensor electrode,

a first electrical contact pad corresponding to each amorphous iridium oxide film sensor electrode, wherein each first electrical contact is disposed on the flexible polymer substrate and electrically connected to the corresponding amorphous iridium oxide sensor,

a second electrical contact pad corresponding to each reference electrode, where each second electrical contact pad is disposed on the flexible polymer substrate and electrically connected to the corresponding reference electrode, and

wherein the amorphous iridium oxide film sensor electrodes provide a potential in reference to the reference electrodes that varies according to a pH of the wound contacting the amorphous iridium oxide film sensor electrodes and the reference electrodes;

a passive radio frequency identification chip electrically connected to the first and second electrical contact pads; and

a tag antenna electrically connected to the passive radio frequency identification chip.

19. A system for detecting a condition of a wound, comprising:

a bandage containing a biocompatible pH sensing apparatus in physical contact with the wound, a passive radio frequency identification chip and a tag antenna electrically connected to the passive radio frequency identification chip;

wherein the pH sensing apparatus comprises;

a flexible polymer substrate,

one or more amorphous iridium oxide film sensor electrodes disposed on the flexible polymer substrate,

a reference electrode corresponding to each amorphous iridium oxide film sensor electrode, wherein each reference electrode is disposed on the flexible polymer substrate in close proximity to the corresponding amorphous iridium oxide film sensor electrode,

a first electrical contact pad corresponding to each amorphous iridium oxide film sensor electrode, wherein each first electrical contact is disposed on the flexible polymer substrate and electrically connected to the corresponding amorphous iridium oxide sensor,

a second electrical contact pad corresponding to each reference electrode, where each second electrical contact pad is disposed on the flexible polymer substrate and electrically connected to the corresponding reference electrode, and

wherein the amorphous iridium oxide film sensor electrodes provide a potential in reference to the reference electrodes that varies according to a pH of the wound contacting the amorphous iridium oxide film sensor electrodes and the reference electrodes;

wherein the passive radio frequency identification chip is electrically connected to the first and second electrical contact pads; and

a radio frequency identification reader comprising a computer connected to an antenna.