Sensor with improved shelf life

a technology of sensor and shelf life, applied in the field of extending the shelf life of such apparatuses, can solve the problems of limiting the useful shelf life and deteriorating the filling time of sensors

Inactive Publication Date: 2008-05-29
LIFESCAN INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Typically, when left to stand for long periods of time, electrodes become prone to instability in subsequent use thus limiting the useful shelf life.
It is thought that such instability is caused by absorption or reaction of the metallic surface with atmospheric contaminants.
It has also been observed that filling time of sensors deteriorates on prolonged storage.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

Preparation

[0027]The electrode coatings were applied to gold or palladium electrodes by immersing the sheet of material from which the electrodes were made into a 1 mM aqueous solution of the coating compound adjusted to pH 12 by the addition of potassium hydroxide. The contact time between the electrode material and the coating bath was typically 30 seconds. After coating, the electrodes were washed by immersion in a bath of water. In some cases, the electrodes were immersed in a third bath containing 1,000 ppm of triton X-100 in water. Finally, the electrode material sheets were dried by blowing with air at room temperature.

example 2

Storage

[0028]The data in Tables 1 and 2 below show the effect on the electrode stability of coating the electrodes with sulphur-containing compounds. The stability was assessed using an accelerated test. The glucose sensors using coated or uncoated electrodes were stored either at 4° C. in the refrigerator (“fridge”) or at 56° C. in an oven for two weeks. The sensors stored at 4° C. do not change significantly from their performance when freshly prepared and tested. Those stored in the oven are subject to accelerated ageing, which simulates longer ageing times at room temperature.

example 3

Testing

[0029]After to weeks the sensors were tested with whole blood samples with various glucose concentrations, from about 3 mM to 30 mM. The background ferrocyanide concentration was measured (the reading obtained when a sample contains no glucose) and the overall precision and fill speed of the sensors was assessed. The effect of the electrode coatings is shown in Table 1. The fill speeds in Table I were assessed qualitatively by eye. The fill speeds in Table 2 were assessed quantitatively by videoing the filling of the sensor with a blood sample using an on-screen timer and subsequently determining the number of seconds required for the blood to fill each sensor.

[0030]It can be seen from the first pair of results, for a non-coated electrode, that artificial ageing dramatically increased the % cv (corresponding to decreased precision).

[0031]In contrast, for the last two pairs of results, the % cv's for the treated electrodes after artificial ageing were comparable to the % cv's ...

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Abstract

The present invention provides a metal electrode stabilised by a coating, the coating comprising a sulfur containing moiety in its molecular structure. The coating may also include a hydrophilic group and a spacer between the sulfur containing moiety and the hydrophilic group. Preferably, the sulfur containing moiety is selected from the group comprising thiol, disulfide and SOx, and the hydrophilic group is selected from the group comprising hydroxyl, amine, carboxyl, carbonyl, oligo (ethylene oxide) chain, and zwitterionic species. Compounds useful in the present invention include 2-mercaptoethanol, 2-mercaptoethylamine, 3-mercaptopropionic acid, thiophene, 4-carboxythiophene, cysteine, homocysteine, and cystine.

Description

RELATED APPLICATIONS[0001]This application is a continuation of U.S. application Ser. No. 10 / 630,441, filed on Jul. 19, 2003, which is a continuation of U.S. application Ser. No. 09 / 664,688, filed on Sep. 19, 2000, now U.S. Pat. No. 6,652,734, which is a continuation of PCT Application No. PCT / AU99 / 00166, filed on 16 Mar. 1999, which claimed priority from Australian Application No. PP 2503, filed on 20 Mar. 1998.TECHNICAL FIELD[0002]The invention relates to apparatus comprising one or more metal electrodes such as electrochemical cells, sensor elements and the like, and more particularly to extending the shelf life of such apparatus.BACKGROUND ART[0003]Metal electrodes have proved useful in sensor elements for sensing a diverse range of biologically important molecules eg glucose, and for determining physical properties such as pH. A range of possible configurations and applications involving metal electrodes are discussed in our co-pending applications PCT / AU96 / 00210, PCT / AU96 / 0036...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G01N27/26G01N27/30B05D1/00A61B5/00A61N1/04A61N1/05
CPCA61B5/14539A61B5/1486A61N1/0476G01N27/3271A61N1/05G01N27/30A61N1/0492
Inventor HODGES, ALASTAIRCHATELIER, RONALD
Owner LIFESCAN INC
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