Chemistry: electrical and wave energy – Apparatus – Electrolytic
Patent
1995-02-17
1996-07-02
Bell, Bruce F.
Chemistry: electrical and wave energy
Apparatus
Electrolytic
204403, 205778, 205792, 205793, 435817, 4352871, 4352879, G01N 2726
Patent
active
055318789
DESCRIPTION:
BRIEF SUMMARY
This invention relates to sensor devices, and more particularly to improved sensor devices useful for analytical methods in enzyme-based electrode systems, and especially for use in biological systems.
It is known to make and use a variety of sensor devices which are based on a form of electrode in which the metal electrode is surrounded by membranes which can exclude interfering materials from the electrode surface while allowing substances to be determined by the analytical procedure to reach the electrode.
A common form is that in which the electrode assembly incorporates an enzyme, which acts on the substrate chemical being evaluated and generates a different chemical which can be determined, thus providing means for determining the substrate chemical indirectly. An especially useful form of this procedure uses glucose as the substrate and a glucose oxidase enzyme, so that these interact and--by catalyzed oxidation of the glucose to gluconic acid--produce hydrogen peroxide and oxygen as products. The hydrogen peroxide is very readily and conveniently determined electrolytically.
A problem encountered with such procedures is that the presence of other materials in the medium being analyzed can interfere with the operation of the sensor device (electrode). This can occur most markedly with high molecular weight materials, as in body fluids (e.g. by proteins and the like), but also can occur when one or more of the components of the electrolyte system is limited, in concentration or mobility, so that the signal output of the sensor (electrode) is in turn limited also. This effect has the most evident effect when it makes the output signal from the sensor (electrode) non-linear or reach a limiting value--as this restricts the range over which the sensor can be used effectively.
It has been proposed to use various materials as membranes, interposed between the electrode's active working surface and the medium under analysis, to prevent interfering materials reaching the electrode surface and fouling it, while still allowing the desired moieties to remain mobile and approach the electrode surface. Although this does produce useful results (controlled permeability and bio-compatibility), the presence of any barrier tends to impose some limitations on mobility of the moieties present, and those barriers hitherto proposed have not yet proved to be entirely satisfactory.
We have now found that the properties of such barriers around the working surfaces of electrodes in sensor devices, usually termed "membranes," can be improved by application of a coating of a carbonaceous material to the material of the membrane. A carbonaceous material which we have found to be very effective is already well-known in itself and described in the art as "diamond-like carbon." It is conveniently referred to in the art by the abbreviation "DLC," and so is referred to in this manner through this specification.
DLC is a form of amorphous carbon or a hydrocarbon polymer with properties approaching those of diamond rather than those of other hydrocarbon polymers. Various names have been used for it, for example "diamond-like hydrocarbon" (DLHC) and "diamond-like carbon" (DLC), but the term "DLC" appears to be the most common. It possesses properties attributable to a tetrahedral molecular structure of the carbon atoms unit, similar to that of diamond but with some hydrogen atoms attached. It has been described in the art as being a designation for "dense amorphous hydrocarbon polymers with properties that differ markedly from those of other hydrocarbon polymers, but which in many respects resemble diamond" [J. C. Angus, EMRS Symposia Proc., 17, 179 (1987)].
Surprisingly, this "diamond-like carbon" coating, applied to a membrane, has an unexpectedly beneficial effect on the range over which the sensor can be used.
Thus according to our invention we provide an improved sensor device, useful in the electrolytic analysis procedures, which comprises a working electrode surrounded by at least one diffusion-limiting membrane, wherein the sai
REFERENCES:
patent: 3979274 (1976-09-01), Newman
patent: 5376244 (1994-12-01), Preidel
Thomson et al: "Biocompatibility of Diamond-like Carbon Coating, BIOMATERIALS", vol. 12, Jan. 1991, pp. 37-40.
Higson et al: "Diamond-like Carbon Coated Microporous Polycarbonate as a Composite Barrier for a Glucose Electrode", ANALYTICA CHIMICA ACTA, vol. 271, No. 1, Jan. 1993, pp. 125-133.
Higson Seamus P. J.
Vadgama Pankaj M.
Bell Bruce F.
The Victoria University of Manchester
LandOfFree
Sensor devices does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sensor devices, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sensor devices will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1503523