Measuring and testing – Gas analysis
Reexamination Certificate
2001-09-18
2004-10-26
Cygan, Michael (Department: 2855)
Measuring and testing
Gas analysis
C073S031050, C338S034000, C422S082020, C422S098000
Reexamination Certificate
active
06807842
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a molecular recognition sensor system for detecting the presence and concentration of an analyte and to a method of detecting the presence and concentration of an analyte.
BACKGROUND OF THE INVENTION
Numerous methods exist for the chemical detection of analytes. For example, resistive sensors measure the change in resistance when an analyte and interferents are absorbed by the semiconductive polymer film on the sensor. The absorption of the analyte and interferents cause the semiconductive polymer film to swell which changes the resistive properties of the sensor.
However, these devices are non-specific to an analyte because they cannot distinguish between the absorption of the analyte and the absorption of the interferents in the polymer film of the sensor. Because both the analyte and the interferent will cause a device to swell and correspondingly affect the resistance, to be selective to the analyte these prior art resistive sensors must rely on an array of chemical coatings on the sensor and on pattern recognition. See U.S. Pat. Nos. 5,571,401, 5,698,089, 5,788,833, 5,891,398, 5,911,872, 5,951,846, 5,959,191, and 6,010,616 to Lewis et al. incorporated herein by this reference. These prior art resistive sensors are non selective and require extensive data manipulation. Further, the chemical coatings on the resistive sensor will absorb virtually any interferents which will impair the ability of the sensor to detect the change in resistance due to the analyte.
Other prior art techniques attempt to detect an analyte by molecularly imprinting a polymer. These techniques employ a polymer film to which an analyte of interest is added, the polymer cured, then the analyte is removed by washing. The result is a polymer with cavities the same size as the analyte. The polymer is typically applied to a fiber-optic sensor to which luminescence is applied via an argon ion laser with a holographic filter, and results analyzed on a computer. Other variations to detect the analyte in the imprinted polymer include measurement of the UV, infrared, and visible light absorption as well as fluorescence and phosphorescence. See e.g.
Polymer
-
Based Lanthanide Luminescent Sensor For Detection Of The Hydrolisis Product Of The Nerve Agent Soman In Water
, Jenkens et al., Anal. Chem. Vol. 71, p.373-378 (1999) and
Progress in the Development of Molecularly Imprinted Polymer Sensors
, Arnold et al., Johns Hopkins APL Technical Digest, Vol. 20, No. 2 (1999) incorporated herein by this reference.
However, these molecular imprinted polymer designs suffer from the distinct disadvantage that they are designed to be specific to only one target analyte, are large, bulky, complex, delicate, and difficult to use.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide a molecular recognition sensor system and method.
It is a further object of this invention to such a molecular recognition sensor system and method which can accurately detect an analyte.
It is a further object of this invention to provide such a molecular recognition sensor system and method which can accurately detect the concentration of an analyte.
It is a further object of this invention to provide such a molecular recognition sensor system and method which can detect a plurality of analytes.
It is a further object of this invention to provide such a molecular recognition sensor system and method which can detect a plurality of analyte concentrations.
It is a further object of this invention to provide such a molecular recognition sensor system which is compact, inexpensive and easy to use.
It is a further object of this invention to provide such a molecular recognition sensor system which is easily transportable.
It is a further object of this invention to provide such a molecular recognition sensor system which is simple in design.
It is a further object of this invention to provide such a molecular recognition sensor system and method which can eliminate the effect of interferents on the change of resistance of a resistive sensor when exposed to an analyte and interferents.
This invention results from the realization that a truly effective and robust molecular recognition sensor system can be achieved by the combination of first a resistive sensor including a semiconductive polymer film which swells when exposed to an analyte and interferents and second a molecular imprinted resistive sensor including a semiconductive polymer film imprinted with the analyte of interest and which swells when exposed to the interferents and then by detecting the change in resistance of the resistive sensor when exposed to the analyte and interferents and the change in resistance in the molecular imprinted resistive sensor when exposed to the analyte and interferents by subtracting the change in resistance of the molecular imprinted resistive sensor from the change in resistance of the resistive sensor thus eliminating the effect of the interferents on the change of resistance to the resistive sensor to thereby more accurately determine the presence and concentration of the analyte of interest.
This invention features a molecular recognition sensor system including a resistive sensor having a semiconductive polymer film which swells when exposed to an analyte and interferents and a molecular imprinted resistive sensor having a semiconductive polymer film imprinted with the analyte which thereby swells when exposed to interferents.
The system also includes a circuit connected to the resistive sensor and the molecular imprinted resistive sensor for detecting a change in the resistance of the resistive sensor when exposed to the analyte and the interferents, the change in the resistance of the molecular imprinted resistive sensor when exposed to the analyte and interferents, and for subtracting the change in resistance of the molecular imprinted resistive sensor from the change in resistance of the resistive sensor to reduce the effect of any interferents on the change in resistance of the resistive sensor thereby determining the presence and concentration of the analyte.
The circuit may be connected to an analog to digital converter which may be interfaced with a computer having software to read resistance.
The molecular recognition sensor system in accordance with this invention may also include a resistive sensor and molecular imprinted resistive sensor pair for each analyte of interest.
Ideally, the resistive sensor and the molecular resistive sensors include carbon or copper to make the polymere film conductive.
This invention also features a method of determining the presence and concentration of an analyte which includes the steps of forming a resistive sensor with a semiconductive polymer film which swells when exposed to the analyte and interferents, imprinting a semiconductor polymer film with an analyte forming a molecular imprinted resistive sensor which swells when exposed to interferents, detecting a change in the resistance of the resistive sensor when exposed to the analyte and the interferents and the change in the resistance of the molecular imprinted resistive sensor when exposed to the analyte and interferents, and subtracting the change in resistance of the molecular imprinted resistive sensor from the change in resistance of the resistive sensor to reduce the effect of any interferents effect on the change of resistance of the resistive sensor thereby determining the presence and concentration of the analyte.
REFERENCES:
patent: 5007283 (1991-04-01), Ambos
patent: 5571401 (1996-11-01), Lewis et al.
patent: 5698089 (1997-12-01), Lewis et al.
patent: 5788833 (1998-08-01), Lewis et al.
patent: 5891398 (1999-04-01), Lewis et al.
patent: 5911872 (1999-06-01), Lewis et al.
patent: 5951846 (1999-09-01), Lewis et al.
patent: 5959191 (1999-09-01), Lewis et al.
patent: 6010616 (2000-01-01), Lewis et al.
patent: 6232783 (2001-05-01), Merrill
patent: 6458327 (2002-10-01), Vossmeyer
patent: 2002/0045275 (2002-04-01), Huang
patent: 2002/0102312 (2002-08-01), Tepper et al.
pate
Dube Christopher E.
Williams John R.
Cygan Michael
Iandiorio & Teska
The Charles Stark Draper Laboratory Inc.
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