Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Means for analyzing liquid or solid sample
Reexamination Certificate
1998-06-29
2001-09-18
Snay, Jeffrey (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Means for analyzing liquid or solid sample
C422S068100, C422S082010, C422S083000, C422S098000, C204S406000, C204S412000, C204S431000
Reexamination Certificate
active
06290911
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to novel devices and methods for preparing and using a plurality of compositionally different sensors that are capable of detecting the presence of a chemical analyte in a fluid.
There is considerable interest in developing chemically sensitive sensors that are capable of detecting the presence of a particular chemical analyte in a fluid for the purpose of achieving a detectable response. Such sensors are often fabricated from a polymeric organic material that is capable of absorbing a chemical analyte which comes in contact therewith, wherein absorbance of the analyte causes the polymeric material to swell, thereby providing a response that is capable of being detected. Variability in the ability to absorb an analyte results in variability in the detectable signal produced. Such organic polymer-based sensors have found use in a variety of different applications and devices including, for example, devices that function as analogs of the mammalian olfactory system (Lewis, U.S. Pat. No. 5,571,401 (incorporated herein by reference), Lundstrom et al., Nature 352:47-50 (1991) and Shurmer and Gardner, Sens. Actuators B 8:1-11 (1992)), bulk conducting polymer films (Barker et al., Sens. Actuators B 17:143 (1994) and Gardner et al., Sens. Actuators B 18:240 (1994)), surface acoustic wave devices (Grate et al., Anal. Chem. 67:2162 (1995), Grate et al., Anal. Chem. 65:A987 (1993) and Grate et al., Anal. Chem. 65:A940 (1993)), fiber optic micromirrors (Hughes et al., J. Biochem. and Biotechnol. 41:77 (1993)), quartz crystal microbalances (Chang et al., Anal. Chim. Acta 249:323 (1991)) and dye impregnated polymeric coatings on optical fibers (White et al., Anal. Chem. 68:2191 (1996)). These and all other references cited herein are expressly incorporated by reference as if set forth herein in their entirety. To date, however, many of the sensors employed in the above-described devices have been fabricated from limited numbers of polymeric components and, therefore, are limited in the responses that they are capable of producing.
Further, today's technology lags far behind the ability of canines or humans to detect or distinguish between chemical analytes. As a consequence, certain work is limited by the suitability of animals or humans to execute tasks. For example, quality control of food products can require production line employees to smell each item. Unfortunately, the ability of individuals to adequately discriminate odors diminishes after a short period of time, e.g., in about two hours. In addition, mammalian olfactory senses are limited in their ability to identify certain vapors. For example, water vapor is not detectable by smell. Further, mammalian olfactory senses are limited to identifying gaseous components, with no ability to identify or “smell” solutes in liquids.
There have been several attempts to construct sensors that can mimic or exceed the capability of olfactory organs. Such attempts have employed, for example, heated metal oxide thin film resistors, polymer sorption layers on the surfaces of acoustic wave resonators, fiber optic micromirrors, arrays of electrochemical detectors, and conductive polymers. Each of these techniques, however, has significant limitations in reproducibility, the ability to discriminate between analytes, or the time required for response. Further, these techniques are often prohibitively expensive or complicated.
Arrays of metal oxide thin film resistors, for example, are typically based on SnO2 films that have been coated with various catalysts. Furthermore, these arrays generally do not allow deliberate chemical control of the response of elements in the array and the reproducibility of response from array to array is often poor. For example, the use of surface acoustic wave resonators, employs a signal transduction mechanism that involves complicated electronics and a frequency measurement to one Hz while sustaining a 200 MHz Rayleigh wave in the crystal. Therefore, a need exists for devices and methods to identify and measure analytes in fluids that overcome or minimize these problems.
Recent studies have shown that arrays of chemically sensitive sensors, formed from a library of swellable insulating organic polymers containing electrically conducting carbon black, are broadly responsive to a variety of analytes, yet allow classification and identification of organic vapors through application of pattern recognition methods. (Lonergan et al., Chem. Mater. 8:2298 (1996)). To date, these array elements have been fabricated from a relatively small number of approximately 10-20 organic polymers, with a single distinct polymer backbone composition in each sensor element. Although a limited number of polymeric sensor compositions might be chosen to perform optimally for specific applications, attempts to perform complex applications, such as to mimic the sense of olfaction, in which the sensing task is time dependent or is not defined in advance of the sensor array construction, will almost certainly require use of polymeric sensor libraries that are far more extensive and compositionally diverse than those presently known. Thus, there is a need for novel methods for producing large libraries of compositionally distinct chemically sensitive sensors, each of which are capable of producing a detectable response in the presence of a chemical analyte of interest.
SUMMARY OF THE INVENTION
While methods for producing a plurality of compositionally distinct chemically sensitive sensors may prove to be very useful in a variety of applications, the utility of such methods is dependent upon whether the response produced by each of the compositionally distinct sensors is a linear function of the mole fraction of any particular component of the sensor. In other words, if the response provided by a sensor is a direct linear function of the mole fraction of a particular component of the sensor, then not much additional information will be obtained from the responses of sensors that comprise a mixture of two different polymeric materials over those sensors that are fabricated solely from one or the other polymeric material. Thus, nonlinearity in the response profile as compared to the mole fraction of an organic material present in the plurality of the sensors is very important for increasing the power of these sensor arrays to resolve multitudes of analytes.
Therefore, it is an object of the present invention to provide a combinatorial approach to the construction of sensor arrays in which blends of two or more organic materials are used as a feedstock to create compositionally varying chemically sensitive sensor films.
It is also an object of the present invention to provide (i) novel methods for making and using a plurality of compositionally different sensors, each of which comprise at least two different organic materials and that are capable of detecting the presence of a chemical analyte in a fluid, and (ii) novel devices made by these methods.
It is another object of the present invention to provide (i) novel methods for making and using a plurality of compositionally different sensors, each of which provide a detectable signal in response to the presence of a chemical analyte, and wherein the detectable signal is not linearly related to the mole fraction of any organic material present in the sensor; and (ii) novel devices made by these methods.
It is yet another object of the present invention to provide (i) novel methods for making and using a plurality of chemically sensitive sensors that can be employed in any system that is dependent upon analyte uptake to achieve a detectable response, and (ii) novel devices made by these methods. Such systems include, for example, analogs to the mammalian olfactory system, arrays of coated surface acoustic wave sensors, fiber optic micromirrors, quartz crystal microbalance sensors, polymer-coated fiber optic sensors, and the like.
It is another object of the present invention to provide (i) novel methods for making a plurality of chemically sen
Grubbs Robert H.
Lewis Nathan S.
Sanner Robert D.
Severin Eric J.
California Institute of Technology
Handy Dwayne K.
Snay Jeffrey
Townsend & Townsend & Crew LLP
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