Patent Application
20080176317
The subject matter of the present invention did not receive federal government research and development funding.
The present invention generally relates to a system and method for detection of substances. More particularly, the present invention relates to a system and method for the detection and quantification of target analyte and includes a transformer capable of transforming a specific substance to another substance. The transformed substance is capable of being detected by an available or currently existing sensing device. Moreover, the system may trap undesired substances while allowing other substances to pass through and to be detected by an available sensing device.
The need for quick and real time detection of toxic substances is of great importance to the health of humans and the environment. The current state of the art and the market have a wealth of portable and hand-held devices capable of quick and real time detection of substances that are available. These devices depend on sensors that operate on different principles which can be generally categorized as electrochemical sensors, mass sensors and optical sensors and are available types of sensors.
Electrochemical sensors operate by measuring a potential difference or voltage (potentiometric), quantifying an electric current (amperometric) or quantifying conductivity (conductometric). All these sensors rely on absorption of the target analyte onto a sensor and a change of physical and/or chemical properties in a reversible fashion. This leads to two main drawbacks. First, there are a limited number of groups of substances that are detectable. Second, the sensors are incapable of specifically distinguishing between different substances within a group that has similar chemical and physical properties. Thus, existing sensors are sometimes unreliable and may lead to false reporting of detected substances.
To overcome the aforementioned limitations, other devices must be used to achieve a wide diversity and a higher specificity of substances detection and quantification. Typically, these other devices are based on technologies such as gas chromatography, liquid chromatography and spectroscopy. However, these devices are expensive, bulky and require well trained personnel to operate them. These limitations hinder the use of chromatography and spectroscopy devices in the field and render their use impractical. The concept of having a substance selective detection system is the subject of several patents. Colorimetric devices were the subject of such systems. Grosskopf (U.S. Pat. No. 3,99,973) teaches a hopkalite-like pre-filter to eliminate carbon monoxide from mixture of gases that can adversely affect the reaction in the calorimetric tube. Leichnilz (U.S. Pat. Nos. 4,230,457 and 4,259,287) teaches a means to convert aerosols into measurable gaseous substances and measure the aerosol content by measuring the proportion of the generated gases. Kretshmer (U.S. Pat. No. 4,022,578) uses a similar approach, where the first layer in the detector tube is impregnated with reagent capable of oxidizing halogenated hydrocarbons to measurable halogen in the second part of the tube. Kramer et al. (U.S. Pat. No. 4,789,638) describes a multi-zone device for hydrazine and hydrazine derivatives, which uses one part of the tube-like device as a reactor zone transforming the analyte to halogen and then detecting the halogen in another zone. In all, these patents that relate to colorimetric tube-like devices, the converting, trapping or transforming part has a length adjusted by trials and errors to accommodate a single use, such that the detector tubes are one-time use devices. Therefore, there is no requirement of controlling or observing their converting, trapping or transforming power. This approach has been in use in calorimetric gas measuring device for fluorine in May (U.S. Pat. No. 4,933,144). In the May patent, the converting media is used to generate a secondary substance identifiable by a detector layer, in a tube-like or moving layer format. In the second case, there is no means to control and observe the dissipation of the converting power advancing with the time and quantity of the converted substance, i.e. fluorine. In U.S. Pat. No. 4,197,177, two stages of analyte preparation are applied, the first is humidity removal and the second is conversion of nitrogen oxides to nitrogen dioxide and consecutive detection of the nitrogen dioxide by an electrochemical sensor. None of the filtration and conversion layers has means to observe the anticipated depletion. In order to make more selective inherited non-specific sensors such as a photo-ionization detector, U.S. Pat. No. 5,654,498 to Kessel or electrochemical sensor, U.S. Pat. No. 6,840,084 to Nikolskaya, include converting layers that are adjusted to deliver to the sensor air flow with the desirable component in a continuous time regime. In both cases, the converting layer is affected and depleted by the humidity and the satellite gases or vapors to be converted and there is no means to observe the depletion of the converting material.
The present invention is a system and method for the detecting and quantifying target analytes. The system includes a transformer capable of transforming a first substance to a second substance. The first substance is difficult, if not impossible, to detect by existing or available detectors; whilst the second substance is readily detectable by an available sensing device such as the previously mentioned, existing electrochemical sensor. The transformer is capable of localizing and trapping undesired satellites of target analyte from passing through and being detected by an available sensing device. The available sensing device detects and quantifies the transformed analyte that passes through the transformer. An end of service life indicator includes a selection of one or more substances to perform chemical change and/or biochemical change and/or physical change to indicate the depletion and/or progress and/or end of service life of the transformer. A pump draws fluids through the transformer and sensor to aid in the detection process.
It is an objective of the present invention to provide a new and improved device for protecting humans in the workplace from harmful substances by readily detecting and quantifying these substances.
It is another objective of the invention to provide a means of selectively detecting and quantifying a wide range of toxic substances in fluids.
Another objective of the invention is to provide a simple low cost device and method for selectively detecting and quantifying a wide range of toxic substances in fluids.
Yet another objective of the present invention is to provide a handheld device to detect and quantify a wide range of toxic substances in the field.
In accordance with one aspect of the invention, the foregoing and other objectives are achieved by providing a transformer capable of transforming a specific substance to another substance capable of being detected by a sensing device readily available in the marketplace. Moreover, the invention bolsters the capabilities of existing sensors to accurately detect harmful substances.
Another aspect of the invention is achieved by providing a transformer capable of localizing and trapping undesired satellites of target analyte from passing through and being detected by currently available sensors that are readily purchasable.
Another aspect of the invention is achieved by providing a collecting means to move fluids through the transformer. The collecting means may be a pump that collects more analyte and increases the sensitivity of the detection. A means to measure ambient temperature and humidity may also be provided to optimize the performance of the detection system. Further, a means that heats the transformer to a preset temperature may be provided.
In another embodiment, a suction pump having a log system which includes a programmable microprocessor control system comprising a memory having a program for executing instructions and containing relevant information. Personal computer-based built-in software provides programming and relevant sampling information unique to a specific transformer application. This information may include pumping flow rate, battery charge, time, temperature, humidity, as well as correction factors for aiding in detecting and quantifying the target analyte and atmospheric pressure, barometer or the like. The correction factors may be provided in way of a database stored in an internal memory.
The transformer can incorporate an EE PROM, E square or read/writable or other Radio Frequency Identification (RFID) tag or other programmable memory device that stores the following information: part number, serial number, manufacturer's lot number, application name, range, date and time of each alarm, start date and time of each service date, date and time for each end of service time, type of product, the cumulative exposure to the analyte, usage times, dates and durations, manufacturing date, shipping date, unit of measure, flow rate, flow duration, password or interface code and expiration date. The memory chip may be removable and the memory cleared such that the device may be reused.
Additionally, the following information can be stored on or in the transformer as a barcode; part number, application name, product type, serial number, manufacturer's lot number, range, type of product, unit of measure, flow rate, flow duration and expiration date. The transformer can download the data to the sensor or the RFID reader or a computer and/or receive uploaded information from the sensor or a computer or from the RFID reader.
The transformer housing can be made from metal, glass, clear or opaque plastic such as polypropylene, polyethylene, polyesters, and/or Teflon.
The transformer has a single or a plurality of layers incorporating chemical and/or biochemical formulations capable of transforming the target analyte to another substance that is detectable by a readily available sensor.
The transformer comprises at least one layer incorporating chemical and/or biochemical formulations capable of localizing and/or trapping undesired satellites of the target analyte from passing through to be detected by the available sensors mentioned above. The chemical and/or biochemical formulations may include formulations that undergo colorimetric, fluorescent, luminescent or bioluminescent responses upon reacting or interacting with the target analyte.
The transformer may further include a layer that functions as an end-of-service-life-indicator (ESLI) to provide early indication of the consumption and/or saturation.
In one embodiment, the ESLI layer is located next to a layer having a reagent that reacts with the target analyte to convert it to a more readily detectable substance. That is, the single or multiple layers that incorporate chemical and/or biochemical formulations are capable of transforming the target analyte to another substance that is detectable by an available sensor.
The ESLI layer may be arranged next to a buffer layer. This buffer layer acts as safety buffer and can be constructed from the same materials as the single or multiple layers incorporating chemical and/or biochemical formulations capable of transforming the target analyte to another substance that is readily detectable by an available sensor. Additionally, the buffer layer can be constructed from the same materials as the single or plurality of layers incorporating chemical and/or biochemical formulations capable of localizing and/or trapping undesired satellites of the target analyte from passing through to be detected by the available sensors.
The ESLI layer undergoes characteristic changes upon exposure to the transformable target analyte or to the undesired satellites of the target analyte. These changes in the characteristics may include optical, electrical, pyroelectric, piezoelectric, any combination thereof and/or any measurable change in a characteristic of the ESLI layer.
The optical, electrical, pyroelectric, piezoelectric and/or any measurable change in a characteristic can be measured visually and/or with any available detectors and sensors capable of detecting and/or measuring a chemical and/or the physical change of the properties and characteristics of the ESLI.
An improvement of the transformer of the present invention may be included, for example, a construction of the end of service life indicator and the transformer as an integral unit. In this example, the analyte moves through single or multiple layers to react with the chemical and/or biochemical formulations. The extent of the analyte's movement through the reagent material can be ascertained and the consumption of the reagent material is determined by a color change, fluorescence and/or illuminations of the reacted reagent material as the fluid analyte moves through the layer(s). One or more of the layers are inert to the analyte as the fluids moves through, therefore it does not change color, and/or does not fluoresce or illuminate when exposed to light, ultraviolet light, infrared light and the like. The material in the inert layer has a contrasting color to the reactive materials. Otherwise, the inert material can have a non-contrasting color to the reactive material. This may be the case with fluorescent, luminescent or bioluminescent reagents. As the fluid analyte passes through the inert layer, there is no reaction, no color change, no fluorescence, and no illumination. The inert layer forms a clear line of demarcation between the consumed material and the unconsumed material. By reading the amount of reacted material, it is possible to estimate the remaining useful life of the transformer. Once the analyte passes through the inert layer, the analyte comes in contact with the reactive layer or multiple active layers and changes color or fluoresces or illuminates, as described above. There can be one or more inert layers in the transformer to measure the progress of the analyte moving through the entire transformer or a just a portion of the transformer.
The transformer allows fluids to pass through with optimized resistance to achieve high capacity, as well as uniform and fluent flow of fluids.
In the preferred embodiment, the transformer best functions at temperatures ranging between 0° F. to 105° F. Operation at lower temperatures can be achieved by incorporating a heater. Operation at higher temperatures is usually accompanied by a higher reaction rate, in this case correction factors can be applied. The correction factor data can be supplied in tables or it can be incorporated in an EE PROM, E square or read/writable or other Radio Frequency Identification (RFID) tag or other memory device or bar code on the transformer and/or the pump and/or the sensing device.
The chemical and/or biochemical formulations include a support substrate that has a macro porous structure to support and encapsulate the chemical and/or biochemical active ingredients. The macro porous member includes micro porous and/or nonporous member to support and encapsulate the chemical and/or biochemical active ingredients.
The chemical and/or biochemical formulations may include a binding substrate to bind and/or localize the chemical and/or biochemical active ingredients to the micro porous and/or nonporous support member. The micro porous and/or nonporous support member can be silica, alumina, zeolite, porcelain, molecular sieves or any similar inert materials that are compatible with the chemical and/or biochemical active ingredients.
The transformer of the present invention includes variations of chemicals and/or biochemical formulations capable of localizing and/or trapping individually the following substances while allowing other substances to pass through intact. The trapped substances may include Ammonia, Aromatic hydrocarbons (such as toluene, xylene), Br2, Carbon tetrachloride, Cl2 CO2, H2S, HCl, HF, Lower class hydrocarbons (C1 through C6), Mercaptans, Nitric Acid, Nitrogen oxides NO2, Organic gases and vapors, O3, SO2, SO3, Unsaturated halogenated hydrocarbons and water vapor.
An example of a possible formulation capable of localizing and/or trapping individually the following substances while allowing other substances to pass through intact is a chemical transformer that includes alkaline glass fibers which react with HF while allowing other substances including other acids to pass through intact. This formulation is especially useful in localizing and/or trapping HF. For H2S, the transformer may include lead acetate which reacts with H2S and allows other substances pass through intact.
Yet another example of a possible formulation capable of localizing and/or trapping individually the following substances while allowing other substances to pass through intact is a chemical transformer that includes chromium oxide and sulfuric acid. The oxidation potential of these two chemicals can be adjusted to react, and hence, trap toluene, xylene and other hydrocarbons while allowing benzene to pass intact and be detected selectively by a commercially available sensor. The transformer includes an ESLI to indicate the progress in consumption of the active trapping layer, a buffer layer to ensure that none of the undesired substances passes through to the sensor and a pre-layer of dryer to remove moisture and hence increase the capacity and efficiency of the transformer.
The transformer of the present invention includes variations of chemical and/or biochemical formulations capable of transforming individually the following target analytes to other substances and/or generating, due to the presence of the individual following target analytes, other substances that are readily detectable by available sensors while allowing other substances to pass through intact. Some of these target analytes include Acetaldehyde, Acetone, Acetylene, Acrolein, Acrylonitrile, Arsine, Benzene, Tert-Butyl Mercaptan, Carbon Disulfide, Carbon Monoxide, Carbon tetrachloride, Carbonyl Sulfide, Chlorobenzene, Chloroform, Diborane, o-Dichlorobenzene, 1,2-Dichloroethylene, Ethylene Glycol, Ethylene Oxide, Ethyl Mercaptan, Formaldehyde, Hydrocarbons (Aliphatic), Hydrogen Cyanide, Mercaptans, Methacrylonitrile, Methyl Bromide, Nitrogen Oxides, Phosphine, Stoddard Solvent, Sulfur Dioxide, Tetrachloroethylene, Toluene, 1,1,1-Trichloroethane, Trichloroethylene, Vinyl Chloride, Vinylidene Chloride and Xylene.
An example of an appropriate formulation for detection of acetaldehyde includes a chemical transformer of the present invention that comprises (NH2OH)3.HCl. Acetaldehyde reacts with (NH2OH)3.HCl to generate HCl. HCl is detectable by an HCl portable handheld sensor such as an electrochemical sensor currently available in the marketplace.
An example of an appropriate formulation for detection of acrylonitrile includes a chemical transformer of the present invention that comprises a Cr+6 compound, H2SO4 and HgCl2. Acrylonitrile reacts with Cr+6 compound and H2SO4 to generates HCN which in turn reacts with HgCl2 to produce HCl. HCl is detectable by an HCl portable handheld sensor such as electrochemical sensor that is currently available.
An example of an appropriate formulation for detection of chloroform includes a chemical transformer of the present invention that comprises I2O7 and H2S2O7. Chloroform reacts with I2O7 and H2S2O7 to generate Cl2. Cl2 is detected by a Cl2 portable handheld sensor currently available in the marketplace.
An example of an appropriate formulation for detection of Carbon Disulfide includes a chemical transformer of the present invention that comprises I2O7 and H2S2O7. Carbon Disulfide reacts with I2O7 and H2S2O7 to generate SO2. SO2 is detected by an SO2 portable handheld sensor currently available. Alternatively, the chemical formulation in the chemical transformer of the present invention may include I2O7, H2S2O7 and BaCl2. Carbon Disulfide reacts with I2O7 and H2S2O7 to generate SO2. SO2 reacts BaCl2 with to generate HCl. HCl is detectable by an HCl portable handheld sensor.
The transformer of the present invention may be connected upstream and operate in accordance with of any of the following sensors or combinations thereof: an acoustic IR sensor, an argon ion electron capture detector, a biological sensor, a chemfet, a calorimetric sensor, a conductive polymer sensor, an enzyme sensor, a fiber optic sensor, a flame ionization detector, a fluorescence detector, an immobilization of recombination bioluminescent bacterium sensor, an immunoassay sensor, an infrared coherent laser source sensor, an infrared sensor, an ion mobility detector, an ionization sensor, a laser sensor, a metal oxide sensor, a paper tape sensor, a piezoelectric sensor, a piezopyretic sensor, a SAW sensor, a solid state semi-conductor sensor, a solid state sensor, a solid state thin film semi-conductor sensor, a TiO2 sensor, a thermal conductivity sensor, a thin film titanium dioxide sensor, a voltametric electrocatalytic sensor and/or a wave guide sensor.
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Although the present system, apparatus and device of detecting a target analyte and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, and composition of matter, means, methods and steps described in the specification. For example, various exemplary configurations of a detection system have been described. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, various elements from measurement or instrumentation technology, or measuring methods or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such machines, apparatus, methods, or steps.
This application claims priority from U.S. Provisional Patent Application Ser. No. 60/792,373, filed on Apr. 17, 2006.
| Number | Date | Country | |
|---|---|---|---|
| 60792373 | Apr 2006 | US |
