Abstract:
Disclosed is a medical diagnostic device for analyzing breath gases and/or skin emissions, including a highly sensitive sensing component for obtaining an emission concentration profile and a database of breath analysis profiles medical condition characteristics.

Description:
PRIORITY 
       [0001]    This application is a continuation in part of application Ser. No. 11/351,171, filed with the U.S. Patent and Trademark Office on Feb. 11, 2006, and is a continuation in part of U.S. application Ser. No. 10/419,349, filed Apr. 21, 2003, and claims priority to application Ser. No. 60/374,189, filed with the U.S. Patent and Trademark Office on Apr. 20, 2002, to application Ser. No. 60/845,917, filed with the U.S. Patent and Trademark Office on Sep. 20, 2006, to application Ser. No. 60/845,918, filed with the U.S. Patent and Trademark Office on Sep. 20, 2006 and on Oct. 26, 2006, and to application Ser. No. 60/973,066, filed with the U.S. Patent and Trademark Office on Sep. 17, 2007, the contents of each of which is incorporated herein by reference. 
     
    
     GOVERNMENT SUPPORT 
       [0002]    This invention was made with Government support of Grant No. SGER DMR0224642 awarded by the National Science Foundation. The Government has certain rights in this invention. 
     
    
     BACKGROUND 
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates generally to a medical device and protocols to facilitate diagnosis of medical conditions based on breath analysis profiles (E-nose) and, in particular, to use of highly sensitive nanostructured polymorphs of metal oxides in such devices and methods. 
         [0005]    2. Background of the Invention 
         [0006]    Since the time of Hippocrates, exhaled breath was known to enable non-invasive detection of disease. Exhaled gases, such as ammonia, nitric oxide, aldehydes and ketones have been associated with kidney and liver malfunction, asthma, diabetes, cancer, and ulcers. Other exhaled compounds like ethane, butane, pentane, and carbon disulfide have been connected to abnormal neurological conditions. However, though analysis of body fluids (blood, sputum, urine) for disease diagnoses and monitoring is routine clinical practice, human breath analysis methodologies that exploit the non-invasive nature of such diagnoses are still under-developed and conventional technologies lack specificity, are excessively expensive or lack portability. 
         [0007]    Technologies for monitoring exhaled breath require complex and expensive apparatuses that are difficult to calibrate and are often not sufficiently sensitive to provide a high degree of certainty in regard to medical condition diagnosis. To address a concern regarding recalibration of portable, at-home sensors, U.S. Pat. No. 7,220,387 to Flaherty et al., the contents of which are incorporated by reference, discloses a disposable sensor for measuring an analyte in a gaseous sample. A conventional apparatus disclosed by Kearney, D, et al. in  Breath Ammonia Measurement in Helicobacter pylori Infection  (Digestive Diseases and Sciences, Vol. 47, No. II, pp. 2523-2530, Nov. 2002), provides a fiber optic device placed in the stream of expelled breath that is connected to an optical sensor for detecting whether a patient has  H. pylori  by measuring for ammonia excreted by the lungs. The fiber optic device of Kearney utilizes a hydrophobic TFE-based membrane to avoid affect of dissolved ions such as ammonia. 
         [0008]    However, conventional point of care devices are expensive, and a portable point of care system is required, particularly in regard to assessment of  H. pylori  and similar infections that colonize the gastroduodenal mucosa discontinuously, causing biopsies to miss infected areas. 
         [0009]    Conventional testing is performed utilizing instrumentation that ranges from variations of mass spectrometers to IR detectors that are costly and require a trained operator. Breath sample transportation is also an issue with most conventional devices. The limited availability of instruments operable by patients and available at the point of care require samples to be shipped to central testing facilities, adding cost and inconvenience. A further difficulty arises in regard to a Urea Breath Test (UBT) from the high cost of  13 C-urea, as well as the cost and operational expenses of instruments to detect exhaled  13 CO 2 . To solve this shortcoming, the present invention departs from detection of  13 CO 2  by using unlabeled urea as a substrate, detecting ammonia in breath instead of CO 2 , provides an ammonia-specific nanosensor and provides a simple, inexpensive hand-held device for the detection of breath NH 3 . 
         [0010]    Accordingly, a highly accurate medical device is provided that is economical, easy to operate, portable and sufficiently sensitive to diagnose medical conditions with a high degree of accuracy. The present invention provides a device and method for diagnostic analysis of exhaled/skin emission gases for reliable, low cost and non-invasive health care use. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention substantially solves the above shortcoming of conventional devices and provides at least the following advantages. 
         [0012]    The present invention can avoid and reduces the need for serologic testing, for upper gastrointestinal endoscopy with mucosal biopsies, for  H. pylori  culture, including antimicrobial susceptibility testing, which is invasive and cumbersome, and for detection of  H. pylori  antigens in stool samples. 
         [0013]    In a preferred embodiment, a medical device is provided to sample nasal air or gases emitted from a patient&#39;s skin to diagnose specific diseases, such as asthma, Chronic Obstructive Pulmonary Disease (COPD), cancer and metabolic disorders including high cholesterol and diabetes, via identification of disease-specific biomarkers. 
         [0014]    An embodiment of the invention provides a medical device for analyzing gases in expired breath for facilitating diagnosis of a medical condition; the device includes sensing and gold substrates arranged on a TO8 substrate to provide highly reliable analysis. The sensing device is positioned to allow a gaseous sample to contact the sensing electrodes. 
         [0015]    Another embodiment of the present invention provides a method for using the medical device of the present invention to analyze a patient&#39;s breath sample to diagnose the presence of a medical condition, by obtaining a breath sample from a patient; analyzing volatile components of the patient sample to provide a breath profile that includes both qualitative and quantitative data; comparing the patient&#39;s breath profile to a database of breath profiles, with each database profile being characteristic of at least one medical condition, to provide information pertinent to diagnosis of the presence or absence of a medical condition. 
         [0016]    In a preferred embodiment, multiple tests performed on a single sample may be independent, or may be the results of several tests combined to produce a template or pattern representative of a patient&#39;s condition or representative of the presence of a particular compound or set of compounds. The high sensitivity of the nanomorphs of metal oxides prepared by sol-gel practices used in the medical device of the present invention are both more selective and more quantitatively precise than similar information obtained by currently available electronic nose technology. As a result, correlating the data pattern or changes in the data pattern over time identifies a wider range of conditions or compounds. 
         [0017]    The present invention departs from the detection of  13 CO 2  and provides a simplified assay that uses unlabeled urea as a substrate and detect ammonia in breath instead of CO 2 , to provide specific nanosensors that detect breath ammonia or other breath components using a simple, portable and inexpensive hand-held device. 
         [0018]    In preferred embodiments, the invention utilizes arrays of biocomposite and bio-doped films to provide a low cost, portable analyzer for detection of chemical products of biochemical reactions, such as ammonia and NO, in a real-time manner. 
     
    
     
       DETAILED DESCRIPTION OF THE FIGURES 
         [0019]    The above and other objects, features and advantages of certain exemplary embodiments of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0020]      FIG. 1  is a schematic representation of an embodiment of the present invention; 
           [0021]      FIGS. 2   a  and  2   b  show heater and sensing electrodes of an embodiment of the present invention; 
           [0022]      FIGS. 3   a  and  3   b  show sensor response; 
           [0023]      FIGS. 4   a  and  4   b  show NH 3  sensing and sensor response when exposed only to CO 2 ; 
           [0024]      FIG. 5  shows NH 3  sensing with a CO 2  filter; and 
           [0025]      FIG. 6  provides a block diagram of an apparatus of an embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    The below description of detailed construction of preferred embodiments provides a comprehensive understanding of exemplary embodiments of the invention. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Descriptions of well-known functions and constructions are omitted for clarity and conciseness. 
         [0027]    Analysis of breath and skin emission samples for diagnostic purposes has the advantage that the sample to be analyzed is collected from the patient in a non-invasive manner with a minimum of discomfort or inconvenience. Basic components of the medical device used for analysis in accordance with a preferred embodiment of the present invention are shown in  FIG. 1 . In preferred embodiments of the invention, breath samples are quantitatively and qualitatively processed. Notably, the sensor is tuned to detect NH 3  levels lower than 50 parts per billion (&lt;50 ppb) and as high as 500 ppm, thereby covering all NH 3  levels encountered in humans, and in particular in patients undergoing UBT. Quantitative analyzers preferably include a sensing substrate surrounded by a gold substrate surrounded by a TO8 substrate. The medical to device of the present invention is preferably qualitatively used, to test for presence of an exhaled gas an/or gas emitted from a person&#39;s skin. 
         [0028]    Qualitative tests performed by the present invention fall into two general types. First, the presence of the breath component alone may be significant to the health of the patient. This is particularly important where the chronic monitoring of the breath components of the patient indicate the absence of a component and that component appears in a new breath sample analysis. The converse change may also be significant, that is, a component formerly present is absent in the new breath sample analysis. A device in accordance with the present invention detects both conditions if maintenance of a patient&#39;s specific data history is desired and preserved in memory. 
         [0029]    It can be significant that a newly detected component falls within a given range and the qualitative assessment of this newly detected component can be obtained using the medical device of the present invention. This is important where it is necessary to alert an attending physician whether the course of treatment, e.g. diet control, either for weight loss or for diabetes is actually working as desired. In accordance with embodiments of the present invention, data from a particular patient is stored so that multiple samples over an extended period of time may be taken. This permits a baseline to be established for a particular patient, and trend analysis is performed on the resulting data, relative to the database of spectroscopic breath profiles. If there is an acute and significant change in the chronic condition of the patient&#39;s breath, indications of this change may be communicated to a physician or healthcare provider via communications components linked to the computer. 
         [0030]    The types of tests that may be employed include carbon dioxide content, alcohol content, lipid degradation products, aromatic compounds, thio compounds, ammonia and amines or halogenated compounds. As an example of the usefulness of detecting these components, lipid degradation products such as breath acetone are useful in monitoring diabetes. Compounds such as methanethiol, ethanethiol, or dimethyl sulfides have diagnostic significance in detecting widely differing conditions, such as psoriasis and ovulation. Increased ammonia has been associated with hepatic disease, although the present invention is not limited to detection of ammonia levels. Halogenated compounds may be indicative of environmental or industrial pollutants. 
         [0031]    A baseline or breath composition history for a particular patient may also be compiled using the present invention. In this embodiment, an initialization test is first run on a sample of the patient&#39;s exhaled breath, with additional samples analyzed thereafter. As additional samples are analyzed and stored in memory at specific times over an extended period of time, the last stored or baseline sample data is then recalled from memory and the change or delta information between the new sample data and stored sample data is determined. 
         [0032]    In a preferred embodiment, multiple different tests performed on a single sample may be independent, or may be the result of several tests combined to produce a template or pattern representative of a patient&#39;s condition or representative of the presence of a particular compound or set of compounds. The high sensitivity of the nanomorphs of metal oxides prepared by sol-gel practices used in the medical device of the present invention are both more selective and more quantitatively precise than similar information obtained by currently available electronic nose technology. As a result, correlating the data pattern or changes in the data pattern over time identifies a wider range of conditions or compounds. 
         [0033]    The present invention departs from detection of  13 CO 2  and provides a simplified assay that uses unlabeled urea as a substrate and detect ammonia in breath instead of CO 2  utilizing Equation (1): 
         [0000]      CO(NH 2 ) 2 +HOH—urease→CO 2 +2NH 3   (1)
 
         [0000]    In an embodiment of the present invention, a nanosensor is provided to detect breath ammonia and a simple, portable, inexpensive hand-held device is thereby provided to detect breath NH 3 . The nanosensor is tuned according to the method described below for other breath gases, and the nanosensor is in a preferred embodiment provided as a plug-in component. The sensor is constructed of a metal oxide that is not crystalline, raising sensitivity to ammonia and other gases. 
         [0034]    In  FIG. 1 , a gas sample, i.e. breath or skin emission, accesses analyzer  110  via entry and exit orifices  102  and  104 . A stainless steel chamber preferably connects the orifices to avoid absorption/distortion. Sensing electrode  122  and heater electrode  124  are positioned within the analyzer  110 . The sensing electrode  122  includes a sensor  130  having gold substrate  132 , sensing substrate  134  and TO8 substrate  136 . Heater and sensing electrodes  122  and  124  of an embodiment of the present invention are shown in  FIGS. 2   a  and  2   b . Those of skill in the art recognize use of the TO8 substrate. Hirata et al. in U.S. Pat. No. 5,252,292, the contents of which are incorporated by reference herein, disclose a type of ammonia sensor. 
         [0035]    In the present invention, the sensing electrode  124  is selectively tuned by spin or drop coating of sensing substrates generating film of MoO 3 . In a preferred embodiment, a gel-sol synthesis was employed to produce three-dimensional (3-D) networks of nanoparticles, with the sol-gel processing preparing a sol, gelating the sol and removing the solvent. Molybdenum trioxide (MoO3) was prepared by an alkoxide reaction with alcohol according to Equation (2): 
         [0000]      Molydenum (VI) Isopropoxide+1-Butanol→Precursor(0.1M)  (2)
 
         [0036]    The prepared sol was spin coated and drop coated onto sensing substrates generating thin films of MoO 3 . The sensing substrates (3 mm×3 mm) were made of Al 2 O 3  and were patterned with interdigitated Pt electrodes. Pt heater electrodes were embedded on the rear of the sensor. The amorphous films were then calcined at higher temperatures generating polymorphic form. Differential scanning calorimetry confirmed the phase transformation. 
         [0037]      FIG. 3   a  shows sensor response to NH 3 , with the sensor generating a clear and measurable response to two NH 3  concentrations, 50 and 100 ppb. The measured amounts of ppb, i.e. parts per billion, are much lower than amounts typically expected in human breath, allowing for more accurate and expedited measurement and results.  FIG. 3   b  shows sensor response to various breath gases, and the specificity regarding same. Shown in  FIG. 3   b  are NH 3 , NO 2 , NO, C 3 H 6  and H 2 , gases that potentially interfere with NH 3  determination. 
         [0038]      FIG. 4   a  shows NH 3  sensing without a CO 2  filter, as gas-sensing properties of the nanosensor. As shown in  FIGS. 4   a - b , when the sensor was exposed to various concentrations of NH 3  gas in a background mixture of N 2  and O 2  simulating ambient air, NH 3  was detected easily, down to 50 ppb, and even lower concentrations. 
         [0039]    In  FIG. 4   a , CO 2  and NH 3 , each at 1 ppm, produce similar responses to gas pulses, shown as vertical lines in  FIG. 4   a . Sensor response when exposed only to CO 2  gas, in the presence of the CO 2  filter, is shown in  FIG. 4   b . The CO 2  filter completely eliminates CO 2  from the gas stream, abrogating the sensor response to it. 
         [0040]    Sensor specificity, in regard to sensing of NH3, was evaluated by exposing the sensor to various gases typically encountered in human breath, including NO 2 , NO, C 3 H 6 , and H 2 , each up to 490 ppm. Conductivity changes were measured in dry N 2  with 10% O 2 . At 440° C. the film was very sensitive to NH 3 , with 490 ppm increasing the conductivity by approximately a factor of 70, approximately 17 times greater than the response to the other gases. The NH 3  response, however, was relatively unaffected by 100 ppm of NO 2 , NO, C 3 H 6 , and H 2 . X-ray photoelectron spectroscopy (XPS) showed that the increased conductivity in the presence of NH 3  was accompanied by a partial reduction of the surface MoO 3 . The resistance of the films increased after extended time at elevated temperatures. 
         [0041]    CO 2  is an important component of human breath, with concentration in expired breath reaching up to 5%. Under test conditions, CO 2  interfered with NH 3  sensing. To overcome this limitation, a commercially available CO 2  filter (NaOH premixed with Vermiculite (V-lite) used in a 10:1 ratio; Decarbite absorption tube, PW Perkins and Co) was used. Decarbite reacts only with highly acidic gases such as CO 2 , H 2 S, thus excluding the possibility of cross adsorption; and the latter was verified. Exposing the sensor to various concentrations of NH 3  and CO 2 , in the presence of N 2  and O 2 , indicated that the presence of CO 2  did not affect NH 3  sensing. This was found to be true even when the two gases were at equal concentrations ranging between 0.5 and 10 ppm. Representative results of the evaluation of CO 2  interference with the NH 3  assay are shown. It was noted that the NaOH Decarbite traps CO 2  more efficiently at high CO 2  concentrations, and the data shown in  FIGS. 4   a - b  are from experiments with a low CO 2  concentration (1 ppm).  FIG. 5  shows NH 3  sensing with a CO 2  filter. In  FIG. 5 , the sensor is exposed to NH 3  in the presence of the filter, with no interference of the measurement.  Combining NH 3  and CO 2  generated similar results, with the filter eliminating the experimental 1 ppm of CO 2  in the gas stream. Even at low concentrations, interference by CO 2  is eliminated. 
         [0042]    Operation of apparatus of the present invention is based on sensor response modifying electrical resistance. That is, the MoO3 sensor is prepared with properties required for its intended use, with lower limits of detection for NH 3  well below the NH 3  concentrations typically found in human breath and, of course, below the increased NH 3  levels of a positive UBT. 
         [0043]    In a preferred embodiment, MoO 3  nanosensor determines parameters of human breath and potentially interfering substances, such as those generated by  H. pylori  are detected.  FIG. 6  shows a prototype for sensing breath, having a sensor, acquisition module, memory/computation module and displays. 
         [0044]    While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.