Abstract:
A breath alcohol testing device has a removable tamper-resistant sampling chamber assembly that provides a disposable interface between the test subject and the alcohol sensor, other sensors and electronics of the testing device. Hydrophobic membranes prevent bodily fluids and other liquids from entering the alcohol sensor and other sensitive components of the testing device. A set of chambers with one-way valves direct the gas flow within the sample chamber assembly to ensure the breath sample delivered to the alcohol sensor is not diluted by the subject inhaling, and is a deep-lung breath sample.

Description:
RELATED APPLICATION 
     The present application is based on and claims priority to the Applicant&#39;s U.S. Provisional Patent Application 62/010,912, entitled “Removable Tamper-Resistant Breath Alcohol Sampling System,” filed on Jun. 11, 2014. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates generally to the field of breath alcohol testing devices. More specifically, the present invention discloses a removable tamper-resistant breath alcohol sampling system for use in a breath alcohol testing device. 
     Statement of the Problem 
     Breath alcohol testing systems have been widely used for many years. These systems typically require the test subject to exhale a breath sample into a mouthpiece attached to a sampling system and an alcohol sensor. The alcohol sensor can be an electrochemical fuel cell that oxidizes any alcohol present in the breath sample and outputs an electrical signal based on the amount of alcohol present in the sample. Many such systems rely on valves and precision pumps between the mouthpiece and the alcohol sensor to ensure that a predetermined sample volume flows into the alcohol sensor to allow accurate calibration of the testing system. The mouthpiece is typically disposable and is intended only for use with one test subject. 
     While these prior-art systems replace the mouthpiece from test subject to test subject, none replace the sampling system components where exhaled microbes can reside and potentially transmit disease from subject to subject. These systems are reliant on precise activation of sampling pumps to draw a predetermined volume of the exhaled breath sample into the fuel cell. Test subject inhalation during the sampling process could result in potential exposure to microbes contained in a prior test subject&#39;s exhaled breath. Another key shortcoming of the disposable mouthpiece is that it is difficult to obtain data on the characteristics of the breath sample exhaled by the subject, such as temperature, volume, and absolute pressure. 
     A variety of sampling systems been used as components in these breath alcohol testing units. For example, U.S. Pat. No. 4,707,336 (Jones) discloses a breath alcohol testing instrument having a removable mouthpiece attached to a gas sampling system containing an alcohol sensor and pressure sensor to measure breath alcohol content. The removable mouthpiece is intended to assist in preventing human fluid and disease transmission from subject to subject. No provision is made to replace sampling system components between test subjects other than the mouthpiece. 
     Many stationary breath alcohol testing devices utilize 10-12 inch long heated tubes attached to a sampling system and alcohol sensor. These heated tubes are a very positive environment for growth of microorganisms. The heated tube is intended stabilize the alcohol content in the breath sample by preventing condensation that can affect the alcohol content of the breath alcohol sample over such a long distance. The use of a pressure sensor attached to the mouthpiece has been known since the late 1980&#39;s to automate the sampling process, as shown for example in the Jones patent. While these approaches are helpful in minimizing disease transmission, these measures have limited effectiveness. The new class of remote alcohol monitoring devices requires that many tests are taken by a subject over a prolonged period of time (e.g., for six months to a year). The testing device is then returned to the monitoring organization and subsequently reassigned to a new test subject. The prolonged exposure of the testing device and sampling system to an individual who may have a contagious respiratory disease, or a disease that is passed in bodily fluids introduces a new level of disease transmission risk that may not be fully mitigated by a removable mouthpiece alone. 
     The alcohol sensor, other sensors and electronic components of a breath alcohol testing device are relatively expensive, so the entire testing device cannot be disposable. Therefore, a need exists for a breath alcohol testing device with a modular design combining disposable components (e.g., the mouthpiece and sample chamber) that can be replaced for each test subject, with permanent components (e.g., the alcohol sensor, other sensors and electronics). In addition, the sample chamber assembly protects the permanent components of the testing device from contact with bodily fluids or biological contamination. 
     In addition, there is always of the risk of tampering by the test subject in breath alcohol testing, particularly if the subject is attempting to circumvent the alcohol testing program. Tampering can lead to inaccurate test results as well as damaging the testing device. Thus, although authorized personnel must be able to readily disassemble the testing device for maintenance and repair, care must be taken to ensure that test subjects cannot easily tamper with the testing device. 
     Therefore, a need exists for a breath alcohol sampling system having a sampling system that can be readily removed by authorized personnel so that the testing device can be repaired and maintained, but that resists tampering by test subjects. In addition, the sampling system should shield the fuel cell and other components of the testing device from contact with bodily fluids or biological contamination. 
     Solution to the Problem 
     The present invention provides a sampling system for a breath alcohol testing unit that is tamper-resistant, but completely removable from the remainder of the breath alcohol testing unit. The present invention enables replacement of the components and surfaces exposed to potential disease-causing microorganisms and saliva mist. Bodily fluids are blocked from entering the alcohol sensor and sensor measurements systems, thereby preventing damage and subsequent transmission to new test subjects. In addition, the sample chamber is tamper-resistant due to a unique wire lock and locking sample chamber cap system. 
     SUMMARY OF THE INVENTION 
     This invention provides a removable tamper-resistant sampling chamber assembly for a breath alcohol testing device. The sampling chamber assembly provides a disposable interface between the test subject and the alcohol sensor, other sensors and electronics of the testing device. Hydrophobic membranes prevent bodily fluids and other liquids from entering the alcohol sensor and other sensitive components of the testing device. In addition, a set of chambers with one-way valves direct the gas flow within the sample chamber assembly to ensure the breath sample delivered to the alcohol sensor is not diluted by the subject inhaling, and is a deep-lung breath sample. 
     These and other advantages, features, and objects of the present invention will be more readily understood in view of the following detailed description and the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention can be more readily understood in conjunction with the accompanying drawings, in which: 
         FIG. 1  is an exploded perspective view of a breath alcohol testing device  10  with a removable sample chamber assembly  20 . 
         FIG. 2  is a perspective view of the assembled breath alcohol testing device  10  corresponding to  FIG. 1 . 
         FIG. 3  is an exploded perspective view of the sample chamber assembly  20  corresponding to  FIGS. 1 and 2 . 
         FIG. 4  is a cross-sectional view of the sample chamber assembly  20  showing the flow paths of the breath sample. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 and 2  are perspective views showing an embodiment of the present invention. As a general overview, the main housing of the breath alcohol testing device  10  contains the major non-disposable components of system, such as an alcohol sensor (e.g., a fuel cell), other sensors for biometric identification and test validation, and associated electronics. The sample chamber assembly  20 , mouthpiece  70  and sample chamber cap  60  are disposable components that removably attach to the unit, as shown in  FIG. 2 , and are intended to be replaced for each test subject. The sample chamber assembly  20  includes an inlet port into which the test subject exhales, and controls the gas flow into and through a sample chamber used by the alcohol sensor. 
     The sample chamber assembly  20  is removably attached to the top of the main housing of the testing device  10  by means of a locking wire clip  65  and sample chamber cap  60 , as depicted in the exploded view in  FIG. 1 . The sample chamber cap  60  locks onto prongs on the sample chamber assembly  20  as depicted in  FIGS. 1 and 3 . A removable medically-clean mouthpiece  70  (shown in  FIG. 1 ) is then placed onto the sample chamber inlet  25  in preparation for use by a testing subject. The sample chamber assembly  20  is easily removed by pressing a 0.5 in. wide blade through the sample chamber cap  60  vents to release the retaining hooks on the top of the main housing of the testing device  10 , and thereby allow removal of the sample chamber cap  60  and wire clip  65 . Once the wire retaining clip  65  is removed from the sample chamber base, the sample chamber assembly  20  is simply lifted off the main housing of the testing device  10 . 
       FIG. 3  depicts the components that make up the sample chamber assembly  20 .  FIG. 5  illustrates the air flow through the sample chamber assembly  20 . The removable mouthpiece  70  is placed on the inlet  25  of the sample chamber assembly  20 . The subject then exhales into the inlet  25 . The exhaled breath passes into the inlet chamber  30  and then passes through a fixed outlet or orifice  33  of a known size covered by a one-way flapper valve  32 . This provides a pressure buildup within the inlet chamber  30  to allow a series of pressure measurements to be taken by a pressure sensor  14  over time during exhalation. Other types of one-way valves could be substituted. 
     A processor with data storage can be used to store and analyze readings from the pressure sensor  14  to provide information on the volume of the exhalation to along with other spirometric data. The temperature of the breath sample can also be measured by a temperature sensor  12  shown in  FIG. 4 . This breath temperature data and spirometric data may be utilized to ensure that a high-quality breath alcohol sample has been acquired and assist in providing test subject identification. It should be noted that other types of sensors could also be included. as needed. Such sensors can be described in general as biometric sensors. 
     The biometric sensor array  12 ,  14  is preferably located within the main housing of the testing device  10 . These biometric sensors  12 ,  14  are connected to the inlet chamber  30  in the sample chamber housing  20  via a sensor port  35 , shown in  FIGS. 3 and 4 . The sensor port  35  extends downward into a corresponding opening in the top of the main housing of the testing device  10 , as shown in  FIG. 1 , which leads to the sensor array  12 ,  14 . The sensor port  35  is protected by a hydrophobic membrane  36  to assure that bodily fluids cannot readily escape the inlet chamber  30  and enter the pressure sensor  14  or temperature sensor  12 . 
     Returning to the gas flow path illustrated in  FIG. 4 , the exhaled breath then travels from the inlet chamber  30  through the outlet  33  and one-way valve  32  into the sample chamber  40 . This one-way valve  32  prevents backflow of gas from the sample chamber  40  into the inlet chamber  30 . Excess gas in the breath sample is expelled from the sample chamber  40  through an outlet at the top of the sample chamber  40  (e.g., via an orifice with a second one-way flapper valve  42  and the vents in the sample chamber cap  60 ). The combination of one-way valves  32  and  42  ensure the test subject can only exhale, but not inhale through the sample chamber  40  and dilute the sample with fresh air. Sample dilution is a major problem for many conventional open-tube type mouthpieces. 
     The combination of one-way valves  32 ,  42  also ensures that gas from the end-phase of the test subject&#39;s breath sample is trapped in the sample chamber  40 . This end-phase exhaled gas tends to be from deep within the lungs, and provides a higher-quality breath sample. 
     The alcohol sensor  16  and sampling pump  18  are located with the main housing of the testing device  10 , as previously noted. An alcohol sensor port  45  and an exhaust port  55  extend downward from the bottom of the sample chamber assembly  20 , as depicted in  FIGS. 3 and 4 , and removably insert into corresponding openings in the top of the main housing of the testing device  10  leading to the alcohol sensor  16  and sampling pump  18 . 
     The last step of the sampling process occurs when the pressure drops to zero or ambient pressure levels triggering the sampling pump  18  to pull a predetermined sample from the sample chamber  40  into the alcohol sensor (e.g., fuel cell  16 ) via the sample chamber port  45 . After analysis, the breath alcohol sample is then expelled from the fuel cell  16  through the exhaust port  55  and sample chamber cap  60  ports. 
     The alcohol sensor port  45  is protected by a second hydrophobic membrane  46  (such as manufactured by Pall Corporation or W. L. Gore &amp; Associates) to ensure that no bodily fluids can escape the sample chamber  40  and enter the alcohol sensor  16  or sampling pump  18 . The exhaust port  55  is also protected by a third filter  56  (e.g., a hydrophobic membrane), as shown in  FIGS. 3 and 4 . Thus, it should be noted that the hydrophobic membranes  36 ,  46  and  56  prevent bodily fluids and other liquids from escaping the sample chamber assembly  20  and entering the alcohol sensor  16 , sensor array  12 ,  14  or the exhaust port  55 . Preferably, all of these ports  35 ,  45  and  55  form relatively tight seals with their corresponding openings in the main housing, and include O-rings to minimize to possibility of liquids or dirt finding their way into the interior of the testing device  10 . The present sample chamber assembly  20  is a significant improvement in the art providing significant strides in user disease prevention, and protecting sensitive sensor arrays from dirt, bodily fluids, water, and tampering while enhancing data acquisition from a breath alcohol sample. 
     The above disclosure sets forth a number of embodiments of the present invention described in detail with respect to the accompanying drawings. Those skilled in this art will appreciate that various changes, modifications, other structural arrangements, and other embodiments could be practiced under the teachings of the present invention without departing from the scope of this invention as set forth in the following claims.