Patent Application
20200069295
The present invention relates to a custom filter assembly which utilizes a conventional “off-the-shelf” hydrophobic filter media component in which the custom filter assembly is designed to have a very low internal volume or dead space so as to minimize, during use, turbulent flow of a gas flowing through the hydrophobic filter media component.
As is well known in the art, inline filters are provided for microfiltration of exhaled gases used for medical sampling applications. Such filter are designed to prevent moisture and other undesirable particles from flowing/ingressing into medical sampling instrumentation. It is to be appreciated that if undesired liquid and particles ingress into medical instrumentation, such ingress eventually leads to loss of functionality of the medical sampling instrumentation and/or damage to the medical sampling instrumentation.
Long term usage of medical sampling devices, such as an EtCO2 sampling cannula, necessitates the filtration and separation of moisture as well as other contaminants from the sampled gas, prior to that sampled gas entering into a sampling port of the medical sampling instrumentation. It is to be appreciated that exhaled breath, which mixes with ambient air that is colder than body temperature, will increase the relative humidity of that moisture rich exhaled breath. If the relative humidity rises to 100%, for example, then condensation of the breath typically occurs. Such condensation will be drawn in, via an inlet of a sampling device, e.g., a cannula, and flow towards the hydrophobic filter which is located downstream of the sampling device but upstream of the medical sampling instrumentation, to filter and remove this undesired moisture.
As is well known in the art, moisture and other biohazard contaminants, such as microbes, mucosal secretions, skin cells, hair, particulates, etc., can flow along a sampling line and be delivered to the medical sampling instrumentation together with the collected gas sample. It is to be appreciated that such contaminants can degrade the sensor electronics and/or create potential occlusions within the medical instrument itself thereby adversely affecting the performance and/or accuracy of the medical instrumentation.
While a number of off-the-shelf filter assemblies, equipped with a hydrophobic media, are currently available, they suffer from a number of associated drawbacks. For example, the internal volume of such know filter assemblies, which accommodate the hydrophobic media, are not optimized and thus such known filter assemblies tend to cause undesired mixing and turbulent flow of the exhaled gases, within the filter assembly, which leads to a compromised waveform as well as inaccurate measurements by the medical sampling instrumentation.
It is to be appreciated that a hydrophilic media promotes the transfer of liquids which defeats the purpose of a moisture barrier designed to protect the medical sampling instrumentation. It is noted that hydrophilic media is generally available in greater supply and in different formats (e.g., hollow fiber, membrane, etc.) due to higher demand in the liquid processing industry. Hydrophobic filter media, on the other hand, is not as readily available and this, in turn, makes sourcing off-the-shelf turnkey filter assemblies somewhat more challenging, difficult and expensive.
Wherefore, it is an object of the present disclosure is to overcome the above mentioned shortcomings and drawbacks associated with the prior art filter assemblies.
Another object of the present disclosure is to provide a custom filter assembly which utilizes a conventional off-the-shelf hydrophobic filter media component in which the custom filter assembly is designed to have a very low internal volume or dead space and is also designed to reduce turbulent flow through the hydrophobic filter media component while the exhaled gas is filtered by the filter assembly.
A further object of the present disclosure is to captively retain the hydrophobic filter media component, between the inwardly facing surfaces of the first and the second enclosures, and thereby minimize the associated volume or dead space of the internal chamber which is defined by and between the inwardly facing surfaces of the first and the second enclosures.
Still another object of the present disclosure is to minimize the associated expense and labor in connection with manufacturing and assembling the custom filter assembly.
Yet another object of the present disclosure is to sandwich a conventional off-the-shelf hydrophobic filter media component between the pair of inwardly facing surfaces of the first and the second enclosures so as to prevent movement thereof.
A still further object of the present disclosure is to induce generally laminar flow along the channels and through the custom filter assembly so that the exhaust gas is filtered, by the custom filter assembly, on a first in/first out basis with the exhaust gas experiencing minimal turbulence as such gas flows through the filter assembly.
A further object of the disclosure is to provide a custom filter system which is capable of filtering exhaust gases at the rate of about 50 millimeters per minute.
The present invention also relates to a filter assembly for filtering an exhaust gas and preventing a contaminate from reaching a medical sampling instrumentation, the filter assembly comprising: a hydrophobic filter media component; a first enclosure having a first port communicating with an inwardly facing surface carrying a plurality of first channels, a first annular sidewall surrounding the first channels, and the first annular sidewall carrying a mating feature at a free end thereof; a second enclosure having a second port communicating with an inwardly facing surface carrying a plurality of second channels, and a mating second feature surrounding the second channels; and the first and second enclosures matingly engaging with one another so that the first and the second mating features mate with one another and the first and second enclosures define a sealed filter chamber therebetween which captively retains the hydrophobic filter media component within the filter chamber such that the filter assembly has minimal dead space.
The present invention also relates to a method of filtering an exhaust gas and preventing a contaminate from reaching a medical sampling instrumentation, the method comprising: providing a hydrophobic filter media component; providing a first enclosure having a first port communicating with an inwardly facing surface carrying a plurality of first channels, a first annular sidewall surrounding the first channels, and the first annular sidewall carrying a first feature at a free end thereof; providing a second enclosure having a second port communicating with an inwardly facing surface carrying a plurality of second channels, and a second mating feature surrounding the second channels; and matingly engaging the first and second enclosures with one another so that the first and the second mating features mate with one another and the first and second enclosures define a sealed filter chamber therebetween which captively retains the hydrophobic filter media component within the filter chamber such that the filter assembly has minimal dead space
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate various embodiments of the invention and together with the general description of the invention given above and the detailed description of the drawings given below, serve to explain the principles of the invention. The invention will now be described, by way of example, with reference to the accompanying drawings in which:
It should be understood that the drawings are not necessarily to scale and that the disclosed embodiments are sometimes illustrated diagrammatical and in partial views. In certain instances, details which are not necessary for an understanding of this disclosure or which render other details difficult to perceive may have been omitted. It should be understood, of course, that this disclosure is not limited to the particular embodiments illustrated herein.
The present invention will be understood by reference to the following detailed description, which should be read in conjunction with the appended drawings. It is to be appreciated that the following detailed description of an embodiment is by way of example only and is not meant to limit, in any way, the scope of the present invention.
Turning first to
While the second enclosure 6 is described as being the inlet (second) port 10 for receiving the exhaust gas from a gas sampling device 11 and the first enclosure 4 is described as being the outlet (first) port 12 for discharging the filtered exhaust gas from the custom filter assembly 2 and supplying the same to a desired medical sampling instrumentation 13, it is to be appreciated that their rolls may be reversed. That is, the first (outlet) port 12 of the first enclosure 4 may be connected to the gas sampling device 11 for receiving the exhaust gas therefrom while the second (inlet) port 10 of the second enclosure 6 may be connected to medical sampling instrumentation 13 for discharging the filtered exhaust gas from the custom filter assembly 2 and supplying the same thereto, without departing from the spirit and scope of the present invention.
Now turning to
An annular sidewall 20 surrounds in the inwardly facing surface 16 of the first enclosure 4 and extends substantially normal thereto. A remote, free end of this annular sidewall 20 carries a tapering tip or an annular tongue 22, the purpose and function of this annular tongue 22 will become apparent from the following description. The annular sidewall 20 is shaped and sized to closely receive and accommodate a perimeter surface of the hydrophobic filter media component 8 on the inwardly facing surface 16 of the first enclosure 4. The annular sidewall 20 typically has a height of between 0.060 inches and 0.015 inches, generally about 0.032 inches.
A (first) outlet extension 24 is formed integral with and extends away from a main body of the first enclosure 4 and this outlet extension 24 defines the exhaust gas first (outlet) port 12 of the custom filter assembly 2. As shown in
A second extension 26 extends away from the first enclosure 4 in an opposite direction to the first outlet extension 24. As shown in
Turning now to
A mating annular groove 38 is formed in the inwardly facing surface 34 of the second enclosure 6 and this annular groove 38 extends substantially normal to the inwardly facing surface 34. The mating annular groove 38 is sized, shaped and located to receive and captively retain the annular tongue 22 of the first enclosure 4 during assembly. The annular groove 38 is also sized and shaped so as to be slightly larger in size than a perimeter surface of the hydrophobic filter media component 8 so as to facilitate completely receiving, accommodating and captively retaining the same. The annular groove 38 typically has a depth of between 0.030 inches and 0.005 inches, generally about 0.019 inches. If desired, the sidewalls of the annular groove 38 may taper inwardly somewhat toward one another. When the first and the second enclosures 4, 6 mate with one another, as shown in
After the first and the second enclosures 4, 6 are assembled with one another as generally shown in
As shown in
Since the lateral regions of both the first and second enclosures 4, 6 are not provided with any first or second channels 18, 36, substantially none of the supplied exhaust gases will flow or be filtered by such lateral regions of the hydrophobic filter media component 8. That is, all of the filtering of the exhaust gases occurs primarily through the hydrophobic filter media component 8 which is located between and separates the first channels 18 from the second channels 36.
An inlet extension 44 extends away from a main body of the second enclosure 6 and this inlet extension 44 defines the exhaust gas second (inlet) port 10 for receiving exhaust gases to be filtered by the filter assembly 2. The second (inlet) port 10 typically has a constant diameter along the length thereof which then transitions into a reduce diameter before the second (inlet) port 10 eventually turns or bends and then terminates as an opening formed in the inwardly facing surface 34 of the second enclosure 6. As shown, after the bend or turn, the size or the diameter of the inlet (second) port 10 again increases in size.
An outwardly facing surface 46 of the inlet extension 44 carries a second (male) interlocking feature 48, e.g., an oval shaped boss or some other interlocking feature, which is sized and shaped to mate closely with and be received by the centrally located first (female) interlocking feature 28, e.g., the elongate slot of the first enclosure 4, to thereby couple and interconnect the first and second enclosures 4, 6 with one another. The mating engagement between the mating male and female or interlocking features 28, 48 prevents rotation of the first enclosure 4 relative to the second enclosure 6.
Once the first and the second enclosures 4, 6 are connected with one another, as generally shown in
After the mating male and female or interlocking features 28, 48 are welded together, the hydrophobic filter media component 8 occupies substantially all of the spaced defined within the filtered chamber 42 except for the first and the second channels 18, 36, thereby minimizing the unoccupied volume or the dead space contained within the filtered chamber 42. That is, a first surface of the hydrophobic filter media component 8 generally directly engages with the inwardly facing surface 16 of the first enclosure 4, or is possibly spaced a very small distance therefrom, e.g., less than 0.010 of an inch and more preferably less than 0.005 of an inch, while a second surface of the hydrophobic filter media component 8 generally directly engages with the inwardly facing surface 34 of the second enclosure 6, or is possibly spaced a very small distance therefrom, e.g., less than 0.010 of an inch and more preferably less than 0.005 of an inch.
The first channels 18 together define a total volume of between 0.0632 mL (minimum) and 0.103 mL (maximum), typically about 0.0843 mL, while the second channels 36 together also define a total volume of between 0.0632 mL (minimum) and 0.103 mL (maximum), typically about 0.0843 mL and the hydrophobic filter media component 8 separates first channels 18 from the second channels 36. The thickness of the custom filter assembly 2, measured from the outwardly facing surface 14 of the first enclosure 4 to the outwardly facing surface 32 of the second enclosure 6, is generally between 0.665 inches and 0.250 inches, typically about 0.372 inches, and is thus low profile.
The conventional off-the-shelf hydrophobic filter media component 8 typically has a diameter of less than 1.0 inch, generally less than 0.996 inches, a thickness typically between 155 μm (minimum) and 185 μm (maximum), generally about 170 μm and a porosity of about 0.2 microns. The hydrophobic filter media component 8 is designed to filter the supplied exhaust gases and remove moisture and other contaminants, such as microbes, mucosal secretions, skin cells, hair, particulates, etc., therefrom as the exhaust gases pass through the hydrophobic filter media component 8 of the filter assembly 2 and thereby prevent such moisture and contaminants from flowing toward and into the medical sampling instrumentation 13.
While both the first and the second enclosures 4, 6 are shown as being circular in shape and the annular sidewall of the first enclosure 4 is shown as being substantially cylindrical in shape, it is to be appreciated that the first and the second enclosures 4, 6 and the annular sidewall of the first enclosure 4 can have a variety of other different shapes and sizes without departing from the spirit and scope of the present invention. The most important aspect is that the first and the second enclosures 4, 6 together define a sealed filtering chamber 42 therebetween which defines a minimal dead space therein.
While the above disclosure indicates that the filter assembly 2 has four parallel channels 18, 36, it is to be appreciated that the overall number, size, location, shape, etc., of each one of the channels 18, 36 can varied from application to application without departing from the spirit and scope of the present invention. The important aspect is that the channels 18, 36 are designed to reduce the overall size of the dead space within the filter chamber 42 as well as minimize turbulence of the exhaust gases as such gases flow through and are filtered by the off-the-shelf hydrophobic filter media component 8 within the filter chamber 42 of the filter assembly 2.
It is to be appreciated that the annular tongue 22 and the annular groove 40 may, instead of being welded, possibly be glued, fused, or otherwise permanently affixed or connected to one another in a conventional manner to form the sealed filtered chamber 42 with the hydrophobic filter media component 8 being captively retained therein, without departing from the spirt and scope of the present invention.
Preferably the hydrophobic filter media component 8 is relatively thin and is disc shaped so as to be closely and captively received by and between the inwardly facing surfaces of the first and second enclosures 4, 6.
The first and second enclosures 4, 6 are preferably each injection molded from a plastic material, such as acrylonitrile butadiene styrene (ABS), acrylic, polycarbonate, etc. Due to the low profile of the filter assembly 2, the overall axial length L of the filter assembly 2, from an end face of the outlet (first) port 12 to an end face of the second (inlet) port 10, is at least three times overall height H of the filter assembly 2—see
While a single embodiment of the present invention is described in detail, it is apparent that various modifications and alterations of that embodiment will occur to and be readily apparent to those skilled in the art. However, it is to be expressly understood that such modifications and alterations are within the scope and spirit of the present invention, as set forth in the appended claims. Further, the invention(s) described herein is capable of other embodiments and of being practiced or of being carried out in various other related ways. In addition, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items while only the terms “consisting of” and “consisting only of” are to be construed in a limitative sense.
The foregoing description of the embodiment of the present disclosure is presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the present disclosure to the precise form disclosed. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the present disclosure be limited not by this detailed description, but rather by the claims appended hereto.
