Abstract:
A liquid sample collection device is provided. The liquid sample collection device comprises a housing including a liquid collection chamber, and a liquid supply conduit extending from an inlet port and in use generally downwardly to the collection chamber, wherein the collection chamber includes an air vent port located such that in use liquid supplied to the collection chamber through the liquid supply conduit displaces air through the air vent port, and wherein the liquid supply conduit follows a meandering path including at least one air trap section defined at the junction between portions of the conduit extending with upward and downward components respectively, whereby in use once the air vent port is closed, air is displaced along the liquid supply conduit until it is trapped by the air trap section thereby preventing further liquid flow through the conduit.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a liquid sample collection device for targeting, separating and isolating a specific portion of a continuous stream of liquid to be collected. 
       DESCRIPTION OF BACKGROUND ART 
       [0002]    Biomarkers, micro-organisms, proteins, DNA and chemicals are often suspended in a liquid or transported by a liquid flow. It is often desirable to collect such liquids for storage, processing or to detect the presence, concentration, state, or other property of the suspended matter. Collecting such a liquid often requires instigating a flow or stream of the liquid from its reservoir to a collection receptacle. An example of a liquid containing suspended matter which is collected from a liquid stream is urine. 
         [0003]    Traditionally urine is collected by asking the patient to fill a cup to a level marked on the side. This is often imprecise, and it is common for patients to overfill or underfill the cup. Furthermore, in urine collection for STI (sexually transmitted infection) testing, the first part of the stream is regarded as that which provides the most useful sample, containing the highest concentration of suspended matter detected in STI tests. Collecting and isolating this first portion of the stream would therefore lead to improved sensitivity and specificity of testing. Conversely, it may be desirable to target a later portion of the liquid stream, in which there is a lower concentration of suspended matter detected in STI testing. 
         [0004]    It is therefore desirable to allow for sample collection which targets a specific portion of a liquid stream and ensures that the targeted portion is isolated to prevent dilution by liquid from other portions of the stream. 
         [0005]    A number of liquid sample collection devices which target specific portions of a liquid stream are known. 
         [0006]    US 2006/0184064 A1 discloses a urine collection device which redirects a first portion of the urine flow and collects a “mid-stream” portion of the urine flow. The device comprises a support apparatus which, in use, sits on top of a conventional toilet seat. The apparatus features a flow divider which comprises a chamber with a hole, through which the first portion of the urine steam flows. The rate at which urine flows through the hole is much slower than the typical rate that urine enters the chamber, leading to an increasing liquid level. As the liquid level increases, it overflows the chamber and is directed to an attachment section where a sample cup collects the overflow. 
         [0007]    US 2006/0184064 A1 comprises an overflow chamber, in which the urine to be collected mixes before overflowing into the sample cup thereby resulting in contamination of different portions of the stream. 
         [0008]    WO 2004/010873 A1 discloses a liquid sampler for sampling a first portion of a liquid flow. The sample entering the device passes through a valve, which closes once a predetermined volume of liquid is collected. Excess liquid is then directed to waste. 
         [0009]    WO 2010/058210 A1 discloses a device for collecting first pass urine. The device comprises an opening for collecting a urine sample and directing it downstream where a circular orifice opens into a collecting vessel. Urine entering the device flows into the collecting vessel and begins to fill the collection vessel with a first portion of the urine. As the collection vessel fills, a collection member, which floats on the urine, rises up inside the vessel until it blocks the circular orifice into the collection vessel, thereby isolating the first portion of the urine sample from any further urine entering the device. 
         [0010]    Both of WO 2004/010873 A1 and WO 2010/058210 A1 use moving parts which are difficult to manufacture, may contaminate the sample and to which the sample may stick following collection. 
         [0011]    It is therefore desirable to create a liquid sample collection device which does not suffer from the same problems as the liquid sample collection devices known in the art. 
       SUMMARY OF THE INVENTION 
       [0012]    In accordance with a first aspect of the present invention, a liquid sample collection device comprises a housing including a liquid collection chamber, and a liquid supply conduit extending from an inlet port and in use generally downwardly to the collection chamber, wherein the collection chamber includes an air vent port located such that in use liquid supplied to the collection chamber through the liquid supply conduit displaces air through the air vent port, and wherein the liquid supply conduit follows a meandering path including at least one air trap section defined at the junction between portions of the conduit extending with upward and downward components respectively, whereby in use once the air vent port is closed, air is displaced along the liquid supply conduit until it is trapped by the air trap section thereby preventing further liquid flow through the conduit. 
         [0013]    This invention provides a liquid sample collection device with no moving parts that contact the sample, capable of targeting and isolating a first portion of a liquid stream. The device comprises a meandering channel, which forms part of a liquid supply conduit supplying a liquid to be collected from an inlet port generally downwardly into a collection chamber. The collection chamber features an air vent port that connects the collection chamber to the atmosphere and acts as a pressure relief channel. As a liquid sample to be collected flows from the inlet port, through the meandering channel, and into the collection chamber, the air displaced escapes to the atmosphere via the vent port. However, once the vent port is obstructed, any additional liquid entering the collection chamber displaces air back up the meandering channel, where it becomes trapped in a local high point in the channel, thereby forming an air lock. The air lock prevents further liquid entering the collection chamber, and any additional liquid overflows the inlet port and is directed to waste. 
         [0014]    In a particularly preferable embodiment, the air vent port is adapted to be closed, in use, by liquid collected in the collection chamber. In these embodiments, the air vent port may be positioned such that, as liquid collects within the collection chamber, the rising liquid level eventually obstructs the air vent port and engages the air lock. This embodiment is particularly preferable as it results in a device which can target and isolate a first portion of a liquid stream with no moving parts at all, reducing the complexity, manufacture cost and failure rate of the device. While this is preferable, other embodiments are foreseen in which the air vent port is obstructed by the manual closing of a valve along the air vent port. Advantageously, using a device in which the air vent port is obstructed by liquid collecting in the collection chamber results in a device which automatically engages an air lock, removing the need for manual human intervention. In embodiments where the air vent port is adapted to be closed, in use, by liquid collected in the collection chamber, the volume of the sample collected may be predetermined by the positioning of the vent port during manufacture of the device. When the liquid rises to the known level at which it obstructs the vent port, the air lock will take effect almost immediately resulting in a known volume of liquid being held within the collection chamber. 
         [0015]    Preferably, the liquid sample collection device comprises a second air trap section defined at a second junction between portions of the conduit extending with upward and downward components respectively. By providing a second air trap section, located at a second local high point, the device becomes resistant to shaking and overturning. In a case where the device is shaken or overturned once a sample has been collected and an air lock has taken effect, the airlock may move further up the meandering channel to the second air trap section, thereby maintaining an air lock within the device, and preventing escape of the collected sample and further liquid collection by the device. Advantageously, a device comprising two air trap sections would allow a user to turn the device upside down to remove all excess liquid from the device while maintaining the air lock. 
         [0016]    Once a sample is collected, it is desirable to be able to conveniently access and remove the sample from the collection chamber. Therefore, preferably, the liquid sample collection device comprises a sample extraction port configured to allow access to the collection chamber, such that in use a liquid sample stored within the collection chamber may be extracted through the sample extraction port. While preferable, an extraction port is not necessary, and the sample may be extracted via the meandering channel by tipping of the device, or the sample may be tested in situ. An extraction port may simply allow the liquid to be poured out of the device, but preferably would allow the sample to be collected using a device, such as a syringe, without exposing it to contamination by the atmosphere. In order to allow sample extraction without contamination from the environment, it is preferable that the sample extraction port comprises an opening through the housing and extending into the collection chamber, wherein the opening is filled by a plug, such as a solid piece of rubber, adapted to allow a sample to be injected therethrough. A solid piece of rubber would form a membrane which could be pierced by a needle to allow extraction of the sample using a syringe. Once the needle is removed, the rubber would flex back, thereby blocking the channel formed by the needle. In order for the rubber to form a strong seal once a needle has been inserted and removed, it is preferable that the rubber has a Shore hardness equal to or less than A30. While an extraction port comprising a rubber membrane is preferable, other extraction ports are foreseen, such as a Luer lock or screw cap. 
         [0017]    With a sample collected in the collection chamber, it may be desirable to mix the sample with an additive, either immediately after collection or at some point before extraction. Preferably, the liquid sample collection device comprises an additive port configured to allow an additive to be introduced into the collection chamber. While preferable, it is foreseen that devices may alternatively be used which contain an additive already within the collection chamber, ready for immediate mixing with a collected sample. Preferably an additive port comprises an opening through the housing and extending into the collection chamber, wherein the additive port interfaces with a blister pack located external to the housing. In such embodiments, the blister pack would be depressed by a user after collection of a sample to burst the blister and introduce its contents into the collection chamber via the opening in the housing. This is particularly preferable as it allows a user to conveniently mix their sample with an additive immediately after collection. While preferable, it is foreseen that other additive ports may be used. For example, a rubber membrane similar to the above described sample extraction port may be used. The rubber membrane could be pierced by a needle so that a syringe could be used to introduce an additive into the collection chamber. The rubber would flex back upon removal of the needle, thereby blocking the channel formed by the needle and ensuring that liquid within the collection chamber does not leak into the environment. 
         [0018]    Preferably, the air vent port opens into the collection chamber through a side wall of the collection chamber. While preferable, it is also foreseen that the air vent port may open into the collection chamber through a top wall of the collection chamber. 
         [0019]    Preferably, the device further comprises means for closing the vent port in an overturned configuration. Closing the vent port in an overturned configuration allows for an air lock which may be maintained when the device is overturned. The closing of the vent port may be achieved, for example, using a cap inserted into the vent port, or alternatively using a valve in the vent port which may be closed. However preferably, the vent port is closed in the overturned configuration by liquid in the collection chamber. 
         [0020]    According to a second aspect of the present invention, a liquid sample collection system comprises at least two liquid sample collection devices according to the first aspect of the invention, wherein the at least two liquid sample collection devices are connected by an external liquid supply conduit configured to, in use, supply a liquid sample to be collected to the inlet port of the first of the at least two liquid sample collection devices, and when air trapped in the air trap section of the first liquid supply conduit prevents further liquid flowing through the liquid supply conduit of the first liquid sample collection device, supply further liquid sample to be collected to the inlet port of the second of the at least two liquid sample collection devices. Advantageously, using two liquid sample collection devices connected in series allows for a first portion and a second, subsequent portion of a liquid stream to be targeted and isolated. 
         [0021]    Preferably, the external liquid supply conduit comprises a funnel, and preferably the funnel comprises a stem, an upstream part of which opens into the inlet port of the first liquid sample collection device, and a downstream part of which opens into the inlet port of the second liquid sample collection device at a position downstream of the inlet port of the first liquid sample collection device. By having the stem open into the inlet port of the first liquid sample collection device, and then downstream into the inlet port of the second liquid sample collection device, the second device may be filled with liquid which overflows the first liquid sample collection device, thereby targeting the second portion of the liquid stream without the use of any moving parts to divert the stream. While a funnel and stem are both preferable in forming the external liquid supply conduit, any apparatus capable of supplying a liquid flow to the first and then second device may be used, for example, a conduit comprising an internal valve located at a fork between conduit portions extending to the first and second devices. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    Some examples of liquid sample collection devices according to the invention will now be described with reference to the accompanying drawings in which: 
           [0023]      FIG. 1  is a perspective view of a liquid sample collection device according to a first embodiment of the present invention; 
           [0024]      FIG. 2  is a cross-section through the liquid sample collection device of  FIG. 1 ; 
           [0025]      FIG. 3  is a cross-section through the liquid sample collection device of  FIG. 1 , in use; 
           [0026]      FIG. 4  is cross-section through the liquid sample collection device of  FIG. 1  with corresponding funnel; 
           [0027]      FIG. 5  is a cross-section through two liquid sample collection devices of  FIG. 1 , connected by an appropriate funnel; 
           [0028]      FIG. 6  is cross-section through a liquid sample collection device according to a second embodiment; 
           [0029]      FIG. 7  is cross-section through a liquid sample collection device according to a third embodiment; 
           [0030]      FIG. 8  is a perspective view of the liquid sample collection device of  FIG. 7 , with its front face shown as transparent to reveal the internal features 
           [0031]      FIGS. 9A to 9E  are cross-sections through the liquid sample collection device of  FIG. 7 , showing different stages during sample collection. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    A liquid sample collection device  1  comprising a single meander is shown in  FIGS. 1, and 2 . The liquid sample collection device  1  comprises a solid cuboidal body  2   a  with dimensions of approximately 3 cm wide, 5 cm high and 4 cm deep. The device  1  also comprises a cover  2   b  which covers a front face of the body of the device  2   a.  The front face of the body of the device  2   a  has a series of recesses which partially define a number of features in its surface. These features include an inlet slot  3 , a channel  5 , a collection chamber  7 , and pressure relief channel  8 . The features partially defined by these recesses are completed and made internal to the device when the cover  2   b  is attached to the front of the body of the device  2   a.  The body of the device  2   a  also includes two location features  2   c,    2   d  for aligning and attaching the cover  2   b  using corresponding location features (not shown) on the cover. 
         [0033]    The body of the device  2   a  is a single piece of material, preferably formed into the desired shape in a single process. The body  2   a  is injection moulded using polypropylene. The cover  2   b  is a separate piece of polypropylene with an adhesive coating on one side. The device  1  is assembled by adhering the cover  2   b  to the front of the body of the device  2   a.  The location features  2   c,    2   d  serve to align the cover  2   b  so that it adheres correctly. 
         [0034]    The slot opening  3  in the upper surface of the body  2   a  of the device  2   a  forms the start of a liquid supply conduit for guiding liquid towards the collection chamber  7 . The slot extends a substantial portion of the front-to-back depth of the body  2   a,  and extends down into the device by approximately 3 cm. In use, this slot funnels a liquid sample supplied into the slot towards an opening  4  of the channel  5  at a lower side of the slot. 
         [0035]    The channel  5  is of substantially constant cross-section, the front-to-back depth, at 0.5 cm, being significantly less than the front-to-back depth of the slot  3 , and the breadth of the channel being approximately 0.5 cm. The channel  5  proceeds from the opening  4  diagonally upwards and away from the slot  3  for approximately 1 cm at an angle of approximately 45° to the horizontal. The channel  5  then reaches a first turning point  6   a  where the channel changes direction by approximately 90° to proceed diagonally down and away from the slot  3 . At the first turning point  6   a  the channel  5  is located entirely above the opening  4 , at a high point relative to the rest of the channel  5 ; however, it is not located above the height of the top of the slot  3 , i.e. the entrance to the liquid supply conduit. This first turning point  6   a  and the portions of channel extending either side of it form a first air trap section of the device. 
         [0036]    As the channel proceeds diagonally down and away from the first turning point  6   a,  it reaches a second turning point  6   b  after approximately 0.5 cm. At the second turning point  6   b  the channel turns again by approximately 90° and proceeds diagonally down past a top corner of a collection chamber  7 . The channel  5  then runs vertically, adjacent to the collection chamber  7 . The channel  5  opens into the collection chamber through their adjacent running walls, thereby completing the liquid supply conduit. 
         [0037]    The collection chamber  7  is a substantially cuboidal hollow chamber in the lower portion of the body  2   a  of the liquid sample collection device  1 , having dimensions of approximately 1.5 cm wide, 20 cm high and 25 cm deep. In use, the collection chamber  7  stores a liquid sample collected by the device  1 . The collection chamber is also connected to the pressure relief channel  8 . The pressure relief channel  8  is narrower than the channel  5  and extends from an entrance  9   a  extending through a sidewall of the collection chamber, the entrance  9   a  being at a position between the top and bottom of the chamber, up through the body of the device  2   a  to a pressure relief channel exit  9   b  through the upper surface of the device, thereby connecting the collection chamber to the atmosphere. 
         [0038]    The process of collecting a sample using the device discussed above will now be described with reference to  FIGS. 3A to 3E . The device is shown empty in  FIG. 3A , the liquid conduit, collection chamber  7 , and pressure relief channel  8  being filled with air only. In use, a liquid sample to be collected enters the liquid sample collection device, via the slot  3 . The liquid enters the channel  5  through the channel opening  4  at a lower side of the slot and, being urged along by further liquid supplied into the slot  3  behind, proceeds along the channel as shown in  FIG. 3B . The air present in the channel  5  prior to use is displaced along the channel by the advancing liquid. The pressure relief channel  8  allows the air being displaced by the increasing volume of liquid in the channel  5  to escape to the atmosphere, thereby maintaining atmospheric pressure within the device  1 . 
         [0039]    As shown in  FIG. 3C , the liquid sample proceeds along the channel  5  and into the collection chamber  7 . As the liquid sample collects within the collection chamber  7 , the liquid level rises continuing to displace air within the collection chamber  7  along the pressure relief channel  8 . The liquid in the collection chamber  7  eventually rises until it is above the entrance  9   a  to the pressure relief channel  8 , as shown in  FIG. 3D . At this point, the air within the collection chamber can no longer escape along the pressure relief channel  8 . As liquid continues to flow into the collection chamber  7 , air trapped within the device is now displaced back up the channel  5 . The air reaches the first air trap section located at the first turning point  6   a  and becomes trapped in the high point formed by the channel  5 , thereby forming an air lock, as shown in  FIG. 3E . With the trapped air forming an air lock, liquid entering through the slot  3  can no longer proceed through the channel  5 , and instead overflows the slot and is directed to waste. In this way, a first portion of the liquid sample is collected and isolated from any remaining liquid. 
         [0040]    As a result of this structure, the sample collected in the collection chamber  7  is of an approximately known volume. This is because the air lock always forms when the liquid level rises to a point just above the entrance  9   a  to the pressure relief channel  8 . The whole device  1  may be scaled up or down in manufacture to collect a larger or smaller volume of liquid before the air lock takes effect. However, preferably, devices  1  are manufactured with the same dimensions for the liquid channel, collection chamber etc. and the volume of liquid collected is determined during manufacture by altering the height of the entrance  9   a  to the pressure relief channel  8  in the side wall of the collection chamber  7 . That is to say, an increased volume of liquid may be collected by positioning the entrance  9   a  higher on the side wall of the collection chamber  7  and conversely, a smaller volume of liquid may be collected by positioning the entrance  9   a  lower on the side wall of the collection chamber  7 . 
         [0041]    Once the air lock has taken effect, the sample within the device  1  is substantially protected from contamination by the atmosphere. Provided that an amount of liquid remains within the slot, filling to at least above the entrance  4  to the channel  5 , the sample is only exposed to the atmosphere via the pressure relief channel  8 . In some embodiments of the invention (not shown), there may be provided means for sealing the pressure relief channel  8  once a sample has been collected. For example, a cap may be installed on the top of the device for blocking the relief channel. 
         [0042]    The device  1  also comprises a sample extraction port  7   a  in the form of a frangible membrane which closes a circular opening through the rear of the device that opens into the collection chamber  7 . The frangible membrane is a solid piece of rubber with a Shore hardness equal to or less than A30. The sample extraction port  7   a  may be pierced by a needle to allow extraction of a collected sample using, for example, a syringe, preferably without exposing the sample to the environment. Once the needle is removed from the extraction port  7   a,  the rubber flexes back to block the channel formed by the needle. In alternative embodiments (not shown), the sample extraction port  7   a  may be a screw cap opened to conveniently access and extract a sample stored in the collection chamber  7 , or may be a Luer lock for interfacing with a syringe. 
         [0043]    A funnel  101  suitable for use with the liquid sample collection device  1  is shown in  FIG. 4 . In use, the funnel is mounted on top of the device and guides liquid to be collected towards the slot  3  in the upper surface of the device  1 . The funnel has a mouth  102  that collects the liquid sample and guides it towards the stem  103 . The stem  103  of the funnel  101  guides liquid towards the slot  3  from one side of the slot opening. Liquid flowing through the funnel enters the slot and fills the device, as described above, until the air lock prevents further filling. The slot  3  then overflows and any further liquid entering the funnel  101  is directed to waste via a runoff portion  104  of the funnel. The runoff portion of the funnel is located at the opposite side of the slot  3  to the stem  103 . 
         [0044]    An alternative funnel  111  is shown in  FIG. 5 . This funnel is shaped to connect with two devices  1   a,    1   b  to allow the devices to target two separate portions of the liquid sample. The funnel  111  guides liquid toward the first device in an identical manner to the funnel  101  shown in  FIG. 4 . The first device  1   a  collects the first portion of the liquid sample before an air lock prevents further filling. The air lock causes further liquid entering the funnel  111  to overflow the slot  3   a  and enter the run off  114   a  of the funnel  111 . This runoff  114   a  then directs the overflow liquid to a second device  1   b  located next to the first device  1   a.  The second device  1   b  works in a manner identical to the first device  1   a,  but in this configuration collects a second portion of the liquid sample and isolates this from any further liquid entering the funnel  111 . When the air lock takes effect in the second device  1   b  and the slot  3   b  overflows, any further liquid enters a second runoff portion  114   b  and is directed to waste. 
         [0045]    It will be appreciated that any number of devices may be connected in the way described above to target different portions of the liquid sample. Further, the devices may collect the same or different volumes of liquid depending on the positioning of the entrance  9   a  of the pressure relief channel  8  within each device. 
         [0046]    In a second embodiment, shown in  FIG. 6 , the liquid sample collection device  10  comprises an additive port  21 . In this embodiment, those parts that are the same as in the first embodiment will not be described again. The additive port  21  is an opening through the rear of the device that opens into the collection chamber  37 . The additive port interfaces with a blister pack (not shown) on the rear of the device. The user may depress the blister pack from the rear of the device, bursting it and releasing an additive into the collection chamber  37 . The use of a blister pack would allow a user to mix a sample with an additive immediately after collection. In an alternative embodiment (not shown), the additive port  21  comprises an opening through the rear of the device that is filled with a solid piece of rubber with a Shore hardness of less than A30. In such embodiments, a needle and syringe may be used to inject an additive into the collection chamber  27 . The rubber forming the additive port  21  would flex back upon removal of the needle to block the channel formed by the needle and prevent any liquid leaking through the additive port. In a further alternative (not shown), the additive port  21  is a Luer lock suitable for interfacing with a syringe which may be used to introduce an additive into the collection chamber  27 . 
         [0047]    A liquid collection device  30  comprising a double meander according to a third embodiment is shown in  FIGS. 7 and 8 . The liquid collection device comprises a slot opening  33  in the upper surface of the device with an opening  34  in its lower side, as in the first embodiment. This forms the start of the liquid supply conduit. The opening  34  connects to a channel  35  which proceeds diagonally upwards and away from the slot  33  at an angle of approximately 45° to the horizontal. The channel  35  reaches a first turning point  36   a  where it turns through approximately 90° to proceed diagonally downwards and away from the slot  33 . The turning point  36   a  forming a first high point in the channel  35 , in which the channel  35  is entirely above the opening  34  to the channel  35 . The first turning point  36   a  and the portions of channel extending either side of it form a first air trap section in the device. The channel  35  then reaches a second turning point  36   b  at which it turns and proceeds back on itself; running parallel and beneath the portion of the channel  35  between the first and second turning points  36   a,    36   b.  The channel  35  then reaches a third turning point  36   c,  at which the channel  35  is entirely above the second turning point  36   b,  where it turns through approximately 90° and proceeds diagonally downward; running parallel and beneath the portion of the channel  35  between the first turning point  36   a  and the opening  34 . The third turning point  36   c  forms a local high point relative to the portions of the channel  35  on either side. The third turning point  36   c  and the portions of channel extending either side of it form a second air trap section in the device. The channel  35  then runs between the third turning point  36   c  and a top corner of a collection chamber  37  in the lower portion of the device  30 . 
         [0048]    The process of collecting a sample using the double meander device discussed above will now be described with reference to  FIGS. 9A to 9   d.  The device is shown empty in  FIG. 9A , the liquid conduit, collection chamber  37 , and pressure relief channel  38  being filled with air only. In use, a liquid enters the slot  33  and passes into the channel  35  via the opening  34 . The liquid is urged along the channel  35  by the liquid collecting in the slot  33  behind, displacing the air occupying the channel along and out of the system via the pressure relief channel  38 . The liquid proceeds along the channel  35  and into the collection chamber  37  which it begins to fill, as shown in  FIG. 9B . Once the collection chamber  37  fills with liquid to a point where the liquid level is above the entrance  39   a  to the pressure relief channel  38 , as shown in  FIG. 9C , the gas within the collection chamber can no longer escape to the atmosphere and is displaced back up the channel  35 . The gas becomes trapped in the local high point formed by the third turning point  36   c,  thereby forming an air lock in the channel  35 , as shown in  FIG. 9D , preventing any additional liquid entering the collection chamber  37 . 
         [0049]    Advantageously, because the double meander embodiment features two high points formed by turning points  36   a  and  36   c,  the device becomes resistant to shaking and overturning after collection of a sample. If the device is shaken or rotated through 360° the air lock may move from the third turning point  36   c  to the first turning point  36   a,  as shown in  FIG. 9E , thereby maintaining the air lock. The device may also be overturned without breaking the air lock provided that the pressure relief channel remains blocked in the overturned position. If the pressure relief channel remains blocked, the air trapped in the third turning point may move to the second turning point, which in an overturned orientation forms a local high point. Preferably, the pressure relief channel is positioned such that in the overturned position the liquid level remains above the entrance to the pressure relief channel, i.e. the pressure relief channel is located above the median line of the collection chamber. Alternatively, the pressure relief channel may be blocked manually, for example using a cap, so that in an overturned position air cannot enter the collection chamber through the pressure relief channel.