Method and apparatus

Abstract

A detector for detecting a target biomolecule comprising: a housing, a detection assembly containing an active material and a liquid medium, a gas sample inlet and an air mover selectively operable to

Description

Field of Invention The present invention relates to methods and apparatus, and more particularly to methods and apparatus for the detection of biomolecules and compositions comprising such biomolecules, and still more particularly to methods and apparatus for the detection of biological warfare agents for use by personnel in areas where such agents may have been dispersed. Background The possibility of hostile militaries or terrorist groups developing and using biological weapons is a persistent threat. Detection of hazardous agents, such as biological and chemical weapons, represents a complex and difficult technical problem. The circumstances in which it is necessary to detect such agents add further difficulty. In addition, the personnel and / or resources available for the purpose may be extremely limited. For example, whilst reliable biological assays may be performed in the laboratory by a scientist, biological warfare agents may be deployed in circumstances where it is only appropriate for military or emergency services personnel to be present. It may also not be possible to provide sufficient numbers of such personnel with the training needed to conduct such assays and, of course, there may be other urgent demands on their time and attention - such as caring for and evacuating people from the field in which such agents are suspected of having been used. The applicant has previously addressed similar problems in chemical detection with their lightweight chemical detector (LCD) device. This uses Ion Mobility Spectrometry (IMS) technology that alarms to gas and vapour threats detected and identified at or below immediately dangerous to life and health (IDLH) levels, by determining the agent or type, class, concentration and dosage of chemical exposure. It can also be used as a screening and survey device. The LCD device can be handheld or clipped to a belt, harness or shoulder strap, to enable the user to undertake their primary role without obstruction. Features include both audible and visual alarms plus a clear, easy-to-read liquid crystal display. This device is very simple to operate and requires no calibration or complicated routine maintenance. This provides a wide range of user capability while ensuring a minimal logistic burden. There is however currently no device which can fulfil the need for detecting biological agents in the way that the LCD device detects chemicals - namely in a way that is simple and reliable for emergency services and military personnel to use and carry in the field. Summary Aspects and embodiments of the present disclosure aim to address the above technical problem and other technical problems. Embodiments provide personal monitoring for individual personnel in the form of a wearable sensor for sensing biological warfare agents. Embodiments are configured for the detection of airborne particles of such agents. In an aspect there is provided a detector for detecting a target biomolecule or composition comprising the target biomolecule, the detector comprising: a housing, configured to couple the detector to a carrier; a detection assembly for containing an active material in a liquid medium, wherein the detection assembly and the housing are mutually configured to provide an indication of a reaction of the active material to the target biomolecule or to the composition; a gas sample inlet provided on the housing and an air mover, wherein the gas sample inlet and the air mover are selectively operable to: draw, into the housing, a sample of air from around the apparatus; and to provide the sample of air to the detection assembly for interaction with the active material; the housing further comprising an indicator output for providing the indication to the carrier. The detection assembly may comprise a cartridge dock, for docking a removable cartridge of active material in the housing. The cartridge dock may comprise a first fluid channel configured to enable mixing between the sample of air and the liquid medium. The air mover and the first fluid channel may be arranged to mix the sample of air with the liquid medium. The sample inlet and the air mover may be configured to provide flow of the sample of air through the first fluid channel for mixing with the liquid medium. The first fluid channel may be branched for providing mixing between the sample of air and a plurality of liquid media. The detector may comprise a pressure relief configured to relieve a pressure of the cartridge associated with flow into the cartridge from the first fluid channel. The pressure relief may comprise a second fluid channel. The second fluid channel may be configured to allow the sample of air to flow from the first fluid channel, through the liquid medium, and out of the cartridge through the second fluid channel, for example to be bubbled through it. The pressure relief may comprise at least one of a valve and a displaceable element, such as a piston or membrane. The detection assembly may comprise a visual indicator, configured to provide a visual indication of a reaction of the active material. The visual indicator may comprise a display. The detection assembly may comprise a sensor for sensing a reaction of the active material, and a controller configured to control the display based on said sensing. The detection assembly may comprise a light transmissive element and the display is provided, from the active material, via the light transmissive element. The light transmissive element may comprise a window, for example wherein the cartridge comprises a light transmissive portion for providing light between the active material and the detection assembly. The reaction of the active material may comprise fluorescence. The detector may be wearable, for example the detector may be suitable to be carried by a single human, such as an adult human. The housing may be sized and arranged to enable the detector to be carried on a garment, or otherwise worn by, the human carrier. The detector of any preceding claim further comprising a replaceable cartridge containing the active material and the liquid medium and having means for coupling the sample of air into the cartridge to enable the sample of air to interact with the active material. The replaceable cartridge may comprise a reservoir of the liquid medium and a compartment holding the active material separate from the liquid medium, wherein the cartridge comprises an actuator operable to permit the liquid medium and the active material to combine. For example, a membrane may be provided which holds the liquid medium in the reservoir. When the liquid medium is released from the reservoir, it may flow out into the cartridge, such as into a space surrounding the compartment. The actuator may be operable to break the membrane. Operation of the air mover may cause air to flow into the cartridge. This may increase pressure in the cartridge surrounding the compartment. When the pressure is sufficiently high, this may open a one-way valve to cause the liquid medium, and the air sample, to combine with the active material. The compartment may comprise a degassing valve, configured to open when the pressure inside the compartment exceeds a threshold to allow air to flow out of the cartridge. The cartridge may be configured so that the degassing valve is open only when the one way valve is closed and vice versa. The detection assembly may comprise a plurality of components arranged mechanically to hold cartridge(s) in place to allow reactions of the active material to be detected. It may be further configured to provide access to the actuator from an exterior of the housing. For example, the detector may be configured to be opened to allow a cartridge to be inserted into and / or removed from and / or replaced into a cartridge receiving area of the cartridge dock. The cartridge may be actuated to activate it for detection 5 before being inserted into or replaced into the cartridge receiving area of the detection assembly. The detection assembly may hold a plurality of cartridges and a plurality of active materials, each active material held in a 10 respective corresponding one of the plurality of cartridges. Each of the plurality of active materials may be configured to detect a different target biomolecule or composition. 15 The, or each, cartridge may comprise a first fluid coupling interface comprising a fluid channel and being configured to engage with a dock of the detection assembly to connect the fluid channel of the detection assembly with a corresponding fluid channel of the dock to enable mixing between the sample of air and the liquid 20 medium. The detection assembly and the, or each, cartridge may be configured so that loading the or each cartridge into the detection assembly causes the dock and the interface to engage to connect 25 the first fluid channel in the cartridge dock with the first fluid coupling interface of the cartridge. An aspect provides a cartridge for use in a detector for detecting a target biomolecule or composition comprising the target 30 biomolecule, the cartridge comprising: a reservoir of a liquid medium; and a compartment holding active material separate from the liquid medium; an actuator operable to provide fluid communication between the compartment and the reservoir for mixing of the liquid medium and the active material; and, a fluid coupling interface comprising at least one fluid channel, connectable to the reservoir and being configured to engage with a dock of the detector. The active material may comprise at least one of cell-free biomolecules, purified biomolecules, such as antibodies, proteins, or peptides. The active material may comprise freeze-dried material, for example it may consist essentially of a freeze-dried material. The active material may be immobilised, such as on beads, so that it is not mobilised by the liquid medium. In these embodiments, the cartridge may thus be configured so that the visual indication provided by the cartridge provides an indication of the concentration of the target biomolecule or composition in the sample of air. For example, the compartment of active material may occupy a length of the cartridge (e.g. an axial extent) the visual indication provided by the cartridge may indicate the concentration of the target in the sample based on the length (axial extent) of the regions of active material in the cartridge that react to indicate presence of the target. The active material may comprise an engineered fluorescent immunoassay reagent. The active material may comprise an antibody or its fragment and may incorporate a fluorophore so as to provide a fluorescence intensity which increases upon antigen-dependent removal of the fluorophore. The liquid medium may comprise a solvent selected for activating the active material to perform an assay. The actuator may be provided by a cap of the cartridge, such as a twist cap. An aspect of the disclosure provides a detection assembly, for use in any one of the detectors described or claimed herein. Such a detection assembly may be made and sold separately. The detection assembly may comprise a plurality of the cartridges described and / or claimed herein. Brief Description of Drawings Embodiments of the disclosure will now be described in detail with reference to the accompanying drawings, in which: Figure 1 shows a very schematic illustration of a detector according to the present disclosure, which comprises a schematic plan view in Fig 1A and a schematic section view in Fig. IB; Figure 2 shows an illustration of a set of cartridges suitable for use in the detector illustrated in Figure 1; and, Figure 3 shows a very schematic illustration of a detector according to the present disclosure loaded with replaceable cartridges such as those shown and described with reference to Figure 2, Figure 3 comprises a schematic plan view in Fig 3A and a schematic section view in Fig. 3B. In the drawings like reference numerals are used to indicate like elements . Specific Description Figure 1 comprises two schematic views of a detector 1 for detecting a target biomolecule or composition of such target biomolecules. The first view, in Figure 1A, shows a schematic plan view of internal components of the detector 1. The view below that, in Figure IB, shows a schematic section view through the same detector 1 to illustrate the disposition of certain components in the detector 1. Articles shown in broken lines are included in this section view for illustration purposes, but are shown in broken lines to indicate that they illustrate relative position of elements, rather than precise location in the section shown in Figure IB. The detector 1 of the present disclosure provides a compact and highly portable device, which can be worn on a garment of a human or carried by a lightweight vehicle, such as a UAV adapted for small payloads, such as cameras or other data collection devices (as opposed to cargo vehicles). These detectors may use one or more replaceable cartridges, each of which contains an active material 6 configured to react to the presence of a target biomolecule or composition comprising such a target biomolecule. The reaction may comprise a fluorescence. The active material 6 can be activated by actuating the cartridge 22. This actuation may mix a liquid medium 8 with a dry (e.g. lyophilised) form of the active material 6. It may also configure the cartridge 22 so that a sample of air 16 can be provided to the active material 6, for example by being passed through the cartridge 22. The cartridge 22 and the detector 1 may be configured so that the reaction of the active material 6 to the presence of the target biomolecule in the sample provides a visual indication external to the detector 1. The detector 1 comprises housing 2, a detection assembly 26 provided in the housing 2, and a gas sample inlet 10 which provides a conduit from the exterior of the housing 2 to the detection assembly 26. The detector 1 also comprises a gas sample exhaust 11, and an indicator output. The housing 2 encapsulates the detection assembly 26 and other components of the detector 1. The housing 2 may also carry an attachment for securing the housing 2 to a carrier, such as by fixing the detector 1 to a garment worn by a human user of the device . The gas sample inlet 10 comprises a first conduit, such as a pipe, which extends from an opening on the exterior of the housing 2 into the detection assembly 26 inside the housing 2. Similarly, the gas sample exhaust 11 is a second conduit which couples the detection assembly 26 to the exterior of the housing 2. Typically, the second conduit is separate from first conduit. In the example illustrated in Figure 1, the exhaust gas sample exhaust 11 returns air flow from the detection assembly 26 to the same opening as the inlet. An air mover 12, 14, such as a fan, pump or blower, may be provided in the gas sample inlet 10, or in the gas sample exhaust 11, or in both. When operated, the air mover(s) 12, 14 provide a flow of air into the detector 1 through the gas sample inlet 10 and carry that flow of air to the detection assembly 26. The flow of air can then flow from the detection assembly 26 through the gas sample exhaust 11 back out of the housing 2. The detection assembly 26 illustrated in Figure 1 comprises a cartridge dock 24. The cartridge dock 24 also comprises at least one cartridge receiving area 20, comprising a space into which the cartridge can be provided to enable a removable cartridge 22 to be positioned and held in the dock. The cartridge dock 24 shown in Figure 1 comprises four cartridge receiving areas 20, so that four removable and replaceable cartridges 22 can be docked into the detection assembly 26. As will be described below, the dock is arranged so that providing such a cartridge 22 into the cartridge receiving area 20 connects an active material 6 carried by that cartridge 22 for receiving the above-described flow of air, and providing interaction between that flow of air and the active material 6 held in the cartridge 22. This can be done by passing the flow of air through the cartridge 22. The cartridge dock 24 further comprises a fluid channel which connects the gas sample inlet 10 to the cartridge receiving area 20 and which, in the example illustrated in Figure 1, comprises four branches 18, one branch 18 for each of the four cartridge receiving areas 20 illustrated in the drawing. In the illustration shown in Figure la each branch 18 connects the gas sample inlet 10 to a corresponding one of the four cartridge receiving areas 20 so that the flow of air from the gas sample inlet 10 can be provided equally to each of four cartridges 22 held in each of the four cartridge receiving areas 20. The cartridge receiving areas 20 are also connected by a second fluid channel 19 to the exhaust 11. Just as with the first fluid channel 17, the second fluid channel 19 has four branches, and one branch connects a respective corresponding one of each of the four cartridge receiving areas 20 to the gas sample exhaust 11. It can thus be seen that the air mover 12, 14 (or air movers) can be operated to provide a flow of air into the gas sample inlet 10 and to the first fluid channel 17, where it is divided between each of the four branches so that part of the sample of air 16 from the gas sample inlet 10 is provided to each of the four cartridge receiving areas 20. The sample of air 16 can then flow through the cartridge receiving areas 20 to the second fluid channel 19, through which it can flow to the gas sample exhaust 11 and be vented from the housing 2 through that exhaust 11. Provided adjacent to the cartridge receiving areas 20 is an indicator output in the form of a visual indicator, for providing output from the detector 1. As shown in Figure lb the visual indicator 32, 34, 36 may comprise three elements. The first element, which may form part of the housing 2, is a light transmissive window. Beneath the light transmissive window 32 may be provided a controllable electronic display 34, which is visible from outside the housing 2 through the window 32. In addition, an optical detector 36 is also provided adjacent to the cartridge receiving area 20, optionally this is provided between the cartridge receiving area 20 and the electronic display 34. The detector 1 typically also comprises a controller 40 and a communications interface 42, such as a wireless and / or wired communication interface which may have the ability to communicate via a wide area communications network. The controller 40 may be programmable and may be preconfigured to control the detector 1 to perform one or more of the methods described herein. The optical detector 36 is connected to the controller 40, for providing detection signals from the optical detector 36 to the controller 40. The controller 40 is also connected to the communications interface 42 for sending data from the detector 1 based on the detection signals. An actuator may also be provided to allow operation of an actuator 50 of a cartridge 22 in the cartridge receiving area 20 from an exterior surface of the housing 2. Figure 2 shows a plurality of replaceable cartridges 22 for use in a detector 1 such as that shown and described above with reference to Figure 1. These cartridges 22 may each comprise a container such as a cylinder, which may be of glass or plastic. In the container may be provided a compartment 46 holding an active material 6 and, separate from the compartment 46, a reservoir 48 of a liquid medium 8. At one end of the container is provided an actuator 50, which in Figure 2 is in the form of a screw cap with a pin or plunger attached to the cap. The cartridge also comprises a first fluid coupling interface 27, configured to engage with a dock of the detector 1 to allow air to be provided from the first fluid channel 17 of the dock 24 into the interior of the container for mixing with the active material 6 and the liquid medium 8. In addition, the replaceable cartridge may also comprise a second fluid coupling interface 28 which in this example is in the form of a degassing valve. It may also comprise connections for connecting to the second fluid channel 19 of the dock 24. To assist clarity in the drawing, the second fluid coupling interface 28 is shown at the other end of the container from the first fluid coupling interface 27. However the second fluid coupling interface 27 is generally also provided in the cap (rather than at the other end of the cartridge as shown in the drawings). However, a variety of configurations are possible. Irrespective of the position of the second fluid coupling interface 28 a sample of air 16 which enters the interface of the cartridge, from the first fluid channel 17 of the dock, is passed through the active material 6 in the compartment 46 of the cartridge 22 to leave the cartridge via the second fluid coupling interface 28. This may be achieved by the use of conduits or other means to channel gas flow inside the cartridge. The second fluid coupling interface 27 may also be configured to be pressure controlled, so that it opens to allow air to leave the cartridge when the pressure from gas inside the cartridge exceeds a threshold level. For example, it may comprise a pressure controlled valve, configured to open when the internal pressure exceeds threshold. The actuator cap 50 of the container 22 shown in Figure 2 is configured so that, by screwing down the cap, the pin or plunger ruptures a wall, such as a membrane, between the compartment 46 holding the active material 6 and the reservoir 48 of liquid medium 8. Rupturing this wall may enable the liquid medium 8 to released in the cartridge, for example it may be released from the reservoir 4 8 into an outer shell of the cartridge which may surround the compartment . The sample of air 16 can then be drawn in to the outer shell. The sample of air 16 can then flow, as described below, with the liquid medium into the compartment to be mixed with the active material 6 and to activate it. For example, the air mover may operate to provide the sample of air into the cartridge and this air flow may open a one-way valve into the compartment so that the liquid medium can flow into the compartment. Typically, at least one wall of the cartridge 22, and often the entirety of the exterior surface of the compartment 46 is provided by a light transmissive material such as a glass or light transmissive plastic. As noted above, the cartridge may comprise a one-way valve, which may be provided between the compartment and an outer shell of the cap. The compartment which holds the active material may be provided by a capsule that houses the active material. The compartment may be surrounded by an outer shell of the cartridge. The cartridge may be configured so that the liquid medium only enters this internal capsule to mix with the active material when a sufficient pressure differential is built up, across the one-way valve, by the air mover providing the flow of sample into the cartridge. In addition the degassing valve may also be one way so that a flow of gas can be introduced through the fluid into the cartridge, through the fluid coupling interface where it can pass through the reservoir 48 and compartment 46 (after the wall between them has been ruptured) and pass through the mixture of active material 6 and liquid medium 8 to reach the degassing valve through which it is able to exit the compartment 46. In an embodiment the air mover may be operated for a period of time, such as 30 seconds, to provide the sample of air through the one-way valve. In this embodiment, the degassing valve may be configured to open only opens once a sufficient pressure has built up in the compartment. This is one way to allow a sample of air 16 to be bubbled or otherwise passed through the mixture of liquid medium 8 and active material 6 to allow any analyte carried by the air to mix with the liquid medium 8 and to interact with the active material 6. Other possibilities are envisaged. In the illustration shown in Figure 2 the active material 6 comprises a freeze-dried substance, which is immobilised on an immobilising structure (such as on the surface of beads) in the compartment 46 in the cartridge. The active material may be configured so that it remains immobilised (whether on beads or on any other immobilising structure in the compartment) even when activated by the liquid medium. This may enable the cartridge to provide a visual indication of the concentration of the target in the sample of air as described elsewhere herein. Other arrangements of active material 6 may be provided but it may be advantageous if the active material 6 is held inactive until it is mixed with a liquid medium 8. It may be further advantageous if the activation (whether provided by this or other means) can be done separately from the step of loading the cartridge into the dock. A wide variety of different configurations of the cartridge are envisaged. For example, there is no need for a separate fluid coupling interface at the bottom of the cartridge. Embodiments are envisaged in which only the first fluid coupling interface is present. This single fluid coupling interface may be provided in a cap of the cartridge. In these and other embodiments a degassing valve may be provided as part of the compartment which holds the active material (e.g. an internal capsule of the cartridge). Air which leaves the compartment may be vented from the cartridge through the cap which may provide a first (single) fluid coupling interface . It can also be seen in Figure 2 that each of the three cartridges comprises a different active material 6. The active material 6 in question may be specific for a particular target biomolecule or a particular composition comprising such a target biomolecule. For example, one cartridge may comprise active material 6 which reacts in the presence of a first selected biological warfare agent. The reaction may comprise fluorescence. The second cartridge may comprise active material 6' which reacts to the presence of a second biomolecule, different from the biomolecule to which the first active material 6 reacts. Again, the reaction may comprise fluorescence. The third or any additional cartridges may comprise further different active materials which are sensitive to different biomolecules and / or different classes of biomolecules. They may also fluoresce. It can thus be seen that by providing an ensemble of cartridges each with a different active material 6 the replaceable cartridges permit a detector to be made sensitive to any one or more of a set of different biomolecules, or different classes of such biomolecules. This also permits different configurations of the detector 1, for example if a detector 1 is loaded with cartridges which all comprise the same active material 6 which is sensitive to the same target biomolecule or composition then it can provide repeat measurements for the same target which may extend the useful life of the device and / or provide increased confidence in any detection. Alternatively, where different active materials are provided in each of the different cartridges this may provide a broad-spectrum detector 1 and / or provide an operator of the device with the ability to adapt his or her device to sensitise it to a different desired target biomolecule or composition. Figure 3 shows a detector 1 such as that illustrated in Figure 1 loaded with four cartridges such as those illustrated in Figure 2. The cartridges typically carry data indicating the target biomolecule or composition, or class of target biomolecules, to which the active material 6 in the cartridge is sensitive. This data may be carried in a machine-readable marker 30. This may be configured to be readable using the detector 1. Figure 3 shows two schematic views of a detector 1 such as that described above loaded with replaceable cartridges. Figure 3A is a plan view corresponding to the view shown in Figure 1A and Figure 3B is a section view corresponding to that shown in Figure IB. The detector 1 illustrated in Figure 3 may be identical to that described with reference to Figure 1 and like reference numerals indicate like elements. In Figure 3 it can be seen that loading a replaceable cartridge into the cartridge receiving area 20 of the dock causes the fluid coupling interface of that cartridge to engage with the branch of the first fluid channel for that cartridge receiving area 20. In this position, the cartridge is able to provide a fluid path from the first fluid channel 17 of the cartridge dock 24 to the second fluid channel 19 of the cartridge dock 24 and then onward to the exhaust 11. It can also be seen in Figure 3b that the actuator of the detector 1 also engages with the actuator 50 (e.g., the cap) of a cartridge positioned in the cartridge receiving area 20. This may enable the actuator 50 of the cartridge to be operated from outside the device - e.g., without opening the detector 1. A separate actuator may be provided for each of the four cartridge receiving areas 20 so that each of the cartridges can be operated, either separately or together. Loading the cartridge into the detection assembly 26 may also enable data identifying the target biomolecule or composition, or class of target biomolecules, to which the active material 6 in the cartridge is sensitive to be read using the detection assembly 26. This data may be provided to the detector 1. This may be done automatically, for example by the controller 40 reading a machine-readable marker 30 carried by the cartridge. In these embodiments the detector 1 may comprise a reader 37, coupled to the controller 40, for reading a marker 30 carried by the cartridge. The data carried by the cartridge may indicate a type of biomolecule, composition comprising the biomolecule, or class of biomolecule. The data may be encoded in a marker 30, which may be visible. The data may be readable via the detection assembly 26. The detection assembly 26 may be configured to display an indication of a detection of that type or class of biomolecule or composition by providing, to the user via the detection assembly 26, a visual indication of a reaction of the active material 6. The visual indication may be displayed to the user in association with (e.g. adjacent to) the data carried by the marker 30. In operation a detector 1 such as that illustrated in Figure 1 may be provided with a set of cartridges such as those illustrated in Figure 2. A user of the device may open the housing 2 of the device and load each of the cartridges into a corresponding one of the plurality of cartridge receiving areas 20 of the detector 1. This may be done manually by the user and without any modification of the detector 1. Loading a cartridge into the cartridge receiving area 20 causes the fluid coupling interface of the cartridge to engage with the first fluid channel 17 of the cartridge dock 24. This connects the gas sample inlet 10 to the gas sample exhaust 11 via the compartment 46 and reservoir 48 of the cartridge. Loading the cartridge into the cartridge receiving area 20 may enable data to be read from the cartridge, for example it may position a marker 30 carried by the cartridge for display by the detection assembly 26 and / or reading by the controller 40 or by an operator of the device (for example through a window 32 of the detection assembly 26) . Accordingly, the controller 4 0 may read data from the cartridge to determine the target biomolecule to which the material of the cartridge is sensitive. When the user of the device wishes to activate the cartridge, he or she may operate the actuator 50 of the cartridge to open the reservoir 48 of liquid medium 8 into the compartment 46 to allow the active material 6 and the liquid to mix. In the embodiment illustrated in Figure 3, this is done by the cap (50; Figure 2) of the cartridge 22 being rotated to screw down so that the pin or plunger carried on the cap ruptures the reservoir 48 of liquid medium 8 and causes the liquid medium 8 to mix with the active material 6. To sample air for detecting a target biomolecule (such as a biological warfare agent), the controller 40 causes the air mover 12, 14 to operate thereby providing a flow of air through the gas sample inlet 10 to the first fluid coupling channel. The flow of air then passes through the first fluid channel 17 to the first fluid coupling interface 27 of the cartridge. This flow of air then passes from the first fluid coupling interface 27 of the cartridge, through the liquid medium 8, where it is able to interact with the active material 6. The sample of air 16 may then pass out of the cartridge via the second fluid coupling interface 28 (e.g., degassing valve) at the other end of the cartridge. The sample of air 16 is then passed from the cartridge via the second fluid channel 19 of the cartridge dock 24 and the gas sample exhaust 11 where it flows out of the detector 1. If the sample of air 16 carries a target biomolecule or a composition to which the active material 6 is sensitive, this may cause the active material 6 to react with the sample of air 16, such as by fluorescence. The reaction may then be detected by the optical detector 36 which can provide a detection signal to the controller 40 indicating the presence of that target. The reaction of the active material 6 may provide a visual indication of the presence of the target via the display 34. As explained above, if the active material is immobilised, the spatial extent of the fluorescence of the active material may provide an indication of the amount of the target biomolecule or composition which is present in the sample of air. This may provide a concentration dependent signal. The controller 40 may be configured to operate the display 34 and / or send an alert signal via the communication interface 42 -for example in the form of a network message or radio signal or other electronic signal for a remote device. The indication may be based on both the reaction of the active material 6 and the data carried by the cartridge indicating the target biomolecule to which the active material 6 is sensitive. The operation of the display 34 or the content of the alert signal may be further based on the spatial extent of the reaction of the active material in the cartridge, so as to convey concentration dependent information. The controller 40 may operate the display 34 to indicate to a wearer or carrier of the device that the active material 6 is fluorescing. In the florescence may also be visible from the exterior of the device, for example where a window 32 is provided. Thus, a visual indication of the reaction of the active material 6 may be provided at the detector 1 housing 2. This may be done actively or passively depending on the arrangement of the visual indication - either via electronic display 34 or via a light transmissive window 32 of the detection assembly 26 as described herein. It will be appreciated in the context of the present disclosure that a wide variety of active materials 6 may be used but that in general such active materials are sensitised to a particular target biomolecule or a particular target composition. In some embodiments the active material 6 may be sensitised to a class of biomolecules or a class of such compositions. Now this may permit the detector 1 of the present disclosure to provide broad spectrum detection. It will also be appreciated that the arrangement of an exhaust 11 and the second fluid channel 19 of the dock are optional gas may simply be vented from the second fluid coupling interface 28 of the cartridge into the housing, which may not be sealed. It will also be appreciated that the cartridges 22 described herein may be sold separately. For example, the cartridges may be a disposable consumable part, intended to be loaded into the detector 1, used once or a limited number of times and then discarded or disposed of safely so that the detector 1 can continue to be used with a replacement cartridge. The drawings show four cartridge receiving areas 20 and four replaceable cartridges in the detector 1. However, it will be appreciated in the context of the present disclosure that a greater or lesser number of cartridge receiving areas may be provided in any one detector 1. For example, the detector 1 may be configured to receive only a single cartridge or to receive a greater or lesser number of cartridges. A number of features shown in the drawings are optional. For example, the actuator need not be provided by the detector 1 itself and instead the user may actuate the cartridge at the point it is loaded into the device. For example, the user may operate the cartridge so as to rupture the wall between compartment 4 6 and reservoir 4 8 and then load the cartridge into the detector 1. The indicator output provided in the embodiments described herein may be in the form of a visual indication. This may be provided by an electronically controlled display 34 or by the fluorescence of the active material 6 being made visible outside the housing 2, such as by the provision of a window 32 through which the active material 6 in the cartridge(s) can be viewed. However, the indicator output need not be provided visually and such output may be provided as a signal, such as a digital signal comprising data. Such signals may be provided as messages suitable for communication over a network. Examples of such networks include wired and wireless networks. The detector 1 need not include an optical detector 36 and a controller 40 and a window may be provided if the active material 6 provides visible florescence. Additional means may be provided to assist in visualising fluorescence, such as an infrared detector. The communications interface 42 is also optional. Where a communications interface is provided this may be wireless interface such as a wide area communications device or a short-range radio interface such a personal area network using any appropriate protocol such a Bluetooth or similar. In addition, a wired interface may be used either on its own or in addition to a wireless interface. The air movers 12, 14 described herein may be provided by a pump or fan or any appropriate means of providing a flow of air into the sampling let and through the cartridges. The display 34 described herein may be provided by any appropriate means, such as an actively controlled electronic display. Such displays include OLED, TFT, and LCD displays and other types of electronically controllable displays. However simpler displays may also be used, such as displays of indicator lights and other types of display which indicate information to a user by visual means. An active display is optional and the reaction of the active material 6, and the other information described herein may be displayed to a user passively such as via the light transmissive window 32. Any feature of any one of the examples disclosed herein may be combined with any selected features of any of the other examples described herein. For example, features of methods may be implemented in suitably configured hardware, and the configuration of the specific hardware described herein may be employed in methods implemented using other hardware. It will be appreciated in view of the foregoing disclosure that embodiments of the inventions described herein may provide a wearable biological warfare agent detector. This detector may be lightweight, for example it may weigh less than 5 kg, for example less than 2kg, for example less than 1 kg, for example about 0.58 kg (1.3 lbs) including its operating power supply, such as a battery. Embodiments comprise an active material 6 based on bead-immobilized on-demand real-time direct immunoassay specific to a biological-warfare agent (BWA). Embodiments may provide BWA-specific antibodies, which may be bead-immobilized. The active material 6 may provide on-demand reagent release, and / or direct immunoassay. Embodiments adapt these technological components to a wearable biological detector for aerosol samples. Embodiments may provide a definitive biological identifier with a 'zero' false alarm rate, such alarm rate may be achieved by purified antibody used as a target recognition active material, which is specific to its target antigen. It will be appreciated from the discussion above that the embodiments shown in the Figures are merely exemplary, and include features which may be generalised, removed or replaced as described herein and as set out in the claims. With reference to the drawings in general, it will be appreciated that schematic functional block diagrams are used to indicate functionality of systems and apparatus described herein. It will be appreciated however that the functionality need not be divided in this way, and should not be taken to imply any particular structure of hardware other than that described and claimed below. The function of one or more of the elements shown in the drawings may be further subdivided, and / or distributed throughout apparatus of the disclosure. In some embodiments the function of one or more elements shown in the drawings may be integrated into a single functional unit. In some examples the functionality of the controller 40 may be provided by a general purpose processor, which may be configured to perform a method according to any one of those described herein. In some examples the controller may comprise digital logic, such as field programmable gate arrays, FPGA, application specific integrated circuits, ASIC, a digital signal processor, DSP, or by any other appropriate hardware. In some examples, one or more memory elements can store data and / or program instructions used to implement the operations described herein. Embodiments of the disclosure provide tangible, non-transitory storage media comprising program instructions operable to program a processor to perform any one or more of the methods described and / or claimed herein and / or to provide data processing apparatus as described and / or claimed herein. The controller may comprise an analogue control circuit which provides at least a part of this control functionality. An embodiment provides an analogue control circuit configured to perform any one or more of the methods described herein. The above embodiments are to be understood as illustrative examples. Further embodiments are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims. List of elements shown in drawings a detector 1 a housing 2 an active material 6 liquid medium 8 a gas sample inlet 10 a gas sample exhaust 11 an air mover 12, 14 sample of air 16 first fluid channel 17 branches 18 second fluid channel 19 cartridge receiving area 20 a removable cartridge 22 a cartridge dock 24 a detection assembly 26 a first fluid coupling interface 27 second fluid coupling interface 28 marker 30 a visual indicator 32, 34, 36 a light transmissive element (window) 32 a display 34 an optical detector 36 for sensing a reaction of the active material a reader 37 for reading data from a cartridge a controller 40 a communications interface 42 a reservoir 48 a compartment 46 an actuator 50

Claims

1. A detector for detecting a target biomolecule or composition comprising the target biomolecule, the detector comprising:a housing, configured to couple the detector to a carrier;a detection assembly for containing an active material and a liquid medium, wherein the detection assembly and the housing are mutually configured to provide an indication of a reaction of the active material to the target biomolecule or to the composition;a gas sample inlet provided on the housing and an air mover, wherein the gas sample inlet and the air mover are selectively operable to:draw, into the housing, a sample of air from around the apparatus; and toprovide the sample of air to the detection assembly for interaction with the active material;the housing further comprising an indicator output for providing the indication to the carrier.

2. The detector of claim 1 wherein the detection assembly comprises a cartridge dock 24, for docking a removable cartridge of active material in the housing.

3. The detector of claim 2 wherein the cartridge dock 24comprises a first fluid channel configured to enable mixing betweenthe sample of air and the liquid medium.

4. The detector of claim 3 wherein the air mover and the first fluid channel are arranged to mix the sample of air with the liquid medium.

5. The detector of claim 4 wherein the sample inlet and the air mover are configured to provide flow of the sample of air throughthe first fluid channel for mixing with the liquid medium.

6. The detector of claim 5 wherein the first fluid channel is branched for providing mixing between the sample of air and a plurality of liquid media.

7. The detector of claim 6 comprising a pressure reliefconfigured to relieve a pressure of the cartridge associated withflow in the first fluid coupling channel.

8. The detector of claim 7 wherein the pressure relief comprises asecond fluid channel.

9. The detector of claim 8 wherein the second fluid channel is configured to allow the sample of air to flow through the liquid medium, for example to be bubbled through it.

10. The detector of claim 8 wherein the pressure relief comprises at least one of a valve and a displaceable element, such as a piston or membrane.

11. The detector of any preceding claim, wherein the detectionassembly comprises a visual indicator, configured to provide avisual indication of a reaction of the active material.

12. The detector of claim 11 wherein the visual indicatorcomprises a display.

13. The detector of claim 12 wherein the detection assembly comprises an optical detector for sensing a reaction of the active material, and a controller configured to control the display basedon said sensing.

14. The detector of claim 12 wherein the detection assemblycomprises a light transmissive element and the display is provided,from the active material, via the light transmissive element.

15. The detector of claim 14 wherein the light transmissive element comprises a window, for example wherein the cartridge comprises a light transmissive portion for providing light between the active material and the detection assembly.

16. The detector of any preceding claim wherein the visual indication comprises an indication of a concentration of the target biomolecule or composition comprising the target biomolecule, for example wherein the indication is based on a spatial extent of a reaction of the active material.

17. The detector of any preceding claim wherein the reaction ofthe active material comprises fluorescence.

18. The detector of any preceding claim wherein the detector is wearable, for example wherein the detector is suitable for carrying by a single human carrier, for example wherein the housing is sized and arranged to enable the detector to be carried on a garment, or otherwise worn by, the single human carrier.

19. The detector of any preceding claim comprising a reader for reading data from a cartridge indicating the target biomolecule or composition to which the active material in the cartridge is sensitive .

20. The detector of claim 19 comprising a controller configuredto control the indicator output based on the data read from the cartridge and the reaction of the active material.

21. The detector of any preceding claim further comprising a replaceable cartridge containing the active material and the liquid medium and having means for coupling the sample of air into the cartridge to enable the sample of air to interact with the active material.

22. The detector of any claim 21 wherein the replaceable cartridge comprises a reservoir of the liquid medium and a compartment holding the active material separate from the liquid medium, wherein the cartridge comprises an actuator operable to combine the liquid medium and the active material.

23. The detector of claim 22 wherein the detection assembly isconfigured to provide access to the actuator from an exterior ofthe housing.

24. The detector of claim 22 or 23 comprising a plurality of cartridges and a plurality of active materials, each active material held in a respective corresponding one of the plurality of cartridges.

25. The detector of claim 24 wherein each of the plurality of active materials configured to detect a different target biomolecule or composition.

26. The detector of any of claims 19 to 25 wherein the or each cartridge comprises an interface comprising at least one fluid channel and being configured to engage with a dock of the detection assembly to connect the fluid channel of the detection assembly with a corresponding fluid channel of the dock to enable mixing between the sample of air and the liquid medium.

27. The detector of claim 26 wherein the detection assembly andthe or each cartridge are configured so that loading the or eachcartridge into the detection assembly causes the dock and the interface to engage to connect the fluid channels.

28. A cartridge for use in a detector for detecting a target biomolecule or composition comprising the target biomolecule, the cartridge comprising:a reservoir of a liquid medium; anda compartment holding active material separate from the liquid medium;an actuator operable to provide fluid communication between the compartment and the reservoir for mixing of the liquid medium and the active material; and,a fluid coupling interface comprising at least one fluid channel, connectable to the reservoir and being configured to engage with a dock of the detector.

29. The cartridge of claim 28 wherein the active material comprises at least one of cell-free biomolecules, purified biomolecules, such as antibodies, proteins, or peptides.

30. The cartridge of claim 26 or 27 wherein the active materialis freeze-dried.

31. The cartridge of claim 28, 29, or 30 wherein the active material is immobilised on beads, for example wherein the cartridge is configured to provide a visual indication of a concentration of the target biomolecule or composition comprising the target biomolecule based on a spatial extent of a reaction of the active material.

32. The cartridge of any of claims 28 to 31 wherein the active material comprises a fluorescent immunoassay reagent, for example an antibody or its fragment incorporated with a fluorophore so asto provide a fluorescence intensity which increases upon antigendependent removal of the fluorophore.

33. The cartridge of any of claims 28 to 32 wherein the liquid 5 medium comprises a solvent selected for activating the active material to perform an assay.

34. The cartridge of any of claims 28 to 33 wherein the actuator is provided by a cap of the cartridge, such as a twist cap.1035. The cartridge of any of claims 28 to 34 comprising data indicating the target biomolecule or composition to which the active material is sensitive, for example wherein the data is carried by a marker such as a machine-readable marker.1536. A detection assembly, for use in the detector of any of claims 1 to 27, the detection assembly comprising a plurality of cartridges according to any of claims 28 to 35.

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