WO2022171804A2

WO2022171804A2 - Gas analysis device

Info

Publication number: WO2022171804A2
Application number: PCT/EP2022/053384
Authority: WO
Inventors: Thomas Michaël BRASCHLER; Karl-Heinz Krause; Arthur SÉRÈS; Julien LEVALLOIS
Original assignee: Université De Genève
Priority date: 2021-02-12
Filing date: 2022-02-11
Publication date: 2022-08-18
Also published as: WO2022171804A3; EP4291087A2

Abstract

The invention relates to a gas analysis device for detecting the presence of an analyte, such as an analyte indicative of a respiratory condition. The invention also relates to a filter that may be used in such a device, and to methods of detecting an analyte, or of detecting a disease or condition, using the device.

Description

GAS ANALYSIS DEVICE

Field

The field of the invention is a gas analysis device for detecting the presence of an analyte, such as an analyte indicative of a condition. The gas analysis device may be a breath analysis device. The gas analysis device may comprise a dissolvable filter, a reservoir for storing liquid for dissolving the filter, and an analyser for detecting the presence of a condition in dependence on an analysis of the dissolved liquid. Advantages may include the gas analysis device being inexpensive and providing quick detection results. The gas analysis device may be used to detect conditions such as COVID-19.

Background

Breath analysis devices, also referred to as breath analysers, are convenient devices for detecting the presence of a condition. A user needs only to breathe into the breath analysis device and so the user experience is non-intrusive.

Problems with known breath analysis devices may include one or more of the breath analysis device being unable to detect a specific condition of interest, substantial medical training being required to operate the breath analysis device and/or obtain the detection result, the analysis process that the detection result is based on being relatively weak, and the length of time required to obtain the detection result being long.

Known techniques include using a device to collect a sample from a user’s breath and for the breath analysis to be performed in a separate apparatus. However, such techniques may not be suitable for use in the field where it is preferable for the same device to collect a sample from a user’s breath, analyse the sample, and provide the detection result.

There is a general need to improve on known implementations of breath analysis devices. More generally, there is a need to improve on known implementations of gas analysis devices. Gas analysis devices include, for example, devices for detecting the presence of viruses, or other conditions, in a transport hub, a room or an aircraft cabin.

Summary

Aspects of the invention are set out in the appended independent claims.

List of figures

Figure 1 shows an implementation of a rapid detection method according to an embodiment;

Figure 2 shows schematic diagrams of a breath analysis device according to a first embodiment;

Figure 3 shows the positive control area, negative control area and test control area of a analyser according to the first embodiment; and

Figure 4 schematically shows components of a breath analysis device according to a second embodiment.

Description

Embodiments generally provide gas analysis devices. A gas analysis device according to embodiments may be a breath analysis device and this is described first below.

Embodiments provide a breath analysis device, that may also be referred to as a breath analyser, with a number of advantages over known breath analysis devices.

A breath analysis device according to embodiments may provide a simple and robust detection technique. The breath analysis device may be portable, such as handheld. The breath analysis device may comprise one or more visual indicators of the result of the detection so that the breath analysis device is suitable for use in the field. Further advantages of the breath analysis device may include the analysis process comprising a simple amplification technique so that a relatively strong detection may be made and/or the length of time required to obtain the detection result being relatively short. The breath analysis device may also be configured to detect a number of conditions or analytes. Such conditions include infections by pathogenic microorganisms (such as pulmonary infections) and cancer, as discussed in more detail below. In particular, the device may be configured to detect one or more variants of COVID19 or to detect COVID19 and/or influenza. The device may alternatively be configured to detect any analyte of interest that may be present in exhaled breath, such as a drug or toxin, a non-pathogenic microorganism (such as a beneficial microorganism of the respiratory tract), or an antibody, such as an antibody of a particular isotype, in particular IgA.

The breath analysis device according to embodiments is advantageous over known breath analysis techniques that may require one or more of pipetting, solution changes, specific separate equipment to analyse an obtained sample, and/or provide the detection result, and comprise no amplification in the detection process.

The breath analysis device according to embodiments comprises a filter for capturing exhaled analytes, such as exhaled particles, by a user of the breath analysis device. The filter is soluble, for example water-soluble, and may comprise reactants for the detection process of specific particles.

The process for using the breath analysis device according to embodiments may comprise the following steps:

1 ) A user of the breath analysis device breathes into the breath analysis device and particles in the user’s breath are captured in the filter;

2) A liquid capable of dissolving the filter and which may comprise one or more reactants, wherein the liquid may be water-based or organic, for example water, is released from a reservoir in the breath analysis device and dissolves the filter; 3) A reaction process between reactants in the filter and captured particles commences;

4) The water comprising the dissolved filter and reactants flows to an analyser in the breath analysis device; and 5) The analyser indicates the detection result, such as by a colour change.

Aspects of embodiments are described in more detail below.

The breath analysis device according to embodiments may comprise a sensitive two- component amplification method embedded in the water-soluble filter. The detection system may comprise:

1. Two distinct binding proteins with high affinity for different sites of the same microbial protein (e.g. SARS-CoV-2 spike protein, or influenza HA protein).

2. Each one of two binding proteins may contain (covalently attached or as continuous polypeptide) a part of a split reporter.

3. The split reporter may be, for example, an enzyme or a fluorescent protein.

4. The two binding proteins may not interact with each other in the absence of the microbial protein.

5. The two binding proteins may be antibodies, diabodies, or other types of high affinity ligands.

6. In the presence of the microbial protein, the two parts of the split reporter may be in close proximity and therefore the reporter will be active.

7. Detection of reporter activity will typically be dependent on the nature of the reporter gene, but the detection may be a colorimetric reaction.

8. Multiplexing may be possible by including a second set (or multiple sets) of binding proteins with different types of split reporters and different detection systems (e.g. two diabodies against the SARS-Cov-2 spike protein with a split beta-lactamase assay (red colour) and two diabodies against the influenza HA protein with a split B-Galactosidase (blue colour).

9. The elements of the detection system (binding proteins with split reporter, as well as reporter substrates) may be included in a water-soluble filter to allow dry storage and avoid spontaneous activation during storage.

Figure 1 shows an implementation of a rapid detection method according to an embodiment.

Figure 1 shows a first beta-lactamase fragment 101, a second beta-lactamse fragment 102, a non-fluorescent substrate 104, a spike protein 103 and a fluorescent product 105.

The left side of Figure 1 shows binding proteins (diabodies to SARS-Cov-2 spike protein) fused to beta-lactamase fragments in a filter according to embodiments with the filter in a ready for use state. The filter is in a dry state with the fused binding protein-beta- lactamase fragments inactive. The fused binding protein-beta-lactamase fragments are located in close proximity to each other in the filter.

The right side of Figure 1 shows fused binding protein-beta-lactamase fragments in the filter after the breath analysis device has been breathed through. The filter has captured exhaled particles and been dissolved in water. The captured exhaled particles include a spike protein and binding of the binding proteins to the spike protein causes enzymatic activity of the beta-lactamase fragments on a non-fluorescent substrate. This may generate a fluorescent product 105.

The specific reactants, e.g. beta-lactamase fragments, that are comprised by the filter may be selected in dependence on a specific particle, e.g. spike protein, to be detected by the breath analysis device.

Figure 2 shows schematic diagrams of a breath analysis device according to a first embodiment. In particular, subfigure A shows the breath analysis device according to the first embodiment when it is in a ready to use state. Subfigures B to F are schematic diagrams of the breath analysis device according to the first embodiment at different stages during use of the breath analysis device.

The breath analysis device comprises a mouthpiece, a main chamber, a filter, a baseplate, a reservoir and an analyser.

The mouthpiece is arranged so that a user of the breath analysis device may breath into it.

The main chamber may be substantially elongate and tubular. The mouthpiece is arranged at a first end of the main chamber. The filter is arranged at a second end of the main chamber. The second end of the main chamber is opposite the first end. The main chamber is arranged to receive breath that enters the breath analysis device via the mouthpiece. The received breath may flow through the filter and out of the breath analysis device. The main chamber therefore supports a gas flow path, i.e. breath flow path, through the breath analysis device.

The filter may be arranged across an entire cross-section of the main chamber. A property of the filter is that the substantial part of the gas that is breathed into the breath analysis device is able to flow through the filter. All of the gas that flows out of the main chamber may therefore be forced to flow through the filter. The filter may be retained in a dry state prior to use of the breath analysis device. As described above, the filter may comprise one or more reactants/reagents, such as binding protein-beta-lactamase fragments, in its dry state. The reactants/reagents are thus typically in dry form, such as lyophilised form. The filter may be at least partially soluble. In particular, some, or all, of the filter may be water-soluble.

The filter may comprise filter material with any immune-enzymatic or nucleic acid detection components, as described in more detail below. In particular, the filter may have any, or all, of the following properties:

1. The filter structure may be one or more of a meshwork, sponge, punctuated plate, or micro-sieve. The filter structure should let a breath flow pass but retain at least part of the exhaled particles and droplets in the breath. Upon dissolution of some, or all, of the filter in a liquid, the liquid comprising the dissolved filter (which may have a high polymer concentration) should not have such a high viscosity that the liquid is unable to flow. Acceptable viscosities may be about 2 Pa*s or lower, preferably less than or equal to 1 Pa*s. The viscosity should not be as high as 1000s of Pa*s, at estimated solute concentrations of some 2-10%. Suitable materials for the filter to be constructed from may include lower molecular weight PEGs (polyethylene glycols), mono- and di-saccharides, or carbohydrate oligomers. These materials may easily be lyophilized to sponge-like structures, although other fabrication techniques such as molding are possible too.

The filter may be a porous structure. Chemical and/or physical processes may be used to manufacture the porous structure.

A chemical process used in the manufacture of the filter according to embodiments may include using acetic bacteria to synthesise a thin sheet of bio-cellulose. The pores in the sheet may be enlarged by bombarding the sheet with a carbon dioxide plasma.

Alternative chemical processes used in the manufacture of the filter according to embodiments may include synthesising acrylamide cryogel and/or sugar cryogel.

A physical process for manufacturing the filter according to embodiments may include manufacturing a filter body and then mechanically piecing the filter body. In particular, the filter body may first be synthesised. The filter body may comprise methyl-cellulose and/or salt. The filter body have been dried in an oven. The filter body may then be pierced by a plurality of nano-needles. The nano-needles may be a plurality of thin metallic pins with each pin having a diameter of lpm to 10pm, or less than lpm. The piercing may generate pores/holes in the filter body with the diameter of each pore/hole being substantially the same as the diameter of the pin that generated it. Preferably, the filter body comprise methyl-cellulose and has pores of lpm to 10pm created by mechanical piercing of the filter body with nano-needles. Advantageously, the size and arrangement of the nano-needles allows a well defined pattern of pores/holes to be formed in the filter and this is a reliable way of achieving a desired porosity.

Specific methods for manufacturing the filter according to embodiments are described below. The filter may comprise a methylcellulose film. The film may be made by dissolving methylcellulose (e.g. Sigma, M0512-250G, Lot #079K0054) at a concentration of 2% in deionized water, DI (i.e. lg of methylcellulose may be dissolved in 49g of DI). This may comprise pouring hot water, at a temperature of about 80°C, onto the methylcellulose, and then letting the solution cool down to 20°C or lower, with occasional agitation. Alternatively, the methylcellulose may be dissolved in cold water by leaving the solution overnight.

A drop of about lmL of the methylcellulose solution may then placed onto a polypropylene surface (this is a lot more effective than glass or polystyrene surfaces that may not work). The polypropylene surface may be a substrate for supporting the generation of a methylcellulose film. Air blowing (e.g. at 1 bar pressure, 5mm/50cm length), or spin-coating (e.g. at 100-4000rpm), may then used to flatten out the drop, while simultaneously drying it. Drying may be completed by inserting the substrate into an oven at a temperature of about 80°C for about 1 hour. The film may then be carefully detached from the substrate, such as with tweezers. The film may have a thickness of about 1-50 microns, depending on the air flow rate or spin coating speed.

A hole stamping process may then be performed for generating holes in the methylcellulose film. This may be performed with the above-described nano-needles. The nano-needles may be metallic and the tip radius may be lpm or less. The tip opening angle may be a few degrees up to 45°. There may be a single, or small number of, nano needles that are repeatedly used serially. Alternatively, there may be an array comprising a plurality of nano-needles.

The film may be placed onto a substrate that is substantially softer than the tips of the nano-needles (e.g. an aluminium substrate may be used when the tips of the nano-needles are a harder material, such as tungsten carbide or silicon-carbide). The tips of the nano needles may be lowered onto the film and pressed into the film towards the substrate. Depending on the opening angle, the tips of the nano-needles may be lowered one to several opening diameters into the substrate. This process may create a well defined pattern of holes that may each have a diameter in the range of about 1-50 micrometers, depending on the sizes and shapes of the tips and extent of insertion through the film.

Another method for manufacturing the methylcellulose film is described below.

An assembly may be generated that comprises 2% methylcellulose cast between a polypropylene sheet that has been activated by oxygen plasma (e.g. for 30s at 100W), and a polypropylene mesh with a thickness of 40 micron. The polypropylene mesh may be untreated and therefore hydrophobic. The height of the filter may be set with a spacer that may be 50 microns thick. The assembly may then be frozen rapidly with liquid nitrogen, after which the temperature may be raised back to -20°C in a freezer. At this temperature, the polypropylene sheets may have some flexibility so that the upper polypropylene sheet may be pealed off. The assembly may then be put into a lyophilizer with a temperature- controlled shelves (e.g. SP Scientific, Advantage PRO) and lyophilized at 50mtorr and a shelve temperature of -30°C. After completion of lyophilisation, that may be an overnight process, the film may be used as a filter. The film may be used, or tested, with the polypropylene sheet in place.

The filter may be installed in a mouthpiece, such as a a Falcon tube with a 15mL diameter. To do this the tube may be cut open, and the edges heated with a hot air gun (set to 300°C). Once the edges are liquid, the open Flacon tube may be pressed onto the filter/backing assembly and hot welded together. After this, two lateral access holes may be drilled and filled with filter paper. With this setup, it may be possible to breathe some air through the filter, followed by dissolution with liquid after removal of one of the two filter papers. After and at the same time as the dissolution process, the liquid may be drawn into the second filter paper.

Further details of method for manufacturing the filter are described below.

Embodiments include contiguous dissolvable substrates, such as the above-described methylcellulose films, being prepared. The dissolvable substrates may then be covered with a photolithographically structured mask and subsequently exposed to oxygen plasma. The etching parameters may be 10-100W/L of oxygen plasma. The etching process may generate holes in the dissolvable substrates in dependence on the pattern of the mask.

Each filter may be backed with a polypropylene mesh that is a hydrophobic baseplate. The pore sizes of the baseplate are preferably in the range of 1-1000 micrometers, more preferably 10-500 micrometers, and even more preferably about 50-300 micrometers.

Such meshes are commercially available, e.g. from PlastOK, UK. Backed with such meshes, the filters can withstand full atmospheric pressure and the expected pressures during typical use.

When the filter thickness is about 10 microns, and the hole/pore diameter about 10 microns, the gas flow rate through the filter may be about in the 1-lOL/s/cm² range. This enables a large concentration of viral particles in a very low area and mass of filter. There is in fact a synergy between thin filter providing both for very low mass to be diluted and extremely low air flow resistance, and hydrophobic backing providing filter strength despite very low thickness and ease of collection of the analyte by lateral fluidic withdrawal or sampling after dilution.

2. The filter may comprise a hydrophilic material. The filter material may be sufficiently hydrophilic to permit rapid wetting while avoiding substantial entrapment of air bubbles. Contact angles lower than 45°, or preferably lower than 20°, may be suitable.

3. To further accelerate dissolution of the filter in water, inert, the filter may comprises rapidly dissolving substances. These may, for example, comprise sodium chloride or sodium bicarbonate, provided either as separate powders or dissolved during filter fabrication.

4. The filter material, once dissolved, preferably does not have a strong affinity to any of the assay components so that it does not interfere with the assay components, or trigger the enzymatic assembly. It may therefore be “non-fouling”, at least with respect to the enzymatic assay components. Protein interaction (“fouling”) is typically a problem with ionic substances. However, with carbohydrates it is less of a problem and some of these are indeed used to stabilize proteins during lyophilization (maltose, maltodextrin and substances of the like).

5. A property of the filter material is that it is able to capture analytes, such as particles, in exhaled breath. The main force of adhesion for analytes, such as particles, for example viral particles, may be a capillary water film formation. The filter material preferably allows adsorption of a fluid film at the surface. The capture efficiency of analytes may be further improved by the filter being electrostatically charged. This can be as a result of its chemical composition, such as in electret materials, with orientable charged moieties. For example, peptides or polysaccharides with block-co-polymer structure with schematically a positive and negative end and a neutral connection segment; or separable charged moieties may be included during synthesis of the filter material. Induced or permanent dipoles may then be oriented during fabrication with an applied external fieldand, fixed thereafter once the material becomes sufficiently dry, typically to achieve a glassy state with very limited molecular mobility. Alternatively, charges may be deposited secondarily by any known techniques of charge deposition, for example by means known in the art such as corona discharge, electron guns or of the like.

Alternatively, the breath analysis device may further comprise an electric charger arranged to electrically charge the filter. The electric charge may be generated by applying an external voltage, for instance generated by a manual piezo actuator connected to a metal mesh embedded in or on the filter, or a breath-activated electrical generator likewise connected to the embedded metal mesh, the voltage being relative to a second metal mesh in or on the filter but electrically isolated from the first one. The analytes in exhaled breath may thus be electrostatically attracted to the filter. AC actuation or DC charging may be used.

In some aspects, the capture efficiency of the filter may be further improved by inclusion of one or more elements having affinity for one or more analytes of interest (also described herein as capture elements or ligands) in the filter, thus assisting retention of analytes of interest in the filter. The filter may comprise an affinity matrix (for example a protein or nucleic acid affinity matrix). One or more ligands for one or more analytes of interest may be coupled to the filter, for example coupled (typically covalently coupled) to an affinity matrix. The capture elements or ligands may be any capture elements or ligands reversibly binding the analyte(s) of interest, such as antibodies or antibody derivatives, peptides, lectins, nucleic acids (such as complementary oligonucleotides or aptamers), receptor or carrier proteins, and the like.

6. When the filter is in the dry state, reactions may be more or less prohibited due to the very low molecular mobility. Early reaction/hydrolysis is therefore unlikely to occur. However, the likelihood of early reaction/hydrolysis occurring may be further reduced by the filter comprising reaction components in separate granules, such as in a pressed filter. Early reaction/hydrolysis may therefore occur at nanometric grain boundaries, but not as a bulk. Such grain-boundary reactions may further be suppressed by dilution with further, inert granules.

The baseplate is arranged to support the filter in the breath analysis device. The baseplate may comprise a plurality of openings so that gas may flow through the baseplate. The diameter of openings in the baseplate may be in the range of about 1 pm to about 1mm, and preferably in the range 5 pm to 100pm. The base plate may be arranged on the opposite side of the filter to the main chamber. The base plate may provide part of the external surface of the breath analysis device. The surface of the base plate may be entirely, or partially, coated with a hydrophobic material. This may prevent a substantial amount of liquid leaking through the baseplate.

The filter may be arranged so that it is easily insertable and/or replaceable in the breath analysis device. For example, the baseplate may be detachable from the breath analysis device so that a new filter may be inserted into the breath analysis device. The baseplate may then be re-attached to the breath analysis device.

The reservoir comprises a liquid. The liquid comprised by the reservoir may be water.

The breath analysis device may comprise a liquid release mechanism arranged to release the liquid in the reservoir. The liquid release mechanism may comprise, for example, a controllable valve or a breakable wall for retaining the liquid within the reservoir until the liquid release mechanism is activated. Upon activation of the liquid release mechanism, some, or all, of the liquid may be released from the reservoir. For example, activation of the liquid release mechanism may comprise a valve changing from a closed state to an open state, or a wall of the reservoir being broken. The breath analysis device may comprise one or more sensors for detecting the amount, and/or rate, of gas flow into, or through, the breath analysis device. The liquid release mechanism may arranged to release liquid from the reservoir in response to a determination by the one or more sensors that there has been at least a predetermined flow/volume of gas, i.e. breath, into the device.

The breath analysis device may comprise a part that is arranged to be pressed by a user of the device. The part may configured so that liquid is forced out of the reservoir when the part is pressed. A breakable wall holding liquid within the reservoir may be broken in response to the part being pressed.

The reservoir may be configured so that the released liquid flows to the filter. The filter may therefore be dissolved by the released liquid. The reservoir may comprise an openable, and closable, external opening so that the reservoir may be easily refilled with liquid. The reservoir may alternatively, or additionally, be an easily replaceable part of the breath analysis device.

The breath analysis device may comprise one of more capillary conduits/tubes so that liquid comprising the dissolved filter may flow to the analyser.

The analyser comprises one or more sections/detection areas for receiving and analysing the components of liquid that comprise a dissolved filter. In particular, as shown in Figure 3, the analyser may comprise a positive control area, a negative control area and a test control area. The positive control area may comprise an immobilised antigen. The negative control area may neither comprise an immobilised antigen nor a capture antibody. The test control area may comprise a capture antibody, e.g a secondary antibody such as an antibody which is anti-species for the binding proteins (such as antibodies) for the analyte. The different detection areas in the analyser may comprise materials that have capillary action, but do not adsorb the assay or analytes (such as particles) captured from the breath. Implementations of this may include fine tubing, that may be passivated, or non-absorbing meshes.

The breath analysis device may comprise one or more visual indicators for displaying the result of the analyser. For example, the breath analysis device may comprise an electronic display configured to provide the analysis result. Alternatively, the breath analysis device may comprise one or more surfaces that comprise substances that are configured so that their colour/fluorescence/luminescence is dependent on the detection result. The one or more surfaces may be viewable from the outside of the breath analysis device, or the breath analysis device may be partially opened so that the surfaces may be viewed. In particular, embodiments include the colour of one or more of the positive control area, the negative control area and the test control area being dependent on the detection result.

The flow of liquid to the analyser may be stopped before excess flow occurs. If there is an excess flow of liquid, then washout of the coloured/fluorescent/luminescent product and/or cross-contamination may occur. Appropriate flow of liquid to the analyser may be achieved by one or more of the design of the capillary conduits/tubes for transporting the liquid, changing the viscosity of the liquid after a filter has been dissolved, and the use of a solid, or covalently immobilised substrate.

In Figure 2, subfigures A to F show the breath analysis device in different operational states.

In subfigure A, the breath analysis device is in a read to use state. The filter is dry.

In subfigure B, the breath analysis device is in the process of being used. A user of the breath analysis device is breathing into the mouthpiece and there is a flow of breath through the main chamber and the filter. Particles comprised by the breath may be captured in the filter.

In subfigure C, the process of releasing liquid in the reservoir is shown. This may be performed after the user has finished breathing into the breath analysis device. Liquid may be released from the reservoir by any of a number of techniques. For example, a valve may be manually, or electronically, opened. As shown in subfigure C, the reservoir may comprise a pressable part that, when pressed, forces liquid out of the reservoir. This process may comprise the breaking of a breakable wall that was retaining liquid in the reservoir.

More generally, the activation of a liquid release mechanism may be by a manual technique, such as pushing, bending, or of the like. The activation may alternatively be coupled to a sufficient air volume, for example by the force of a balloon or by electronic detection of sufficient total air flow volume. The breath analysis device may comprise an air flow gauge for such electronic detection.

Subfigure D shows the breath analysis device after the filter, and captured particles (such as antigens), have been dissolved by the liquid that was released from the reservoir.

Subfigure E shows the liquid that has dissolved the filter in the process of flowing to the analyser via one or more capillary tubes. The flow of liquid to the analyser may be a lateral flow.

Subfigure F shows the particles that were captured by the filter undergoing enzymatic development in the analyser.

Figure 3 shows processes performed in the positive control area, negative control area and test control area of the analyser. The colour of one or more of the test areas may indicate the result of the particle detection. Alternatively, or additionally, the result of the particle detection may be provided by the fluorescence and/or luminescence of one or more of the test areas.

Figure 4 is a schematic diagram of components of a breath analysis device according to a second embodiment. The breath analysis device of the second embodiment differs from that of the first embodiment by the breath analysis device comprising a plurality of separate filters.

As already described for the first embodiment, the breath analysis device of the second embodiment may comprise a main chamber. A filter for capturing particles in breath may be arranged at the opposite end of the main chamber to the mouthpiece. This is indicated in the leftmost subfigure in Figure 4. The substantial gas flow through the breath analysis device may be through this filter.

The main chamber of the breath analysis device may be referred to as a first chamber/compartment. The filter comprised by the main chamber may be referred to as a first filter. The breath analysis device may further comprise second and third chambers/compartments that each comprise a filter. The filter comprised by the second chamber/compartment may be referred to as a second filter. The filter comprised by the third chamber/compartment may be referred to as a third filter. There may be very little, or substantially no, flow of breath through the filters in the second and third chambers/compartments. The first, second and third chambers/compartments may be substantially separate from each other.

The first filter may be substantially the same as the filter as described for the first embodiment. That is to say, the first filter may be water-soluble and comprise the earlier described reactants.

The second filter, which is shown in the central subfigure in Figure 4, may be used as a negative control. There may be substantially no air flow through the second filter and the second filter may comprise substantially the same reactants as the first filter.

The third filter, which is shown in the rightmost subfigure in Figure 4, may be used as a positive control. There may be substantially no air flow through the third filter. The third filter may comprise substantially the same reactants as the first filter but also comprise a known amount of antigen. The operation of the breath analysis device according to the second embodiment may comprise each filter being dissolved in liquid from a reservoir. Liquid may flow to each filter at about the same time so that each filter is dissolved at about the same time.

The breath analysis device may comprise a single reservoir of liquid, such as water, with liquid flow paths to each filter. The liquid release mechanism may be configured to release a flow of liquid from the reservoir to each filter when the liquid release mechanism is triggered. All of the first, second and third filters may thereby be dissolved at about the same time by liquid from the same reservoir.

Alternatively, the breath analysis device may comprise more than one reservoir, such as a respective reservoir to each filter. There may a flow path from each reservoir to at least one of the first, second and third filters. There may a single liquid release mechanism that, when triggered, releases a flow of liquid from each reservoir. All of the first, second and third filters may thereby be dissolved at about the same time by liquid from the different reservoirs.

In other respects from those described above, the breath analysis device of the second embodiment may be substantially as described for the first embodiment.

The breath analysis device of the second embodiment is operated in a similar way to that of the first embodiment. A user of the breath analysis device breathes through the mouthpiece and particles in the user’s breath are captured in the first filter. The liquid release mechanism is then triggered so that fluid flows from one or more reservoirs to all of the first, second and third filters. All of the first, second and third filters are dissolved by liquid. The liquid comprising each dissolved filter flows laterally, via capillary tubes or another technique, to separate analysers, or separate sections of the same analyser, where the liquids are analysed. Similar to as described of the first embodiment, the analyser(s) may indicate the result of the detection by their colour, or by, for example, an electronic display. In the second embodiment, the flow of liquid to the different analysers, or different sections of the same analyser, may need to be stopped to avoid excess flow of liquid occurring. However, the diffusion of a coloured/fluorescent/luminescent substrate is much less of an issue than for the first embodiment and no capture antibody is required. The control of the flow of liquid for the second embodiment is therefore easier than for the first embodiment.

An advantage of the second embodiment over the first embodiment is that no capture antibody is required when analysing each liquid that comprises a dissolved filter. There is also substantially no risk of diffusion occurring of the colour/fluorescent/luminescent enzymatic reaction product.

A main implementation of embodiments is a breath analyser that provides quick in-situ virus detection and provides a visual indication of the detection result.

Embodiments also include using the above-described breath analyser to capture analytes and then performing a de-localised analysis of the captured analytes. For example, the filter, or a liquid that has dissolved the filter, may be removable from the device and then analysed in a separate apparatus. The separate apparatus may perform any of a number of analysis techniques to analyse the filter, or liquid that has dissolved the filter. For example, it may perform one or more of a qPCR analysis, RT-PCR, RNAseq, DNA sequencing and mass spectrometry.

Embodiments also include the provision of a gas analysis device. As described above for the breath analysis device of embodiments, the gas analysis device may comprise a dissolvable filter that is arranged to capture analytes. The gas analysis device may differ from the breath analysis device by comprising an air intake arrangement for drawing in air from its surrounding environment instead of a mouthpiece. The air intake arrangement may comprise a fan for sucking in air. At least some of the air that is drawn in through the air intake arrangement may flow through the filter.

The gas analysis device may be able to perform an in-situ analysis of the captured analytes, and provision of a detection result, as described for an embodiment of the breath analyser. Embodiments also include the gas analysis device being configured for a de localised analysis of the analytes and provision of a detection result, as is also described for an embodiment of the breath analyser.

The breathing of people in an environment generates airborne analytes. The gas analysis device of embodiments may be located anywhere that airborne analytes may be captured. For example, the gas analysis device may be located in a transport hub (such as an airport or railway station), a waiting room, cinema, aircraft cabin or any other enclosed environment. The gas analysis device according to embodiments allows an environment to be monitored for specific viruses and other conditions. For example, when the gas analysis device is installed on an aircraft, a new filter may be placed in the gas analysis device before each flight. The analytes captured by the filter may be analysed after each flight and used to determine if anyone present on the flight was carrying a virus, or other condition. This helps to track the spread of a virus, or other condition, without the need to perform a breath analysis of everyone on the flight. The analysis may also allow early detection of new viruses or new variants of viruses through, for example, RNA sequencing.

Embodiments therefore provide a gas analysis device, that may be a breath analysis device, with a number of advantages over known such devices. The gas analysis device may be used to detect COVID-19 and/or influenza. The gas analysis device may alternatively, or additionally, be used to detect other diseases and conditions where analytes indicative of such a disease or condition are present in air/breath. The analyte may be a particle or molecule, such as a volatile molecule, for example a volatile organic compound. Such diseases or conditions may include infections (typically respiratory) by any microorganism, in particular pulmonary infections, where the analyte may be a particle or one more components of the microrganism. The infection may be viral (such as an infection by any respiratory virus, such as a coronavirus or influenza virus), bacterial (such as any bacterial respiratory infection including upper and lower respiratory tract infections, pharyngitis or tonsillitis, or any other bacterial infection such as Tuberculosis, H. pylori infection or Pseudomonas infection), fungal (such as any fungal respiratory infection, pneumocystis or aspergillosis, or any mould infection) or parasitic.

Alternatively, the disease or condition may be any other disease or condition where an analyte indicative of the disease or condition (such as a volatile organic compound) is present in air/breath. Such diseases may include any respiratory condition, such as any one or more of bronchiectasis, chronic obstructive pulmonary disease, asthma, acute respiratory distress syndrome, cystic fibrosis, pneumonia, pulmonary embolism, interstitial lung disease and cancer. The cancer may be lung cancer or any tumour of the respiratory tract. The cancer may alternatively be a non-respiratory cancer, typically any cancer where analytes indicative of the cancer may be present in exhaled breath. The cancer may be head and neck cancer, breast cancer, liver cancer, mesothelioma, gastric cancer, pancreatic cancer, colorectal cancer or ovarian cancer. An analyte indicative of cancer may be a cancer cell or any molecule indicative of a cancer, such as a specific metabolite or protein. The analyte may be a nucleotide sequence indicative of a cancer, such as a nucleotide sequence of a genetic anomaly present in a cancer. The disease or condition may be any other non-respiratory condition where an analyte indicative of the disease or condition may be present in exhaled breath. The disease or condition may be an inherited metabolic disease, multiple sclerosis, Alzheimer’s disease, Parkinson’s disease, schizophrenia, allograft or transplant rejection, heart disease, atherosclerosis, renal failure, liver cirrhosis, alcoholic hepatitis, non-alcoholic fatty liver disease, carbohydrate malabsorption, diabetes, or sepsis.

In other aspects, the gas analysis device may be used to detect a drug or toxin, a non- pathogenic microorganism (such as a beneficial microorganism of the respiratory tract), or an antibody, such as an antibody of a particular isotype, in particular IgA. The gas analysis device may also be used to capture and identify any substance in exhaled breath, in particular any volatile organic compound. The device may thus be used for example to identify an analyte in exhaled breath whose presence and/or amount is able to be correlated with presence of, or risk of developing, any disease or condition, such as a disease or condition described above. The analyte may be an analyte not previously identified as associated with the disease or condition.

Embodiments of the invention thus include a method of determining or identifying an analyte in exhaled breath whose presence and/or amount correlates with presence of, or risk of developing a disease or condition, the method comprising breathing, by the user, into a breath analysis device described herein, and identifying an analyte present in the received breath. The analyte is typically captured by the filter. The filter or a solution comprising the dissolved filter may then be removed from the device and analytes captured by the filter then identified by any method allowing for identification and/or quantitation of analytes, such as spectroscopy, mass spectrometry, an immunoassay or nucleic acid analysis, such as nucleic acid sequencing. The absolute or relative quantity of the analyte may be determined. The method may comprise identification of analytes present in exhaled breath of an individual known to have, or be at risk of developing a disease or condition described herein. The method may further comprising determining that an analyte thus identified is not present in (or is present in a different amount in) exhaled breath of an individual that does not have, or is determined as not being at risk of developing, the disease or condition.

In aspects relating to identification of analytes, the breath device may not comprise an analyser and thus may comprise a mouthpiece arranged to receive breath from a user of the device; a reservoir comprising a liquid; a filter configured to capture analytes in the received breath, wherein the filter is arranged in a flow path of the breath through the device and the filter is at least partially soluble in the liquid comprised by the reservoir; and a liquid release mechanism configured to release liquid in the reservoir so that the liquid flows to the filter.

Embodiments include a number of modifications and variations to the techniques described above.

In particular, a filter has been described as capturing particles in breath for analysis by the breath analysis device. The captured particles may be, for example, viral particles. However, embodiments more generally include the filter being configured to capture any exhaled analytes for analysis by the breath analysis device. For example, the captured exhaled analyte may be any drug or toxin, such as alcohol. The reference to particles throughout the present documents may therefore be construed as including any type of exhaled analyte.

In the above described embodiments, a filter is described as comprising reactants. The reactants may react with captured particles by the filter. Embodiments also include the reactants alternatively, or additionally, being provided outside of the filter. For example, the reactants may be provided in capillary conduits for transporting liquid comprising the dissolved filter to the analyser.

The reactants (also described herein as reagents) may be any reagents suitable for detection of an analyte. Typically, the reagents include reagents capable of specifically binding the analyte. Any suitable capture reagents or moieties for an analyte may be employed. The reagents may for example comprise one or more binding proteins specific for at least one antigen of the analyte or one or more nucleic acids specific for at least one target nucleic acid of the analyte. The reagents may also include at least one substance that is configured to change colour, fluorescence and/or luminescence in response to the analysis result. Such reagents provide for a visual indicator of the analysis result.

In aspects relating to use of binding proteins, these may be antibodies or antigen-binding fragments thereof. An antibody “specifically binds” to a protein when it binds with preferential or high affinity to that protein but does not substantially bind, does not bind or binds with only low affinity to other proteins. For instance, an antibody “specifically binds” a target molecule when it binds with preferential or high affinity to that target but does not substantially bind, does not bind or binds with only low affinity to other proteins. An antibody binds with preferential or high affinity if it binds with a Kd of 1 x 10-7 M or less, more preferably 5 x 10-8 M or less, more preferably 1 x 10-8 M or less or more preferably 5 x 10-9 M or less. An antibody binds with low affinity if it binds with a Kd of 1 x 10-6 M or more, more preferably 1 x 10-5 M or more, more preferably 1 x 10-4 M or more, more preferably 1 x 10-3 M or more, even more preferably 1 x 10-2 M or more. The antibody may be, for example, a monoclonal antibody, a polyclonal antibody, a single chain antibody, a chimeric antibody, a bispecific antibody, a CDR-grafted antibody or a humanized antibody. The antibody may be an intact immunoglobulin molecule or a fragment thereof such as a Fab, F(ab’)2 or Fv fragment, or diabody.

The one or more binding proteins are specific for at least one antigen whose presence in the analytes is to be determined. The one or more binding proteins may be specific for at least one epitope of an antigen whose presence in the analytes is to be determined hi some aspects, at least two binding proteins may be employed, with each binding protein specific for a different epitope of the same antigen, or specific for different antigens of the same analyte. For example, the analyte may be SARS-COV2 and binding proteins for different antigens of SARS-COV2 or for different epitopes of the same antigen of SARS-COV2 (such as the spike protein) may be employed. Where the analyte is influenza, binding proteins for different antigens of influenza (for example influenza HA and at least one further influenza antigen) or for different epitopes of the same influenza antigen (such as HA) may be employed.

The one or more binding proteins may comprise at least a portion of a reporter, wherein said reporter, when active, is capable of generating a visual indicator in response to binding of said antigen by the binding protein(s). The one or more binding proteins are typically fused to (N- or C-terminally) or covalently attached to at least a portion of the reporter. The reporter is inactive or substantially inactive in the absence of binding of said antigen. The visual indicator may be a change in colour, fluorescence or luminescence. Any suitable reporter may be employed, such as any enzyme (including any protease) or any fluorescent protein. Reporters are well known in the art and suitable reporters are described for example in Lim & Wells Methods in Enyzymology, 644: 275-296 (2020), whose disclosure is incorporated by reference, including reporters described in Table 1 thereof. Examples of suitable reporters include beta-lactamase, beta-galactosidase, dihydrofolate reductase, horse radish peroxidase, luciferase and GFP.

At least two binding proteins may be employed, specific for different antigens of an analyte, or different epitopes of an antigen of an analyte, wherein the binding proteins comprise different portions of a reporter (also described herein as a “split reporter”, and wherein association of the binding proteins on binding of said antigen(s) provides an active reporter capable of generating a visual indicator. Design principles and strategy for split reporter engineering are known in the art and described for example in Lim & Wells supra. The split reporter may be based on any reporter, including reporters described above, and any binding proteins, such as antibodies, or antigen-binding fragments thereof. The at least two binding proteins may for example bind different epitopes of the spike protein of SARS-COV2 (or influenza HA), and may be at least two diabodies specific for the SARS-COV2 spike protein (or influenza HA). The binding proteins may be fused to different portions of a reporter such as beta-lactamase or beta-galactosidase, which on binding of the binding proteins to the analyte, associate to provide an active enzyme.

The device is also applicable to detection of multiple analytes (such as different microbial or viral particles, such as SARS-COV2 as a first analyte and influenza as a second analyte) by inclusion of different sets of binding proteins for each analyte whose presence is to be determined. Thus, the device may comprise one or more binding proteins for at least one antigen of a first analyte and one or more binding proteins for at least one antigen of a second analyte. The one or more binding proteins for at least one antigen of a first analyte may comprise at least a portion of a first reporter, and the one or more binding proteins for at least one antigen of a second analyte may comprise at least a portion of a second reporter, wherein each said reporter, when active, is capable of generating a visual indicator in response to binding of each analyte, and wherein the visual indicator for binding of each set of analyte is different. For example, the visual indicator for a first analyte may be a first colour and the visual indicator for a second indicator a second, different colour. The first reporter may be beta-lactamase and the second reporter beta- galactosidase.

The reagents for detection in aspects relating to binding proteins and reporters typically further comprise at least one substrate for the reporter that changes colour, fluorescence and/or luminescence on activity of the reporter. The substrate may be any suitable substrate having such a property, and may be a substrate for any suitable reporter described herein.

In aspects relating to use of nucleic acids specific for at least one target nucleic acid of the analyte, any suitable nucleic acid reagents capable of binding a nucleic acid sequence of the target nucleic acid and optionally amplifying said nucleic acid sequence may be employed. The nucleic acid reagents may comprise primers and/or probes for the target nucleic acid sequence. Presence of a target nucleic acid sequence may be determined by binding to a detectably labelled probe (such as a fluorescently labelled probe), which may be immobilised in a test area. A template nucleic acid comprising the target nucleic acid sequence may be immobilised in a positive control area. Presence of a target nucleic acid sequence may also be determined by amplification of the sequence, as determined by colorimetric change in the presence of template-dependent amplification (for example using a pH-sensitive dye that changes colour upon acidification induced by amplification), by real-time detection of fluorescence emission with a DNA-intercalating fluorescent dye, or by analysis and/or sequencing of amplified DNA products. An example of a suitable colorimetric assay is a colorimetric LAMP assay (available for example from New England Biolabs, see for example NEB #E2019).

The primers and probes are typically oligonucleotides of 50 or fewer nucleotides in length which specifically hybridise to the target sequence. The target sequence is typically consecutive nucleotides within the target polynucleotide. A suitable length for the primers and/or probes may be selected by the skilled person based on the target sequence of interest and their common general knowledge and for example any amplification technique to be used for detection. The primers and/or probes may be PCR primers and probes, or primers and probes for isothermal amplification techniques. The nucleotides can be naturally occurring or artificial. A nucleotide typically contains a nucleobase, a sugar and at least one linking group, such as a phosphate, T O-methyl, T methoxy-ethyl, phosphoramidate, methylphosphonate or phosphorothioate group. The nucleobase is typically heterocyclic. Nucleobases include, but are not limited to, purines and pyrimidines and more specifically adenine (A), guanine (G), thymine (T), uracil (U) and cytosine (C). The sugar is typically a pentose sugar. Nucleotide sugars include, but are not limited to, ribose and deoxyribose and modified derivatives thereof. The nucleotide is typically a ribonucleotide or deoxyribonucleotide. The nucleotide typically contains a monophosphate, diphosphate or triphosphate. Phosphates may be attached on the 5’ or 3’ side of a nucleotide.

An oligonucleotide “specifically hybridises” to a target sequence when it hybridises with preferential or high affinity to the target sequence but does not substantially hybridise, does not hybridise or hybridises with only low affinity to other sequences.

An oligonucleotide “specifically hybridises” if it hybridises to the target sequence with a melting temperature (Tm) that is at least 2 °C, such as at least 3 °C, at least 4 °C, at least 5 °C, at least 6 °C, at least 7 °C, at least 8 °C, at least 9 °C or at least 10 °C, greater than its Tm for other sequences. More preferably, the oligonucleotide hybridises to the target sequence with a Tm that is at least 2 °C, such as at least 3 °C, at least 4 °C, at least 5 °C, at least 6 °C, at least 7 °C, at least 8 °C, at least 9 °C, at least 10 °C, at least 20 °C, at least 30 °C or at least 40 °C, greater than its Tm for other nucleic acids. Preferably, the portion hybridises to the target sequence with a Tm that is at least 2 °C, such as at least 3 °C, at least 4 °C, at least 5 °C, at least 6 °C, at least 7 °C, at least 8 °C, at least 9 °C, at least 10 °C, at least 20 °C, at least 30 °C or at least 40 °C, greater than its Tm for a sequence which differs from the target sequence by one or more nucleotides, such as by 1, 2, 3, 4 or 5 or more nucleotides. The portion typically hybridises to the target sequence with a Tm of at least 90 °C, such as at least 92 °C or at least 95 °C. Tm can be measured experimentally using known techniques, including the use of DNA microarrays, or can be calculated using publicly available Tm calculators, such as those available over the internet.

Conditions that permit the hybridisation are well-known in the art (for example, Sambrook et ah, 2001, Molecular Cloning: a laboratory manual, 3rd edition, Cold Spring Harbour Laboratory Press; and Current Protocols in Molecular Biology, Chapter 2, Ausubel et ah, Eds., Greene Publishing and Wiley-lnterscience, New York (1995)). Hybridisation can be carried out under low stringency conditions, for example in the presence of a buffered solution of 30 to 35% formamide, 1 MNaCl and 1 % SDS (sodium dodecyl sulfate) at 37 °C followed by a 20 wash in from IX (0.1650 MNa+) to 2X (0.33 MNa+) SSC (standard sodium citrate) at 50 °C. Hybridisation can be carried out under moderate stringency conditions, for example in the presence of a buffer solution of 40 to 45% formamide, 1 M NaCl, and 1 % SDS at 37 °C, followed by a wash in from 0.5X (0.0825 M Na+) to IX (0.1650 M Na+) SSC at 55 °C. Hybridisation can be carried out under high stringency conditions, for example in the presence of a buffered solution of 50% formamide, 1 M NaCl, 1% SDS at 37 °C, followed by a wash in 0. IX (0.0165 M Na+) SSC at 60 °C.

The oligonucleotide may comprise a sequence which is substantially complementary to the target sequence. Typically, the oligonucleotides are 100% complementary. However, lower levels of complementarity may also be acceptable, such as 95%, 90%, 85% and even 80%. Complementarity below 100% is acceptable as long as the oligonucleotides specifically hybridise to the target sequence. An oligonucleotide may therefore have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more mismatches across a region of 5, 10, 15, 20, 21, 22, 30, 40 or 50 nucleotides. The oligonucleotide may be single stranded. The oligonucleotide may be double stranded. The oligonucleotide may comprise a hairpin. Oligonucleotides may be synthesised using standard techniques known in the art. Alternatively, oligonucleotides may be purchased.

The nucleic acid reagents (oligonucleotides, primers and/or probes) may be specific for a target nucleic acid of a microorganism such as a virus. The target nucleic acid may be DNA or RNA. The target nucleic acid sequence may be any sequence specific to, such as unique to the target microorganism. The primers and/or probes may allow for amplification of a target nucleic acid sequence specific to the target microorganism such as a sequence specific to SARS-COV2 or influenza. Oligonucleotides specific for at least two different target nucleic acids (for example for target nucleic acids from two different target microorganisms such as SARS-COV2 and influenza) may be provided. Thus, at least two sets of nucleic acid reagents may be provided, each specific for a different target nucleic acid.

In aspects relating to detection of nucleic acids, the reagents for detection typically comprise reagents facilitating lysis of the target microorganism. The reagents for detection may further comprise reagents for extraction of nucleic acid. The reagents for detection may further comprise at least one nucleic acid polymerase. The nucleic acid polymerase may be suitable for isothermal amplification of the target nucleic acid sequence or amplification by PCR. Where the target nucleic acid is an RNA, the reagents may comprise a reverse transcriptase enzyme to provide for generation of cDNA prior to amplification of the target nucleic acid sequence. Where the target nucleic acid is an RNA, the RNA may be detected and amplified without RNA extraction, as described for example in Wee et al (Genes 2020, 11, 664). Isothermal amplification and PCR amplification techniques and suitable polymerase and reverse transcriptase enzymes for use in these techniques are well known in the art. An example of a suitable isothermal assay is RT- LAMP as described for example in Augustine et al (Biology 2020, 9: 182). The nucleic acid reagents and/or the nucleic acid polymerase (and reverse transcriptase enzyme if employed) may be provided on the filter in dried (such as lyophilised) form.

The reagents for detection may further comprise one or more reagents suitable for amplification of the target nucleic sequence. Such reagents include the presence of all four dNTPs, ATP, TTP, CTP and GTP, suitable buffering agents/pH and other factors which are required for enzyme performance or stability. The method of determining the presence of a condition of the invention may further comprise the use of suitable conditions for annealing primers to a target sequence (such as suitable temperature and buffer conditions). In some aspects, the method may further comprise the use of suitable conditions promoting amplification of the nucleic acid sequence (such as suitable temperature and buffer conditions). Suitable reagents and conditions include any conditions used to provide for activity of DNA polymerase enzymes known in the art.

In some aspects, amplification of the target nucleic acid sequence may take place within the analyser, particularly where isothermal amplification is employed. In other aspects, the analyser may be configured to be removable from the device and amplification then carried out separately. The analyser may be configured to be inserted into a thermocycler to allow for PCR amplification. In such an aspect, the analyser may have suitable thermal conductivity to allow for temperature cycling, preferably allowing for reaching rapid thermal equilibrium. In all aspects described above, a solution comprising the reagents for detection and the analyte may be removed from the analyser and analysed in a separate analysis device. For example, a solution comprising the reagents for nucleic acid detection as described above and the nucleic acid analyte may be analysed (and for example subjected to nucleic acid amplification) in a separate device, such as a thermocycler. Where the target nucleic acid is RNA, a reverse transcriptase or RT-PCR step may be carried out prior to DNA amplification.

In other aspects, the solution in the analyser may be analysed by any other suitable detection method according to the analyte of interest, for example by DNA sequencing, RNAseq or mass spectrometry.

The liquid in each reservoir may be any liquid that is suitable for dissolving a respective filter and is in no way restricted to being water. For example, the liquid may be alcohol and the filter dissolvable in alcohol.

In the above described embodiments, the analyser is comprised by the breath analysis device. Embodiments also include the analyser being a separate, or removable, component from the breath analysis device. For example, the liquid comprising the filter may flow to a removable collection chamber that may be inserted into a separate analysis device. This may increase the number of detection methods that may be applied. The breath analyser may also not comprise a fluid reservoir. The filter, that preferably comprises reactants, may be removed from the breath analyser and inserted into a separate device where it is dissolved and analysed.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims. In addition, where this application has listed the steps of a method or procedure in a specific order, it may be possible, or even expedient in certain circumstances, to change the order in which some steps are performed, and it is intended that the particular steps of the method or procedure claims set forth herebelow not be construed as being order-specific unless such order specificity is expressly stated in the claim.

Further aspects of the invention

1. A breath analysis device, the device comprising: a mouthpiece arranged to receive breath from a user of the device; a reservoir comprising a liquid; a filter configured to capture analytes in the received breath, wherein the filter is arranged in a flow path of the breath through the device and the filter is at least partially soluble in the liquid comprised by the reservoir; a liquid release mechanism configured to release liquid in the reservoir so that the liquid flows to the filter; and an analyser configured to receive liquid that has dissolved at least part of the filter and to generate an analysis result in dependence on an analysis of analytes in the liquid.

2. The device according to aspect 1, further comprising a baseplate arranged to support the filter.

3. The device according to aspect 2, wherein the baseplate comprises openings configured so that breath may flow through the baseplate; wherein the diameter of openings in the baseplate are in the range of about 1 pm to about 1mm, and preferably 5pm to 100 pm.

4. The device according to aspect 2 or 3, wherein the baseplate comprises a hydrophobic surface.

5. The device according to any preceding aspect, wherein the liquid comprised by the reservoir is water. 6. The device according to any preceding aspect, wherein the filter comprises one or more of a meshwork, a sponge, a punctuated plate or a micro-sieve.

7. The device according to any preceding aspect, wherein the filter comprises one or more of polyethylene glycols, mono- and di-saccharides, or carbohydrate oligomers.

8. The device according to any preceding aspect, wherein the filter comprises a hydrophilic material.

9. The device according to any preceding aspect, wherein the filter comprises sodium chloride and/or sodium bicarbonate. 10. The device according to any preceding aspect, wherein the filter is electrostatically charged or wherein the device further comprises a charger configured to charge the filter so that particles are electro-statically attracted to the filter.

11. The device according to any preceding aspect, wherein the device comprises dried reagents for detection of said analytes, preferably lyophilised reagents. 12. The device according to aspect 11, wherein the filter comprises the reagents for detection of said analytes, optionally wherein different reagents are provided as a plurality of separate granules in the filter.

13. The device according to any preceding aspect, wherein the viscosity of the liquid after dissolving at least part of the filter is less than 2 Pa*s, and preferably less than or equal to 1 Pa*s.

14. The device according to any preceding aspect, wherein the reservoir comprises a breakable wall and/or valve configured to retain liquid in the reservoir until the liquid is released by the liquid release mechanism. 15. The device according to any preceding aspect, wherein the device comprises a part that is arranged to be pressed by a user of the device; and the part is configured so that liquid is forced out of the reservoir when the part is pressed.

16. The device according to any of aspects 1 to 14, wherein the liquid release mechanism is arranged to release liquid from the reservoir in response to a flow/volume of breath into the device.

17. The device according to any preceding aspect, further comprising one or more capillary conduits arranged so that liquid that has dissolved at least part of the filter flows along the one or more conduits to the analyser. 18. The device according to any preceding aspect, wherein the analyser comprises a positive control area, negative control area and test control area.

19. The device according to any one of aspects 11-18, wherein the reagents for detection of said analytes comprise one or more binding proteins specific for at least one antigen, optionally wherein said binding protein(s) are antibodies or antigen-binding fragments thereof.

20. The device according to aspect 19, wherein a said binding protein further comprises at least a portion of a reporter, wherein said reporter, when active, is capable of generating a visual indicator in response to binding of said antigen.

21. The device according to aspect 20, comprising at least two binding proteins specific for different antigens of an analyte or different epitopes of an antigen of an analyte, wherein the binding proteins comprise different portions of said reporter, and wherein association of the binding proteins on binding of said antigen(s) provides an active reporter capable of generating a visual indicator. 22. The device according to any one of aspects 19 to 21, comprising one or more binding proteins for at least one antigen of a first analyte and one or more binding proteins for at least one antigen of a second analyte. 23. The device according to aspect 22, wherein the one or more binding proteins for at least one antigen of a first analyte comprise at least a portion of a first reporter, and wherein the one or more binding proteins for at least one antigen of a second analyte comprise at least a portion of a second reporter, wherein each said reporter, when active, is capable of generating a visual indicator in response to binding of each analyte, and wherein the visual indicator for binding of each analyte is different.

24. The device according to any one of aspects 20 to 23, wherein the reagents for detection further comprise at least one substrate for the reporter that changes colour, fluorescence and/or luminescence on activity of the reporter.

25. The device according to aspect 18, wherein the positive control area comprises an immobilised antigen, the negative control area does not comprise an immobilised antigen or a capture antibody, and the test control area comprises a capture antibody. 26. The device according to any one of aspects 11-18, wherein the reagents for detection of said analytes comprise one or more nucleic acids specific for at least one target nucleic acid, optionally wherein said nucleic acids comprise primers and/or probes specific for a nucleic acid sequence of said target nucleic acid.

27. The device according to aspect 26, wherein the reagents for detection of said analytes further comprise at least one nucleic acid polymerase and optionally at least one reverse transcriptase.

28. The device according to aspect 26 or 27 comprising at least two sets of nucleic acid reagents specific for at least two different target nucleic acids. 29. The device according to any of aspects 1 to 17, wherein said filter arranged in a flow path of the received breath is a first filter, and the device further comprises: a second filter configured to provide a negative control; and a third filter configured to provide a positive control.

30. The device according to aspect 28, wherein: the third filter comprises an immobilised antigen; and the first and second filters do not comprise an immobilised antigen or a capture antibody.

31. The device according to any of aspects 28 or 29, wherein the first, second and third filters are arranged in separate compartments of the device; and the substantial part of the received breath by the device is arranged to flow through the first filter. 32. The device according to any of aspects 28 to 30, wherein the liquid release mechanism configured to release liquid in the reservoir so that the liquid flows to all of the first, second and third filters.

33. The device according to any of aspects 28 to 30, wherein the device comprises one or more further reservoirs; and each reservoir is configured to supply liquid to at least one of the first, second and third filters.

34. The device according to any preceding aspect, comprising one or more visual indicators of the analysis result.

35. The device according to aspect 33, wherein the one or more visual indicators comprise at least one substance that is configured to change colour, fluorescence and/or luminescence in response to the analysis result.

36. The device according to any preceding aspects wherein the analytes in the received breath are microbial particles, preferably viral particles, cancer analytes, analytes of a respiratory condition, antibodies, drugs or toxins. The device according to aspect 36, wherein the viral particles comprise SARS- COV2 and/or influenza particles. A filter configured for use in a breath analysis device, wherein: the filter is configured to capture analytes in received breath by the breath analysis device; the filter comprises dried reagents for detection of said analytes, preferably lyophilised reagents; and the filter is at least partially soluble in liquid, such as water; wherein the filter may be as defined in any one of aspects 6-10, the reagents may be as defined in any one of aspects 19-24 and 26-28 and/or the analytes may be as defined in aspects 36 and 37. A method of detecting an analyte in breath or of determining the presence of a disease or condition in a user of a breath analysis device, the method comprising: breathing, by the user, into a breath analysis device according to any one of aspects 1-37; and determining the presence of the analyte or of the disease or condition in dependence on an analysis of analytes in the received breath. The method according to aspect 39, wherein the analysis is performed within the breath analysis device, optionally wherein the breath device comprises one or more visual indicators of the analysis result. The method according to aspect 39 or 40, wherein the disease or condition is a respiratory condition, an infection by a pathogenic microorganism, a cancer, bronchiectasis, chronic obstructive pulmonary disease, asthma, acute respiratory distress syndrome, cystic fibrosis, pneumonia, pulmonary embolism, interstitial lung disease, an inherited metabolic disease, multiple sclerosis, Alzheimer’s disease, Parkinson’s disease, schizophrenia, allograft or transplant rejection, heart disease, atherosclerosis, renal failure, liver cirrhosis, alcoholic hepatitis, non alcoholic fatty liver disease, carbohydrate malabsorption, diabetes, or sepsis.

42. The method according to aspect 41, wherein the infection by a pathogenic microorganism is by a virus, a bacterium or a fungus, optionally wherein (i) the virus is a respiratory virus, such as a coronavirus or an influenza virus; (ii) the infection is a bacterial respiratory infection including upper and lower respiratory tract infections, pharyngitis or tonsillitis, or is Tuberculosis, H. pylori infection or Pseudomonas infection; or (iii) the infection is any fungal respiratory infection, pneumocystis or aspergillosis, or any mould infection.

43. The method according to aspect 39 or 40, wherein the analyte is a drug, toxin or antibody.

44. The method according to aspect 42, which is for determining the presence of COVID-19 and/or influenza. 45. A method of identifying an analyte in exhaled breath, such as an analyte whose presence and/or amount correlates with presence of, or risk of developing a disease or condition, the method comprising breathing, by the user into a breath analysis device comprising a mouthpiece arranged to receive breath from a user of the device; a reservoir comprising a liquid; a filter configured to capture analytes in the received breath, wherein the filter is arranged in a flow path of the breath through the device and the filter is at least partially soluble in the liquid comprised by the reservoir; and a liquid release mechanism configured to release liquid in the reservoir so that the liquid flows to the filter, and identifying an analyte present in the received breath. 46. The method of aspect 45, wherein the device comprises a baseplate as defined in any one of aspects 2-4, a reservoir as defined in aspect 5 or 14, a filter as defined in any one of aspects 6-10, a part as defined in aspect 15 and/or a liquid release mechanism as defined in aspect 16, and/or wherein the viscosity of the liquid after dissolving at least part of the filter is less than 2 Pa*s, and preferably less than or equal to 1 Pa*s.

Claims

1. A gas analysis device, the device comprising: an air intake arrangement configured to receive a gas; a reservoir comprising a liquid; a filter configured to capture analytes in the received gas, wherein the filter is arranged in a flow path of the gas through the device, the filter is at least partially soluble in the liquid comprised by the reservoir and the filter comprises dried reagents for the detection of analytes; a liquid release mechanism configured to release liquid in the reservoir so that the liquid flows to the filter; and an analyser configured to receive liquid that has dissolved at least part of the filter and to generate an analysis result in dependence on an analysis of analytes in the liquid.

2. The device according to claim 1, further comprising a baseplate arranged to support the filter, optionally wherein the baseplate comprises openings configured so that gas may flow through the baseplate wherein the diameter of openings in the baseplate are in the range of about 1 pm to about 1mm, and preferably 5pm to 100 pm and/or wherein the baseplate comprises a hydrophobic surface.

3. The device according to claim 1 or 2, wherein:

(i) the liquid comprised by the reservoir is water;

(ii) the filter comprises one or more of a meshwork, a sponge, a punctuated plate or a micro-sieve; (iii) the filter comprises one or more of polyethylene glycols, mono- and di saccharides, or carbohydrate oligomers;

(iv) the filter comprises a hydrophilic material;

(v) the filter comprises sodium chloride and/or sodium bicarbonate;

(vi) the filter is electrostatically charged or wherein the device further comprises a charger configured to charge the filter so that particles are electro-statically attracted to the filter;

(vii) the device comprises lyophilised reagents for detection of said analytes; optionally wherein different reagents are provided as a plurality of separate granules in the filter;

(viii) the viscosity of the liquid after dissolving at least part of the filter is less than 2 Pa*s, and preferably less than or equal to 1 Pa*s;

(ix) the reservoir comprises a breakable wall and/or valve configured to retain liquid in the reservoir until the liquid is released by the liquid release mechanism;

(x) the device comprises a part that is arranged to be pressed by a user of the device; and the part is configured so that liquid is forced out of the reservoir when the part is pressed, or wherein the liquid release mechanism is arranged to release liquid from the reservoir in response to a flow/volume of gas into the device;

(xi) the device further comprising one or more capillary conduits arranged so that liquid that has dissolved at least part of the filter flows along the one or more conduits to the analyser;

(xii) the analyser comprises a positive control area, negative control area and test control area, optionally wherein the positive control area comprises an immobilised antigen, the negative control area does not comprise an immobilised antigen or a capture antibody, and the test control area comprises a capture antibody;

(xiii) the device comprises one or more visual indicators of the analysis result, optionally wherein the one or more visual indicators comprise at least one substance that is configured to change colour, fluorescence and/or luminescence in response to the analysis result;

(xiv) the analytes in the received gas are microbial particles, optionally viral particles such as SARS-COV2 and/or influenza particles, or are cancer analytes, analytes of a respiratory condition, antibodies, drugs or toxins.

(xv) the filter comprises a synthesised bio-cellulose material;

(xvi) the filter comprises a synthesised acrylamide cryogel material and/or synthesised sugar cryogel material;

(xvii) the filter comprises a pierced filter body, wherein optionally the filter body comprises methyl-cellulose and/or salt; and/or

(xviii) the filter comprises pores having a diameter of lpm to 1 Omih

4. The device according to claim 3(vi) or claim 3(vii)-(xiv) as dependent on claim 3(vi), wherein the reagents for detection of said analytes comprise one or more binding proteins specific for at least one antigen, optionally wherein said binding protein(s) are antibodies or antigen-binding fragments thereof.

5. The device according to claim 4, wherein a said binding protein further comprises at least a portion of a reporter, wherein said reporter, when active, is capable of generating a visual indicator in response to binding of said antigen, optionally comprising at least two binding proteins specific for different antigens of an analyte or different epitopes of an antigen of an analyte, wherein the binding proteins comprise different portions of said reporter, and wherein association of the binding proteins on binding of said antigen(s) provides an active reporter capable of generating a visual indicator.

6. The device according to claim 4 or 5, comprising one or more binding proteins for at least one antigen of a first analyte and one or more binding proteins for at least one antigen of a second analyte.

7. The device according to claim 6, wherein the one or more binding proteins for at least one antigen of a first analyte comprise at least a portion of a first reporter, and wherein the one or more binding proteins for at least one antigen of a second analyte comprise at least a portion of a second reporter, wherein each said reporter, when active, is capable of generating a visual indicator in response to binding of each analyte, and wherein the visual indicator for binding of each analyte is different.

8. The device according to any one of claims 4 to 7, wherein the reagents for detection further comprise at least one substrate for the reporter that changes colour, fluorescence and/or luminescence on activity of the reporter.

9. The device according to claim 3(vi) or claim 3(vii)-(xiv) as dependent on claim 3(vi), wherein the reagents for detection of said analytes comprise one or more nucleic acids specific for at least one target nucleic acid, optionally wherein said nucleic acids comprise primers and/or probes specific for a nucleic acid sequence of said target nucleic acid.

10. The device according to claim 9, wherein the reagents for detection of said analytes further comprise at least one nucleic acid polymerase and optionally at least one reverse transcriptase and/or at least two sets of nucleic acid reagents specific for at least two different target nucleic acids.

11. The device according to any of claims 1 to 3(xi) or claim 3(xiii) or (xiv) as dependent on claim 3(i)-(xi), wherein said filter arranged in a flow path of the received gas is a first filter, and the device further comprises a second filter configured to provide a negative control; and a third filter configured to provide a positive control, optionally wherein:

(I): the third filter comprises an immobilised antigen and the first and second filters do not comprise an immobilised antigen or a capture antibody;

(II) the first, second and third filters are arranged in separate compartments of the device; and the substantial part of the received gas by the device is arranged to flow through the first filter; and/or

(III) the liquid release mechanism is configured to release liquid in the reservoir so that the liquid flows to all of the first, second and third filters, or the device comprises one or more further reservoirs; and each reservoir is configured to supply liquid to at least one of the first, second and third filters.

12. The device according to any preceding claim, wherein: the gas analysis device is a breath analysis device; and the air intake arrangement is a mouthpiece arranged to receive breath from a user of the device such that the received gas is the user’s breath.

13. The device according to any of claims 1 to 11, wherein: the gas analysis device is configured to detect airborne analytes in an environment such that the received gas by the gas analysis device is air from the environment; and, optionally, the gas analysis device is located in a transport hub, a waiting room, cinema, aircraft cabin or any other enclosed environment.

14. A filter configured for use in a breath analysis device, wherein: the filter is configured to capture analytes in received breath by the breath analysis device; the filter comprises dried reagents for detection of said analytes, preferably lyophilised reagents; and the filter is at least partially soluble in liquid, such as water; wherein the filter may be as defined in any one of claims 3(ii)-(vii) and/or 3(xv)- (xviii), the reagents may be as defined in any one of claims 3(vii) and 4-10 and/or the analytes may be as defined in claim 3 (xiv).

15. A method of detecting an analyte in gas or of determining the presence of a disease or condition by a gas analysis device, the method comprising: receiving gas by a gas analysis device according to any one of claims 1-13; and determining the presence of the analyte or of the disease or condition in dependence on an analysis of analytes in the received gas.

16. The method according to claim 15, wherein: (i) the analysis is performed within the gas analysis device, optionally wherein the gas device comprises one or more visual indicators of the analysis result; and/or

(ii) the analyte is a drug, toxin or antibody, or the disease or condition is a respiratory condition, an infection by a pathogenic microorganism, a cancer, bronchiectasis, chronic obstructive pulmonary disease, asthma, acute respiratory distress syndrome, cystic fibrosis, pneumonia, pulmonary embolism, interstitial lung disease, an inherited metabolic disease, multiple sclerosis, Alzheimer’s disease, Parkinson’s disease, schizophrenia, allograft or transplant rejection, heart disease, atherosclerosis, renal failure, liver cirrhosis, alcoholic hepatitis, non-alcoholic fatty liver disease, carbohydrate malabsorption, diabetes, or sepsis, optionally wherein the infection by a pathogenic microorganism is by a virus, a bacterium or a fungus; optionally wherein

(a) the virus is a respiratory virus, such as a coronavirus or an influenza virus, preferably wherein the method is for determining the presence of COVID-19 and/or influenza;

(b) the infection is a bacterial respiratory infection including upper and lower respiratory tract infections, pharyngitis or tonsillitis, or is Tuberculosis, H. pylori infection or Pseudomonas infection; or

(c) the infection is any fungal respiratory infection, pneumocystis or aspergillosis, or any mould infection.

17. A method of identifying an analyte in exhaled breath whose presence and/or amount correlates with presence of, or risk of developing a disease or condition, the method comprising breathing, by the user into a breath analysis device comprising a mouthpiece arranged to receive breath from a user of the device; a reservoir comprising a liquid; a filter configured to capture analytes in the received breath, wherein the filter is arranged in a flow path of the breath through the device and the filter is at least partially soluble in the liquid comprised by the reservoir; and a liquid release mechanism configured to release liquid in the reservoir so that the liquid flows to the filter, and identifying an analyte present in the received breath; optionally wherein the device comprises a baseplate as defined in claim 2, a reservoir as defined in claim 3(i) or (ix), a filter as defined in any one of claims 3(ii)-(vi) and/or 3(xv)-(xviii), a part or liquid release mechanism as defined in claim 3(x) and/or wherein the viscosity of the liquid after dissolving at least part of the filter is less than 2 Pa*s, and preferably less than or equal to 1 Pa*s.

18. A method of manufacturing a film for use in a filter of a gas analysis device, the method comprising: manufacturing a methyl cellulose based film; and piercing the film to form holes in the film; wherein the diameter of each hole is less than 100 pm and preferably less then lOpm.

19. A filter comprising a film manufactured according the method of claim 18.

20. The gas analysis device according to any of claims 1 to 13, wherein the filter is according to claim 19.