Detachable cartridge for breath sensor and methods of using same

Abstract

Apparatus for detecting an analyte in a breath sample provided by a user. A modular sensor cartridge is detachably engageable with a receiving block. The receiving block has an inlet for receiving the breath sample, a central cavity in communication with the inlet, and an exhaust outlet. The modular sensor cartridge can be placed in fluid communication with the central cavity via a sample delivery channel and has an analyte sensor and a pump for drawing a portion of the breath sample from the central cavity to the analyte sensor. Methods of analyzing a breath sample are provided.

Description

DETACHABLE CARTRIDGE FOR BREATH SENSOR AND METHODS OF USING SAMETECHNICAL FIELD

[0001] Some embodiments relate to apparatus or methods for detecting the presence of substances in breath, for example alcohol, cannabis, volatile organic compounds (VOCs), or other controlled substances. Some embodiments provide for a detachable sensor module, so that a sensor for detecting such substances in breath can be removed from the breath capture apparatus and sent offsite for calibration, while a fresh sensor module can be installed onsite for use.BACKGROUND

[0002] There exist a variety of controlled substances such as alcohol, cannabis or other drugs that impair or interfere with the mental functions and response times of those who consume such substances. Authorities or employers may set maximum acceptable limits for the presence of such substances in order for people to be able to drive or operate vehicles, machinery or other heavy or hazardous equipment.

[0003] For example, public authorities have generally determined that, for alcohol, a maximum concentration of alcohol that may be present in order for a person to legally operate a motor vehicle on public roads is in the range of 0.05 blood alcohol content (BAC) (i.e. 50 milligrams of alcohol per 100 mL of blood). If a person has a higher concentration of alcohol in their blood, they are generally not able to safely operate a motor vehicle and are prohibited from driving on public roads.

[0004] Apparatus such as breathalyzers that can be used to detect the presence of controlled substances in breath are known. Such breathalyzers can be installed in portable devices, or can be installed at a fixed location, for example in a specific position within a workplace so that workers can readily provide a breath sample for analysis prior to starting a shift.

[0005] A disadvantage of conventional breath analysis apparatus is that the sensor used to detect the controlled substance would drift over time, and therefore requires regular calibration to maintain accuracy. Without proper calibration, false positive and / or false negative results may be obtained. Such calibration istechnically complex and can be time consuming, generally requiring a trained technician to attend at the site of the breath analysis apparatus to carry out the calibration. This can be time consuming and expensive and is undesirable to users of the breath analysis apparatus. Alternatively, calibration equipment such as calibration gas containers and valves can be directly incorporated into the breath analysis apparatus itself, but this makes the device more complicated and cumbersome for end users.

[0006] There is a need to provide methods and apparatus that allow an end user to more easily calibrate a sensor in a breath analysis apparatus.SUMMARY

[0007] One aspect provides apparatus for detecting an analyte in a breath sample provided by a user. The apparatus has a modular sensor cartridge detachably engageable with a receiving block, the modular sensor cartridge and the receiving block being contained within an external housing; an inlet for receiving the breath sample from the user in the receiving block; a central cavity in the receiving block downstream of and in fluid communication with the inlet for receiving the breath sample; an analyte sensor provided within the modular sensor cartridge and positioned to be placed in fluid engagement with a sampling outlet of the central cavity via a sample delivery channel when the modular sensor cartridge is engaged with the receiving block, the modular sensor cartridge further comprising a suction apparatus to draw a portion of the breath sample from the central cavity into the analyte sensor; and an exhaust fan provided on the receiving block and positioned downstream of and in fluid communication with the central cavity to draw an excess portion of the breath sample out of the central cavity through an exhaust outlet provided in the receiving block.

[0008] In some aspects the apparatus further has a cooling fan positioned to exhaust air from within an external housing containing both the receiving block and the modular sensor cartridge, an exhaust fan to exhaust the breath sample from the central cavity, and / or one or more heaters positioned to heat the receiving block.

[0009] In some aspects, the modular sensor cartridge has cartridge vents and the receiving block has block vents on a guide portion of the receiving block that receives the modular sensor cartridge, the cartridge vents and the block vents being shaped and positioned to be complementary in shape to and aligned with one another when the modular sensor cartridge is installed in the receiving block.

[0010] In some aspects, an interconnection pin provides a mechanical connection between the modular sensor cartridge and the receiving block, and the interconnection pin contains the sample delivery channel for placing the central cavity in fluid communication with the analyte sensor.

[0011] In some aspects, the sampling outlet of the central cavity is positioned at a location within approximately 30% to approximately 70% of a distance between the inlet for receiving the breath sample and the exhaust outlet.

[0012] In some aspects, a method of detecting an analyte in a breath sample provided by a user using a modular sensor cartridge insertable within a receiving block is provided. The method includes receiving a breath sample into a central cavity provided within the receiving block; drawing a first portion of the breath sample through a sensor for detecting the analyte, the sensor being provided within the modular sensor cartridge and in fluid communication with the central cavity; and drawing a remaining portion of the breath sample through an exhaust fan on the receiving block. In some aspects, the receiving block is heated during the step of drawing the first portion of the breath sample through the sensor. In some aspects, heat is vented out of the modular sensor cartridge through vents provided on the modular sensor cartridge. In some aspects, a cooling fan is used to draw warm air out of an external housing

[0013] Additional aspects will become apparent by reference to the following specification and accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Example embodiments are illustrated with reference to the following drawings, which are illustrative and not limiting in nature.

[0015] FIG. 1 shows a front view of a modular sensor cartridge according to an example embodiment.

[0016] FIG. 2 shows a side view of the modular sensor cartridge of FIG. 1 with a portion of the housing cut away, and FIG. 3 shows an enlarged view of a portion thereof.

[0017] FIG. 4 shows a top view of the modular sensor cartridge of FIG. 1.

[0018] FIG. 5 shows a sectional view of the modular sensor cartridge of FIG. 1.

[0019] FIG. 6 shows a right side view of an example embodiment of a receiving block for receiving a modular sensor cartridge.

[0020] FIG. 7 shows a schematic sectional view of the example embodiment of a receiving block.

[0021] FIG. 8 shows a schematic front view of the example embodiment of the receiving block shown in FIG. 6, and FIG. 9 shows in more detail how the female PCB connector on the receiving block engages with the modular sensor cartridge.

[0022] FIG. 10 shows a schematic sectional view showing the internal components of an example embodiment of a modular sensor cartridge engaged with an example embodiment of a receiving block and contained within an external housing.

[0023] FIG. 11A shows a side view and FIG. 11B shows a sectional view of an example embodiment of an interconnection pin for coupling a modular sensor cartridge to a receiving block.

[0024] FIG. 12 shows schematically how heat and air flows through an external housing containing a modular sensor cartridge and a receiving block to help maintain an even temperature and avoid condensation of a breath sample therein.

[0025] FIG. 13 shows an example embodiment of a method of replacing a modular sensor cartridge in a receiving block.

[0026] FIG. 14 shows an example embodiment of a method for detecting an analyte in a breath sample using a modular sensor cartridge.

[0027] FIG. 15 shows an example embodiment of a method for detecting an analyte in a breath sample using a modular sensor cartridge.

[0028] FIGs. 16A and 16B show signals including baseline for a cartridge design both without (FIG. 16A) and with (FIG. 16B) vents.

[0029] FIG. 17 shows the pressure drop across a cylindrical sample delivery channel at a plurality of different lengths and internal diameters of the sample delivery channel, with a portion thereof enlarged for clarity.

[0030] FIG. 18 shows the impact on signal caused by changing the volume of the internal diameter of the sample delivery channel of the interconnection pin by varying the length of the sample delivery channel for a consistent internal diameter.DESCRIPTION

[0031] The following description contains details which are illustrative and not limiting in nature.

[0032] With reference to FIG. 1, a front view of an example embodiment of a modular cartridge 100 for a breath sensing apparatus is shown. Modular cartridge 100 has a housing 102 which has an outward end 104, an inward end 106, and lateral sides 108. Housing 102 is in some embodiments provided with arrows or other indicia 110 to show the direction of insertion of modular cartridge 100 into the breath sensing apparatus as further described below. In some embodiments, modular cartridge 100 can be provided with a handle (not shown) at its outward end 104, to assist with insertion and removal of modular cartridge 100 into a receiving block as described further below.

[0033] With reference to FIG. 2, at least one lateral side 108 and in some embodiments both lateral sides 108 of modular cartridge 100 are provided with one or more vents 112. With reference to FIG. 4, the outward end 104 of modular sensor cartridge 100 is also provided with one or more vents 112 in some embodiments. In the illustrated embodiment, vents 112 are provided as a plurality of horizontally extending slits through housing 102. In alternative embodiments, vents 112 could be provided with other shapes, so long as vents 112 work to allow the release of heat from inside modular cartridge 100 as described below.

[0034] A plate 114 is provided at the inward end 106 of housing 102 to secure O-ring 128 in position as described below.

[0035] Modular sensor cartridge 100 has a miniaturized design that allows all of the components necessary for detecting and analysing the presence of a target analyte such as alcohol in a breath sample to be housed therein. With reference tothe schematic illustration of FIG. 5, a sensor to be used to detect the presence of a particular target analyte in a breath sample of a user of the device is incorporated within modular sensor cartridge 100. In the illustrated embodiment, analyte sensor 116 is a fuel cell that is provided within modular sensor cartridge 100 to detect alcohol in a breath of a user, although any suitable sensor for detecting any desired target analyte could be used in alternative embodiments. Analyte sensor 116 is in electronic communication with a printed circuit board 118 that acts as an alcohol sensor amplifier. In some embodiments, the amplifier circuit provides for multiple gain options, which may allow the use of both direct sampling and contactless sampling, for example as described in Patent Cooperation Treaty publication No. WO 2023 / 178454, the entirety of which is incorporated by reference herein.

[0036] In some embodiments, one or more temperature sensors are provided within modular sensor cartridge 100 to assist with managing and controlling the temperature therein. In some embodiments, at least one such temperature sensor 115 is provided at the centre of analyte sensor 116 to provide real-time information about the temperature at the location where the analyte is being measured to help ensure that any readings taken by analyte sensor 116 can be adjusted based on the actual temperature of the sample. In some embodiments, the at least one temperature sensor 115 is in communication with printed circuit board 118 to provide feedback thereto, so that information as to the temperature at analyte sensor 116 can be used to help control the operation of the heater or heaters associated with the receiving block 200, as described below.

[0037] A pump 120 or other similar apparatus such as a fan or the like that can be used to move air to draw a portion of a breath sample into analyte sensor 116 is also provided within modular sensor cartridge 100. Pump 120 is provided in fluid communication with fuel cell 116 which is in turn in fluid communication with a sample inlet 122, best seen in FIGs. 2 and 3.

[0038] In the illustrated embodiment, a second printed circuit board can be provided within housing 102, for example in the lid 124 that secures the various components inside of housing 102. Such printed circuit board and / or printed circuit board 118 can include all of the functions required to analyze a providedbreath sample, including electronics such as an amplifier circuit, erasable programmable read-only memory (EPROM) for saving cartridge information, including calibration information and date, and the like. In this way, entire calibration information including calibration parameters, number of tests done with the modular sensor cartridge 100, unique ID and expiry date can be saved on the EPROM that is on the PCB inside the cartridge. This will result in an ability to precalibrate the cartridges and send them to users with no need to apply any changes at the destination. Those skilled in the art will understand that various controllers including appropriate printed circuit boards can be deployed at any suitable location and in any suitable manner (e.g. as one single controller rather than as multiple separate PCBs), and the description provided herein is illustrative of one possible embodiment and not limiting.

[0039] With reference to FIGs. 6-8, an example embodiment of a receiving block 200 for receiving modular sensor cartridge 100 is schematically illustrated. Receiving block 200 has a housing 202 on a guide portion thereof that defines a generally rectangular opening 204 for receiving modular sensor cartridge 100. Although modular sensor cartridge 100 and opening 204 have been illustrated as having a generally rectangular shape, in other embodiments other shapes can be used so long as modular sensor cartridge 100 can be removably inserted into opening 204.

[0040] In the illustrated embodiment, modular sensor cartridge 100 is free to move only in the vertical direction within opening 204. This facilitates easily removing and inserting the modular sensor cartridge 100 within receiving block 200 as required for replacement thereof, while ensuring that a reliable electrical and mechanical connection between the two components can be maintained when modular sensor cartridge 100 and receiving block 200 are engaged for use.

[0041] As best seen in FIGs. 7 and 8, sides 206 of housing 202 of the guide portion of receiving block 200 are provided with a plurality of vents 208. Vents 208 are shaped, configured and positioned to be complementary to vents 112 provided in modular sensor cartridge 100, so that vents 112 and vents 208 will overlap when modular sensor cartridge 100 is mounted within receiving block 200, to allow heat to move out of modular sensor cartridge 100 and outside of receivingblock 200 into the external environment (e.g. illustrated schematically in FIG. 10 as being the interior of an external housing 250). In the illustrated embodiment, vents 208 are provided as a plurality of horizontally extending slots that overlap with vents 112 on modular sensor cartridge 100 to form an aperture extending to the interior of opening 204 when modular sensor cartridge 100 is fully inserted into receiving block 200.

[0042] Both modular sensor cartridge 100 and receiving block 200 are designed to provide both an electrical and a mechanical connection between the two components when in use. To this end, to provide a mechanical connection an interconnection pin 210 (best seen in FIGs. 7, 11A and 11B and described in further detail below) is provided. Additionally, modular sensor cartridge 100 is provided with features that ensure a robust sealing engagement with interconnection pin 210. In the illustrated embodiment, a double O-ring radial seal 126 is provided on the side of modular sensor cartridge 100 and a further O-ring radial seal 128 is provided on the side of receiving block 200 (best seen in FIG. 3), to seal modular sensor cartridge 100 against the outward end 205 of interconnection pin 210. In other embodiments, other types of seals could be used, so long as they provide a robust sealing engagement between modular sensor cartridge 100 and receiving block 200, for example, a tube seal, a single 0- ring radial seal, or the like. Robust sealing around interconnection pin 210 is important to ensure that analyte sensor 116 is not exposed to a flow of a breath sample prematurely, which could lead to erroneous test results.

[0043] In some embodiments, the outer surface of interconnection pin 210 is provided with a threaded surface 209 at its inward end 207 that can engage with a correspondingly threaded surface provided on receiving block 200 to help ensure a solid mechanical interconnection and / or sealing between these components. In some embodiments, a portion of the outer surface of interconnection pin 210 is provided with a hexagonal cross-sectional shape 213, to facilitate use of a wrench or other suitable tool to affix interconnection pin 210 in position. In some such embodiments, a central portion 203 of interconnection pin 210 is provided with hexagonal cross-sectional shape 213.

[0044] With reference to FIG. 11B, the interconnection pin 210 has a sample delivery channel 211 defined therethrough to allow the delivery of a portion of a provided breath sample from central cavity 214 to modular sensor cartridge 100. The sample delivery channel 211 has a length L and an internal diameter D.

[0045] In some embodiments, the interconnection pin 210 is made from a material that is water-resistant, to avoid damage due to the humid nature of human breath samples. In some embodiments, the interconnection pin 210 is made from a material that is heat tolerant since the system may be heated for extended periods of time. In some embodiments, the interconnection pin 210 is made from stainless steel.

[0046] To provide an electrical connection between modular sensor cartridge 100 and receiving block 200, a female PCB connector 230 (FIG. 9) is provided on receiving block 200 to electrically engage with a male PCB connector 119 on printed circuit board 118 of modular sensor cartridge 100. In the illustrated embodiment, female PCB connector 230 is an edge connector that connects modular sensor cartridge 100 to a customized PCB 229 mounted in receiving block 200. This engagement provides power and ground as well as analog and digital lines enabling receiving block 200 to communicate with the sensors inside modular sensor cartridge 100.

[0047] As best seen in FIG. 7, a breath sample from a user is introduced into receiving block 200 through tubing 212. From tubing 212, the breath sample enters a central cavity 214 defined within receiving block 200 through an inlet 216. Central cavity 214 has two outlets for the breath sample: sampling outlet 218 which allows a portion of the breath sample to be drawn into modular sensor cartridge 100 as described below, and exhaust outlet 220, which allows the remainder of the breath sample to exit central cavity 214 via exhaust collector 222. An exhaust fan 224 is provided at the downstream end of exhaust collector 222, to draw air through exhaust collector 222. Exhaust fan 224 can be used to exhaust excess breath sample while a breath sample is being provided, and can also be used to purge the system including modular sensor cartridge 100 and analyte sensor 116 for further use after a breath sample has been provided and analysed. Receiving block 200 further includes a cooling fan 232 positioned todraw air out of the internal cavity of external housing 250 containing receiving block 200 (i.e. not air from the fluid flow path travelled by the breath sample), to further assist in cooling and maintaining the temperature within receiving block 200 to help regulate the temperature at which analyte sensor 116 is operating.

[0048] As best seen in FIGs. 7 and 8, receiving block 200 is provided with a pair of opposed heaters, one on either lateral side of central cavity 214. In the illustrated embodiment, the heaters 226, 228 are provided on printed circuit boards that are disposed on opposite sides of central cavity 214, with heater 228 being provided on printed circuit board 229, so that the operation of the heaters 226 and 228 can be controlled via the printed circuit boards. In alternative embodiments, heaters 226 and 228 could be provided separately from printed circuit boards and provided with any suitable temperature controller such as a PID to enable the operation of the heaters 226, 228 to be controlled. Without being bound by theory, it is believed that the heaters 226 and 228 can be used to heat receiving block 200, and in particular the region of central cavity 214, to minimize formation of condensation from a provided breath sample which might interfere with the proper detection of analytes in the breath sample. While in the illustrated embodiment, a pair of heaters provided on opposed lateral sides of central cavity 214 have been provided, those skilled in the art will recognize that other numbers of heaters and other locations for such heaters could be provided, e.g. three or four heaters, or heaters positioned above and below central cavity 214 rather than on lateral sides or central cavity 214, could be used in alternative embodiments.

[0049] With reference to FIGs. 7, 11A and 11B, the interconnection pin 210 is provided for sample delivery channel 211 to be in fluid engagement with central cavity 214. In the design of the fluid flow path for the sample, the optimal positioning of interconnection pin 210 for sample collection has been determined to be a position that is somewhat spaced apart from the from the two 90-degree turns made by the fluid flow path at the inlet 216 and outlet 218. For example, in some embodiments, the interconnection pin 210 is positioned within approximately 30% to approximately 70% of the distance 240 between inlet 216 and outlet 218, i.e. spaced apart from inlet 216 by at least 30% of distance 240 and spaced apart from outlet 218 by at least 30% of distance 240, while being positioned betweeninlet 216 and outlet 218. In other embodiments, the interconnection pin 210 can be positioned at any point within approximately 30% to approximately 70% of the distance 240 between inlet 216 and outlet 216, e.g. at a position downstream of inlet 216 at a distance of approximately 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or 70% of the distance from inlet 216 to outlet 218.

[0050] Without being bound by theory, it is believed that this configuration contributes to more accurate and repeatable measurements due to several potential factors. Firstly, the flow stabilizes into a more laminar profile at the midpoint of central cavity 214 compared to a more turbulent flow in the corners created by inlet 216 and outlet 218, contributing to a consistent velocity profile, which can contribute to accurate sampling. This can avoid potential stagnation points and vortex shedding, ensuring a representative sample of the flow. Additionally, placing the interconnection pin 210 too close to the corners could introduce backpressure fluctuations and instability in the flow, leading to potentially inconsistent sampling conditions. Closer to the midpoint of central cavity 214, the fluid flow has had time to stabilize, offering a direct flow path and potentially reducing errors in sample collection. This strategic placement leverages principles of fluid dynamics to optimize device performance, ensuring that samples are collected in a stable and uniform flow environment, thereby enhancing accuracy and reliability.

[0051] As best seen in FIGs. 11A and 11B, interconnection pin 210 is provided with an externally threaded surface 209 that can be engaged with a correspondingly threaded receiving surface within receiving block 200. Interconnection pin 210 also has a portion 213 with a hexagonal outer crosssection positioned upstream of threaded surface 209, to facilitate use of a wrench or other tool to install interconnection pin 210. Interconnection pin 210 also has an external sealing surface 215 positioned upstream of threaded surface 209, which can engage with the sealing mechanism such as O-ring seals 126, 128 that are used to ensure a robust sealing engagement between interconnection pin 210 and modular sensor cartridge 100.

[0052] With reference to FIG. 10, a schematic illustration of the engagement between a modular sensor cartridge 100 and corresponding receiving block 200 is provided. Both receiving block 200 and modular sensor cartridge 100 are receivedwithin an external housing 250. Modular sensor cartridge 100 slides into opening 204 of housing 202 of the guide portion of the receiving block 200 so that vents 208 of receiving block 200 are aligned with vents 112 of modular sensor cartridge 100, to allow the passage of heat and / or air therethrough into the interior of modular sensor cartridge 100. Interconnection pin 210 provides a mechanical interconnection between receiving block 200 and modular sensor cartridge 100, allowing a portion of the breath sample to flow from sampling outlet 218 of receiving block 200 into sample inlet 122 of modular sensor cartridge 100 and through into analyte sensor 116 when sampling pump 120 is activated. Cooling fan 232 can draw air out of external housing 250, to help exhaust heat generated by the internal electronic components of both receiving block 200 and modular sensor cartridge 100, as well as from heaters 226, 228, as described below with reference to FIG. 12.

[0053] As best seen in FIG. 12, the heat supplied by the heaters 226, 228, as well as the electronic components of modular sensor cartridge 100 and receiving block 200, warms the air within external housing 250 containing receiving block 200 and modular sensor cartridge 100. Such heat tends to rise, while cooling fan 232 draws the warmed air downwardly out of external housing 250, causing the movement of air within external housing 250, and consequently a movement of heat carried by such moving air, downwardly and inwardly within external housing 250 towards cooling fan 232, as indicated by arrows 260. In addition to the heat supplied by the heaters 226, 228, heat is generated by the electronic components of receiving block 200 and modular sensor cartridge 100. In some embodiments, the heaters 226, 228 are used to heat the receiving block 200 and therefore modular sensor cartridge 100 to a temperature of approximately 45°C, which is slightly warmer than the temperature of an exhaled breath sample (about 34-36 °C) and which also allows for a consistent temperature to be provided across different operating conditions (e.g. if the device is being used in hot or cold temperatures).

[0054] When modular sensor cartridge 100 is mounted in receiving block 200, analyte sensor 116 is positioned vertically above the heaters 226, 228 and above exhaust fan 224 and cooling fan 232, and is vertically spaced apart from both fans.In addition to heat from the heaters 226, 228, the components within receiving block 200 and modular sensor cartridge 100 can also produce heat. The heat produced by these components and the heaters 226, 228 will tend to rise within modular sensor cartridge 100 so that analyte sensor 116 will be warmed by the heat produced, to help prevent any of the breath sample from condensing in particular within analyte sensor 116 which could interfere with the measurements taken by analyte sensor 116. However, the downward movement of air within external housing 250 caused by cooling fan 232 helps to prevent too much heat from accumulating within modular sensor cartridge 100 by drawing warm air downwardly and inwardly and then out of external housing 250, as indicated by arrows 260 (i.e. so that analyte sensor 116 will not become too hot but can be maintained at a desired temperature). Cooler air from within external housing 250 can enter modular sensor cartridge 100 through aligned vents 112, 208, and heat inside modular sensor cartridge 100 can be vented out through aligned vents 112, 208, to help keep the temperature within modular sensor cartridge 100 within a desired range. Warm air can be pulled downwardly by cooling fan 232 and exhausted out of external housing 250, as indicated by arrows 260. Exhaust fan 224 also helps to pull moist air out of receiving block 200, in particular out of central cavity 214. Without being bound by theory, positioning exhaust fan 224 spaced well downwardly of analyte sensor 116 can also help to minimize or avoid any interference with analyte sensor 116 that may be caused by air turbulence caused by exhaust fan 224. Further, it may be desirable to space cooling fan 232 well downwardly of analyte sensor 116 to again minimize any possible air turbulence or changes in pressure that analyte sensor 116 may experience as a result of the operation of cooling fan 232 and / or to minimize the impact of any sudden changes in temperature that may be caused by the operation of cooling fan 232 on analyte sensor 116.

[0055] In some embodiments, it has been determined that the geometry of the interior of the sample delivery channel 211 of interconnection pin 210 through which the sample is delivered from the receiving block to the analyte sensor 116 in the modular sensor cartridge 100 can significantly impact the accuracy with which the analyte is detected within the breath sample. Without being bound by theory,the interior volume of sample delivery channel 211 represents a dead volume that must be fully drawn through analyte sensor 116 before analyte sensor 116 will be provided with any of the actual breath sample. Pump 120 must be able to draw both this dead volume and a sufficient amount of the actual breath sample through analyte sensor 116 in order to provide a sufficiently accurate measurement of the level of analyte in the breath sample. If analyte sensor 116 is provided with too large a volume of the breath sample or with too small a volume of the breath sample, then the results provided by analyte sensor 116 may be outside an acceptable margin of error (e.g. greater than about 5% error or greater than about 10% error).

[0056] To address this issue, the inventors have determined that the ability of the pump 120 to draw an appropriate volume of the breath sample through the analyte sensor 116 is impacted for a specific pump by the volumetric flow rate through sample delivery channel 211, which for a tubular sample delivery channel 211 varies linearly with the length of sample delivery channel 211 and exponentially with the diameter of sample delivery channel 211. Thus, making adjustments to the length of sample delivery channel 211, and to a greater extent making adjustments to the diameter of sample delivery channel 211, affects the volumetric flow rate and accordingly the accuracy of the readings that can be obtained using the analyte sensor 116.

[0057] If the geometry of sample delivery channel 211 is outside of a set of parameters that delivers an appropriate volumetric flow rate for delivery of the provided breath sample to analyte sensor 116 by a particular pump 120, then it may be observed that the signal provided by the analyte sensor 116 is not good, for example if the area under the curve is too small or the baseline of the signal is shifted indicating premature leakage of analyte into the analyte sensor 116. In such cases, adjustments should be made to the geometry of sample delivery channel 211, for example by adjusting its diameter and / or length, to bring the volumetric flow rate of fluid flowing therethrough back into a desirable range. Without being bound by a specific embodiment, in one example apparatus the inventors have found that the length L of the sample delivery channel 211 of interconnection pin 210 should be in the range of about 18 mm to about 22 mm,including any value or subrange therebetween, e.g. about 18.5, 19.0, 19.5, 20.0, 20.5, 21.0 or 21.5 mm, and the diameter D of the sample delivery channel 211 of interconnection pin 210 should be in the range of about 0.7 mm to about 0.85 mm, including any value or subrange therebetween, e.g. about 0.72, 0.74, 0.76, 0.78, 0.80, 0.82, or 0.84 mm. Those skilled in the art could vary such dimensions to achieve a similar volumetric flow rate of fluid or adjust the desired volumetric flow rate of the fluid for a different specific pump if the various proportions of the device or properties of the pump 120 are changed.

[0058] In some embodiments, the pressure drop across a cylindrical sample delivery channel 211 varies with the ratio ofIn one specific embodiment in which the pump 120 provides a volumetric flow rate of approximately 0.83pb / second, the inventors have found that a ratio ofthat is within the range of about 30 mm-3to about 95 mm'3is desirable, including any value or subrange therebetween, e.g. about 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85 or 90 mm'3. In other embodiments using a pump 120 with different properties, one skilled in the art could adjust the ratio ofaccordingly to match the volumetric flow rate of the specific pump being used.

[0059] In some embodiments, the choice of pump 120, including the volumetric flow rate Q for the pump as used in the apparatus (i.e. sample volume / sampling time) and the geometry of sample delivery channel 211, including values of L and D, are selected such that the pressure drop across the cylindrical sample channel is within the range of about 20 to about 60 Pa, including any value or subrange therebetween, e.g. 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56 or 58 Pa. The pressure drop across the sample channel will vary with theratio of the volumetric flow rate Q timesi.e. with Q ~. In some embodiments, to yield such a pressure drop across the sample channel within the range of about 20 Pa to about 60 Pa, Q-^ is selected to give a rate of volume exchange per unit time within the range of about 25,000 s'1to about 80,000 s'1, including any value or subrange therebetween, e.g. about 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, 70,000 or 75,000 s'1. In some embodiments, the pressuredrop across the sample delivery channel 211 is within the range of about 20 to about 60 Pa, including any value or subrange therebetween, e.g. 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56 or 58 Pa.

[0060] With reference to FIG. 13, a method 300 of replacing a modular sensor cartridge such as modular sensor cartridge 100 in a receiving block 200 is illustrated. At 302, the user should ensure that the receiving block 200 is mounted in a stable position. At 304, the user should ensure that the receiving block 200 is powered off. At 306, the user should remove the modular sensor cartridge 100 from the opening 204 in housing 202 of the guide portion of receiving block 200. In some embodiments in which modular sensor cartridge 100 is provided with a handle at its outward end 104, a user can pull on the handle at 306 to assist in removing the modular sensor cartridge 100 from receiving block 200. At 308 the user can insert a replacement modular sensor cartridge 100 into opening 204 in housing 202 of the guide portion of receiving block 200 and ensure that the cartridge is pressed into good engagement with interconnection pin 210.Optionally in some embodiments, the opening 204 of receiving block 200 is provided with a lid that can be fastened into position, for example using threaded fasteners, to help ensure that modular sensor cartridge 100 remains secured in place within receiving block 200 while in use.

[0061] With reference to FIG. 14, an example embodiment of a method 400 for using a modular sensor cartridge to analyze a breath sample while the modular sensor cartridge is engaged with a receiving block is illustrated. At 402, a breath sample is received into a central cavity formed within the receiving block. At 404, a first portion of the breath sample is drawn out of the central cavity. At 406, the analyte is evaluated by a sensor, with the sensor being provided within the modular sensor cartridge and being in fluid communication with the central cavity. At 408, a remaining portion of the breath sample is removed from the central cavity via an exhaust fan on the receiving block.

[0062] With reference to FIG. 15, a second example embodiment of a method 500 for using a modular sensor cartridge to analyze a breath sample while the modular sensor cartridge is engaged with a receiving block is illustrated. At 502 a breath sample is received into a central cavity formed within the receiving block. At504, one or more heaters is used to heat the receiving block. At 506, air is permitted to enter the modular sensor cartridge through aligned vents provided in both the modular sensor cartridge and the receiving block and / or heat is permitted to exit the modular sensor cartridge through the aligned vents. At 508, a cooling fan is used to draw air out of an external housing containing both the receiving block and the modular sensor cartridge, with the cooling fan being positioned below and vertically spaced apart from a sensor for detecting the analyte provided in the modular sensor cartridge. At 510, a first portion of the breath sample is drawn out of the central cavity for analysis by a sensor. At 512, the analyte is evaluated by the sensor, with the sensor being provided within the modular sensor cartridge and being in fluid communication with the central cavity. At 514, a remaining portion of the breath sample is removed from the central cavity via an exhaust fan on the receiving block.Examples

[0063] Certain embodiments are further described with reference to the following examples, which are intended to be illustrative and not limiting in nature.Example 1.0 - Comparison of Cartridge Designs With and Without Ventilation

[0064] Two different embodiments of a modular sensor cartridge were constructed and tested, one with vents corresponding to vents 112 described above and one without such vents. With reference to FIGs. 16A and 16B, the vented cartridge design shown in FIG. 16B dissipates heat better than the non-vented cartridge design shown in FIG. 16A. This is evidenced by the inconsistent signal baselines (see time 0 to 1 second in FIG. 16A) and response shape (see the area column in Table 1) that lead to errors in the measured blood alcohol concentration (BAC).

[0065] There is a linear relationship between the area under the curve of the fuel cell signal and the BAC, which is used for calculating the BAC. The area under the curve is measured from the start of the test until the signal recovers to 80 percent of its peak. The area under the curve and the obtained BAC values for the signals shown in FIGs. 16A and 16B are provided in Table 1. According to Table 1, themaximum measured error for a 0.050 g / 100 mL alcohol solution was 6 percent for the vented cartridge design, which is within the maximum permissible error (10 percent) range provided by various standards. On the other hand, using a non- vented cartridge results in errors of almost 40 percent and 80 percent for cold and hot conditions, respectively. This example demonstrates how the provision of vents on the cartridge can significantly enhance the accuracy of the determinations made by the analyte sensor contained within the cartridge.Table 1. Error margin in measured blood alcohol concentration (BAC) at different temperatures for a vented cartridge versus a non-vented cartridge.Example 2.0 - Effect of Variation of Geometry of Sample Delivery Channel

[0066] The geometry of the sample delivery channel of the interconnection pin was varied by varying the internal diameter or length of the sample delivery channel to examine the effect of changing geometry on the accuracy of readingsobtained with the fuel cell. For laminar flows the friction factor f is related to theReynolds number as follows:Where v is the fluid velocity in m / sec.

[0067] Substituting into the main equation and simplifying:128 u Q LAP = - n D4Where: p is dynamic viscosity of the fluid p = 1.895 * 10^-5 [Pa.s]Q = 0.25 ml sample volume per 0.3 sec sampling time for the specific apparatus tested

[0068] Thus, for a constant volumetric flow rate Q, and flow density p, the pressure drop across the sample delivery channel which has a circular cross section is directly proportional to the length of the pin while it is inversely proportional to the fourth power of the diameter. Thus, changes in length are expected to have an approximately linear effect on volumetric flow rate, while changes in diameter are expected to have an exponential effect on volumetric flow rate (see FIG. 17).

[0069] For the specific embodiments tested by the inventors, pressure drops across the sample delivery channel in the range of 20-60 Pa were found to be the best for the performance of the tested exemplary device. Without being bound by theory, in the tested embodiments, pressures higher than about 60 Pa may cause pre-mature leakage into the fuel-cell and pressures less than 20 Pa may cause small signal to noise ratios for the voltage produced across the fuel cell sensor and therefore higher error margins in the BAC levels. In this specific tested embodiment, the sampling pump used produced a volumetric flow rate Q of approximately 0.25 mL sample per 0.3 seconds sampling time (i.e. 0.83 pL / second), and the inventors found that the desired pressure drop in the range of about 20 to about 60 Pa could be provided by a sample delivery channel having aratio of length L and internal diameter D of in the range of between about 31 mm-3to about 93 mm'3.

[0070] In other embodiments, the sampling pump used may produce other volumetric flow rates Q. In such embodiments, the relationship between the rate of volume exchange per unit time varies with Q-^. In such embodiments, values for the volumetric flow rate Q, L and D can be selected so that Q-^ is in the range of about 26,000 s'1to about 78,000 s'1, which is the value of the rate of volume exchange per unit time determined to be effective for this exemplary embodiment.

[0071] FIG. 18 shows the signals obtained for a sample corresponding to a BAC of 0.05 g / 100 ml using interconnection pins with sample delivery channels having consistent lengths with internal diameters (IDs) of 0.8 mm, 1.0 mm, and 1.2 mm to demonstrate the impact of this geometry on sensor performance. When the pin ID is reduced, the pressure drop from the central cavity to the fuel cell increases. This results in a scenario where low IDs (less than 0.8 mm) impede the fuel cell pump's ability to draw the necessary sample volume, thereby compromising the delivery efficiency to the fuel cell. Conversely, employing pins with higher IDs leads to premature sample leakage into the fuel cell (due to a lower flow resistance), occurring before the commencement of the test, which can skew results. Furthermore, increasing the pin ID complicates the cleaning process due to the larger volume, introducing a higher risk of contamination errors. Using a sample delivery channel with too small an ID (pins with IDs below 0.8 mm in this exemplary test system) may fail to deliver adequate sample volumes, leading to diminished repeatability and reliability of the measurements. On the other hand, using pins with larger delivery channel volumes (pins with IDs greater than 0.8 mm in this exemplary test system) causes the baseline of the signal to shift higher. This shift results in inaccurately higher BAC readings because the fuel cell is exposed to alcohol before the test begins.

[0072] To show the effects of changes in the volumetric flow rate on accuracy, a series of different interconnection pins having a fixed length L of 20 mm and varying internal diameters D were tested and used to analyze blood alcohol concentration using a standard sample having a BAC of 0.50 g / mL. Results areshown in Table 2 together with the determined error in the measured BAC. This example shows that for a sample delivery channel length of 20 mm in the context of the specifically tested apparatus, internal diameters of the sample delivery channel of between about 0.70 mm to about 0.85 mm provided the best results by minimizing the determined error, with a sample delivery channel diameter of 0.80 mm performing best.Table 2. Error margin in measured blood alcohol concentration (BAC) for different internal diameters of the interconnection pin.

[0073] The impact of altering the length of the interconnection pin on sample collection was also tested with interconnection pin lengths of 16 mm, 18 mm, 20 mm, 22 mm, and 25 mm. In this particular test system, 20 mm was determined to provide the optimal geometry. Shorter pins, like greater IDs, result in lower pressure drops but risk premature sample delivery before the test begins. Longer pins, like smaller IDs, cause increased pressure drops, impeding sample draw and complicating cleaning, leading to reliability issues.

[0074] While specific illustrative aspects and embodiments have been described in this specification, those skilled in the art will recognize that modifications and variations of such aspects and embodiments can be made, and it is intended that the claims that follow should be interpreted in a manner consistent with the broadest interpretation of the specification as a whole.

Claims

WHAT IS CLAIMED IS:

1. Apparatus for detecting an analyte in a breath sample provided by a user, the apparatus comprising: a modular sensor cartridge detachably engageable with a receiving block, the modular sensor cartridge and the receiving block being contained within an external housing; an inlet for receiving the breath sample from the user in the receiving block; a central cavity in the receiving block downstream of and in fluid communication with the inlet for receiving the breath sample; an analyte sensor provided within the modular sensor cartridge and positioned to be placed in fluid engagement with a sampling outlet of the central cavity via a sample delivery channel when the modular sensor cartridge is engaged with the receiving block, the modular sensor cartridge further comprising a suction apparatus to draw a portion of the breath sample from the central cavity into the analyte sensor; and an exhaust fan provided on the receiving block and positioned downstream of and in fluid communication with the central cavity to draw an excess portion of the breath sample out of the central cavity through an exhaust outlet provided in the receiving block.

2. The apparatus as defined in claim 1, further comprising a cooling fan positioned to exhaust air from the external housing.

3. The apparatus as defined in claim 2, wherein the cooling fan is positioned vertically below and spaced apart from the analyte sensor4. The apparatus as defined in any one of claims 2 to 3, wherein the cooling fan is positioned in a bottom of the external housing.

5. The apparatus as defined in any one of claims 1 to 4, comprising a heater within the receiving block.

6. The apparatus as defined in claim 5, comprising two opposed heaters positioned within the receiving block, each one of the two opposed heaters being provided on an opposite side of the central cavity, optionally wherein the opposite sides of the central cavity comprise opposed lateral sides of the central cavity.

7. The apparatus as defined in any one claims 1 to 6, wherein the analyte sensor is an alcohol sensor, a cannabis sensor, a volatile organic compound sensor, or a controlled substance sensor.

8. The apparatus as defined in any one of claims 1 to 7, wherein the modular sensor cartridge comprises cartridge vents and the receiving block comprises block vents on a guide portion of the receiving block that receives the modular sensor cartridge, the cartridge vents and the block vents being shaped and positioned to be complementary in shape to and aligned with one another when the modular sensor cartridge is installed in the receiving block.

9. The apparatus as defined in any one of claims 1 to 8, wherein the exhaust fan is positioned vertically below the analyte sensor when the modular sensor cartridge is installed on the receiving block.

10. The apparatus as defined in claim 9, wherein the exhaust fan is positioned vertically spaced apart from the analyte sensor.

11. The apparatus as defined in any one of claims 2 to 10, wherein the cooling fan is positioned vertically below the analyte sensor when the modular sensor cartridge is installed on the receiving block within the external housing.

12. The apparatus as defined in claim 11, wherein the cooling fan is positioned vertically spaced apart from the analyte sensor.

13. The apparatus as defined in any one of claims 1 to 12, comprising a mechanical connection and an electrical connection between the modular sensor cartridge and the receiving block.

14. The apparatus as defined in claim 13, wherein the mechanical connection comprises an interconnection pin, wherein the interconnection pin comprises the sample delivery channel for placing the central cavity in fluid communication with the analyte sensor, optionally wherein the interconnection pin comprises a threaded surface for engagement with the receiving block.

15. The apparatus as defined in claim 14, wherein the interconnection pin comprises an external sealing surface positioned for engagement with a seal between the interconnection pin and the modular sensor cartridge.

16. The apparatus as defined in claim 15, wherein the seal comprises at least one radial seal.

17. The apparatus as defined in any one of claims 13 to 16, wherein the electrical connection comprises a printed circuit board connector to connect a printed circuit board in the modular sensor cartridge with a printed circuit board in the receiving block.

18. The apparatus as defined in any one of claims 1 to 17, wherein the sampling outlet of the central cavity is positioned between the inlet for receiving the breath sample and the exhaust outlet.

19. The apparatus as defined in claim 18, wherein the sampling outlet of the central cavity is positioned proximate a midpoint between the inlet for receiving the breath sample and the exhaust outlet.

20. The apparatus as defined in any one of claims 1 to 19, wherein the sampling outlet of the central cavity is positioned at a location within approximately 30% to approximately 70% of a distance between the inlet for receiving the breath sample and the exhaust outlet.

21. A method of detecting an analyte in a breath sample provided by a user using a modular sensor cartridge insertable within a receiving block, the method comprising:receiving a breath sample into a central cavity provided within the receiving block; drawing a first portion of the breath sample through a sensor for detecting the analyte, the sensor being provided within the modular sensor cartridge and in fluid communication with the central cavity; and drawing a remaining portion of the breath sample through an exhaust fan on the receiving block.

22. The method as defined in claim 21, comprising heating the receiving block during said step of drawing the first portion of the breath sample through the sensor for detecting the analyte.

23. The method as defined in any one of claims 21 to 22, further comprising venting heat out of the modular sensor cartridge through vents provided on the modular sensor cartridge.

24. The method as defined in any one of claims 21 to 23, comprising using a cooling fan to draw warm air out of an external housing containing the receiving block and the modular sensor cartridge.

25. The method as defined claim 24, wherein the cooling fan is provided vertically below the sensor, optionally wherein the cooling fan is provided in the bottom of the external housing.

26. The apparatus or method as defined in any one of claims 1 to 25, wherein a sample delivery channel of the interconnection pin has a length of between about 18 mm and about 22 mm, and an internal diameter of between about 0.70 mm to about 0.85 mm.

7. The apparatus or method as defined in any one of claims 1 to 26, wherein the sample delivery channel of the interconnection pin has a length L and internal diameter D selected such that - £^)4is between about 30 mm-3and about 95 mm-3.

28. The apparatus or method as defined in any one claims 1 to 27, wherein a rate of volume exchange per unit time through the sample delivery channel is within the range of about 25,000 s’1to about 80,000 s’1.

29. The apparatus or method as defined in any one of claims 1 to 28, wherein the volumetric flow rate Q through the sample delivery channel, a length L and an internal diameter D of the sample delivery channel are selected so that Q-^ is within the range of about 25,000 s’1to about 80,000 s’1.

30. The apparatus or method as defined in any one of claims 1 to 29, wherein the suction apparatus provides a volumetric flow rate Q and the sample delivery channel of the interconnection pin has a length L and diameter D selected to provide a pressure drop across the sample delivery channel of between about 20 Pa to about 60 Pa.

31. The apparatus or method as defined in any one of claims 1 to 30, wherein a pressure drop across the sample delivery channel is between about 20 Pa to about 60 Pa.

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