Aerosol generating device and system with a conductivity sensor

Abstract

The aerosol generation system includes a liquid storage portion for holding a liquid aerosol-forming substrate, an atomizer in fluid communication with the liquid storage portion, a conductivity sensor, a power source, and control electronics. The conductivity sensor includes at least two electrodes (104, 106) and is arranged to sense the electrical conductivity of the liquid aerosol-forming substrate from the liquid storage portion. The control electronics is configured to control the supply of power from the power source to the atomizer to atomize the liquid aerosol-forming substrate from the liquid storage portion, and to control the supply of power from the power source to the electrodes (104, 106) of the conductivity sensor, where the power supply is supplied to the conductivity sensor as an alternating current voltage. The control electronics is further configured to receive one or more measurements indicative of the conductivity of the liquid aerosol-forming substrate from the conductivity sensor, and to determine the nicotine concentration of the liquid aerosol-forming substrate based on one or more of the measurements from the conductivity sensor.

Description

[Technical field]

[0001] The present invention relates to an aerosol generating system that generates an aerosol by spraying an aerosol-forming substrate containing nicotine. In particular, the present invention relates to an aerosol generating system that includes a conductivity sensor. The present invention also relates to an aerosol generating device that includes a conductivity sensor and a cartridge that includes the conductivity sensor.

[0002] Aerosol generating systems, such as e-cigarettes, are widely used that operate by heating a liquid formulation to generate an aerosol for inhalation by a user. Typically, these systems include a liquid reservoir that holds the liquid formulation, a heater for vaporizing the liquid formulation, a wick that transfers liquid from the liquid reservoir to the heater, a power source, and control electronics. Some of these systems include a refillable liquid reservoir. Some of these systems include a device portion and a replaceable cartridge. In some systems, the device portion contains a power source and control electronics, and the cartridge contains a liquid reservoir that holds the liquid formulation, a heater for vaporizing the liquid formulation, and a wick that transfers liquid from the liquid reservoir to the heater.

[0003] In a system with a refillable liquid storage portion, liquid formulations with different compositions may be introduced into the liquid storage portion when the liquid storage portion is refilled.Similarly, in a system with a device portion and a replaceable cartridge, different cartridges may contain liquid formulations with different compositions.In particular, different liquid formulations may contain different amounts or concentrations of nicotine.Thus, the aerosol generated from one particular liquid formulation may contain different amounts or concentrations of nicotine from the aerosol generated from a different liquid formulation.

[0004] It would be desirable for an aerosol generation system to be able to assess the nicotine concentration of a liquid formulation, it would be desirable for an aerosol generation system to be able to control the nicotine concentration of aerosols generated from different liquid formulations, and it would be desirable to be able to standardize the manufacture of an aerosol generation system regardless of the aerosol-forming substrate used with the aerosol generation system.

[0005] According to the present disclosure, an aerosol generating system is provided, comprising a liquid storage portion for holding a liquid aerosol-forming substrate, an atomizer in fluid communication with the liquid storage portion, a conductivity sensor, a power source, and control electronics. The conductivity sensor comprises at least two electrodes and is arranged to sense an electrical conductivity of the liquid aerosol-forming substrate from the liquid storage portion. The control electronics is configured to control a supply of power from the power source to the atomizer to atomize the liquid aerosol-forming substrate from the liquid storage portion, and to control a supply of power from the power source to the electrodes of the conductivity sensor, the supply of power being supplied to the conductivity sensor as an alternating voltage. The control electronics is further configured to receive one or more measurements indicative of the conductivity of the liquid aerosol-forming substrate from the conductivity sensor, and to determine a nicotine concentration of the liquid aerosol-forming substrate based on one or more of the measurements from the conductivity sensor.

[0006] The liquid aerosol-forming substrate may include three main components, typically nicotine, an aerosol former, and water. Advantageously, the inventors have recognized that the electrical conductivity of the liquid aerosol-forming substrate may provide an indication of the nicotine concentration of the liquid aerosol-forming substrate. In particular, the inventors have recognized that manufacturers of aerosol generating devices may also manufacture or sell proprietary liquid aerosol-forming substrates having different nicotine concentrations, and by providing a conductivity sensor in the aerosol generating device, the device may be able to determine which proprietary aerosol-forming substrate is received into the device based on the electrical conductivity of the aerosol-forming substrate.

[0007] The term "aerosol-forming substrate" as used herein refers to a substrate capable of releasing a volatile compound capable of forming an aerosol. The volatile compound may be released by heating the aerosol-forming substrate. The volatile compound may be released by moving the aerosol-forming substrate through the passage of a vibrable element.

[0008] The aerosol-forming substrate is a liquid aerosol-forming substrate. The aerosol-forming substrate may comprise a mixture of liquid and solid components. The aerosol-forming substrate comprises nicotine. The aerosol-forming substrate preferably comprises a nicotine salt. The aerosol-forming substrate may comprise a plant-derived material. The aerosol-forming substrate may comprise tobacco. The aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds that are released from the aerosol-forming substrate upon heating. The aerosol-forming substrate may comprise a non-tobacco-containing material. The aerosol-forming substrate may comprise a homogenized plant-derived material. The aerosol-forming substrate may comprise a homogenized tobacco material. The aerosol-forming substrate may comprise at least one aerosol former. The aerosol former is any suitable known compound or mixture of compounds that facilitates the formation of a dense and stable aerosol in use and is substantially resistant to thermal decomposition at the operating temperature of the system. Suitable aerosol formers are well known in the art and include, but are not limited to, polyhydric alcohols (such as triethylene glycol, 1,3-butanediol, glycerin, etc.), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate, dimethyl tetradecanedioate, etc.). Preferred aerosol formers are polyhydric alcohols or mixtures thereof, such as triethylene glycol, 1,3-butanediol, and glycerin (most preferred). The aerosol-forming substrate may contain other additives and ingredients, such as flavorings.

[0009] In some preferred embodiments, the nicotine is in the form of a nicotine salt. In some particularly preferred embodiments, the nicotine salt may be the only electrolyte present in the liquid aerosol-forming substrate. In some embodiments, the nicotine electrolyte concentration may be substantially higher than the concentrations of other electrolytes in the liquid aerosol-forming substrate. Therefore, it may be possible to ignore the effect of variations in the concentrations of other components of the liquid aerosol-forming substrate on the electrical conductivity of the substrate.

[0010] A manufacturer of liquid aerosol-forming substrates may produce different proprietary aerosol-forming substrates with different concentrations of nicotine. To vary the concentration of nicotine in an aerosol-forming substrate, the manufacturer may conversely increase or decrease the amount of nicotine in a given amount of substrate by decreasing or increasing the amount of solvent, e.g., the amount of water, in a given amount of substrate. For example, the manufacturer may produce a low-nicotine aerosol-forming substrate that includes a first amount of nicotine and a first amount of water for a given amount of substrate, and a high-nicotine aerosol-forming substrate that includes a second amount of nicotine that is greater than the first amount of nicotine and a second amount of water that is less than the first amount of water for a given amount of substrate. The low-nicotine aerosol-forming substrate may have a lower concentration of nicotine than the high-nicotine aerosol-forming substrate. The low-nicotine aerosol-forming substrate may have a first electrical conductivity, and the high-nicotine aerosol-forming substrate may have a second electrical conductivity that is greater than the first electrical conductivity. The difference between the first electrical conductivity and the second electrical conductivity may increase with temperature.

[0011] The liquid aerosol-forming substrate may typically have an electrical conductivity between about 1 microSiemens / centimeter and about 500 microSiemens / centimeter at 20 degrees Celsius, and preferably between about 1 microSiemens / centimeter and about 400 microSiemens / centimeter at 20 degrees Celsius. The conductivity sensor is preferably suitable for measuring the electrical conductivity of the aerosol-forming substrate within these ranges.

[0012] The conductivity sensor may be any suitable type of sensor for sensing the conductivity of the liquid aerosol-forming substrate in the system.

[0013] The conductivity sensor may be disposed in any suitable location within the aerosol generation system. The conductivity sensor may be disposed within the liquid storage portion. The conductivity sensor may be disposed at or around the liquid storage portion. The conductivity sensor may be disposed at or around the atomizer. The conductivity sensor may be disposed between the liquid storage portion and the atomizer. In some embodiments, the conductivity sensor is a separate component from the atomizer. In some preferred embodiments, the atomizer comprises the conductivity sensor. In these preferred embodiments, the atomizer may comprise one or more elements, and at least one of the electrodes of the conductivity sensor may comprise an element of the atomizer.

[0014] The electrodes of the conductivity sensor may have any suitable form. For example, the electrodes may be coil electrodes, ring electrodes, or mesh electrodes comprising multiple filaments. In some embodiments, the electrodes may be arranged to contact the liquid aerosol-forming substrate. In some embodiments, the electrodes may be arranged such that the electrodes do not contact the liquid aerosol-forming substrate. In other words, the electrodes may be separated from the liquid aerosol-forming substrate.

[0015] In some first preferred embodiments, the conductivity sensor comprises two electrodes. The conductivity sensor of these first preferred embodiments may be referred to as a two-point conductivity sensor.

[0016] The two electrodes may be spaced apart such that a recess is formed between the electrodes. For example, the two electrodes may be spaced apart by a distance of about 1 millimeter to about 20 millimeters. As used herein, the term "recess" refers to any suitable gap or space between the two electrodes, including both a two-dimensional space between two completely flat electrodes disposed in the same plane, and a three-dimensional space between the two electrodes. The two electrodes may be arranged such that a liquid aerosol-forming substrate can be disposed within the recess between the electrodes. The two electrodes are preferably arranged to contact the liquid aerosol-forming substrate from the liquid storage portion. The two electrodes may be arranged such that the two electrodes are electrically insulated from each other when the liquid aerosol-forming substrate is not disposed within the recess between the electrodes.

[0017] In these first preferred embodiments, the control electronics may be configured to provide power from the power source to the electrodes as an alternating voltage. The control electronics may also be configured to receive one or more measurements from the electrodes indicative of the electrical conductivity of the liquid aerosol-forming substrate.

[0018] In these first preferred embodiments, when an alternating voltage is applied across the two electrodes when the liquid aerosol-forming substrate is disposed within the cavity between the electrodes, an alternating current may flow between the two electrodes through the liquid aerosol-forming substrate within the cavity between the electrodes. The control electronics may be configured to measure the current between the two electrodes. The control electronics may be configured to measure the voltage between the two electrodes. One or more of the measured current and voltage may be used to determine the electrical conductivity of the liquid aerosol-forming substrate disposed within the cavity between the two electrodes.

[0019] In these first preferred embodiments, the control electronics may be configured to supply an AC voltage to the conductivity sensor at a frequency between about 1 kHz and about 500 kHz.

[0020] In some second preferred embodiments, the conductivity sensor comprises four electrodes. The conductivity sensors of these second preferred embodiments may be referred to as four-point conductivity sensors.

[0021] The conductivity sensor may include two inner electrodes and two outer electrodes. The two outer electrodes may be spaced apart such that an outer recess is formed between the two outer electrodes. For example, the two outer electrodes may be spaced apart by a distance of about 5 millimeters to about 20 millimeters. The two inner electrodes may be spaced apart such that an inner recess is formed between the two inner electrodes. For example, the two inner electrodes may be spaced apart by a distance of about 5 millimeters to about 20 millimeters. In some embodiments, the two inner electrodes are disposed within the outer recess between the two outer electrodes. In these embodiments, the two inner electrodes may be spaced apart by a distance of about 1 millimeter to about 18 millimeters.

[0022] The two outer electrodes may be arranged such that the liquid aerosol-forming substrate can be disposed in the outer recess between the two outer electrodes. The two outer electrodes may be arranged such that the two outer electrodes are electrically insulated from each other when the liquid aerosol-forming substrate is not disposed in the outer recess between the outer electrodes.

[0023] The two inner electrodes may be arranged such that a liquid aerosol-forming substrate may be disposed in the inner recess between the two inner electrodes. The two inner electrodes may be arranged such that the two inner electrodes are electrically insulated from each other when a liquid aerosol-forming substrate is not disposed in the inner recess between the inner electrodes. The two inner electrodes may also be arranged such that the two inner electrodes are electrically insulated from the two outer electrodes when a liquid aerosol-forming substrate is not disposed in the inner recess between the inner electrodes.

[0024] The two outer electrodes and the two inner electrodes are preferably arranged to contact the liquid aerosol-forming substrate from the liquid reservoir.

[0025] In these second preferred embodiments, the control electronics may be configured to supply power from the power source to the outer electrode as an AC voltage. The control electronics may be configured to receive one or more measurements indicative of the conductivity of the liquid aerosol-forming substrate from the outer electrode. The control electronics may be configured to receive one or more measurements indicative of the conductivity of the liquid aerosol-forming substrate from the inner electrode.

[0026] In these second preferred embodiments, when the liquid aerosol-forming substrate is disposed in the outer recess between the two outer electrodes, applying an AC voltage across the two outer electrodes can cause an AC current to flow between the two outer electrodes through the liquid aerosol-forming substrate disposed in the outer recess. When the liquid aerosol-forming substrate is disposed in the outer recess, the liquid aerosol-forming substrate is also disposed in the inner recess between the two inner electrodes. When an AC current flows between the two outer electrodes, an AC current also flows between the two inner electrodes establishing an AC voltage across the two inner electrodes.

[0027] The control electronics may be configured to measure a voltage drop between the two inner electrodes. The voltage drop measured between the two inner electrodes may be used to determine the electrical conductivity of the liquid aerosol-forming substrate disposed in the inner recess between the two inner electrodes. The control electronics may be configured to measure a current between the two outer electrodes. The current measured between the two outer electrodes may be used to determine the electrical conductivity of the liquid aerosol-forming substrate disposed in the outer recess. In some particularly preferred embodiments, the control electronics is configured to determine the electrical conductivity of the liquid aerosol-forming substrate using the voltage drop measured between the two inner electrodes and the current measured between the two outer electrodes. The electrical conductivity of the liquid aerosol-forming substrate may be proportional to the applied current.

[0028] Advantageously, the four-point conductivity sensor may minimize the effect of parasitic resistance on the voltage measurements by the conductivity sensor. Parasitic resistance of the conductivity sensor, such as contact resistance between the leads in contact with the electrodes, may cause errors in the voltage measurements. Advantageously, the four-electrode arrangement of the second preferred embodiment allows for the voltage measurements to be separated from the current measurements. By separating the voltage measurements from the current measurements, it may be possible to minimize the effect of parasitic resistance on the voltage measurements.

[0029] In the four-point conductivity sensor of the second preferred embodiment, the inner electrodes are arranged such that the current between the inner electrodes is substantially the same as the current drive between the outer electrodes. If the voltage across the inner electrodes is measured with high impedance, negligible current may be drawn through the leads connected to the inner electrodes compared to the current between the inner electrodes. Because the current through the leads connected to the inner electrodes is negligible compared to the current between the inner electrodes, the voltage drop across the leads connected to the inner electrodes resulting from parasitic resistance may be negligible compared to the voltage drop across the inner electrodes. As a result, the measurement of the voltage across the inner electrodes may include minimal or negligible contribution from the parasitic resistance.

[0030] Furthermore, since the measurement of the voltage across the two inner electrodes draws negligible current, polarization of the liquid aerosol-forming substrate at the two inner electrodes may also be negligible, minimizing the effect of polarization on the voltage measurements in the four electrode arrangement of the second preferred embodiment.

[0031] In these second preferred embodiments, the control electronics may be configured to supply an AC voltage to the conductivity sensor at a frequency between about 1 kHz and about 500 kHz.

[0032] In some of these second preferred embodiments, the two inner electrodes may be susceptor elements. The term "susceptor element" as used herein refers to an element that includes a material capable of converting electromagnetic energy into heat. When the susceptor element is located in an alternating electromagnetic field, the susceptor is heated. The heating of the susceptor element may be the result of at least one of hysteresis losses and eddy currents induced in the susceptor, depending on the electrical properties and magnetic properties of the susceptor material. Thus, applying an alternating voltage to the two outer electrodes to heat the outer electrodes may induce currents in the two inner electrodes. The currents induced in the two inner electrodes may be sufficient to heat the two inner electrodes.

[0033] The susceptor element may comprise any suitable material. The susceptor element may be formed from any material that can be inductively heated to a temperature sufficient to release volatile compounds from the aerosol-forming substrate. Suitable materials for the elongated susceptor element include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. Preferred susceptor elements comprise metal or carbon. Advantageously, the susceptor element may comprise or consist of ferromagnetic materials, such as ferromagnetic alloys, such as ferritic iron, ferromagnetic steel or stainless steel, ferromagnetic particles, and ferrites.

[0034] In some third preferred embodiments, the conductivity sensor comprises two electrodes, a first electrode and a second electrode. Preferably, each electrode forms a coil. The first electrode is arranged to induce a current in the second electrode when an alternating voltage is supplied to the first electrode. The two electrodes may be spaced apart such that a recess is formed between the electrodes. The two electrodes may be arranged such that the two electrodes are electrically insulated from each other.

[0035] Where the first electrode and the second electrode form a coil, the first electrode coil may be wrapped around the first inner recess. The second electrode coil may be wrapped around the second inner recess. The first electrode and the second electrode may be arranged such that the first inner recess is aligned with the second inner recess. The first inner recess and the second inner recess may define an inner recess. The inner recess may define a passageway through which the liquid aerosol-forming substrate may flow.

[0036] These third preferred embodiment conductivity sensors may be referred to as inductive conductivity sensors.

[0037] In these third preferred embodiments, the control electronics may be configured to supply an alternating voltage to the first electrode. The control electronics may be further configured to receive one or more measurements indicative of the electrical conductivity of the liquid aerosol-forming substrate from the second electrode.

[0038] In these third preferred embodiments, when a liquid aerosol-forming substrate is disposed within the inner recess between the first and second electrodes, applying an alternating voltage to the first electrode can cause an alternating current to be generated in the second electrode via induction. The alternating voltage applied to the first electrode generates a fluctuating magnetic field, which causes a current to flow through the liquid aerosol-forming substrate disposed within the inner recess. The magnitude and direction of the current flowing through the liquid aerosol-forming substrate disposed within the inner recess affects the alternating current generated at the second electrode. The control electronics can be configured to measure the current or voltage induced in the second electrode. The measured current or voltage can be used to determine the electrical conductivity of the liquid aerosol-forming substrate disposed within the inner recess between the first and second electrodes. The current induced in the second electrode can be proportional to the electrical conductivity of the liquid aerosol-forming substrate.

[0039] In these third preferred embodiments, the first and second electrodes may be shielded or separated from the aerosol-forming substrate. In other words, the first and second electrodes may be arranged such that the first and second electrodes do not contact the liquid aerosol-forming substrate. The first and second electrodes may be arranged within a conductivity sensor housing. The conductivity sensor housing may define an inner recess, including a first inner recess and a second inner recess. The conductivity sensor housing may be made of any suitable material. The conductivity sensor housing may be made of a material that is substantially impermeable to the liquid aerosol-forming substrate. The conductivity sensor housing may be made of an electrically insulating material. For example, suitable electrically insulating materials include glass, plastic, and ceramic materials. As used herein, an electrically insulating material is defined as a material that has a resistance of about 1×10 at 20° C. 6 Ωm, generally about 1X10 9 Ωm~approx. 1X10 21 Refers to a material that has a volume resistivity of Ωm.

[0040] The inductive conductivity sensor may be disposed at any suitable location in the aerosol generating system. The inductive conductivity sensor is preferably disposed in the liquid storage portion. Preferably, the inductive conductivity sensor is disposed in the liquid storage portion, and the liquid aerosol-forming substrate held in the liquid storage portion can flow through the inner recess between the first electrode and the second electrode.

[0041] In these third preferred embodiments, the control electronics may be configured to supply an AC voltage to the conductivity sensor at a frequency between about 1 MHz and about 100 MHz.

[0042] In these third preferred embodiments, the first electrode coil may have any suitable number of turns. The second electrode coil may have any suitable number of turns. The second electrode coil preferably has the same number of turns as the first electrode coil. The first electrode coil may have any suitable form. For example, the first electrode coil may be a spiral coil or a toroid. The second electrode coil may have any suitable form. For example, the second electrode coil may be a spiral coil or a toroid. The second electrode coil preferably has the same form as the first electrode coil. Particularly preferably, the first electrode coil and the second electrode coil comprise identical toroids.

[0043] The control electronics controls the supply of power from the power source to the electrodes of the conductivity sensor. The supply of power provided to the conductivity sensor is provided as an alternating voltage. The alternating voltage may be provided to the electrodes of the conductivity sensor at any suitable frequency.

[0044] The control electronic circuitry is configured to determine the nicotine concentration of the liquid aerosol-forming substrate based on one or more of the measurements from the conductivity sensor. The control electronic circuitry may be configured to determine the nicotine concentration in any suitable manner. In one embodiment, a predetermined functional relationship between electrical conductivity and nicotine concentration may be known. A suitable algorithm may be stored in a memory of the control electronic circuitry, and the control electronic circuitry may be configured to calculate the nicotine concentration by applying the measured values ​​of conductivity to the stored algorithm. In another embodiment, electrical conductivity values ​​of the predetermined aerosol-forming substrate for known nicotine concentrations may be stored in a look-up table in a memory of the control electronic circuitry, and the measured values ​​of electrical conductivity may be compared to the stored electrical conductivity values ​​to determine the nicotine concentration of the aerosol-forming substrate. The electrical conductivity values ​​of the predetermined aerosol-forming substrate for known nicotine concentrations may be determined by calibration, which is typically performed at the factory before the aerosol generating system is provided to a user for use.

[0045] Of course, determining an indication of the concentration of nicotine in the liquid aerosol-forming substrate may not necessarily involve calculating a nicotine concentration value or storing a value of the nicotine concentration in a look-up table stored in the memory of the control electronics. For example, in some embodiments according to the invention, determining the nicotine concentration in the liquid aerosol-forming substrate includes using a measurement of electrical conductivity to determine a specific power to supply to the atomizer. In these embodiments, the determination of the power to supply to the atomizer using the measurement of electrical conductivity is based on a predetermined relationship between the nicotine concentration and the electrical conductivity of the liquid aerosol-forming substrate.

[0046] In some embodiments, the control electronics is further configured to control the supply of power from the power source to the atomizer to atomize the liquid aerosol-forming substrate based on the determined nicotine concentration of the liquid aerosol-forming substrate. Advantageously, this may enable the aerosol generation system to control the amount of aerosol generated by the system based on the nicotine concentration of the aerosol-forming substrate.

[0047] Preferably, the control electronic circuit is configured to control the supply of power from the power source to the atomizer to atomize the liquid aerosol-forming substrate based on the determined nicotine concentration of the liquid aerosol-forming substrate by comparing the determined nicotine concentration with a predetermined threshold. The control electronic circuit may be further configured to supply a first power to the atomizer when the determined nicotine concentration is equal to or less than the predetermined threshold. The control electronic circuit may be further configured to supply a second power, lower than the first power, to the atomizer when the determined nicotine concentration exceeds the predetermined threshold. Such a configuration may generate a relatively large amount of aerosol during the user experience when the determined concentration of nicotine is relatively low, and may generate a relatively small amount of aerosol when the determined concentration of nicotine is relatively high. Varying the amount of aerosol generated in the user experience may vary the amount of nicotine delivered to the user during the user experience. Advantageously, this may enable the aerosol generation system to deliver a consistent amount of nicotine to the user during the user experience, regardless of the nicotine concentration of the liquid aerosol-forming substrate.

[0048] The control electronics may be configured to control the power provided from the power source to the atomizer in discrete increments. For example, a plurality of discrete power settings may be stored in a look-up table in a memory of the control electronics, each power setting being associated with a particular predetermined nicotine concentration and electrical conductivity, and the control electronics may be configured to compare the conductivity measurement to the electrical conductivity values ​​stored in the look-up table and apply power from the power source to the atomizer based on the power setting associated with the stored electrical conductivity value that matches the conductivity measurement.

[0049] The control electronics may be configured to continuously control the power supplied from the power source to the atomizer. The control electronics may be configured to control the power supplied from the power source to the atomizer as a function of the electrical conductivity. A predetermined algorithm may be stored on a memory of the control electronics, and the conductivity measurements may be applied to the predetermined algorithm to determine the power supplied from the power source to the atomizer.

[0050] The control electronics may be configured to supply power from the power source to the electrodes of the conductivity sensor at any suitable time. Preferably, the control electronics is configured to supply power from the power source to the electrodes of the conductivity sensor before power is supplied from the power source to the atomizer to atomize the liquid aerosol-forming substrate. Advantageously, this may enable the control electronics to control the power supplied from the power source to the atomizer based on the determined nicotine concentration of the liquid aerosol-forming substrate.

[0051] The electrical conductivity of the liquid aerosol-forming substrate may vary depending on the temperature of the aerosol-forming substrate.

[0052] In some embodiments, the aerosol generating device may include a temperature sensor. The control electronics may be configured to receive one or more temperature measurements from the temperature sensor. The control electronics may be further configured to adjust the determination of the nicotine concentration based on the one or more temperature measurements from the temperature sensor.

[0053] The temperature sensor may be any suitable type of temperature sensor for sensing the temperature of the liquid aerosol-forming substrate, including, for example, a thermocouple, a thermistor, or a resistance temperature sensor, among others.

[0054] The temperature sensor may be arranged to sense the temperature of the liquid aerosol-forming substrate. The temperature sensor may be arranged at any suitable location relative to the conductivity sensor. Preferably, the temperature sensor is arranged at or around the conductivity sensor to minimize a temperature difference between the liquid aerosol-forming substrate sensed by the temperature sensor and the liquid aerosol-forming substrate sensed by the conductivity sensor. The temperature sensor may be arranged in the liquid storage portion. The temperature sensor may be arranged at or around the atomizer. The temperature sensor may be arranged between the liquid storage portion and the atomizer. In some embodiments, the temperature sensor is a separate component from the atomizer. In some embodiments, the atomizer comprises a temperature sensor.

[0055] The control electronics may adjust the determination of the nicotine concentration based on the temperature measurement in any suitable manner.

[0056] In one embodiment, a predetermined functional relationship between temperature and electrical conductivity is known. An algorithm may be stored in a memory of the control electronics, and the control electronics may be configured to calculate the nicotine concentration by applying the measurements of conductivity and temperature to the stored algorithm.

[0057] In another example, electrical conductivity values ​​of a given aerosol-forming substrate at a particular temperature for known nicotine concentrations may be stored in a look-up table in the memory of the control electronics, and measured values ​​of electrical conductivity and temperature may be compared to the stored electrical conductivity and temperature values ​​to determine the nicotine concentration of the aerosol-forming substrate.

[0058] In some embodiments, the aerosol generation system may include a heater. The heater may be arranged to heat the liquid aerosol-forming substrate from the liquid storage portion. The heater may be configured to heat the liquid aerosol-forming substrate to a predetermined temperature. The power source may be configured to provide power to the heater. The control electronics may be configured to provide power from the power source to the heater to heat the liquid aerosol-forming substrate from the liquid storage portion to a predetermined temperature.

[0059] The heater may be disposed at any suitable location relative to the conductivity sensor. Preferably, the heater is disposed at or around the conductivity sensor to minimize the temperature difference between the liquid aerosol-forming substrate heated by the heater and the liquid aerosol-forming substrate sensed by the conductivity sensor. The heater may be disposed in the liquid storage portion. The heater may be disposed at or around the atomizer. The heater may be disposed between the liquid storage portion and the atomizer. Typically, the heater is disposed upstream of the conductivity sensor such that the heater may heat the liquid aerosol-forming substrate to a predetermined temperature before the liquid aerosol-forming substrate reaches the conductivity sensor. In some embodiments, the heater is a separate component from the atomizer. In some embodiments, the atomizer comprises a heater.

[0060] The control electronics may be configured to supply power from the power source to the heater at any suitable time. In some embodiments, the control electronics is configured to continuously supply power from the power source to the heater to maintain the temperature of the liquid aerosol-forming substrate at a predetermined temperature. In some embodiments, the control electronics is configured to supply power from the power source to the heater for a predetermined period of time before the conductivity measurement is taken to ensure that the liquid aerosol-forming substrate has sufficient time to reach the predetermined temperature before the conductivity measurement is taken.

[0061] The predetermined temperature may be any suitable temperature. Typically, the predetermined temperature is above the expected ambient temperature so that the ambient temperature does not affect the temperature of the liquid aerosol-forming substrate at the conductivity sensor. For example, the predetermined temperature may be at least about 60 degrees Celsius, at least about 70 degrees Celsius, or at least about 80 degrees Celsius. The predetermined temperature is below the boiling point of the liquid aerosol-forming substrate.

[0062] In embodiments comprising a heater for heating the aerosol-forming substrate to a predetermined temperature, it may not be necessary to provide a temperature sensor for sensing the temperature of the liquid aerosol-forming substrate, as it may be reasonable to assume that the temperature of the liquid aerosol-forming substrate sensed by the conductivity sensor is the predetermined temperature.

[0063] The aerosol generating system may include a housing. The housing may be formed from any suitable material or combination of materials. Suitable materials include, but are not limited to, aluminum, polyetheretherketone (PEEK), polyimide (such as Kapton®), polyethylene terephthalate (PET), polyethylene (PE), high density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE), polyoxymethylene (POM), epoxy resins, polyurethane resins, vinyl resins, liquid crystal polymers (LCPs), and modified LCPs (such as LCPs containing graphite or glass fibers).

[0064] The housing may define a liquid reservoir. The liquid reservoir may be of any suitable shape and size to hold sufficient liquid aerosol-forming substrate for multiple user experiences. For example, the liquid reservoir may have a capacity sufficient to allow continuous generation of aerosol for approximately six minutes, or a multiple of six minutes. In another embodiment, the liquid reservoir may have a capacity sufficient to allow a predetermined number of puffs, or discrete activations of the atomizer.

[0065] In some embodiments, a porous carrier material may be provided within the liquid reservoir. The liquid aerosol-forming substrate may be adsorbed or otherwise loaded onto the porous carrier material. The porous carrier material may be made of any suitable absorbent plug or body. For example, suitable absorbent plugs or bodies may be foamed metal or plastic materials, polypropylene, terylene, nylon fibers, or ceramics.

[0066] The aerosol generation system may further comprise a liquid transfer element. The liquid transfer element may be configured such that, in use, the liquid aerosol-forming substrate is transferred along the liquid transfer element from the liquid storage portion to the atomizer by capillary action. In an embodiment in which the liquid storage portion comprises a porous carrier material, the liquid transfer element is configured to transfer the liquid aerosol-forming substrate from the porous carrier material to the atomizer. The liquid transfer element may comprise a capillary material. A capillary material is a material that actively carries liquid from one end of the material to another. The capillary material may be advantageously oriented within the liquid storage portion to deliver the liquid aerosol-forming substrate to the atomizer.

[0067] The liquid transfer element may comprise any suitable material or combination of materials capable of transporting the liquid aerosol-forming substrate along its length. The liquid transfer element can be, but need not be, formed from a porous material. The liquid transfer element may be formed from a material having a fibrous or spongy structure. The liquid transfer element preferably comprises a bundle of capillaries. For example, the liquid transfer element may comprise a plurality of fibers or threads, or other fine tubes. The liquid transfer element may comprise a sponge-like or foam-like material. The structure of the liquid transfer element forms a plurality of small holes or tubes through which the liquid aerosol-forming substrate can be transported by capillary action. The particular preferred material will depend on the physical properties of the liquid aerosol-forming substrate. Examples of suitable capillary materials include sponge or foam materials, ceramic or graphite-based materials in the form of fibers or sintered powders, foamed metal or plastic materials, fibrous materials made of spun or extruded fibers (cellulose acetate, polyester, or bonded polyolefin, polyethylene, terylene or polypropylene fibers, nylon fibers, ceramic, glass fibers, silica glass fibers, carbon fibers, metal fibers of medical grade stainless steel alloys such as austenitic 316 stainless steel and martensitic 440 and 420 stainless steel, etc.). The liquid transfer element may have any suitable capillary to be used with different liquid physical properties. The liquid aerosol-forming substrate has physical properties such as, but not limited to, viscosity, surface tension, density, thermal conductivity, boiling point, vapor pressure, etc. that allow it to be transferred through the liquid transfer element. The liquid transfer element may be formed of a heat-resistant material. The liquid transfer element may include a plurality of fiber strands. The plurality of fiber strands may be generally aligned along the length of the liquid transfer element.

[0068] In embodiments in which the liquid storage section comprises a porous carrier material, the porous carrier material and the liquid transfer element may comprise the same material. Preferably, the porous carrier material and the liquid transfer element comprise different materials.

[0069] The atomizer may be any suitable type of atomizer. For example, the atomizer may be an acoustic atomizer. An acoustic atomizer may release volatile compounds from an aerosol-forming substrate by moving the aerosol-forming substrate through a number of nozzles using vibrations, typically at ultrasonic frequencies. In another example, the atomizer may be a thermal atomizer. A thermal atomizer may release volatile compounds from an aerosol-forming substrate by heating the aerosol-forming substrate.

[0070] In some embodiments, the atomizer comprises a conductivity sensor. In these embodiments, the atomizer may comprise one or more electrical conductivity elements. One or more of the electrodes of the conductivity sensor may comprise one or more of the electrical conductivity elements of the atomizer. Advantageously, combining the atomizer with the conductivity sensor may reduce the number of components of the aerosol generation system, and may reduce the cost and complexity of manufacture.

[0071] In some preferred embodiments, the atomizer is a thermal atomizer. The thermal atomizer may be an electric heater. The thermal atomizer may comprise one or more heating elements. Preferably, the thermal atomizer comprises multiple heating elements.

[0072] In some particularly preferred embodiments, the atomizer is a thermal atomizer comprising a plurality of heating elements, and each of the electrodes of the conductivity sensor comprises a heating element of the thermal atomizer. In these particularly preferred embodiments, the control electronics may be further configured to provide a first power from the power source to the electrodes of the conductivity sensor for measuring the electrical conductivity of the liquid aerosol-forming substrate, and a second power from the power source to the plurality of heating elements of the atomizer for atomization of the liquid aerosol-forming substrate. The second power is greater than the first power. The first power may be sufficient to allow the control electronics to receive electrical conductivity measurements from the conductivity sensor without increasing the temperature of the heating element to a temperature sufficient to release volatile compounds from the liquid aerosol-forming substrate. The second power may be sufficient to increase the temperature of the heating element to a temperature sufficient to release volatile compounds from the liquid aerosol-forming substrate.

[0073] The thermal atomizer may include a resistive heating coil.The thermal atomizer may include multiple resistive heating coils.

[0074] The thermal atomizer may comprise a resistive heating mesh.The thermal atomizer may comprise a plurality of resistive heating meshes.

[0075] The resistive heating mesh may comprise a plurality of conductive filaments. The conductive filaments may be substantially planar. As used herein, "substantially flat" means formed in a single plane and not wound or conformed to fit a curved or other non-planar shape. A flat heating mesh is easily handled during manufacturing and provides a robust structure.

[0076] The conductive filaments may define gaps between the filaments, and the gaps may have a width of about 10 micrometers to about 100 micrometers. The filaments preferably create capillary action within the gaps such that, in use, the liquid aerosol-forming substrate is drawn into the gaps, increasing the contact area between the heater assembly and the liquid.

[0077] The conductive filaments may form a mesh with a size of 160 to 600 mesh US (±10%) (i.e., about 160 to about 600 filaments per inch (±10%)). The gap width is preferably about 75 micrometers to about 25 micrometers. The percentage of open area of ​​the mesh, which is the ratio of the gap area to the total area of ​​the mesh, is preferably about 25 percent to about 56 percent. The mesh may be formed using different types of weave or lattice structures. The conductive filaments may be an array of filaments arranged parallel to one another.

[0078] The conductive filaments may have a diameter of about 8 micrometers to about 100 micrometers, preferably about 8 micrometers to about 50 micrometers, and more preferably about 8 micrometers to about 39 micrometers.

[0079] The resistive heating mesh may cover an area of ​​about 25 square millimeters or less. The resistive heating mesh may be rectangular. The resistive heating mesh may be square. The resistive heating mesh may have dimensions of about 5 millimeters by about 2 millimeters.

[0080] The conductive filaments may comprise any suitable conductive material. Suitable materials include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilicide, etc.), carbon, graphite, metals, alloys, and composites made of ceramic and metallic materials. Such composites may include doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable alloys include stainless steel, constantan, nickel-containing, cobalt-containing, chromium-containing, aluminum-containing, titanium-containing, zirconium-containing, hafnium-containing, niobium-containing, molybdenum-containing, tantalum-containing, tungsten-containing, tin-containing, gallium-containing, manganese-containing, and iron-containing alloys, and nickel-, iron-, cobalt-, stainless steel-based superalloys, Timetal®, iron-aluminum-based alloys, and iron-manganese-aluminum-based alloys. Timetal® is a registered trademark of Titanium Metals Corporation. The filaments may be coated with one or more insulators. Preferred materials for the conductive filaments are 304, 316, 304L, and 316L stainless steel, and graphite.

[0081] Preferably, the electrical resistance of the resistive heating mesh is from about 0.3 to about 4 ohms, more preferably the electrical resistance of the mesh is from about 0.5 to about 3 ohms, and even more preferably about 1 ohm.

[0082] In embodiments in which the thermal atomizer comprises a resistive heating coil, the coil pitch is preferably between about 0.5 millimeters and about 1.5 millimeters, and most preferably about 1.5 millimeters. The coil pitch refers to the spacing between adjacent turns of the coil. The coil may include less than 6 turns, and preferably has less than 5 turns. The coil may be formed of an electrically resistive wire having a diameter of about 0.10 millimeters to about 0.15 millimeters, and preferably about 0.125 millimeters. The electrically resistive wire is preferably formed of 904 or 301 stainless steel. Examples of other suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of other suitable alloys include constantan, nickel-containing, cobalt-containing, chromium-containing, aluminum-containing, titanium-containing, zirconium-containing, hafnium-containing, niobium-containing, molybdenum-containing, tantalum-containing, tungsten-containing, tin-containing, gallium-containing, manganese-containing, and iron-containing alloys, as well as nickel, iron, cobalt, stainless steel-based superalloys, Timetal®, iron-aluminum-based alloys, and iron-manganese-aluminum-based alloys. Resistive heating coils may also include metal foils (such as aluminum foil) provided in the form of ribbons.

[0083] In embodiments in which the thermal atomizer comprises a resistive heating coil, the resistive heating coil may be wrapped around the liquid transfer material.

[0084] The power source may include any suitable type of power source. The power source may include a battery. The power source may include a nickel metal hydride battery, a nickel cadmium battery, or a lithium-based battery (e.g., lithium cobalt, lithium iron phosphate, or lithium polymer battery). The power source may include another form of charge storage device, such as a capacitor. The power source may require recharging. The power source may have a capacity that allows for the storage of sufficient energy for use of the aerosol generation system over multiple user experiences. For example, the power source may have a capacity sufficient to allow continuous generation of aerosol for about 6 minutes, or a multiple of 6 minutes. In another embodiment, the power source may have a capacity sufficient to allow a predetermined number of puffs, or discrete activation of the atomizer.

[0085] The control electronics may comprise a microprocessor, which may be a programmable microprocessor, a microcontroller, or an application specific integrated circuit chip (ASIC) or other electronic circuit capable of providing control. The control electronics may comprise additional electronic components. The control electronics is configured to regulate the supply of power to the heater assembly. Power may be supplied to the heater assembly continuously after activation of the system, or may be supplied intermittently (e.g., after each puff). Power may be supplied to the heater assembly in the form of current pulses.

[0086] The control electronics may advantageously comprise a DC / AC inverter, which may comprise a class D or class E power amplifier. The DC / AC inverter may enable the control electronics to supply an alternating voltage from the power source to the conductivity sensor.

[0087] The conductivity sensor may be disposed in any suitable location within the aerosol generation system.

[0088] In some embodiments, the conductivity sensor is disposed within the liquid reservoir. In particular, an inductive conductivity sensor may be disposed within the liquid reservoir.

[0089] In some embodiments, the system comprises one or more porous carrier materials for holding and optionally moving the liquid aerosol-forming substrate. When the system comprises a porous carrier material in which the liquid aerosol-forming substrate is contained, one or more of the electrodes of the conductivity sensor may be disposed in or around the porous carrier material. One or more of the electrodes of the conductivity sensor may be disposed in contact with the porous carrier material. One or more of the electrodes of the conductivity sensor may be disposed in contact with an end of the porous carrier material.

[0090] In some embodiments, the conductivity sensor may be disposed between the liquid storage portion and the atomizer. In these embodiments, at least two electrodes of the conductivity sensor may be disposed in or around a flow path of the liquid aerosol-forming substrate that extends between the liquid storage portion and the atomizer.

[0091] In some embodiments, the atomizer may include a conductivity sensor. In other words, at least two electrodes of the conductivity sensor may be included in the atomizer. In some preferred embodiments, the atomizer includes multiple elements, such as a heating element, and at least one of the at least two electrodes of the conductivity sensor may include an element of the atomizer. In some embodiments, each electrode of the conductivity sensor includes an element of the atomizer.

[0092] In embodiments in which the atomizer comprises a conductivity sensor, the control electronics may be connected to the atomizer and the conductivity sensor in any suitable manner. The control electronics may include an aerosol generation circuit and a conductivity measurement circuit. The aerosol generation circuit may control the supply of power to the elements of the atomizer to atomize the liquid aerosol-forming substrate. The conductivity measurement circuit may control the supply of power to the electrodes of the conductivity sensor to measure the conductivity of the liquid aerosol-forming substrate.

[0093] In some embodiments, the control electronics includes separate aerosol generation and conductivity measurement circuits. In these embodiments, each element of the atomizer that is also configured as an electrode of the conductivity sensor may include at least one electrical contact that electrically connects the element to the aerosol generation circuit and at least one electrical contact that electrically connects the element to the conductivity measurement circuit. Each element of the atomizer that is also configured as an electrode of the conductivity sensor preferably includes two electrical contacts that electrically connect the element to the aerosol generation circuit and one electrical contact that electrically connects the element to the conductivity measurement circuit.

[0094] In some embodiments, the control electronics comprises a shared aerosol generation circuit and a conductivity measurement circuit. In these embodiments, each element of the atomizer that is also configured as an electrode of the conductivity sensor may comprise at least one electrical contact that electrically connects the element to the aerosol generation circuit and the conductivity measurement circuit. Each element of the atomizer that is also configured as an electrode of the conductivity sensor preferably comprises two electrical contacts that electrically connect the element to the aerosol generation circuit and the conductivity measurement circuit.

[0095] In some embodiments, the aerosol generation system comprises a device and a cartridge. The cartridge is removably housed in the device. Typically, the cartridge comprises a liquid reservoir and the device comprises a power source and control electronics. In these embodiments, the conductivity sensor may be provided either in the device or in the cartridge. In some embodiments, the atomizer is provided in the device. In some preferred embodiments, the atomizer is provided in the cartridge.

[0096] According to the present disclosure, there is provided an aerosol generation system as described above, comprising a device portion and a cartridge portion, the cartridge portion being removably housed within the device portion, the device portion comprising power and control electronics, and the cartridge portion comprising a liquid reservoir, an atomizer, and a conductivity sensor.

[0097] Advantageously, providing an aerosol generating system with a conductivity sensor either in the device or in the cartridge may allow manufacturers to standardize cartridge manufacturing and device manufacturing, regardless of the aerosol-forming substrate held in the cartridge or liquid storage portion of the device. In other words, providing an aerosol generating system with a conductivity sensor may allow manufacturers to manufacture identical cartridges and identical devices, regardless of the liquid aerosol-forming substrate held in the cartridge or liquid storage portion of the device. Such standardization may reduce the cost and complexity of cartridge and device manufacturing.

[0098] In some embodiments, the conductivity sensor is provided within the device. Advantageously, providing a conductivity sensor within the device can reduce the number of components within the cartridge, in particular the number of relatively expensive electrical components within the cartridge, and can reduce the cost and complexity of manufacturing the cartridge.

[0099] In some embodiments, the conductivity sensor is provided in the cartridge. In some preferred embodiments, where the atomizer is a thermal atomizer with multiple heating elements and each electrode of the conductivity sensor is formed from the heating elements of the atomizer, the conductivity sensor may be provided in the cartridge. In these preferred embodiments, the thermal atomizer is provided in the cartridge. Such a cartridge is typically called a cartomizer. The cartomizer may allow a high level of hygiene to be maintained in the aerosol generating system, since components that come into contact with the aerosol-forming substrate may be replaced periodically and the user is not exposed to components that come into contact with the aerosol-forming substrate.

[0100] According to the present disclosure, a cartridge for an aerosol generation system is provided, the cartridge comprising a liquid storage portion for holding a liquid aerosol-forming substrate, an atomizer in fluid communication with the liquid storage portion, and a conductivity sensor arranged to sense the electrical conductivity of the liquid aerosol-forming substrate from the liquid storage portion.

[0101] In some particularly preferred embodiments, the conductivity sensor of the cartridge comprises two electrodes, a first electrode and a second electrode, disposed within the liquid reservoir, each electrode forming a coil, where the first electrode is disposed to induce a current in the second electrode when an alternating voltage is supplied to the first electrode. In other words, the cartridge may comprise an inductive conductivity sensor as described above.

[0102] The cartridge may have a simple design. The cartridge may have a housing for storing the liquid. The cartridge housing is preferably a rigid housing with a material impermeable to liquids. As used herein, "rigid housing" means a free-standing housing. The device may also have a housing. The device housing is preferably a rigid housing. The cartridge housing and the device housing may be made of the same material. The device may have a recess for receiving the cartridge.

[0103] If the cartridge includes an atomizer, the device may include electrical contacts for electrically connecting a power supply and control electronics in the device to the atomizer in the cartridge. If the cartridge includes a conductivity sensor, the electrical contacts of the device may electrically connect the control electronics and power supply in the device to the conductivity sensor in the cartridge.

[0104] The aerosol generation system may include a mouthpiece that a user can inhale to receive the aerosol generated by the aerosol generation system. In some systems that include a device and a cartridge, the device includes the mouthpiece. In some systems that include a device and a cartridge, the cartridge includes the mouthpiece. Advantageously, providing a mouthpiece on the cartridge may help maintain a high level of hygiene within the system, as the cartridge is disposable and replaceable more frequently than the device.

[0105] It will be appreciated that features described above in relation to one embodiment may also be applicable to other embodiments, for example features described with reference to a cartridge may be equally applicable to an aerosol generating system, particularly an aerosol generating system including a cartridge. The invention will now be further described, by way of example only, with reference to the accompanying drawings in which: [Brief description of the drawings]

[0106] [Figure 1a] 1 shows a schematic diagram of an aerosol generation system comprising an aerosol generation device and a cartridge inserted into the aerosol generation device. [Figure 1b] FIG. 1 shows a schematic diagram of the aerosol generation system of FIG. 1a, in which the cartridge is received within the aerosol generation device. [Diagram 2] 1 shows a schematic diagram of an end of a liquid transfer element of an aerosol generation system according to an embodiment of the present invention, where the end of the liquid transfer element has an atomizer and a conductivity sensor. [Diagram 3] 1 shows a schematic diagram of an atomizer and a conductivity sensor according to another embodiment of the present invention. [Figure 4] 1 shows a schematic diagram of an end of a liquid transfer element of an aerosol generation system according to another embodiment of the present invention, where the end of the liquid transfer element has an atomizer and a conductivity sensor. [Diagram 5]FIG. 5 shows a schematic diagram of an end of the liquid transfer element of FIG. 4, including electrical connections between the atomizer, conductivity sensor, and control electronics of the aerosol generating device. [Figure 6a] FIG. 5 shows a schematic diagram of elements of one embodiment of control electronics suitable for use with the atomizer and conductivity sensor of FIG. [Figure 6b] FIG. 5 shows a schematic diagram of elements of one embodiment of control electronics suitable for use with the atomizer and conductivity sensor of FIG. [Figure 6c] FIG. 5 shows a schematic diagram of elements of one embodiment of control electronics suitable for use with the atomizer and conductivity sensor of FIG. [Figure 6d] FIG. 5 shows a schematic diagram of elements of one embodiment of control electronics suitable for use with the atomizer and conductivity sensor of FIG. [Figure 7] FIG. 2 shows a schematic diagram of a four-point conductivity sensor according to another embodiment of the present invention. [Figure 8] FIG. 8 shows a schematic diagram of a first side of the four-point conductivity sensor of FIG. 7. [Figure 9] 1 shows a schematic diagram of an inductive conductivity sensor according to another embodiment of the present invention. [Figure 10] FIG. 10 shows a schematic diagram of a cross section through the length of the inductive conductivity sensor of FIG.

[0107] Figures 1a and 1b are schematic diagrams of an exemplary aerosol generation system including a cartridge in which a conductivity sensor may be provided according to an embodiment of the present invention, and are respectively Figures 1a and 1d of International Patent Application Publication WO2015 / 117702 A1.

[0108] FIG. 1a is a schematic diagram of an aerosol generating device 10 and a separate cartridge 20, which together form an aerosol generating system.

[0109] The cartridge 20 contains an aerosol-forming substrate and is configured to be received in a cavity 18 in the device. The cartridge 20 should be replaceable by a user when the aerosol-forming substrate provided therein is depleted. Figure 1a shows the cartridge 20 immediately prior to insertion into the device, with arrow 1 in Figure 1a indicating the direction of insertion of the cartridge.

[0110] The cartridge 20 comprises a generally cylindrical housing 24 having a size and shape selected to be received within the cavity 18. The housing contains a capillary material (not shown) immersed in a liquid aerosol-forming substrate. In this example, the aerosol-forming substrate comprises 39 percent by weight glycerin, 39 percent by weight propylene glycol, 20 percent by weight water and flavorants, and 2 percent by weight nicotine. The capillary material is a material that actively transports liquid from one end to the other and may be made from any suitable material. In this example, the capillary material is formed from polyester.

[0111] The housing has an open end in which a heater assembly 30 is secured. The heater assembly 30 comprises a base having an opening formed therein, a pair of electrical contacts secured to the base and separated from one another by a gap, and a plurality of conductive heater filaments secured across the opening to the electrical contacts on opposite sides of the opening.

[0112] The heater assembly 30 is covered by a removable cover 26. The cover comprises a liquid impermeable plastic sheet that is adhered to the heater assembly but is easily removable. Tabs are provided on the sides of the cover to allow a user to grasp the cover when removing it. It will be apparent to one of ordinary skill in the art that although adhesion is described as a method of securing the impermeable plastic sheet to the heater assembly, other methods familiar to those skilled in the art may also be used, including heat sealing or ultrasonic welding, so long as the cover can be easily removed by the consumer.

[0113] The aerosol generating device 10 is portable and has a size comparable to a conventional cigar or cigarette. The device 10 comprises a body 11 and a mouthpiece portion 12. The body 11 comprises a battery 14 (such as a lithium iron phosphate battery), control electronics 16, and a recess 18. The mouthpiece portion 12 is connected to the body 11 by a hinged connection 21 and is movable between an open position shown in FIG. 1 and a closed position shown in FIG. 1b. The mouthpiece portion 12 is placed in the open position to allow insertion and removal of a cartridge 20, and in the closed position when the system is used for aerosol generation, as described below. The mouthpiece portion includes a number of air inlets 13 and air outlets 15. In use, a user draws or inhales the outlets to draw air from the air inlets 13, through the mouthpiece portion, to the outlets 15, and then into the user's mouth or lungs. An internal baffle 17 is provided to force air flow through the mouthpiece portion 12 and past the cartridge 20, as described below.

[0114] The cavity 18 has a circular cross-section and is sized to receive the housing 24 of the cartridge 20. An electrical connector 19 is provided on the side of the cavity 18 to provide electrical connection between the control electronics 16 and battery 14 and corresponding electrical contacts on the cartridge 20.

[0115] The cartridge 20 is inserted into the cavity 18 and the cover 26 is removed from the cartridge. In this position, the electrical connectors are placed against electrical contacts on the cartridge, as described below. The mouthpiece portion 12 is then moved to the closed position.

[0116] Figure 1b shows the system with the mouthpiece portion 12 in a closed position. The mouthpiece portion 12 is held in the closed position by a clasp mechanism (not shown).

[0117] The mouthpiece portion 12 in the closed position keeps the cartridge in electrical contact with the electrical connector 19 so that a good electrical connection is maintained in use regardless of the orientation of the system. The mouthpiece portion 12 may include an annular resilient element that engages a surface of the cartridge and is compressed between a rigid mouthpiece housing element and the cartridge when the mouthpiece portion 12 is in the closed position. This ensures that a good electrical connection is maintained regardless of manufacturing tolerances. Of course, other mechanisms for maintaining a good electrical connection between the cartridge and the device may be employed.

[0118] Figure 2 is a schematic diagram of an exemplary atomizer and conductivity sensor 100 of an aerosol generation system, such as the aerosol generation system of Figures 1a and 1b. The atomizer and conductivity sensor 200 constitute a two-point conductivity sensor.

[0119] 2 shows a plan view of a combined atomizer and conductivity sensor 100 in a cartridge received in an aerosol generating device and in electrical communication with the device's control electronics 110. The cartridge comprises a liquid reservoir comprising a generally cylindrical body of capillary material 102 in which a liquid aerosol-forming substrate is held. The atomizer and conductivity sensor 100 shown in FIG. 2 is disposed on and in contact with an end of the generally cylindrical body of capillary material 102. The capillary material 102 is configured such that the liquid aerosol-forming substrate held in the capillary material is drawn by capillary action to the end of the capillary body in contact with the atomizer and conductivity sensor 100.

[0120] The atomizer and conductivity sensor 100 comprises two electrodes, a first electrode 104 and a second electrode 106. Each of the first electrode 104 and the second electrode 106 comprises a resistive heating mesh comprising a plurality of electrically conductive heater filaments. The first electrode 104 is spaced from the second electrode 106 such that there is a recess 108 between the first electrode 104 and the second electrode 106. The recess 108 between the first electrode 104 and the second electrode 106 is sufficiently wide to electrically insulate the first electrode 104 from the second electrode 106 on the capillary material 102 when no liquid aerosol-forming substrate is present within the capillary material 102.

[0121] The first electrode 104 and the second electrode 106 are configured such that the liquid aerosol-forming substrate at the end of the capillary body is in contact with the first electrode 104 and the second electrode 106 .

[0122] In the embodiment shown in Figure 2, the first electrode 104 and the second electrode 106 are electrically connected to control electronics of an aerosol generating device (not shown), such as the aerosol generating device of Figures 1a and 1b. The control electronics of the aerosol generating device are configured to control the supply of power to the first electrode 104 and the second electrode 106 of the device.

[0123] In this embodiment, the control electronics of the aerosol generation device includes separate conductivity measurement circuit 111 and aerosol generation circuit 112. The conductivity measurement circuit 111 and the aerosol generation circuit 112 each include electrical contacts in the form of resilient pin contacts to provide a reliable electrical connection between the control electronics of the aerosol generation device and the first electrode 104 and second electrode 106 when the cartridge is received within the device.

[0124] Each of the first electrode 104 and the second electrode 106 is electrically connected by a single electrical contact to the conductivity measurement circuit 111. The conductivity measurement circuit therefore comprises two electrical contacts, one for each electrode 104, 106.

[0125] The conductivity measurement circuit 111 is configured to provide an alternating voltage between two electrical contacts of the conductivity measurement circuit, which in turn establishes an alternating voltage between the first electrode 104 and the second electrode 106. The alternating voltage between the first electrode 104 and the second electrode 106 drives an alternating current across the recess 108 between the first electrode 104 and the second electrode 106 through the liquid aerosol-forming substrate disposed within the recess 108. The conductivity measurement circuit 111 is further configured to measure the current between the first electrode 104 and the second electrode 106 and determine the electrical conductivity of the liquid aerosol-forming substrate disposed within the recess 108 based on the measured current. The electrical conductivity of the liquid aerosol-forming substrate provides an indication of the nicotine concentration of the liquid aerosol-forming substrate.

[0126] Each of the first electrode 104 and the second electrode 106 is also separately electrically connected to the aerosol generation circuit 112 by two electrical contacts. Each of the first electrode 104 and the second electrode 106 is electrically connected to a first electrical contact at a first end of the electrode and to a second electrical contact at a second end of the electrode opposite the first end. The aerosol generation circuit 112 is configured to provide a voltage between the first electrical contact and the second electrical contact for each of the first electrode 104 and the second electrode 106. The voltage across the first electrode 104 drives a current through the first electrode 104 between the first electrical contact and the second electrical contact. The voltage across the second electrode 204 between the first electrical contact and the second electrical contact drives a current through the second electrode 204, which drives a current through the second electrode 106 between the first electrical contact and the second electrical contact. The current through each electrode is suitable for heating the electrode. The aerosol generation circuit 112 is configured to supply a direct current in pulses between two electrical contacts of each electrode 104, 106. The aerosol generation circuit 112 is configured to vary the positive duty cycle of the direct current to vary the temperature of the electrodes 104, 106.

[0127] The conductivity measurement circuit 111 is configured to supply a first power to the first electrode 104 and the second electrode 106, and the aerosol generation circuit 112 is configured to supply a second power to the first electrode 104 and the second electrode 106. Preferably, the first power is not sufficient to heat the heater filaments of the electrodes 104, 106 and vaporize the liquid aerosol-forming substrate in contact with the heater filaments. The second power is sufficient to heat the heater filaments of the first electrode 104 and the second electrode 106 and vaporize the liquid aerosol-forming substrate in contact with the heater filaments. The aerosol generation circuit 112 is configured to vary the second power based on the electrical conductivity of the liquid aerosol-forming substrate determined by the conductivity measurement circuit 111, which provides an indication of the nicotine concentration in the liquid aerosol-forming substrate.

[0128] In this embodiment, the conductivity measurement circuit 111 is configured to measure the electrical conductivity of the liquid aerosol-forming substrate disposed within the recess 108 before the aerosol generation circuit 112 supplies a first power to the first electrode 104 and the second electrode 106 and aerosol generation circuit 112 supplies a second power to the first electrode 104 and the second electrode 106 to heat the liquid aerosol-forming substrate. This enables the aerosol generation circuit 112 to adjust the second power in response to the determined nicotine concentration of the liquid aerosol-forming substrate prior to each aerosol generation cycle, such as each time a user draws on the aerosol generation system to receive aerosol from the system.

[0129] 3 is a schematic diagram of another exemplary atomizer and conductivity sensor 200 for an aerosol generation system. The atomizer and conductivity sensor 200 is configured as a two-point conductivity sensor.

[0130] In this embodiment, a cartridge (not shown) comprises a liquid transfer element 202 in the form of a wick having at least one end in contact with the liquid aerosol-forming substrate in the liquid storage portion of the cartridge. The combined atomizer and conductivity sensor 200 of this embodiment comprises two electrodes 204, 206 in the form of coils disposed on a portion of the liquid transfer material 202 outside the liquid storage portion. The liquid transfer material 202 is disposed to draw the liquid aerosol-forming substrate from the liquid storage portion to the first coil electrode 204 and the second coil electrode 206 of the combined atomizer and conductivity sensor 200. Each coil electrode 204, 206 comprises a resistive heating wire wound concentrically around a portion of the wick outside the liquid storage portion. The two coil electrodes 204, 206 are substantially identical, wound together around the wick in the same direction, and include the same number of turns. The second coil 206 is offset from the first coil 204 along the core such that a recess 208 is provided between corresponding turns of the first and second coils 204, 206. The recess between corresponding turns of the first and second coils 204, 206 is such that liquid aerosol-forming substrate within the core can be drawn into the recess 208 and disposed between the coil electrodes 204, 206.

[0131] The first coil electrode 204 and the second coil electrode 206 are configured such that a liquid aerosol-forming substrate in a recess 208 between the first coil electrode 204 and the second coil electrode 206 is in contact with the first coil electrode 204 and the second coil electrode 206.

[0132] In the embodiment shown in Figure 3, the first coil electrode 204 and the second coil electrode 206 are electrically connected to control electronics of an aerosol generating device (not shown), such as the aerosol generating device of Figures 1a and 1b. The control electronics of the aerosol generating device are configured to control the supply of power to the first electrode 204 and the second electrode 206 of the device.

[0133] In this embodiment, the control electronics of the aerosol generation device comprises a shared conductivity measurement circuit 211 and an aerosol generation circuit 212. The conductivity measurement circuit 211 and the aerosol generation circuit 212 comprise shared electrical contacts.

[0134] Each of the first coil electrode 204 and the second coil electrode 206 is electrically connected to the aerosol generation circuit 212 by two electrical contacts, one electrical contact at each end of the coil electrode. The aerosol generation circuit 212 is configured to provide a voltage between the contacts at the opposing ends of each coil such that a voltage is established across each of the first electrode 204 and the second electrode 206. The voltage across the first electrode 204 drives a current through the first electrode 204 to heat the electrode. The voltage across the second electrode 206 drives a current through the second electrode 206 to heat the electrode. The aerosol generation circuit 212 is configured to provide a direct current in pulses through each of the first electrode 204 and the second electrode 206. The aerosol generation circuit 212 is configured to vary the positive duty cycle of the direct current to vary the temperature of the first and second electrodes 204, 206.

[0135] In this embodiment, the conductivity measurement circuit 211 shares electrical contacts with the aerosol generation circuit 212. Each of the first coil electrode 204 and the second coil electrode 206 is electrically connected to the conductivity measurement circuit 211 by one electrical contact. The conductivity measurement circuit 211 is electrically connected to the first coil electrode 204 by an electrical contact at a first end of the first coil electrode 204 and is electrically connected to the second coil electrode 206 by an electrical contact at a second end of the second coil electrode 206, which is the end of the second coil electrode 206 furthest from the first end of the first coil electrode 204. Thus, the conductivity measurement circuit 211 comprises two electrical contacts, one for each coil electrode 204, 206.

[0136] The conductivity measurement circuit 211 is configured to provide an alternating voltage between two electrical contacts of the conductivity measurement circuit 211, which in turn establishes an alternating voltage between the first coil electrode 204 and the second coil electrode 206. The alternating voltage between the first coil electrode 204 and the second coil electrode 206 drives an alternating current across the recess 208 between the first electrode 204 and the second electrode 206 through the liquid aerosol-forming substrate disposed within the recess 208. The conductivity measurement circuit 211 is further configured to measure the current between the first coil electrode 204 and the second coil electrode 206 and determine the electrical conductivity of the liquid aerosol-forming substrate disposed within the recess 208 based on the measured current. The electrical conductivity of the liquid aerosol-forming substrate provides an indication of the nicotine concentration of the liquid aerosol-forming substrate.

[0137] The conductivity measurement circuit 211 is configured to supply a first power to the first coil electrode 204 and the second coil electrode 206, and the aerosol generation circuit 212 is configured to supply a second power to the first electrode 204 and the second electrode 206. Preferably, the first power is not sufficient to heat the coil electrodes 204, 206 and vaporize the liquid aerosol-forming substrate in contact with the coil electrodes. The second power is sufficient to heat the first coil electrode 204 and the second coil electrode 206 and vaporize the liquid aerosol-forming substrate in contact with the coil electrodes. The aerosol generation circuit 212 is configured to vary the second power based on the electrical conductivity of the liquid aerosol-forming substrate determined by the conductivity measurement circuit 211, which provides an indication of the nicotine concentration in the liquid aerosol-forming substrate.

[0138] Of course, in other embodiments, the first coil electrode 204 and the second coil electrode 206 may be separately electrically connected to the conductivity measurement circuit and the aerosol generation circuit of the aerosol generating device, similar to the first electrode 104 and the second electrode 106 of the atomizer and conductivity sensor described above in connection with FIG. 2.

[0139] 4 and 5 are schematic diagrams of another exemplary atomizer and conductivity sensor 300 for an aerosol generation system, such as the aerosol generation system of Figures 1a and 1b. The atomizer and conductivity sensor 300 is configured as a four-point conductivity sensor.

[0140] FIG. 4 shows a plan view of the combined atomizer and conductivity sensor 300 of the cartridge, and FIG. 5 shows a plan view of the cartridge received within an aerosol generating device and in electrical connection with the device's control electronics 310.

[0141] The cartridge comprises a liquid storage portion comprising a generally cylindrical body of capillary material 302 in which a liquid aerosol-forming substrate is held. The atomizer and conductivity sensor 300 shown in Figures 4 and 5 is disposed on and in contact with an end of the generally cylindrical body of capillary material 302. The capillary material 302 is configured such that the liquid aerosol-forming substrate held in the capillary material is drawn by capillary action to the end of the capillary body in contact with the atomizer and conductivity sensor 300.

[0142] The atomizer and conductivity sensor 300 comprises four electrodes: a pair of outer electrodes 304 and a pair of inner electrodes 306. Each of the electrodes 304, 306 comprises a resistive heating mesh, which comprises a plurality of electrically conductive heater filaments.

[0143] The pair of outer electrodes 304 are spaced apart such that there is an outer recess 308 between the outer electrodes 304. The outer recess 308 between the outer electrodes 304 is wide enough to electrically insulate the outer electrodes 304 from one another on the capillary material 302 when no liquid aerosol-forming substrate is present in the capillary material 302.

[0144] The pair of inner electrodes 306 are disposed between the pair of outer electrodes 304 in an outer recess 308. The pair of inner electrodes 306 are spaced sufficiently apart from the pair of outer electrodes 304 to electrically insulate the inner electrodes 306 from the outer electrodes 304 on the capillary material 302 when no liquid aerosol-forming substrate is present in the capillary material 302. The pair of inner electrodes 306 are spaced apart such that there is an inner recess 309 between the inner electrodes 306. The inner recess 309 between the inner electrodes 306 is wide enough to electrically insulate the inner electrodes 306 from each other on the capillary material 302 when no liquid aerosol-forming substrate is present in the capillary material 302.

[0145] The liquid aerosol-forming substrate at the end of the capillary body that contacts the atomizer and conductivity sensor 300 contacts the inner electrode 204 and the outer electrode 206 .

[0146] The provision of four electrodes in such an arrangement allows the combined atomizer and conductivity sensor 300 of this embodiment to be used as a four-point conductivity sensor, as described in more detail below.

[0147] In Figure 5, the inner electrode 304 and the outer electrode 306 are shown in electrical communication with control electronics 310 of an aerosol generating device (not shown), such as the aerosol generating device of Figures 1a and 1b. The aerosol generating device control electronics 310 is configured to control the supply of power from the device's power supply to the outer electrode 304 and the inner electrode 306.

[0148] In this embodiment, the control electronics 310 of the aerosol generation device comprises a shared conductivity measurement circuit and an aerosol generation circuit, as described in more detail below with reference to Figure 6. In this embodiment, the conductivity measurement circuit and the aerosol generation circuit comprise shared electrical contacts in the form of resilient pin contacts to provide a reliable electrical connection between the control electronics 310 of the aerosol generation device and the inner and outer electrodes 304, 306. Of course, in other embodiments the aerosol generation circuit and the conductivity measurement circuit may comprise separate electrical contacts.

[0149] In this embodiment, each of the inner electrode 304 and the outer electrode 306 is electrically connected to the control circuit 310 by two electrical contacts. Each of the inner electrode 304 and the outer electrode 306 is electrically connected to a first electrical contact at a first end of the electrode and to a second electrical contact at a second end of the electrode opposite the first end.

[0150] 6a-d show schematic diagrams of some components of an exemplary embodiment of the control electronics 310 of an aerosol generating device associated with the combined atomizer and conductivity sensor of FIGS.

[0151] The control electronics are configured to operate in two different modes: a conductivity measurement mode and a heating mode. In the conductivity measurement mode, an AC voltage is applied between the two outer electrodes 304 and the voltage is measured across the two inner electrodes 306. In the heating mode, a pulsed DC current is applied across each of the inner and outer electrodes 304 and 306, respectively, to heat the heater filaments of the electrodes and vaporize the liquid aerosol-forming substrate in contact with the heater filaments.

[0152] In this embodiment, the control electronics 310 generally comprises a DC power supply V DC , a microcontroller 320, and a number of transistor switches, which are field effect transistors (FETs) and are controlled by the control electronics to power the combined atomizer and conductivity sensor according to a conductivity measurement mode and a heating mode.

[0153] In Figures 6a-d, a first one of the outer electrodes is designated as E1, a second one of the outer electrodes is designated as E4, a first one of the inner electrodes is designated as E2, and a second one of the inner electrodes is designated as E3. As shown in Figure 6a, each electrode E1-E4 is connected to control electronics by two spaced apart electrical contacts at opposite ends of the electrode. Each electrode E1-E4 is connected to a first transistor switch T 1a ~T 4a Each electrode is connected by a first electrical contact to a DC power source via a second transistor switch T 1b ~T 4b and the third transistor switch T 1c ~T 4c A first transistor switch T 1a ~T 4a The second and third transistor switches T allow the control electronics to individually isolate each of the electrodes from the power supply when the transistor is off. 1b ~T 4b , T 1c ~T 4c The functionality is explained in more detail below.

[0154] In the conductivity measurement mode, the control electronics detects the outer electrode, T 1a , T 1b , T 4a , T 4b A high frequency AC switching voltage is applied to the gates of the first and second transistors of the transistor T 1a and T 4b is conducting, and transistor T 1b and T 4a turns off, and during the other half cycle, transistor T 1b and T 4a is conducting, and transistor T 1a and T 4b will be turned off.

[0155] FIG. 4b shows the transistor T 1a and T4b 4b shows the connection of the combined atomizer and conductivity sensor to a power supply in a conductivity measurement mode during the first half of the period, when the electrode is conductive. The arrangement shown in Fig. 4b can be considered to comprise a first drive circuit operative to provide a first periodic voltage drop across the outer electrodes E1, E4 with a selected frequency F and having an amplitude ranging from a first value to a second value lower than the first value.

[0156] Figure 4c shows the transistor T 4a and T 1c 4c shows the connection of the combined atomizer and conductivity sensor to a power supply in a conductivity measurement mode during the latter period when is conductive. The arrangement shown in Fig. 4c can be considered to provide a second periodic voltage drop across the outer electrodes E1, E4 at the same frequency and amplitude as the first periodic voltage drop, but of opposite polarity and at a frequency that is oppositely out of phase with the first periodic voltage drop.

[0157] The first and second voltage drops are of opposite polarity to each other, opposite polarity in this context referring to the relative positions of the high and low voltage sides, rather than requiring positive and negative voltages. The first and second periodic voltage drops are applied from opposite sides of the outer electrode. Because the first and second periodic voltage drops are of opposite polarity and directly out of phase, an AC voltage is effectively provided across the outer electrode. The first and second periodic voltage drops may have any suitable waveform. For example, the two waveforms may be square waves that are directly out of phase with each other. Advantageously, the control electronics may be configured to provide a dead period of at least a few nanoseconds between the end of one voltage drop and the beginning of the next voltage drop of the opposite direction state to avoid overheating failure of the switch.

[0158] In the first half period, the second transistor T 4bis conductive and provides a path to electrical ground through a resistor having a known resistance R2. The microprocessor 220 is configured to measure a voltage V3 across the resistor R2 and can determine the current flowing between the first outer electrode E1 and the second outer electrode E4 from the measured voltage V3 and the known resistance R2.

[0159] In the latter period, the second transistor T 1b is conductive and provides a path to electrical ground through a resistor having a known resistance R1. The control electronics is configured to measure a voltage V1 across resistor R1 and can determine the current flowing between the second outer electrode E4 and the first outer electrode E1 from the measured voltage V1 and the known resistance R1.

[0160] During the conductivity measurement mode, the control electronics switches the second transistor T 1b , T 2b The two inner electrodes E2, E3 of the second transistor T are conductive. 1b , T 2b In the conductivity measurement mode, the control electronics does not supply a voltage to the third transistors of either the inner or outer electrodes, so that all of the third transistors remain off.

[0161] The second transistor T 2b , T 3b Each of provides a path to an input of a differential pressure amplifier 322, the output of which is fed to the microprocessor 320 to provide the microprocessor 320 with a measurement of the voltage V2 across the inner electrodes E2, E1.

[0162] The microprocessor 320 can be configured in many different ways to use the measured voltages V1, V2, and V3 to determine an indication of the concentration of nicotine in the liquid aerosol-forming substrate between the electrodes of the combined atomizer and conductivity sensor. In this embodiment, the microprocessor 320 is configured to use the measured voltages V1, V3 to determine the current between the outer electrodes E1, E4, and to use the current determined across the inner electrodes E2, E3 and the measured voltage V2 to determine the electrical conductivity of the liquid aerosol-forming substrate and to determine an indication of the concentration of nicotine in the liquid aerosol-forming substrate.

[0163] In the heating mode, the control electronics switches all the first transistors T of the electrodes E1, E2, E3, E4 on and off so that all of the first transistors are periodically alternately switched between conductive and off. 1a , T 2a , T 3a , T 4a The control electronics also supplies a high frequency AC switching voltage to the gates of each of the third transistors T of the electrodes E1, E2, E3, E4 so that the third transistors are conductive. 1c , T 2c , T 3c , T 4c A voltage is applied to the gate of each of the third electrodes T 1c , T 2c , T 3c , T 4c provides a path to electrical ground.

[0164] FIG. 4d shows the transistor T 1a , T 2a , T 3a , T 4a , T 1c , T 2c , T 3c , and T 4c 4d shows the connection of the combined atomizer and conductivity sensor 300 in heating mode, where the electrodes are conductive, to a power supply. The arrangement shown in Fig. 4d can be considered to include a third drive circuit, which operates to provide a current across each of the electrodes.

[0165] By periodically switching the first transistor between conductive and off and maintaining the third transistor conductive, the control electronics provides a pulsed direct current across each of the electrodes. The control electronics is configured to control the duty cycle of the pulses to control the temperature to which the electrodes are heated. Preferably, the control electronics is configured to control the duty cycle in the heating mode based on an indication of the nicotine concentration determined in the conductivity measurement mode.

[0166] Of course, in other embodiments, the control electronics of the aerosol generating device may not be arranged to directly supply power to the inner electrode to heat it, but rather the control electronics may be arranged to heat the inner electrode by induction. In these embodiments, an oscillating voltage is applied to the outer electrode to induce a current in the inner electrode. In order to heat the inner electrode to a sufficient temperature, it is preferred that the inner electrode is a susceptor element formed from a magnetic material, such as AISI 4xx stainless steel. The outer electrode may be formed from a magnetic material, although in these embodiments this is not a requirement.

[0167] 7 and 8 show schematic diagrams of another exemplary conductivity sensor 400. In this embodiment, the conductivity sensor 400 is not combined with an atomizer. In this embodiment, the conductivity sensor is configured as a four-point conductivity sensor disposed in a liquid reservoir of a cartridge of an aerosol generating device.

[0168] The cartridge includes a housing 401 that defines a substantially cubic liquid reservoir. The housing is formed from a rigid, electrically insulating material such as PEEK. The conductivity sensor 400 includes four electrodes: two outer electrodes 404 and two inner electrodes 406. A first one of the outer electrodes 404 and a first one of the inner electrodes 406 are disposed on a first inner surface of the cartridge housing 401, and a second one of the outer electrodes 404 and a second one of the inner electrodes 406 are disposed on a second inner surface of the cartridge housing 401 opposite the first surface, such that the first outer and inner electrodes face the second outer and inner electrodes across the liquid reservoir.

[0169] The outer electrode 404 comprises an identical ring electrode and defines an outer electrode recess 407. The inner electrode 406 comprises an identical circular electrode. As shown in FIG. 8, on the first inner surface of the cartridge housing 401, the first outer electrode 404 and the first inner electrode 406 are concentrically arranged, with the first inner electrode 406 disposed in the outer electrode recess 405 of the first outer electrode 404. Similarly, on the second inner surface of the cartridge housing 401, the first outer electrode 404 and the first inner electrode 406 are concentrically arranged, with the second inner electrode 406 disposed in the outer electrode recess 405 of the second outer electrode 404. The outer diameter of the inner electrode 406 is smaller than the inner diameter of the outer electrode 404 such that a recess is provided between the inner electrode 404 and the outer electrode 406. The recess between the inner electrode 404 and the outer electrode 406 electrically insulates the inner electrode 406 from the outer electrode 404 in the absence of a liquid aerosol-forming substrate disposed within the recess.

[0170] 7, the first inner and outer electrodes on a first inner side of the cartridge housing 401 are aligned with the second inner and outer electrodes on a second inner side of the cartridge housing 401. Thus, the first and second outer electrodes 404 are substantially separated by the width of the liquid reservoir portion, forming a recess 408, and the first and second inner electrodes 406 are substantially separated by a recess 408 also formed by the width of the liquid reservoir portion.

[0171] When the liquid aerosol-forming substrate is disposed in the liquid storage portion, the liquid aerosol-forming substrate is disposed in the recess 408 and can contact the first and second electrodes 404, 406. In this embodiment, the liquid aerosol-forming substrate can move freely in the liquid storage portion. However, in other embodiments, a carrier material for holding the liquid aerosol-forming substrate may be provided in the liquid storage portion. Such an antibody material is typically a porous, electrically insulating material that is disposed in the recess 408 in contact with the inner electrode 404 and the outer electrode 406.

[0172] 7, each of the outer electrodes 404 is electrically connected to the aerosol generation device's control electronics 410. Similarly, each of the inner electrodes 406 is electrically connected to the aerosol generation device's control electronics 410. Each electrode 404, 406 is electrically connected to the control electronics 410 by one electrical contact.

[0173] The control electronics 410 are configured to supply an alternating voltage to the outer electrode 404, which can drive an alternating current through a liquid aerosol-forming substrate disposed in the recess 408 between the first and second outer electrodes 404. The control electronics are configured to measure the current between the first and second outer electrodes 404.

[0174] An alternating current between the first and second outer electrodes 404 driven by the control electronics 410 establishes an alternating voltage between the first and second inner electrodes 406. The control electronics 410 is configured to measure the voltage across the first and second inner electrodes. The control electronics is further configured to use the current and voltage measurements to determine the electrical conductivity of a liquid aerosol-forming substrate disposed within the recess 408. The control electronics 410 may further determine the concentration of nicotine in the liquid aerosol-forming substrate based on the determined electrical conductivity.

[0175] Of course, in other embodiments, the four-point conductivity sensor 400 may be replaced with a two-point conductivity sensor having a first electrode on a first side of the liquid storage portion and a second electrode on a second side of the liquid storage portion.

[0176] Of course, in this embodiment, the conductivity sensor 400 is disposed within the liquid storage portion of the cartridge, but in other embodiments, the conductivity sensor 400 may be disposed within the liquid storage portion of the aerosol generating device or within a conduit between the liquid storage portion and the atomizer.

[0177] 9 and 10 show schematic diagrams of another exemplary conductivity sensor 500. In this embodiment, the conductivity sensor 500 is not combined with an atomizer. In this embodiment, the conductivity sensor 500 is an inductive conductivity sensor disposed in a liquid reservoir of a cartridge of an aerosol generating device.

[0178] The conductivity sensor 500 comprises two electrodes 504, 506 in the form of toroidal coils. A first one of the coil electrodes is a drive coil 504 wound around a first ring 505 of ferromagnetic material. A second one of the coil electrodes is a receiver coil 506 wound around a second ring 507 of ferromagnetic material. The receiver coil 506 and ring 507 are substantially identical to the drive coil 504 and ring 505, in particular having the same number of turns and wound in the same direction.

[0179] Each of the drive coil 504 and the receiver coil 506 has an inner cavity through which the aerosol-forming substrate may flow. The receiver coil 506 is aligned with the drive coil 504 on the axis and spaced apart from the drive coil 504 along the axis such that the receiver coil inner cavity and the drive coil inner cavity are aligned to substantially form a continuous cylindrical inner cavity through which the liquid aerosol-forming substrate may flow. The drive coil 504 is arranged and configured to induce a current in the receiver coil 506 when an alternating voltage is supplied to the drive coil 504.

[0180] Each end of the drive coil 504 and the receiver coil 506 are electrically connected to the control electronics 510 of the aerosol generating device.

[0181] The driving coil 504 and ferromagnetic ring 505 and the receiving coil 506 and ferromagnetic ring 507 are embedded in an annular cylindrical body 512 of an electrically insulating material, such as a plastic material, that is substantially impermeable to the liquid aerosol-forming substrate. The body 512 thus has the form of a cylindrical tube having an inner recess 514 extending through the body 512 and open at both ends. The body 512 is provided to protect the coil electrodes from the liquid aerosol-forming substrate. The body 512 is configured to be disposed in a liquid storage portion of the cartridge such that the liquid aerosol-forming substrate in the liquid storage portion can flow through the inner passage 514 and around the outer surface of the body 501.

[0182] In use, the control electronics 510 is configured to supply power to the drive coil 504 in the form of an alternating voltage. The alternating voltage in the drive coil 504 generates a magnetic field that induces a current in the liquid aerosol-forming substrate disposed in the inner recess 514. The current in the inner recess 514 is indicated by arrows 516 in FIG. 7. The induced current 516 in the liquid aerosol-forming substrate also generates a magnetic field that induces a current in the receiver coil 506. The electrical conductivity of the liquid aerosol-forming substrate affects the magnitude of the current 516 induced in the liquid aerosol-forming substrate, which in turn affects the magnitude of the current induced in the receiver coil 506. The control electronics 510 is configured to measure one or both of the voltage and current induced in the receiver coil, and is further configured to determine the electrical conductivity of the liquid aerosol-forming substrate based on one or more of the measured induced current and voltage in the receiver coil. The control electronics may further determine the concentration of nicotine in the liquid aerosol-forming substrate based on the determined electrical conductivity.

Claims

1. 1. An aerosol generation system comprising: a liquid reservoir for holding a liquid aerosol-forming substrate; an atomizer in fluid communication with the liquid reservoir; a conductivity sensor arranged to sense an electrical conductivity of the liquid aerosol-forming substrate from the liquid reservoir, the conductivity sensor comprising at least two electrodes; Power supply, A control electronic circuit comprising: controlling a supply of power from the power source to the atomizer to atomize a liquid aerosol-forming substrate from the liquid reservoir; controlling a supply of power from the power source to the electrodes of the conductivity sensor, the supply of power being provided to the conductivity sensor as an AC voltage; receiving one or more measurements indicative of the conductivity of the liquid aerosol-forming substrate from the conductivity sensor; and determining a nicotine concentration of the liquid aerosol-forming substrate based on one or more of the measurements from the conductivity sensor.

2. 2. The aerosol generating system of claim 1, wherein the control electronic circuit is further configured to control the supply of power from the power source to the atomizer to atomize the liquid aerosol-forming substrate based on the determined nicotine concentration of the liquid aerosol-forming substrate.

3. 3. The aerosol generating system of claim 2, wherein the control electronic circuit is configured to control the supply of power from the power source to the atomizer to atomize the liquid aerosol-forming substrate based on the determined nicotine concentration of the liquid aerosol-forming substrate by comparing the determined nicotine concentration with a predetermined threshold, supplying a first power to the atomizer when the determined nicotine concentration is equal to or less than the predetermined threshold, and supplying a second power lower than the first power to the atomizer when the determined nicotine concentration exceeds the predetermined threshold.

4. The aerosol generation system according to any one of claims 1 to 3, further comprising a heater arranged to heat the aerosol-forming substrate from the liquid storage portion, and the control electronic circuitry configured to supply power from the power source to the heater to heat the liquid aerosol-forming substrate from the liquid storage portion to a predetermined temperature.

5. the system further comprising a temperature sensor arranged to sense a temperature of the liquid aerosol-forming substrate from the liquid reservoir; said control electronics receiving from the temperature sensor one or more measurements of the temperature of the liquid aerosol-forming substrate at the conductivity sensor; 5. The aerosol generating system of claim 1, further configured to: adjust the determination of the nicotine concentration based on one or more of the temperature measurements.

6. 6. The aerosol generating system according to claim 1, wherein each electrode of the conductivity sensor is arranged to contact a liquid aerosol-forming substrate from the liquid storage portion.

7. 7. The aerosol generating system of claim 6, wherein the conductivity sensor comprises two electrodes spaced apart to form a recess into which liquid aerosol-forming substrate from the liquid storage portion is placed.

8. 8. The aerosol generation system of claim 7, wherein the atomizer is a thermal atomizer comprising a plurality of heating elements, and each of the electrodes of the conductivity sensor is formed from a heating element of the atomizer.

9. said control electronics providing a first power to the electrodes of the conductivity sensor to measure the conductivity of the liquid aerosol-forming substrate; 9. The aerosol generating system of claim 8, further configured to: supply a second power to the plurality of heating elements of the atomizer to atomize the liquid aerosol-forming substrate, the second power being greater than the first power.

10. the conductivity sensor comprises two inner electrodes and two outer electrodes; the two outer electrodes are spaced apart to form an outer recess into which a liquid aerosol-forming substrate from the liquid reservoir is disposed; the two inner electrodes are disposed within the outer cavity between the two outer electrodes and spaced apart to form an inner cavity into which a liquid aerosol-forming substrate from the liquid reservoir is disposed; said control electronics supplying the power from the power source to the outer electrode, the supply of power being provided to the outer electrode as an AC voltage; 7. The aerosol generating system of claim 6, further configured to receive from the inner electrode the one or more measurements indicative of the electrical conductivity of the liquid aerosol-forming substrate.

11. 11. The aerosol generation system of claim 10, wherein the atomizer is a thermal atomizer comprising a plurality of heating elements, and each of the electrodes of the conductivity sensor is formed from a heating element of the atomizer.

12. said control electronics providing a first power to the outer electrode of the conductivity sensor to measure the conductivity of the liquid aerosol-forming substrate; 12. The aerosol generating system of claim 11, further configured to: supply a second power to the plurality of heating elements of the atomizer to atomize the liquid aerosol-forming substrate, the second power being greater than the first power.

13. The aerosol generating system of any one of claims 1 to 5, wherein the conductivity sensor comprises two electrodes, a first electrode and a second electrode, each electrode forming a coil, the control electronic circuit is configured to supply the alternating voltage to the first electrode, the control electronic circuit is configured to receive the one or more measurements indicative of the conductivity of the liquid aerosol-forming substrate from the second electrode, and the first electrode is arranged to induce a current in the second electrode when the alternating voltage is supplied to the first electrode.

14. The aerosol generating system of claim 13 , wherein the first electrode and the second electrode are disposed within the liquid storage portion.

15. 1. A cartridge for an aerosol generation system, the cartridge comprising: a liquid reservoir for holding a liquid aerosol-forming substrate; an atomizer in fluid communication with the liquid reservoir; a conductivity sensor arranged to sense the electrical conductivity of a liquid aerosol-forming substrate from the liquid storage portion, the conductivity sensor comprising two electrodes, a first electrode and a second electrode arranged within the liquid storage portion, each electrode forming a coil, the first electrode being arranged to induce a current in the second electrode when an alternating voltage is supplied to the first electrode.

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