Patent Publication Number: US-2022232902-A1

Title: System and method for testing a heating system

Description:
This invention relates generally to a system and method. More specifically, although not exclusively, this invention relates to a system for determining a state of a heating system for use in an aerosol generating article or an aerosol generating device and a method of determining a state of a heating systems for use in an aerosol generating article or an aerosol generating device. 
     A number of devices for generating an aerosol have been proposed in the art. For example, devices for generating aerosols which heat rather than combust an aerosol-generating substrate have been proposed. Heated smoking devices in which tobacco is heated rather than combusted, are one type of such device. An aim of such smoking devices is to reduce the generation of unwanted and harmful smoke constituents as produced by the combustion and pyrolytic degradation of tobacco in conventional cigarettes. These heated smoking devices are commonly known as ‘heat not burn’ devices. 
     Known aerosol generating devices of the ‘heat not burn’ variety typically include a device portion comprising a battery and control electronics, a cartridge portion comprising a supply of liquid aerosol-generating substrate held in a liquid storage portion, and an electrically operated heater assembly acting as a vaporiser. The cartridge portion typically comprises not only the supply of liquid aerosol-generating substrate and the electrically operated heater assembly, but also a mouthpiece, through which a user may draw aerosol into their mouth. A cartridge portion comprising both a supply of aerosol-generating substrate held in the liquid storage portion and a vaporiser is sometimes referred to as a “cartomiser” or “atomiser”. 
     The vaporiser typically comprises “coil and wick” technology (and variants thereof) as its heating technology. That is, a coil of heater wire is wound around an elongate wick soaked in liquid aerosol-generating substrate. Capillary material soaked in the aerosol-generating substrate supplies the liquid to the wick. 
     However, an alternative type of vaporiser is a mesh-heater unit. Mesh-heater units generally include a plurality of wires or a mesh foil, which define a heating surface as well as a liquid permeable surface. A transport material is provided to transport liquid aerosol-generating substrate to the wires or mesh foil. The resistivity of the wires/mesh foil is chosen such that a required heat output is achieved for a given supplied power to the wires/mesh foil. 
     An example of a cartridge including mesh-heater units is illustrated in  FIG. 1 . Further description of this cartridge (above that given below) and other alternative cartridges of this type can be found in WO 2015/117702. 
     The cartridge  20  of  FIG. 1  comprises a generally cylindrical housing  24  that has a size and shape selected to be received into a cavity of a corresponding aerosol generating device. The housing contains a capillary material  22  that is soaked in a liquid aerosol-generating substrate. The housing has an open end to which a heater assembly  30  is fixed. The heater assembly  30  comprises a substrate  34  having an aperture  35  formed in it, a pair of electrical contacts  32  fixed to the substrate and separated from each other by a gap, and a plurality of electrically conductive heater filaments  36  spanning the aperture and fixed to the electrical contacts on opposite sides of the aperture  35 . The heater assembly  30  is covered by a removable cover  26 . The cover comprises a liquid impermeable plastic sheet that is glued to the heater assembly but which can be easily peeled off. A tab is provided on the side of the cover to allow a user to grasp the cover when peeling it off. 
     Another example of a cartridge  1000  including a mesh-heater unit is illustrated in  FIG. 2 . Cartridge  1000  comprises an external housing  1050  having a mouthpiece with a mouthpiece opening  1100 , and a connection end  1150  opposite the mouthpiece. Within the housing  1050  is a liquid storage compartment holding a liquid aerosol-forming substrate  1310 . The liquid storage compartment has a first portion  1300  and a second portion  1350  and liquid is contained in the liquid storage compartment by three further components, an upper storage compartment housing  1370 , a heater mount  1340  and an end cap  1380 . A heater assembly  1200  comprising a fluid permeable heating element  1220  (i.e. a mesh heater) and a transport material  1240  is held in the heater mount  1340 . A retention material  1360  is provided in the second portion  1350  of the liquid storage compartment and abuts the transport material  1240  of the heater assembly  1200 . The retention material  1360  is arranged to transport liquid to the transport material  1240  of the heater assembly  1200 . The first portion  1300  of the liquid storage compartment is larger than the second portion  1350  of the storage compartment and occupies a space between the heater assembly  1200  and the mouthpiece opening  1100  of the cartridge  1000 . Liquid in the first portion  1300  of the storage compartment can travel to the second portion  1350  of the liquid storage compartment through liquid channels  1330  on either side of the heater assembly  1200 . Two channels are provided in this example to provide a symmetric structure, although only one channel is necessary. The channels are enclosed liquid flow paths defined between the upper storage compartment housing  1370  and the heater mount  1340 . 
     As the heating system is integral to the function of the ‘heat not burn’ devices there is a need for appropriate quality control during manufacture and assembly. For example, the resistivity of the mesh heating systems must conform to specification. At present, due to the structural differences between the mesh heating systems and the “coil and wick” systems, there is no suitable system for testing the appropriate characteristics of mesh-based heating systems in a manner suitable for implementation in a larger-scale production line. 
     US 2018/0049478 A1 discloses systems, apparatuses, and methods for assembling cartridges for aerosol delivery devices.
         An aspect of the invention provides a system for determining a resistivity of a heating system for use in an aerosol generating article, the system comprising:
           a receptacle for receiving a plurality of elements, each element comprising a heating system to be tested; and   a testing assembly, the testing assembly comprising:
               a plurality of sensor units each sensor unit comprising at least a pair of electrical contacts configured to pass an electric current therethrough and being configured to obtain signals related to properties of the heating system of one of the plurality of elements; and   a processor configured to receive the signals obtained by the sensor units and determine a resistivity of the heating system of each of the plurality of elements.   
               
               

     In some embodiments the sensor units are held in the testing assembly by gravity. This enables a convenient way to hold the sensor unit but still allow displacement, for example a vertical displacement, should a wrongly fitted element for testing be brought into contact with the sensor unit. 
     In particular embodiments the sensor units are held in the testing assembly and are configured to enable vertical displacement. For example, vertical displacement within the testing assembly. 
     Another aspect of the invention provides a system for determining a state of a heating system for use in an aerosol generating article, the system comprising:
         a receptacle for receiving a plurality of elements, each element comprising a heating system to be tested; and   a testing assembly, the testing assembly comprising:
           sensor means configured to obtain signals related to properties of the heating system of each of the plurality of elements; and   a processor configured to receive the signals obtained by the sensor means and determine a state of the heating system of each of the plurality of elements.   
               

     Aptly, the signals related to properties of the heating system of each of the plurality of elements are obtained substantially simultaneously by the sensor means. This allows a testing process for heating systems as part of a production line to be optimised in terms of speed and efficiency. That is, by testing multiple heating systems substantially simultaneously, the testing process is sped up. 
     Aptly, the testing assembly is configured to obtain the signals when the testing assembly is in a testing configuration. More aptly, the testing assembly is moveable relative to the receptacle to bring the sensor means, for example the sensor units, into the testing configuration. Having separate testing and non-testing configurations, between which the testing assembly can move, allows the testing assembly to be kept separate from the receptacle when testing is not being performed. This provides opportunity for the receptacle to be populated or repopulated between testing operations and hence helps maintain an efficient testing/production line. This allows another batch of elements to be positioned for testing. This can be quickly repeated over and over to give a continuous flow of elements to be tested. 
     Aptly, the sensor means comprises a plurality of sensor units, each sensor unit being configured to obtain signals related to properties of the heating system of one of the plurality of elements. Providing the sensor means as a plurality of sensor units, ensures a compact and customisable method of testing multiple heating systems of each of the plurality of elements simultaneously, whilst monitoring the accuracy of testing each heating system of the individual element. 
     Aptly, the sensor units are removable from the testing assembly. By configuring the sensor units to be removable from the testing assembly, the assembly may be customised/adapted depending on the properties that require testing or the heating systems to be tested, or both. For example, sensor units configured to obtain signals related to a first property may be replaced with sensor units configured to obtain signals related to a second property. 
     Aptly, at least one of the plurality of sensor units comprises at least a pair of electrical contacts. More aptly, the pair of electrical contacts are a pair of electrical pins. More aptly, in the testing configuration the pair of electrical contacts are both in contact with a portion of the heating system of the corresponding element. Including electrical contacts within a sensor unit allows properties related to the resistivity of the heating system to be tested by obtaining signals related to the voltage or current. 
     Aptly, the sensor unit is biasedly held in the testing assembly. By biasing the sensor unit within the testing assembly, the sensor unit can be configured to quickly return to a non-testing configuration. This helps ensures a quick and efficient production line. Alternatively, in specific embodiments the sensor unit is biasedly held in the non-testing configuration. 
     Aptly, at least one of the plurality of sensor units comprises at least an optical sensor. Using an optical sensor allows properties related to the spatial location of the element or the physical condition of the heating system to be tested, for example by obtaining an image of the element/heating system. 
     Aptly, the at least one of the plurality of sensor units further comprises at least one lighting element, for illuminating the corresponding heating system to be tested. This is particularly useful when used in combination with an optical sensor. 
     Aptly, the signals obtained relate to at least one of current, voltage or light. 
     Aptly, the properties tested relate to at least one of resistivity of the heating system of the element, spatial location of the element or physical condition of the heating system of the element. 
     Aptly, the determined state, for example the resistivity, is at least one of integrity of the heating system, conformity of the heating system to a predetermination condition, or functionality of the heating system. 
     Aptly, the receptacle is a plate with a plurality of cavities, each cavity configured to receive an element. More aptly, the number of cavities is greater than the number of sensor units in the sensor means. 
     Aptly, the receptacle is rotatable around an axis. 
     Aptly, the processor determines the state, for example the resistivity, of the heating system by comparing the obtained signals to a given set of data. 
     Aptly, the heating system of each element comprises a mesh foil.
         Another aspect of the invention provides a method of determining a resistivity of a heating systems for use in an aerosol generating article, the method comprising:
           providing a system comprising:
               a receptacle for receiving a plurality of elements; and   a testing assembly, the testing assembly comprising:
                   a plurality of sensor units, each sensor unit comprising at least a pair of electrical contacts configured to pass an electric current therethrough and being configured to obtain signals related to properties of the heating system of one of the plurality of elements; and   a processor;   
                   
               populating the receptacle with a plurality of elements, each element comprising a heating system to be tested;   actuating the plurality of sensor units to obtain signals related to properties of the heating system of each of the plurality of elements; and   determining, with the processor, a resistivity of the heating system of each of the plurality of elements from the obtained signals.   
               

     Another aspect of the invention provides a method of determining a state of a heating systems for use in an aerosol generating article, the method comprising:
         providing a system comprising:
           a receptacle for receiving a plurality of elements; and   a testing assembly, the testing assembly comprising:
               sensor means; and   a processor;   
               
           populating the receptacle with a plurality of elements, each element comprising a heating system to be tested;   actuating the sensor means to obtain signals related to properties of the heating system of each of the plurality of elements; and   determining, with the processor, a state of the heating system of each of the plurality of elements from the obtained signals.       

     Aptly, the method further comprises the step of bringing the testing assembly into a testing configuration. 
     Aptly, the method further comprises the step of removing the plurality of elements from the receptacle and repopulating the receptacle with a further plurality of elements. 
     Aptly, the system of the second aspect of the invention is the system of the first aspect of the invention. 
     Certain embodiments of the invention provide the advantage that a system for determining a state, for example a resistivity, of a heating system for use in an aerosol generating article is provided that is capable of testing a plurality of elements, each including a heating system. 
     Certain embodiments of the invention provide the advantage that the system is capable of testing the heating systems in real-time, to reduce the impact on assembly lines producing and utilising the heating systems. 
     Certain embodiments of the invention provide the advantage that the system is capable of testing a plurality of elements, each including a heating system, simultaneously. 
     Certain embodiments of the invention provide the advantage that the system is suitable for use with mesh-heater systems. 
     As used herein, the term ‘aerosol generating article refers to an article comprising an aerosol-generating substrate that is capable of releasing volatile compounds that can form an aerosol, for example by heating, combustion or chemical reaction. 
     As used herein, the term ‘aerosol-generating substrate’ is used to describe a substrate capable of releasing volatile compounds, which can form an aerosol. The aerosols generated from the aerosol-generating substrates of aerosol generating articles may be visible or invisible and may include vapours (for example, fine particles of substances, which are in gaseous state, that are ordinarily liquid or solid at room temperature) as well as gases and liquid droplets of condensed vapours. 
     As used herein, the term ‘element’ refers to a component including a heating system to be tested (i.e. a state, for example a resistivity, of which is to be determined). In examples, the element is a component of an aerosol generating devices of the ‘heat not burn’ variety, the component incorporating the heating system of the aerosol generating device. 
     As used herein, the term ‘heating system’ refers to a system incorporated within an element capable of providing heat. In examples, the heating system is suitable for heating an aerosol-generating substrate within an aerosol generating device. In examples, the heating system includes a mesh foil for providing heat upon flow of a current therethrough. 
     As used herein, the term ‘receptacle’ refers to a component configured to receive a plurality of elements. In examples, the receptacle is a plate with a plurality of cavities for receiving the plurality of elements. 
     As used herein, the term ‘testing assembly’ refers to an assembly configured to perform a testing operation to a plurality of elements. For the testing operation, the testing assembly utilises sensor means, for example sensor units, to obtain signals and a processor to process the received signals. 
     As used herein, the term ‘sensor means’ refers to a means, including sensors, capable of obtaining signals related to properties of a heating system. The sensor means may include one or more sensors or sensor units or plurality of sensor units (for example an electrical or optical sensor), capable of obtaining signals related to one or more properties of a heating system. In described examples the sensor means includes a plurality of sensor units. As used herein, the term ‘sensor unit’ refers to a unit component (for example a unit that is removable from the testing assembly), including sensors, capable of obtaining signals related to properties of a heating system. 
     As used herein, the term ‘electrical contacts’ refers to electrical conductors configured to pass an electric current therethrough for the purpose of obtaining electrical signals, to measure, for example resistivity or capacitance. 
     As used herein, the term ‘optical sensor’ refers to a sensor configured to obtain light signals, for example optical images, light intensity data, temperature spectra etc. 
     For the avoidance of doubt, any of the features described herein apply equally to any aspect of the invention. Within the scope of this application it is expressly envisaged that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. Features described in connection with one aspect or embodiment of the invention are applicable to all aspects or embodiments, unless such features are incompatible. 
     EXAMPLES 
     
         
         
           
             Ex1. A system for determining a state of a heating system for use in an aerosol generating article, the system comprising:
           a receptacle for receiving a plurality of elements, each element comprising a heating system to be tested; and   a testing assembly, the testing assembly comprising:
               sensor means configured to obtain signals related to properties of the heating system of each of the plurality of elements; and   a processor configured to receive the signals obtained by the sensor means and determine a state of the heating system of each of the plurality of elements.   
               
         
           
         
       
    
     Ex2. A system according to example Ex1, wherein the signals related to properties of the heating system of each of the plurality of elements are obtained substantially simultaneously by the sensor means. 
     Ex3. A system according to any example Ex1 or Ex2, wherein the testing assembly is configured to obtain the signals when the testing assembly is in a testing configuration. 
     Ex4. A system according to example Ex3, wherein the sensor means comprises a plurality of sensor units, each sensor unit being configured to obtain signals related to properties of the heating system of one of the plurality of elements. 
     Ex5. A system according to example Ex4, wherein at least one of the plurality of sensor units comprises at least a pair of electrical contacts, wherein in the testing configuration the pair of electrical contacts are both in contact with a portion of the heating system of the corresponding element. 
     Ex6. A system according to example Ex5, wherein the sensor unit is biasedly held in the testing assembly. 
     Ex7. A system according to any of examples Ex4 to Ex6, wherein at least one of the plurality of sensor units comprises at least an optical sensor. 
     Ex8. A system according to any of examples of Ex1 to Ex7, wherein the signals obtained relate to at least one of current, voltage or light. 
     Ex9. A system according to any of example Ex1 to Ex8, wherein the properties tested relate to at least one of resistivity of the heating system of the element, spatial location of the element or physical condition of the heating system of the element. 
     Ex10. A system according to any of examples Ex1 to Ex9, wherein the determined state is at least one of integrity of the heating system, conformity of the heating system to a predetermination condition, or functionality of the heating system. 
     Ex11. A system according to any of examples Ex1 to Ex10, wherein the receptacle is a plate with a plurality of cavities, each cavity configured to receive an element. 
     Ex12. A system according to any of examples Ex1 to Ex11, wherein the heating system of each element comprises a mesh foil.
         Ex13. A method of determining a state of a heating systems for use in an aerosol generating article, the method comprising:
           providing a system comprising:
               a receptacle for receiving a plurality of elements; and   a testing assembly, the testing assembly comprising:
                   sensor means; and   a processor;   
                   
               populating the receptacle with a plurality of elements, each element comprising a heating system to be tested;   actuating the sensor means to obtain signals related to properties of the heating system of each of the plurality of elements; and   determining, with the processor, a state of the heating system of each of the plurality of elements from the obtained signals.   
               

     Ex14. A method according to example Ex13, wherein the method further comprises the step of bringing the testing assembly into a testing configuration. 
     Ex15. A method according to example Ex13 or Ex14, wherein the method further comprises the step of removing the plurality of elements from the receptacle and repopulating the receptacle with a further plurality of elements. 
    
    
     
       Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which: 
         FIG. 1  illustrates a cartridge for use in an aerosol generating device; 
         FIG. 2  illustrates another cartridge for use in an aerosol generating device; 
         FIG. 3  illustrates a profile view of an example system for determining a state of a heating system; 
         FIG. 4  illustrates a sensor unit for use in a system for determining a state of a heating system; and 
         FIG. 5  illustrates a cutaway view of the system of  FIG. 3 . 
     
    
    
     Referring now to  FIG. 3 , a system  100  for determining a state, for example a resistivity of a heating system is illustrated. The system  100  includes a receptacle  102  for receiving a plurality of elements (not shown), each element including a heating system to be tested. 
     In this example, the element is a component of an aerosol generating article or device of the ‘heat not burn’ variety, the component incorporating the heating system of the aerosol generating article or device. Specifically, the element corresponds to a cartridge for an aerosol generating device, the cartridge being configured to be connected to the main body of an aerosol generating device. In the described example, the heating system of each element includes a mesh-heater unit. That is, the heating system includes a mesh foil configured to provide a heat output in response to a current flow therethrough. For example, the element may be a cartridge as described in WO 2015/117702 or as otherwise described above. 
     In this example, the receptacle  102  is a plate with a plurality of cavities  104 , each cavity configured to receive an element. In the example illustrated in  FIG. 3 , the plate is circular in shape, with the cavities arranged around the circumference of the plate. 
     A proximal end of the cartridge (i.e. the end of the cartridge proximal to the heating system, for example a mouthpiece end of the cartridge) is received by the receptacle. The heating system is exposed upwardly. 
     The system  100  further includes a testing assembly  106 . The testing assembly  106  includes sensor means, for example sensor units, configured to obtain signals related to properties of the heating system of each of the plurality of elements. The testing assembly  106  further includes a processor configured to receive the signals obtained by the sensor means, for example sensor units, and determine a state, for example a resistivity, of the heating system of each of the plurality of elements. 
     As a first step of a method for determining a state, for example a resistivity, of a heating system using a system  100  in its most general form, the receptacle  102  is populated with a plurality of elements, each element comprising a heating system to be tested. In embodiments, the receptacle  102  is populated by a linear feed of elements to the receptacle. That is, the receptacle  102  is configured to be rotated, with respect to a feed point. In this example the receptacle  102  is mounted to the shaft  120  via mounting  150 . As the receptacle is rotated, elements are introduced into each cavity in turn. In embodiments, the elements may be carried in pucks. 
     Secondly, the sensor means, for example sensor units, is actuated to obtain signals related to properties of the heating system of each of the plurality of elements. In embodiments, the signals obtained relate to at least one of current, voltage or light. In such cases, the properties tested relate to at least one of resistivity of the heating system of the element, spatial location of the element or physical condition of the heating system of the element. 
     For example, a signal relating to a current or voltage within the heating system may be used as an indication/measurement of resistivity of the heating system of the element. Such a signal may result from the application of a potential difference across two points of the heating system. 
     Similarly, a signal relating to light may be used as an indication/measurement of the spatial location of the element (or the heating system within the element) or the physical condition of the heating system of the element. For example, the light signal may be used to form an image of the heating system or element, from which the position, orientation or physical condition of the heating system or element may be determined. In embodiments, the measured/monitored light may be at the infra-red frequency, such that the temperature of the heating system may be monitored (for example, the temperature response may be measured in response to an applied voltage), or UV frequency. Alternatively (or in addition), the light signal may be a magnitude of light passing between two points. As an example, a correctly positioned heating system may prevent passage of light passing between the two points. 
     Thirdly, the processor determines a state, for example a resistivity, of the heating system of each of the plurality of elements from the obtained signals. In embodiments, the determined state, for example the resistivity, is at least one of integrity of the heating system of an element, conformity of the heating system of an element to a predetermined condition, or functionality of the heating system of an element. In other words, the determined state may relate to the fitness of the heating system for purpose. For example, the obtained signals may indicate that one or more properties of the heating system of an element are symptomatic of an abnormality or quality problem with the manufacture of the heating system (for example, a loss of integrity, failure to conform to resistivity performance etc). 
     In embodiments, the determined state may relate to the ability of the testing assembly to test the required properties of the heating system of an element. For example, the predetermined condition to which the heating system must conform may be its location within the receptacle. This may be important as if the heating system of an element (or the element itself) is not correctly located within receptacle, the required tests (for example electrical tests) cannot be undertaken. 
     The processor may determine the state, for example the resistivity, of the heating system of an element in any suitable way. For example, the processor may determine the state, for example the resistivity, of the heating system by comparing the obtained signals to a given set of data. That is, if the signal indicates that a property of a heating system (for example resistivity) is above a threshold value, the processor may conclude that the state of the heating system is a first state (for example, the heating system conforms to a predetermined condition). In the same manner, if the signal indicates that a property of the heating system is below the threshold value, the processor may conclude that the state of the heating system is a second state (for example, the heating system does not conform to a predetermined condition). In alternative examples, the processor may conclude that the state of the heating system is a first state if the signal indicates that a property is equal to a value (for example a spatial location) and is a second state if the signal indicates that the property is not equal to the value. The given set of data may be provided by a server, connected within a network to the processor. 
     In embodiments, the processor may determine the state, for example the resistivity, of the heating system from signals relating to multiple properties. For example, a state (for example a resistivity or e.g. conformity to a predetermined condition) may only be assigned once multiple properties of the heating system of an element are above/below (or equal/not equal to) a predetermined threshold. 
     In embodiments, the processor may manipulate the obtained signals prior to the comparison to a given set of data. That is, the obtained signals in their raw state may not directly correspond to a property of the heating system of an element. In such cases, the processor may use the obtained signals to calculate a further metric or value, which corresponds to the desired property. 
     The state, for example the resistivity, of the heating system of an element as determined by the processor may be used to decide how the element (or the heating system thereof) is further processed within a production line. That is, the arrangement allows for real-time data processing and feedback within the production line. 
     For example, it may be required that an element with a heating system having a state, for example resistivity, that indicates that the heating system is not fit for purpose (for example the heating system has a lack of integrity, does not conform to a pre-determined condition or does not function as intended) should be removed from the production line. In such examples, the processor may be configured to actuate a means for removal of the deficient element/elements from the production line (either directly from the receptacle or further down the production line). 
     In further examples, the processor may store the state, for example the resistivity, (or an assigned value related thereto, for example a 1 or a 0) in a memory to allow the state, for example the resistivity, of the element to be used in a decision-making process further down the production line, for example removal of a deficient element from the production line. The state, for example the resistivity, may be stored on a server. For example, the processor may send the state, for example resistivity, to a server, connected within a network to the processor. In further examples, the decision-making process may be undertaken on the server. 
     In a further example, the determined state, for example resistivity, may be that the heating system is in an incorrect position and hence other properties of the heating system cannot be suitably tested. In such examples, the element may be rejected, or its position within the receptacle may be corrected by a suitable actuation means. 
     Once the testing operations have been completed, the plurality of elements may then be removed from the receptacle. The receptacle may then be repopulated with a further plurality of elements, for which testing is required. 
     In this example, the testing assembly  106  is configured to obtain the signals when the testing assembly is in a testing configuration. That is, the testing assembly has a testing, or active, configuration and a non-testing, or non-active, configuration. In other words, a further step of the method may include the step of bringing the testing assembly  106  into a testing configuration prior to actuating the sensor means, for example sensor units. 
     The testing assembly  106  is moveable relative to the receptacle  102  to bring the sensor means, for example sensor units, into the testing configuration. The testing configuration is a configuration for which the sensor means, for example sensor units, is close enough to the plurality of elements for the required signals to be obtained. In specific embodiments, the testing configuration may require the sensor means, for example sensor units, to be in contact with the heating system or the element (i.e. where contact is required for a signal to be obtained, for example where the sensors are a pair of electrical contacts). In alternative examples, the testing configuration may only require that the sensor means, for example sensor units is close enough to collect the desired signal or information to take an image or reading of a surrounding field, in which case no contact between the sensor means, for example sensor units, and the elements is required. 
     In specific embodiments, the testing assembly  106  is vertically moveable with respect to the receptacle  102  to bring the testing assembly  106  into the testing configuration. In this example, the testing assembly  106  and the receptacle  102  are mounted on shaft  120 . The testing assembly  106  is mounted on shaft  120  via a mounting assembly  122 . The testing assembly  106  is slidably mounted on the mounting assembly  122 . Prior to a testing operation, the testing assembly  106  is actuated to slide on the mounting assembly  122  towards the receptacle  102  to bring the testing assembly  106  into the testing configuration. 
     In addition, or alternatively in specific embodiments, the testing assembly  106  may be rotatably mounted on shaft  120  to allow relative rotation between the testing assembly  106  and the receptacle  102  to bring the testing assembly  106  into the testing configuration. 
     Once in the testing configuration, the testing assembly  106  can perform a testing operation on the heating systems received within the receptacle  102 . That is, the sensor means, for example sensor units, can obtain signals related to the required properties from the elements/heating systems of the elements within the receptacle  102 . In embodiments, the signals related to properties of the heating system of each of the plurality of elements are obtained substantially simultaneously by the sensor means, for example sensor units. 
     Following the testing operation, the testing assembly  106  may then be moved out of the testing configuration, back to a non-testing configuration. The elements may then be removed from the receptacle and then optionally repopulated for further testing operations. 
     The non-testing configuration may be defined as a relative configuration between the testing assembly  106  and the receptacle  102  that allows the receptacle  102  to be populated, or de-populated, with elements as required. 
     In the example illustrated in the Figures, the receptacle  102  is configured to receive more elements than the testing assembly  106  can test in a given moment. That is, the number of cavities  104  in the receptacle  102  is greater than the number of sensor units  108  (as described below) in the sensor means for example sensor units. In this manner, the receptacle may be fully populated at a given moment, with more than one plurality of elements. In other words the receptacle may be populated with one or more testing batches of elements. The testing assembly  106  may descend into its testing configuration, to perform a testing operation on a first plurality of elements. The testing assembly  106  and/or the receptacle  102  may then rotate to allow the testing assembly  106  to perform a testing operation on a second plurality of elements. In further examples, the number of sensor units  108  within the testing assembly  106  may correspond to the elements received within the receptacle  102 . In such cases, the receptacle contains a single plurality of elements that can be tested simultaneously by the testing assembly. 
     In this example, the sensor means, for example sensor units, includes a plurality of sensor units  108 , each sensor unit  108  being configured to obtain signals related to properties of the heating system of at least one of the plurality of elements. 
       FIG. 4  illustrates an example of a sensor unit  108 . In this example, the sensor unit  108  includes a housing  116 . The housing  116  is configured to house at least some of the sensing components for the sensor unit  108 . In this example, the sensor unit  108  includes a shoulder portion  118 . 
     The testing assembly  106  is configured to receive the sensor units  108  therein.  FIG. 5  illustrates a cut-away view of the testing assembly  106  with a plurality of sensor units  108  received therein. 
     In this example, the testing assembly  106  includes a plate portion  128 , covered by an optional cover portion  130 . The cover portion  130 , when used, may provide protection to the hardware (for example wiring) within the testing assembly  106 . The plate portion  128  includes holes or channels arranged therethrough, each hole configured to receive a sensor unit  108 . Each hole within the plate portion  128  includes a flange portion (not shown), which engages with the shoulder portion  118  of the corresponding sensor unit  108 , to allow the sensor unit  108  to sit within the hole. This may prevent the sensor unit from rotating within the corresponding hole of the plate portion  128 . 
     In this example, the position of holes in the plate portion  128 , and hence the subsequent position of each sensor unit  108 , corresponds to the position of the elements (i.e. heating systems to be tested) located within the receptacle  102 . That is, the sensor units  108  are positioned such that when the testing assembly  106  is brought into its testing configuration, the sensor units  108  are able to obtain signals from the corresponding element as required. 
     The hardware of the sensor units  108  are coupled to the processor by any suitable connection to allow transfer of the obtained signals to the processor. 
     In the example shown in  FIG. 4 , the plurality of sensor units each include at least a pair of electrical contacts  110 . The sensor unit  108  is configured such that when in the testing configuration, the pair of electrical contacts  110  are both in contact with a portion of the heating system of the corresponding element. For example, for a mesh heating system, in the testing configuration, the electrical contacts  110  may be in contact with portions of the mesh. 
     In this example the electrical contacts  110  are supported by a support structure  114  that extends from the housing  116  to prevent damage to the contacts  110 . In embodiments, the end of the support structure  114 , from which the contacts  110  extend, allows a degree of movement of the contacts  110  (for example lateral movement) without damage thereto. 
     In embodiments, the electrical contacts  110  (which in this example are electrical pins) can obtain electrical signals from the heating system. That is, a potential difference may be applied between the electrical contacts  110  and the resulting current that passes from a first of the contacts to the second of the contacts through the heating system may be measured. In this manner electrical properties, e.g. resistivity, of the heating system may be determined as described previously. The electrical contacts are coupled via connection points  132  (as shown in  FIG. 5 ) to a wiring system (not shown), which allows transfer of the electrical signals to the processor. 
     From the electrical property, the processor can determine a state, for example a resistivity, of the heating system, for example, if the heating system can function as required, if the heating system conforms to a pre-determined condition, or if the integrity of the heating system has not been compromised. Sensor units including electrical contacts are particularly useful for testing mesh-heater systems, which require a given resistivity to operate effectively. 
     In embodiments, the contact areas  112  of the contacts  110  may be configured with different shapes depending on the surfaces/materials of the heating systems being tested, or the specific properties being tested. 
     In other examples, each sensor unit  108  may include an optical sensor. The optical sensor may include an imaging device, for example a camera. The imaging device may be configured to obtain signals related to any required frequency, for example visual frequencies, UV or infra-red frequencies. 
     The optical sensor may be used to test for properties, such as spatial location of the element or physical condition of the heating system of the element. For example, the optical sensor may be used to determine if the element is in a required location for further testing. In another example, the optical sensor may be used to check the position of the testing arrangement with respect to the element (for example to indicate if the element is too close to the testing arrangement). In another example, the optical sensor may be used to check if contact was made between a part of the testing arrangement (for example the electrical contacts of the sensor units) and the heating system, which may be used as an indication of a successful test operation. In such an example, the optical sensor may be used to check if there are any marks resulting from said contact. 
     The sensor units  108  may optionally include at least one lighting element, for illuminating the corresponding heating system to be tested. The lighting element may emit light at any required frequency, for example UV or light of a visible wavelength to illuminate the heating system. The signals obtained by the corresponding optical sensor may correspond to light reflected form the heating system. 
     In specific embodiments, each sensor unit  108  may be configured to obtain signals related to one or more properties (for example each sensor unit  108  may include a pair of electrical contacts and/or an optical sensor and/or further sensor means, for example sensor units, as required. 
     In further embodiments, the plurality of sensor units  108  may each be the same, or alternatively may be varied in their configuration (for example the plurality of sensor units may include at least one sensor unit configured to obtain signals related to a first property and at least one sensor unit configured to obtain signals related to a second property). In the alternative example, the sensors may be arranged in any suitable way. For example, the plurality of sensor units  108  may include two or more different ‘types’ of sensor unit (i.e. two or more different groups of sensor units, each group configured to measure a different property or set of properties). An example of this may be a group of sensor units, each including electrical contacts, and a further group of sensor units including an optical sensor. The groups of sensor units may be arranged side-by-side within the testing assembly, or the sensor units may alternate between sensor units of each group. In each case, the testing assembly and/or the receptacle may be rotated between testing operations to allow for each element to be tested by a sensor unit of each group. 
     In specific embodiments (for example that shown in the illustrated example), the sensor units are removable from the testing assembly  106 . That is, if required the sensor units can be removed from the channels of the testing  106 . Such removal allows different testing operations (i.e. obtaining different signals) to be performed, if required. For example, this may be necessary if there is a requirement to test a batch of different elements. 
     Various modifications to the detailed arrangements as described above are possible. For example, in alternative examples, the heating system of each element may include a coil and wick heating system. 
     It would be understood that the sensor means, for example sensor units, described in the examples above is not exhaustive. For example, the sensor means, for example sensor units, may include temperature sensors (for example to monitor the temperature response to an applied voltage), molecular or gas sensor means. 
     A single sensor unit  108  may be configured to obtain signals from one or more of the heating systems of elements. Specifically, a single sensor unit  108  may be located in a way that it can obtain signals from more than one (for example two adjacent heating systems). In such cases, the single sensor unit  108  may include separate sets of sensors to obtain signals from the one or more heating systems simultaneously. 
     The sensor units  108  may be fixed within the testing assembly  106  prior to a testing operation. In alternative examples, the sensor units remain free within the testing assembly  106 . That is, the sensor units  108  are held within the channels in the testing assembly  106  under their own weight only. In this manner, if, when brought into the testing configuration, the elements (or heating systems thereof) are located in an incorrect position within the receptacle  102 , the testing assembly  106  may still arrive into the testing configuration without damaging the testing assembly  106  or the element to be tested. That is, the sensor units  108  can be displaced from (or within) their respective channels to accommodate the incorrectly positioned element. In specific embodiments, the shoulder portion  118  of the sensor unit  108  may prevent rotation of the sensor unit  108  but still allow displacement or movement from the testing assembly, for example vertical movement. This is to prevent damage. 
     In embodiments, the sensor units  108  may be biasedly held within the testing assembly  106 . For example, the sensor units  108  may be spring actuated, such that the testing configuration is achieved through movement of the sensor units  108  against the bias of a spring, as opposed to movement of the testing assembly  106  as a whole. In this manner, swift ‘reloading’ of the sensor units may be achieved (i.e. a return to a non-testing configuration) once a testing operation is complete. This is of particular relevance for sensor units that require contact with the heating system to obtain a signal (for example sensor units including electrical contacts). In the relevant embodiments, the electrical contacts  110  may be moveable or biased in the same way. 
     It will also be appreciated by those skilled in the art that any number of combinations of the aforementioned features and/or those shown in the appended drawings provide clear advantages over the prior art and are therefore within the scope of the invention described herein. 
     The schematic drawings are not necessarily to scale and are presented for purposes of illustration and not limitation. The drawings depict one or more aspects described in this disclosure. However, it will be understood that other aspects not depicted in the drawings fall within the scope of this disclosure.