Patent Publication Number: US-2022221475-A1

Title: Biological sample analyzer with accelerated thermal warming

Description:
This application claims priority to U.S. Provisional Application No. 62/822,379, filed Mar. 22, 2019, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     CROSS-REFERENCE TO RELATED CASES 
     This application is related to U.S. patent application Ser. No. 62/822,371, filed on the same date as the present application as attorney docket number 2019P06410WO, and U.S. patent application Ser. No. 62/822,391, filed on the same date as the present application as attorney docket number 2019P06412WO, the teachings of both of which are hereby incorporated by reference as if set forth in their entirety herein. 
     TECHNICAL FIELD 
     This disclosure generally relates to biological sample analyzers, and more particularly to heating of consumable biological sample holders used in biological sample analyzers. 
     BACKGROUND 
     In point-of-care services, a benchtop biological sample analyzer is commonly used to analyze biological samples of patients such as blood and urine. Typically, the biological sample is fed into a cartridge having a reagent therein. The cartridge is inserted into the analyzer, and the analyzer moves the cartridge so as to mix the sample with the reagent. Further, the analyzer heats the sample and reagent a target temperature, typically above room temperature, and then analyzes the heated sample. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description, will be better understood when read in conjunction with the appended drawings. The drawings show illustrative embodiments of the disclosure. It should be understood, however, that the application is not limited to the precise arrangements and instrumentalities shown. 
         FIG. 1  shows a top perspective view of a biological sample analyzer according to an illustrative embodiment of the present disclosure; 
         FIG. 2  shows a bottom perspective view of the biological sample analyzer shown in  FIG. 1 ; 
         FIG. 3  shows a perspective view of interior components of the biological sample analyzer of  FIG. 1 , including an air plenum, a motor, a diagnostic consumable holder, and a receptacle for the diagnostic consumable holder; 
         FIG. 4  shows a cross-sectional view of the biological sample analyzer of  FIG. 1 , taken along a center line that extends from the front to the back of the biological sample analyzer in  FIG. 1 ; 
         FIG. 5  shows a cross-sectional view of the biological sample analyzer of  FIG. 1 , taken along line  5 - 5  shown in  FIG. 4  and with the housing removed; 
         FIG. 6  shows the cross-sectional view of the biological sample analyzer of  FIG. 4  with the housing removed; 
         FIG. 7  shows an exploded perspective view of the receptacle and consumable holder of the biological sample analyzer of  FIG. 1 ; 
         FIG. 8  shows an alternative exploded perspective view of the receptacle and consumable holder of the biological sample analyzer of  FIG. 1 ; 
         FIG. 9  shows a simplified flow diagram of a method of heating a biological sample to a target temperature; 
         FIG. 10  shows a simplified flow diagram of a method of detecting a cold consumable holder and compensating for the cold consumable holder; 
         FIG. 11  shows a simplified flow diagram of a method of operating a fan of the biological sample analyzer; 
         FIG. 12  shows a graphical representation of the temperature of heaters of the biological sample analyzer of  FIG. 1  over time during a heating operation of the consumable holder; and 
         FIG. 13  shows a graphical representation of the speed of a fan of the biological sample analyzer of  FIG. 1  over time during a heating operation of the consumable holder. 
     
    
    
     DETAILED DESCRIPTION 
     In a conventional biological sample analyzer, the heaters of the analyzer are set to apply a target temperature to a diagnostic consumable holder such as a cartridge, card, or cassette, that holds a biological sample and reagent. The target temperature corresponds to the temperature at which the biological sample will be analyzed, and is typically above an ambient or room temperature. The diagnostic consumable holder is then permitted to reach the target temperature. However, heating the diagnostic consumable holder in such a manner can be time consuming, thereby delaying the time needed to obtain an analysis of the sample. Therefore, there is a desire to reduce the amount of time needed to heat the diagnostic consumable holder to the target temperature. One method of reducing the amount of time needed is to redesign the diagnostic consumable holder to have a smaller mass, which will heat quicker at a given temperature than a diagnostic consumable holder having a larger mass. However, redesigning the diagnostic consumable holder can render any unused diagnostic consumable holders obsolete, and can also necessitate a redesign of the biological sample analyzer. 
     As an alternative, the biological sample analyzer can be configured to accelerate heating of the diagnostic consumable holder by setting at least one heater of the analyzer to apply an elevated temperature that is greater than the target temperature. In some embodiments, the elevated temperature can correspond to a maximum heating capability of the at least one heater. However, care should be taken to not overheat the diagnostic consumable holder beyond the target temperature. Therefore, the biological sample analyzer can be configured to rapidly cool the at least one heater before the diagnostic consumable holder exceeds the target temperature. As described below, this can be accomplished, at least in part, by reducing the heating applied by the at least one heater. Additionally or alternatively, rapid cooling can be accomplished by causing a fan to force air over the at least one heater of the sample analyzer at a determined time before the diagnostic consumable holder exceeds the target temperature so as to cool the at least one heater to the target temperature. The fan can be operated at a first speed when the at least one heater is heating to the elevated temperature, and can be operated at a second speed that is faster than the first speed, when the heater is heating to the target temperature. The first speed can be zero or greater than zero, and thus, the fan can be moving or can be off when at the first speed. The air from the fan can be directed over the heaters through a plenum disposed within the sample analyzer. 
     A diagnostic consumable holder may have a relatively short shelf life (e.g., approximately eight weeks) when kept at room temperature. This may be due at least in part to the shelf life of a reagent held or contained in the diagnostic consumable holder. Therefore, the diagnostic consumable holder can be refrigerated so as to extend the shelf life of the diagnostic consumable holder (e.g., to approximately two years). However, conventional biological sample analyzers typically do not account for the lowered temperature of a refrigerated diagnostic consumable holder. As a result, the diagnostic consumable holder must be removed from the refrigerator for a period of time (e.g., ½ hour) prior to being inserted into a conventional biological sample analyzer so as to bring the diagnostic consumable holder to room temperature. 
     If the diagnostic consumable holder is not brought to room temperature, then the analyzer might not heat the diagnostic consumable holder to the target temperature. This can result in a bias or error in the analyzed results generated by the biological sample analyzer because the analysis is temperature sensitive. Alternatively, the analyzer might reject the diagnostic consumable holder, and as a result, the operator would need to obtain a new sample from the patient thereby resulting in delay. As described below, a sample analyzer of the present disclosure can be configured to detect a diagnostic consumable holder that has been refrigerated and inserted into the sample analyzer before the diagnostic consumable holder has warmed to an ambient temperature range (herein referred to as a “cold consumable holder”). As used herein, the term “cold consumable holder” is used to refer to a consumable holder that is below an ambient temperature range. In one embodiment, the ambient temperature range can be from about 15 degrees Celsius to about 32 degrees Celsius. In another embodiment, the ambient temperature range is a room temperature range of from about 20 degrees Celsius to about 25 degrees Celsius. The sample analyzer can further be configured to adjust heating of the diagnostic consumable holder so as to bring the diagnostic consumable holder to the target temperature before the sample is analyzed by the sample analyzer. 
     Described herein is a biological sample analyzer  10  that includes a receptacle  154  configured to receive a diagnostic consumable holder  162  with a biological sample disposed therein. In the figures, the diagnostic consumable holder  162  is shown as a cartridge; however, the diagnostic consumable holder  162  can be a cartridge, card, cassette, or any other suitable housing configured to retain a biological sample therein for analysis. At least one heater  186  is attached to the receptacle  154 , and is configured to heat the receptacle  154 . At least one heater sensor  188  is attached to the receptacle  154 , and is configured to detect an instantaneous temperature of the receptacle  154 . Certain terminology is used to describe the biological sample analyzer  10  in the following description for convenience only and is not limiting. The words “lower” and “upper” designate directions with respect to the orientation shown in the drawings. The words “inner” and “outer” refer to directions toward and away from, respectively, the geometric center of the part being described. 
     Unless otherwise specified herein, the terms “longitudinal,” “lateral,” and “vertical” and are used to describe the orthogonal directional components of various components of the biological sample analyzer  10 , as designated by the first direction D 1 , second direction D 2 , and third direction D 3 . It should be appreciated that while the first and second directions D 1 , D 2  are illustrated as extending along a horizontal plane, and the third direction D 3  is illustrated as extending along a vertical plane, the planes that encompass the various directions may differ during use. 
     Referring to  FIGS. 1 and 2 , a biological sample analyzer  10  is shown that is configured to heat a diagnostic consumable holder  162  containing a biological sample and a reagent, and measure a characteristic of the heated biological sample. The biological sample analyzer  10  can be configured to accelerate heating of the consumable holder  162  by setting at least one heater of the analyzer to apply an elevated temperature that is above the target temperature of the biological sample. The biological sample analyzer  10  can include a housing  14  configured to house various components of the biological sample analyzer  10 . The housing  14  can include at least one outer wall  18 . The at least one outer wall has an outer surface, and an inner surface opposite the outer surface. The at least one outer wall  18 , such as the inner surface of the at least one outer wall  18 , defines an internal cavity  34  of the housing  14  that is configured to house various components for heating and measuring characteristics of the biological sample. 
     The housing  14  can have a first end  14   a  and a second end  14   b  that are spaced from one another along a first direction D I . The housing  14  can have a first side  14   c  and a second side  14   c  that are spaced from one another along a second direction D 2 , perpendicular to the first direction D I . The housing  14  can define an upper end  14   e  and a lower end  14   f  that are spaced from one another along a third direction D 3 , perpendicular to both the first and second directions D I  and D 2 . The internal cavity  34  can be defined between the first and second ends  14   a  and  14   b , between the first and second sides  14   c  and  14   d , and between the upper and lower ends  14   e  and  14   f.    
     The at least one outer wall  18  can define a plurality of outer walls. For example, the at least one outer wall  18  can include a first wall  18   a  at the first end  14   a . The at least one outer wall  18  can include a second end wall  18   b  at second end  14   b . The at least one outer wall  18  can include a first sidewall  18   c  at the first side  14   c . The at least one outer wall  18  can include a second sidewall  18   d  at the second side  14   d . The at least one outer wall  18  can include an upper wall  18   e  at the upper end  14   e . The at least one outer wall  18  can include a lower wall  18   f  at the lower end  14   f  It will be understood that the housing  14  can have any suitable shape, including shapes other than that shown, that defines a cavity therein. Accordingly, the at least one outer wall  18  can include as few as a single wall (e.g., in the event that the housing  14  has a spherical shape) or more than one wall, and the walls can have a shape other than that shown. 
     The at least one outer wall  18  defines an opening  22  that extends therethrough. The opening  22  is open to the cavity  34  such that the opening  22  is configured to receive the consumable holder  162   162  into the cavity  34 . The opening  22  can extend into the upper end  14   e  of the housing  14 , such as into the upper wall  18   e . However, it will be understood that, in alternative embodiments, the opening  22  can extend into one or more of the end  14   a , end  14   b , side  14   c , side  14   d , and end  14   e.    
     The biological sample analyzer  10  can include a door  26  that is movably coupled to the housing  14 . The door  26  can be configured to selectively cover the opening  22  so as to prevent heat from escaping the biological sample analyzer  10  through the opening  22 . The door  26  is configured to be transitioned between an open position, where the housing  14  is configured to receive the consumable holder  162  through the opening  22 , and a closed position, where the door  26  covers the opening  22 . In the closed position, the door  26  both prevents a consumable holder  162  from being inserted into the biological sample analyzer  10  through the opening  22 , and prevents a consumable holder  162  already disposed within the internal cavity  34  from being removed from the biological sample analyzer  10 . The biological sample analyzer  10  can include a door sensor  30  configured to detect whether the door  26  is in the open position or the closed position. The door sensor  30  can be, for example, a relay switch or any other suitable sensor that can detect when a door is open or closed. 
     The door sensor  30  can be in signal communication with a controller  46 . The controller  46 , which can be a PID controller, can comprise any suitable computing device configured to host a software application for monitoring and controlling various operations of the biological sample analyzer  10  as described herein. It will be understood that the controller  46  can include any appropriate computing device, examples of which include a processor, a desktop computing device, a server computing device, or a portable computing device, such as a laptop, tablet, or smart phone. The controller  46  can be physically attached to the housing, disposed within the housing  14 , or can be remote to and potentially spaced a distance from the housing  14 . 
     The controller  46  can include a memory  50 . The memory  50  can be volatile (such as some types of RAM), non-volatile (such as ROM, flash memory, etc.), or a combination thereof. The controller  46  can include additional storage (e.g., removable storage and/or non-removable storage) including, but not limited to, tape, flash memory, smart cards, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, universal serial bus (USB) compatible memory, or any other medium which can be used to store information and which can be accessed by the controller  46 . 
     The controller  46  can optionally include a human-machine interface (HMI) device  54 . The HMI device  54  can include inputs that provide the ability to control the controller  46 , via, for example, buttons, soft keys, a mouse, voice actuated controls, a touch screen, movement of the controller  46 , visual cues (e.g., moving a hand in front of a camera on the controller  46 ), or the like. The HMI device  54  can provide outputs, via a graphical user interface, including visual information concerning various components of the biological sample analyzer  10 . Other outputs can include audio information (e.g., via speaker), mechanically (e.g., via a vibrating mechanism), or a combination thereof. In various configurations, the HMI device  54  can include a display, a touch screen, a keyboard, a mouse, a motion detector, a speaker, a microphone, a camera, or any combination thereof. The HMI device  54  can include any suitable device for inputting biometric information, such as, for example, fingerprint information, retinal information, voice information, and/or facial characteristic information, for instance, so as to require specific biometric information for accessing the controller  46 . 
     The controller  46  can be in wired and/or wireless communication with the door sensor  30 , as well as various other components of the biological sample analyzer  10 , as will be described further below. The controller  46 , and specifically the HMI device  54 , can be configured to produce an alert if the door sensor  30  senses that the door  26  is in the open position for a predetermined amount of time. In one embodiment, the predetermined amount of time can be about 15 seconds. However, it is contemplated that the predetermined amount of time can be more or less than 15 seconds as desired. Optionally, the HMI device  54  can be configured to receive a user input such that an operator of the biological sample analyzer  10  can manually select and/or adjust the predetermined amount of time that the door  26  can be in the open position. When the door  26  is maintained in the open position for the predetermined amount of time after a consumable holder  162  is disposed within the housing  14 , the controller  46  may invalidate the intended heating operation and produce a corresponding alert via the HMI device  54 . 
     Referring to  FIG. 2 , the at least one outer wall  18  of the housing  14  can define an air intake  38  that extends through the at least one outer wall  18 . The air intake  38  is configured to receive air from outside the housing  14  and into the internal cavity  34 . The air intake  38  can be defined by at least one opening that extends through the at least one outer wall  18 , such as a plurality of openings spaced about the at least one outer wall  18 . The air intake  38  can extend through a first wall of the at least one of the outer wall  118 . In  FIG. 2 , the air intake  38  is defined at the second end  18   b , and in particular, is defined by the second end wall  18   b . Further, the air intake  38  is oriented substantially along a plane that is parallel to the second and third directions D 2 , D 3 , e.g., a substantially vertically-oriented plane. However, it will be understood that the air intake  38  can be defined at any another side or end of the housing  14 , and can be oriented along a different plane or multiple planes. 
     The at least one outer wall  18  of the housing  14  can define an air exhaust  42  that extends through the at least one outer wall  18 . The air exhaust  42  is spaced from the air intake  38  about the at least one outer wall  18 . The air exhaust  42  can extend through a second wall of the at least one of the outer wall  118 . The second outer wall can be different from the first outer wall through which the air intake  38  extends. In some embodiments, the second outer wall can be angularly offset from the first outer wall. The air exhaust  42  is configured to expel air from the internal cavity  34  to an area outside of the housing  14 . Like the air intake  38 , the air exhaust  42  can be defined by at least one opening that extends through the at least one outer wall  18 , such as a plurality of openings spaced about the at least one outer wall  18 . In  FIG. 2 , the air exhaust  42  is defined at the lower end  18   f  of the housing  14 , and in particular, is defined by the lower end wall  18   f . Further, the air exhaust  42  is oriented substantially along a plane that is parallel to the first and second directions D I , D 2 , e.g., a substantially horizontally-oriented plane. As a result, the air intake  38  can be angularly offset from the air exhaust  42 . In the depicted embodiment, the air intake  38  is angularly offset from the air exhaust  42  by about 90 degrees. However, the air intake  38  and the air exhaust  42  can be alternatively oriented relative to each other as desired. It will be understood that the air exhaust  42  can be defined at any another side or end of the housing  14 , and can be oriented along a different plane or multiple planes. 
     The air intake  38  can be configured to provide received air into the internal cavity  34  along an intake direction D I . The air exhaust  42  can be configured to receive air from the cavity  34  along an exhaust direction D E , and to expel the air out of the cavity  34 . The intake direction D I  can be angularly offset from the exhaust direction D E . In one example, the intake direction D I  can be substantially perpendicular to the exhaust direction D E . In alternative embodiments, the intake direction D I  and exhaust direction D E  can be substantially parallel to one another. In some embodiments, the air intake  38  can receive the air along the intake direction D I . Additionally or alternatively, in some embodiments, the air exhaust  42  can expel air along the exhaust direction D E . However, it will be understood that in alternative embodiments, at least one of the air intake  38  and air exhaust  42  can include louvers that changes the trajectory of the air as it is received into the air intake  38  or expelled from the air exhaust  42 . 
     Turning to  FIG. 3 , the biological sample analyzer  10  includes a plenum  100  disposed within the internal cavity  34  of the housing  14 . The plenum  100  can include at least one plenum wall  104  that has an inner plenum surface, and an outer plenum surface opposite the inner surface. The at least one plenum wall  104 , such as the inner surface of the at least one plenum wall  104 , defines an air duct  120  therein. The plenum  100  can have a first plenum end  100   a  and a second plenum end  100   b  that are spaced from one another along a first direction D I . The plenum  100  can have a first plenum side  100   c  and a second plenum side  100   c  that are spaced from one another along the second direction D 2 . The plenum  100  can define an upper plenum end  100   e  and a lower plenum end  100   f  that are spaced from one another along the third direction D 3 . The air duct  120  can be defined between the first and second plenum ends  100   a  and  100   b , between the first and second plenum sides  100   c  and  100   d , and between the upper and lower plenum ends  100   e  and  100   f.    
     The at least one plenum wall  104  can include a plurality of plenum walls. For example, the at least one plenum wall  104  can include a first plenum end wall  104   a  at the first plenum end  100   a . The at least one plenum wall  104  can include a second plenum end wall  104   b  at the second plenum end  100   b . The at least one plenum wall  104  can include a first plenum sidewall  104   c  at the first plenum side  100   c . The at least one plenum wall  104  can include a fourth plenum wall  104   d  at the second plenum side  100   d . The at least one plenum wall  104  can include an upper plenum wall  110   e  at the upper plenum end  100   e . The at least one plenum wall  100  can include a lower plenum wall  104   f  at the lower plenum end  100   f . It will be understood that the plenum  100  can have any suitable shape, including shapes other than that shown. Accordingly, the at least one outer plenum wall  104  can include as few as a single wall or more than one wall, and the walls can have a shape other than that shown. 
     The at least one plenum wall  104  can define an opening  108  that extends therethrough. The opening  108  is open to the air duct  120  such that the opening  108  is configured to receive the consumable holder  162  into the air duct  120 . The opening  108  is aligned below the opening  22  of the housing  14  such that a straight path is defined from the opening  22  of housing  14  into the air duct  120  through the opening  108 . The opening  108  can extend into the upper end  100   e  of the plenum  100 , such as into the upper plenum wall  104   e . However, it will be understood that, in alternative embodiments, the opening  108  can extend into one or more of the end  100   a , end  100   b , side  100   c , side  100   d , and end  100   e.    
     The plenum  100  defines a plenum intake  112  that extends through the at least one plenum wall  104 . The plenum intake  112  is configured to receive air from the air intake  38  of the housing  14  into the plenum  100 . The plenum intake  112  is disposed adjacent to, and is in fluid communication with, the air intake  38  such that air received at the air intake  38  is received into the plenum intake  112 . The plenum intake  112  can be defined by at least one opening, or a plurality of openings spaced about the at least one plenum wall  104 . In  FIG. 3 , the plenum intake  112  is defined at the second plenum end  100   b , and in particular, is defined by the second plenum end wall  104   b . Further, the plenum intake  112  is oriented substantially along a plane that is parallel to the second and third direction D 2 , D 3 , e.g., a substantially vertically-oriented plane. However, it will be understood that the plenum intake  112  can be defined at any another side or end of the plenum  100 , and can be oriented along a different plane or multiple planes. 
     The plenum  100  defines a plenum exhaust  116  that extends through the at least one plenum wall  104 . The plenum exhaust  116  is spaced from the plenum intake  112  about the at least one plenum wall  104  such that the air duct  120  extends from the plenum exhaust  116  to the plenum intake  112 . The plenum exhaust  116  is configured to expel air from the plenum  100 . The plenum exhaust  116  is disposed adjacent to, and is in fluid communication with, the air exhaust  42  such that air expelled from the plenum exhaust  116  is expelled out of the air exhaust  42 . Like the plenum intake  112 , the plenum exhaust  116  can be defined by at least one opening, or a plurality of openings spaced about the plenum wall  104 . In  FIG. 3 , the plenum exhaust  116  is defined at the lower plenum end  100   f , and in particular, is defined by the lower plenum end wall  104   f . Further, the plenum exhaust  116  is oriented substantially along a plane that is parallel to the first and second directions D I , D 2 , e.g., a substantially horizontally-oriented plane. As a result, the plenum intake  112  can be angularly offset from the plenum exhaust  116 . In the depicted embodiment, the plenum intake  112  is angularly offset from the plenum exhaust  116  by 90 degrees. However, the plenum intake  112  and the plenum exhaust  116  can be angularly offset from one another by any other suitable angle. In alternative embodiments, the plenum exhaust  112  and the plenum intake  116  can be parallel to one another. It will be understood that the plenum exhaust  116  can be defined at any another side or end of the plenum  100 , and can be oriented along a different plane or multiple planes. 
     The plenum intake  112  can be configured to receive air into the air duct  120  along the intake direction D I . The plenum exhaust  116  can be configured to expel air along the exhaust direction D E . As described above, the intake direction D I  can be angularly offset from the exhaust direction D E . In one example, the intake direction D I  can be substantially perpendicular to the exhaust direction D E . In alternative embodiments, the intake direction D I  and exhaust direction D E  can be substantially parallel to one another. In operation, the biological sample analyzer  10  is configured to receive air through the air intake  38  of the housing  14 , through the plenum intake  112 , through the air duct  120 , out of the air duct  120  through the plenum exhaust  116 , and out of the housing  14  through the air exhaust  42 . 
     Now referring to  FIGS. 4, 7, and 8 , the biological sample analyzer  10  comprises a receptacle  154  that is configured to support the consumable holder  162  containing the biological sample. At least a portion of the receptacle  154  is disposed within the plenum  100 . The receptacle  154  can have an open end configured to receive and hold the consumable holder  162  during a heating and measuring operation. The receptacle can have a substantially rectangular shape; however, the shape of the receptacle  154  can vary depending on the shape of the consumable holder to be received. 
     In the depicted embodiment, the receptacle  154  has a first holder end  158   a , and a second holder end  158   b  opposite the first holder end  158   a  along the first direction D I . The receptacle  154  has a first holder side  158   c  that extends from the first holder end  158   a  to the second holder end  158   b , as well as a second holder side  158   d  that is opposite the first holder side  158   c  and extends from the first holder end  158   a  to the second holder end  158   b . The first and second holder sides  158   c  and  158   d  can be considered to be first and second heater plates, although the sides  158   c  and  158   d  can suitable configurations other than plates, such as coils, for heating the consumable holder  166 . The receptacle  154  can also include a bottom holder end  158   e  that defines the lower end of the receptacle  154  and extends between each of the first and second holder ends  158   a  and  158   b  and between the first and second holder sides  158   c  and  158   d . The receptacle  154  can define a receiving area  170  configured to receive the consumable holder  162  in order to heat the consumable holder  162 , where the receiving area  170  is defined between each of the first and second holder ends  158   a  and  158   b , between the first and second holder sides  158   c  and  158   d , and above the bottom holder end  158   e . The dimensions and shape of the receiving area  170  can vary depending on the type and shape of consumable holder to be disposed within the receiving area  170 , though in the depicted embodiment the receiving area  170  has a substantially rectangular profile in a plane that extends along the first and second directions D I  and D 2 . The receptacle  154  can be formed from a thermally conductive material such as aluminum, an aluminum alloy, copper, or any other suitable thermally conductive material. A sensor  174  (shown in  FIGS. 4 and 6 ) can be disposed within the receptacle  164 , and can be configured to detect whether a consumable holder  162  has been inserted into the receptacle  164 . The cartridge sensor  174  can be a relay switch or any other suitable sensor that can detect the presence of a consumable holder. The cartridge sensor  174  can be in signal communication with the controller  46  so as to communicate whether a consumable holder  162  has been inserted into the receptacle  154  to the controller  46 . 
     Turning to  FIG. 5 , the biological sample analyzer  10  can support at least a portion of the receptacle  154  within the air duct  120  of the plenum  100  such that at least one air gap  124  is defined between the receptacle  154  and the at least one plenum wall  104 . This air gap  124 , which comprises a portion of the air duct  120 , allows air to flow along the receptacle  154  in order to cool the receptacle  154 . The air gap  124  can be defined between the at least one plenum wall  104  and any combination of the sides  158   a - 158   e  of the receptacle  154 . For example, the air gap  124  can include a first air gap  124   a  defined between the first holder side  158   c  of the receptacle  154  and the first plenum sidewall  104   c . The air gap  124  can additionally or alternatively include a second air gap  124   b  defined between the second holder side  158   d  of the receptacle  154  and the second plenum sidewall  104   d . The air gap  124  can additionally or alternatively be defined between the bottom holder end  158   e  and the lower plenum wall  104   f.    
     Referring to  FIG. 6 , to force air through the air duct  120 , the biological sample analyzer  10  can include a fan  192  configured to force air along a path P that extends from the air intake  38  of the housing  14 , through the plenum intake  112  of the plenum  100 , through an air gap  124 , through the plenum exhaust  116 , and out the air exhaust  42  of the housing  14 . Specifically, the fan  192  can direct air through the at least one air gap  124 , such as through at least one of the first air gap  124   a  and the second air gap  124   b  along the first and second lateral sides  158   c  and  158   d  of the receptacle  154 . The fan  192  optionally also direct air through the portion of the air gap  124  defined below the receptacle  154  between the bottom side  158   e  and the plenum wall  104 . In the depicted embodiment, the fan  192  is positioned at the plenum intake  112  of the plenum  100 , although alternative positioning of the fan  192  is contemplated. For example, the fan  192  could alternatively be positioned as the planum exhaust  116 . The fan  192  can be in wired and/or wireless communication with the controller  46 , such that the controller  46  can direct operation of fan  192 . As a result, the fan  192  can be selectively transitioned between different speeds at predetermined intervals in a heating operation, as will be described further below. 
     Referring back to  FIG. 4 , the biological sample analyzer  10  can also include a temperature sensor  194  positioned adjacent the fan  192 , where the temperature sensor  194  is configured to detect the ambient temperature of the air being drawn into the plenum  100  by the fan  192 . The temperature sensor  194  can be in wired and/or wireless communication with the controller  46  such that the controller  46  can monitor the air temperature sensed by the temperature sensor  194 . The temperature of the air forced into the plenum  100  can be representative of the ambient temperature that exists outside the biological sample analyzer  10 , which can be useful in calculations related to the heating operation of the consumable holder  162 , as will be discussed further below. In some embodiments, the analyzer  10  can include another temperature sensor (not shown) on the main printed circuit board (PCB) within the air flow to ensure that air temperature sensed by the sensor  194  is not in skewed due to heat output from the at least one heater of the analyzer. 
     The biological sample analyzer  10  can also include a filter  196  (see  FIG. 4 ) positioned upstream from the fan  192 , where the filter  196  is configured to filter out particulates from the air drawn into the plenum  100  by the fan  192 . Over time, the filter  196  can become increasingly clogged, and the filter  196  can become clogged to a sufficient degree that the airflow provided to the fan  192  becomes limited. This reduced airflow can negatively affect the cooling of the receptacle  154 , as less air is available for the fan  192  to force over the receptacle  154 . Obstruction of the filter  196  can be determined by comparing the instantaneous power consumed by the heater  186  to a baseline power consumption. Power consumption by the heater  186  that is lower than expected can be indicative of a clogged filter  196 . The controller  46  can then use this information to adjust the speed of the fan  192 , as will be described further below. 
     Returning to  FIGS. 7 and 8 , the biological sample analyzer  10  can further include at least one heater  186  for heating the receptacle  154 . The at least one heater  186  can apply heat directly or indirectly to the receptacle  154  so as to heat the receptacle  154 . The receptacle  154 , in turn, can apply heat to the consumable holder  162  when the consumable holder  162  is disposed within the receiving area  170  of the receptacle  154 . The at least one heater  186  can be attached to the outer surface of the receptacle  154 . For example, the at least one heater  186  can be attached to the outer surfaces of any of the first and second holder ends  158   a  and  158   b , the first and second holder sides  158   c  and  158   d , and the bottom holder end  158   e . The at least one heater  186  can comprise an electrically conductive coil supported by a flexible or rigid printed circuit board (PCB), such as a polyimide flexible heater, or any other suitable heater that can heat the receptacle  154 . The at least one heater  186  can include a first heater  186   a  attached to the first holder side  158   c  of the receptacle  154 , and a second heater  186   b , opposite the first heater  186   a , and attached to the second holder side  158   d  of the receptacle  154 . However, the heater  186  can include more or less than two heaters as desired. The at least one heater  186 , including the first and second heaters  186   a  and  186   b , can be in wired and/or wireless signal communication with the controller  46  such that the controller  46  can control and adjust the heating profile of the first and second heaters  186   a  and  186   b  as will be discussed further below. 
     The biological sample analyzer  10  can include at least one heater sensor  188  configured to detect a temperature of the receptacle  154 . The at least one heater sensor  188  can include first and second heater sensors  188   a  and  188   b  attached to the receptacle  154 , where each of the first and second heater sensors  188   a  and  188   b  can be configured to detect an instantaneous temperature of the receptacle  154  at a different location. The first heater sensor  188   a  can be attached to the first holder side  158   c  of the receptacle  154  adjacent to the first heater  186   a , and thus, can be configured to detect the temperature of the receptacle  154  at a location adjacent the first heater  186   a . Likewise, the second heater sensor  188   b  can be attached to the second lateral side  158   d  of the receptacle  154  adjacent the second heater  186   b , and can thus be configured to detect the temperature of the receptacle  154  at a location adjacent the second heater  186   b . Each of the first and second heater sensors  188   a  and  188   b  can comprise any suitable temperature sensor such as a thermistor. Though two heater sensors are specifically described, the biological sample analyzer  10  can include more or less than two heater sensors as desired. 
     The temperature of the biological assay, which is disposed in the consumable holder  162 , cannot be measured directly. Instead, the temperature of the assay can be controlled indirectly based on a temperature of the receptacle  154 . Therefore, the biological sample analyzer  10  can comprise a feedback loop that is configured to control heat applied to the receptacle  154 . The feedback loop can be continuously updated at predetermined intervals (e.g., every second). The feedback loop comprises the controller  46 , the at least one heater  186 , and the at least one heater sensor  188 . The at least one heater sensor  188  can be configured to provide a detected (i.e., measured) temperature of the receptacle  154  to the controller  46 . The controller  46  can be configured to determine a temperature error based on the detected temperature and a desired temperature. The controller  46  can then control an amount of heat provided by the at least one heater  186  based on the temperature error so as to drive the temperature error towards zero error. As will be described below, the desired temperature can be the target temperature, the elevated temperature, or a set point temperature. In one example, the temperature error can be determined as a difference between the desired temperature and the detected temperature. In another example, the temperature error can be determined based on a ratio of the desired temperature and the detected temperature In some such cases, a value of one can be subtracted from the ratio. 
     Referring to  FIGS. 3 and 5 , a biological analysis sensor  190  can be disposed within the housing  14 , where the sensor  190  is configured to measure a characteristic of the biological sample disposed within the consumable holder  162 . In one embodiment, the sensor  190  is an optical sensor, such as a photodiode, though other types of sensors are contemplated. The analyzer  10  can include a light source  191  that is configured to emit a light beam through the consumable holder  162 , and hence through the biological sample, to the sensor  190 . The sensor  190  can be configured to detect at least one of an HbAlC level of the biological sample, a ratio of albumin to creatinine, a hemoglobin level, an agglutination measurement, or any other desired biological characteristic. When the consumable holder  162  is inserted into the receptacle  154 , the biological sample contained within the consumable holder  162  may require mixing with the reagent prior to the sensor  190  measuring the characteristic of the biological sample. To accomplish this, the biological sample analyzer  10  can include a motor  178  mounted within the housing  14 . The motor  178  can be configured to move the receptacle  154  within the plenum  100  so as to agitate the biological sample within the consumable holder  162 . The motor  178  can include a shaft  182  that extends through the plenum  100  from the motor  178 , and operatively connects to the receptacle  154  opposite the motor  178 . This allows the motor  178  to be disposed within the housing  14  outside the plenum  100 . The motor  178  can be configured to vibrate, rotate, or otherwise agitate the receptacle  154  through the shaft  182 . 
     The plenum  100  can be specifically designed so as to allow the movement of the receptacle  154  within the plenum  100  so as to mix the biological sample within the consumable holder  162 . For example, the upper portion of the at least one plenum wall  104  can be curved so as to provide a clearance between the plenum  100  and the receptacle  154  and thus allow free movement and/or rotation of the receptacle  154  relative to the plenum  100 . The rest of the plenum wall  104 , including the first and second plenum walls  104   a  and  104   b , can also be spaced from the receptacle  154  sufficiently to accommodate this movement. This design for the plenum wall  104  can also allow for the plenum  100  to guide air through the air gap  124  along the receptacle  154 . By defining the air gap  124  along each side of the receptacle  154 , the plenum  100  provides a surface area on the receptacle  154  over which air may conduct heat from the receptacle  154 . 
     Now referring to  FIGS. 9 and 12 , a method  200  of operating a biological sample analyzer will be described. The method  200  can begin at step  202 , which corresponds to a startup of the at least one heater  186  of the biological sample analyzer  10 . Upon startup, the controller  46  controls the heater  186  to heat the receptacle  154  to an elevated temperature ET. As shown in  FIG. 12 , the receptacle  154  may be at an ambient temperature AT at an initial time to. In step  202 , the heater  186  heats the receptacle  154  from the ambient temperature AT at the initial time t 0  to the elevated temperature ET at the first time t 1 . In so doing, the controller  46  can determine the elevated temperature ET based on the ambient temperature AT and the target temperature TT. The elevated temperature ET can be stored in the memory  50 , and the controller  46  can look up the elevated temperature ET from predetermined value or values of the elevated temperature ET that are stored in the memory  50  based on the ambient and target temperatures AT and TT. Alternatively, the controller  46  can calculate the elevated temperature ET. The elevated temperature ET for a particular heating operation can be determined according to Equation (1): 
     
       
         
           
             
               
                 
                   
                     E 
                     ⁢ 
                     T 
                   
                   = 
                   
                     
                       T 
                       ⁢ 
                       T 
                     
                     + 
                     
                       
                         
                           T 
                           ⁢ 
                           T 
                         
                         - 
                         
                           A 
                           ⁢ 
                           T 
                         
                       
                       
                         S 
                         ⁢ 
                         F 
                       
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
         
         
           
             where: 
             ET=Elevated Temperature 
             TT=Target Temperature 
             AT=Ambient Temperature 
             SF=Initial Slope Factor 
           
         
       
    
     In Equation (1), the target temperature TT represents the temperature to which the biological sample within the consumable holder  162  is to be heated for the particular characteristic of the biological sample to be measured. As such, the target temperature TT will vary based on the particular characteristic to be measured. For example, for HbAl c levels, the target temperature TT can be 34° Celsius with a standard deviation of +/−0.4° Celsius when the characteristic to be measured is Hemoglobin. For HbAl c levels, the target temperature TT can be 34° Celsius with a standard deviation of +/−0.2° Celsius when the characteristic to be measured is agglutination. The target temperature TT can be 36° Celsius with a standard deviation of +/−0.4° Celsius when the characteristic to be measured is a ratio of albumin to creatinine. However, other target temperatures are contemplated. The elevated temperature ET may be in a range from greater than TT to about 50° Celsius, though elevated temperatures outside this range are also contemplated. The ambient temperature AT represents the temperature of the ambient environment outside the biological sample analyzer  10  as measured by the temperature sensor  194  adjacent the fan  192 , as previously described. The ambient temperature AT in which the biological sample analyzer  10  can be in a range from about 15° Celsius to about 32° Celsius, though other ambient temperatures are contemplated. The initial slope factor is a constant that adjusts for the amount of energy needed to apply to the system. If the amount of time that the elevated temperature ET is applied is increased, then the slope factor is increased. The calculations can assume that the consumable holder  162  and heater plates have a fixed mass. Thus, the slope factor can be selected to ensure that the total area under the curve (i.e., the total energy) remains substantially the same from the analysis of one biological sample to the next. 
     During step  202 , the feedback loop can be employed to raise the receptacle  154  to the elevated temperature ET (from time t 0  to time t 1 ), and then subsequently maintain the receptacle  154  at the elevated temperature ET (from time t 1  to time t 2 ). The feedback loop can be continuously updated as described above to control the heat applied by the at least one heater  186  to the receptacle  154 . In this case, the elevated temperature ET is used as the desired temperature to determine the temperature error. 
     Step  202  can be performed before the consumable holder  162  is inserted into the receptacle  154  to shorten the amount of time required to bring the consumable holder  162  up to the target temperature TT once the consumable holder  162  is disposed within the receptacle  154 . In step  206 , the consumable holder  162  can be inserted into the receptacle  154 . Preferably, the consumable holder  162  is inserted at insertion time t 1  between time t 1  and time t 2  as shown in  FIG. 12 . The cartridge sensor  174  can detect the insertion of the consumable holder  162  into the receptacle  154  in step  206 , and can communicate to the controller  46  that a consumable holder  162  has been inserted. During steps  202  and  206 , the controller  46  can operate the fan  192  at a first speed as will be discussed further below. The first speed can be zero or can be a relatively low speed, and thus, the fan can be off or can be moving slowly when at the first speed. 
     In step  210 , the controller  46  can determine whether the door  26  of the housing  14  remains open for a predetermined period. If the door  26  remains open for a certain amount of time after the consumable holder  162  is inserted into the receptacle  154 , then an unknown amount of heat can escape the biological sample analyzer  10  through the opening  22 . As result, the controller may have difficulty in determining how much heat is needed to bring the receptacle  154  to the target temperature TT. In one embodiment, the predetermined period of time can be about 15 seconds, though the period of time can vary. Further, a predetermined period of time can be manually chosen by an operator of the biological sample analyzer by providing an input to the HMI device  54 . If the door  26  is open for more than the predetermined period of time, in step  214  the HMI device  54  can produce an alert to inform the operator that the analysis has faulted. Further, the controller  46  can invalidate the current heating operation. If the door  26  is not open for the predetermined period of time, then the door sensor  30  can continue to monitor whether the door  26  is in the open or closed position throughout the entirety of the method  200 . 
     When an unheated consumable holder  162  is inserted into the receptacle  154  in step  206 , the lower temperature of the consumable holder  162  in relation to the receptacle  154  (which has been heated to the elevated temperature ET) can cause the temperature of the receptacle  154  to drop measurably. This temperature drop will cause an increase in the temperature error. After insertion, the feedback loop can be continuously updated as described above to heat the receptacle  154  at the elevated temperature ET (from time t 1  to time t 2 ) and drive the temperature error to zero. In this case, the desired temperature that is used to determine the temperature error is the elevated temperature ET. In at least some embodiments, the at least one heater  186  can increase the heating at a controlled rate that can be repeatable from one consumable holder to the next. 
     In step  218 , the controller  46  can direct the heater  186  to maintain the receptacle  154  at the elevated temperature ET for a first period of time that extends from the insertion time t 1  to a second time t 2  as shown in  FIG. 12 . During step  218 , the feedback loop can be continuously updated to maintain the receptacle  154  at the elevated temperature ET (from time t 1  to time t 2 ). Further, the fan  192  can be operated at the first speed, which is off or relatively low. Maintaining the receptacle  154  at the elevated temperature ET for the first period of time while the consumable holder  162  is disposed within the receptacle  154  aids in bringing the biological sample disposed within the consumable holder  162  up to the target temperature TT at a quicker rate than in conventional heaters. The first period of time FP can be a predetermined time stored in the memory  50 , and the controller  46  can look up the first period of time FP from predetermined value or values of the first period of time FP that are stored in the memory  50 . Alternatively, the first period of time FP can be entered by the operator into the HMI device  54 . Alternatively still, the controller  46  can calculate the first period of time FP. The first period of time FP can be determined according to Equation (2) as follows: 
       FP=(DTB+AT)*SDM  (2)
 
     where:
         FP=First Period of Time   DTB=Decay Time Base   AT=Ambient Temperature   SDM=Start Decay Multiplier       

     The decay time base DTB is an offset coefficient that is used to determine the first period of time FP. In some examples, DTB can be about 475. In some embodiments, the first period of time can be fixed when the consumable holder  162  is not determined to be cold as discussed below. The start decay multiplier SDM is a coefficient that is used to reduce the length of time that the consumable holder  162  is heated at the elevated temperature ET. In some embodiments, the Start Decay Multiplier SDM can be about 0.05. This ensures that heating at the elevated temperature ET is stopped before the consumable holder  162  reaches the target temperature. The ambient temperature AT represents the temperature of the environment external to the biological sample analyzer, which is determined by measuring the temperature of air entering the plenum  100  using the temperature sensor  194 . In Equation (2), the first period of time FP is determined based on the ambient temperature AT. Thus, the controller  46  assumes that the consumable holder  162  is at the ambient temperature AT when determining the first period of time FP. However, this might not always be the case as an operator can insert a cold consumable holder into the receptacle  154 . Therefore, the biological sample analyzer  10  can be configured to detect a cold consumable holder as described in further detail below. 
     In step  222 , the controller  46  can control the biological sample analyzer  10  to perform a temperature decay at the end of the first period of time FP, wherein the temperature of the receptacle  154  is reduced from the elevated temperature ET to the target temperature TT. In particular, the controller  46  can direct the at least one heater  186  to reduce the amount of heat applied to the consumable holder  162  before the consumable holder  162  exceeds the target temperature TT. In addition, the controller  46  can also operate the fan  192  at a second speed, faster than the first speed, to aid in reducing the amount of heat applied to the consumable holder  162 . In one embodiment, the controller  46  can direct the heater  186  to reduce its temperature from the elevated temperature ET to the target temperature TT over a second period of time that extends from the second time t 2  to the third time t 3  as shown in  FIG. 12 . As a result, the temperature of the receptacle  154  will decrease from the elevated temperature ET to the target temperature TT. As shown in  FIG. 12 , the pattern of temperature decrease from the elevated temperature ET to the target temperature TT can be linear, though other patterns of decreasing the temperature are contemplated. The temperature setpoint of the heater  186  from the second period of time to the third period of time t 3  can be calculated according to Equation (3) below: 
     
       
         
           
             
               
                 
                   SP 
                   = 
                   
                     ISP 
                     - 
                     
                       
                         ISP 
                         - 
                         
                           F 
                           ⁢ 
                           SP 
                         
                         - 
                         ID 
                       
                       
                         
                           T 
                           PID 
                         
                         - 
                         
                           T 
                           SD 
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
     where:
         SP=Instantaneous Temperature Setpoint   ISP=Initial Temperature Setpoint   FSP=Final Temperature Setpoint   ID=Initial Temperature Drop   THD=PID Time   TsD=Time to Start Decay       

     The initial temperature setpoint ISP is the temperature at time t 2  (e.g., the elevated temperature ET). The final temperature setpoint is the temperature at time t 3  (e.g., the target temperature TT). The initial temperature drop ID is an initial drop from the initial temperature setpoint to allow the decay to move quicker. In one example, this value can be set to about a half a degree. The P ID  time is the time as it is kept by the controller  46 . The time to start decay T SD  is the time that the temperature decay starts in step  222 . By reducing the temperature of the heater  186 , and thus the receptacle  154 , from the elevated temperature ET to the target temperature TT before the consumable holder  162  and the biological sample contained therein are raised to the target temperature TT, the biological sample analyzer  10  can ensure that the temperature of the consumable holder  162  can quickly increase to, but not overshoot, the target temperature TT. 
     In step  226 , after the temperature of the receptacle  154  is reduced to the target temperature TT and the consumable holder  162  is raised to the target temperature TT, the controller  46  can direct the heater  186  to maintain the receptacle  154  at the target temperature TT. This is shown in  FIG. 12  as occurring from the third time t 3  to the fourth time t 4 . In addition, the controller  46  can operate the fan  192  at the first speed, or another speed lower than the second speed, so as to limit further cooling of the receptacle  154 . Maintaining the receptacle  154  at the target temperature TT allows the consumable holder  162 , and the biological sample contained therein, to remain at the target temperature TT throughout the process of measuring the characteristic of the biological sample. 
     In step  230 , the controller  46  directs the motor  178  to actively mix the contents of the consumable holder  162 . In so doing, the motor  178  can rotate the shaft  182  so as to rotate, vibrate, or otherwise move the receptacle  154 , which transfers the motion to the consumable holder  162  contained within the receiving area  170 . Step  230  can be performed concurrently with step  222  (i.e., between the second and third times t 2  and t 3  in  FIG. 12 ). Alternatively, step  230  can be performed while the heater  186  maintains the receptacle  154  at the target temperature TT (i.e., concurrently with step  226  between the third and fourth times t 3  and t 4  in  FIG. 12 ), or concurrently with steps  222  and  226 . 
     Once the biological sample has been sufficiently mixed for a particular measuring operation and enough time has passed for the consumable holder  162  to stabilize at the target temperature, the sensor  190  can measure the characteristic of the biological sample in step  234 . As previously stated, the characteristic can be, for example, an HbAl C level of the biological sample, a ratio of albumin to creatinine in the biological sample, or other suitable characteristic. Once measured, the measured characteristic can be transmitted to the controller  46  from the sensor  190 . Referring to the graph in  FIG. 12 , step  234  can be performed after the third time t 3  and before the fourth time t 4 , while the receptacle  154  is maintained at the target temperature TT. 
     Once the characteristic of the biological sample has been measured, an operator can remove the consumable holder  162  from the biological sample analyzer  10  in step  238 . To achieve this, the operator can open the door  26  of the housing  14  and manually remove the consumable holder  162  from the receiving area  170  by grasping the handle  166  connected to the consumable holder  162 . Once the consumable holder  162  has been removed from the receiving area  170 , step  242  can be performed, in which the controller  46  directs the heater  186  to heat the receptacle  154  from the target temperature TT back to the elevated temperature ET. This step is performed so as to preheat the receiving area  170  in preparation for another consumable holder  162  being inserted into the receptacle  154 . As shown in  FIG. 12 , step  242  begins at the fourth time t 4 , and continues until the fifth time t 5 , is which is the time at which the receptacle  154  again reaches the elevated temperature. This allows for a minimal delay between the end of one heating and measuring operation for one consumable holder  162  and the beginning of a subsequent heating and measuring operation for another consumable holder  162 . In one embodiment, this delay can be less than or equal to 20 seconds, though other delays are contemplated. 
     Referring to  FIGS. 9 and 11 , a method of operating the fan  192  will now be described. In step  246 , the controller  46  can direct the fan to operate at a first speed S 1  as the receptacle  154  is brought up to and maintained at the elevated temperature ET (from the from the initial time t 0  to the second time t 2  in  FIG. 13 ). The first speed can also be referred to as an idle or low speed. In embodiments where the first speed S 1  is greater than zero, the air is forced through the air duct  120  of the plenum  100  and along the receptacle  154  at the first speed S 1 . Operating the fan  192  at a first speed S 1  that is greater than zero can function to transfer excess heat to the air flowing through the plenum  100 , and thus remove at least a portion of the excess heat with the air flowing out of the air exhaust  42  of the housing  14 . This can prevent components in the system from overheating, and can prevent the temperature sensor  194  adjacent the fan  192  that measures the ambient temperature of the air from producing biased measurements as a result of the heat produced by the heater  186 . 
     While the fan  192  is operated at the first speed S 1 , the temperature sensor  194  can sense the ambient temperature AT of the air entering the biological sample analyzer  10  through the air intake  38  in step  250  and transmit the ambient temperature to the controller  46 . The controller  46  can use the ambient temperature AT sensed by the temperature sensor  194  in the calculations described above for determining various temperatures in the heating profile. In step  254 , the controller  46  can direct the fan  192  to increase speed from the first speed S 1  to the second speed S 2  as the heater  186  transitions the receptacle  154  from the elevated temperature ET to the target temperature TT as shown in  FIG. 13 . In  FIG. 12 , this occurs during the second time t 2 . The fan  192  can be operated at the second speed S 2  during the second period of time, which is from the second time t 2  to the third time t 3 . The second speed S 2 , which is faster than the first speed S 1 , can also be referred to as a medium speed. The fan  192  thus forces air through the air duct  120  of the plenum  100  and along the receptacle  154  at the second speed S 2 . As the fan  192  is operated at the second speed S 2 , heat can be transferred from the receptacle  154  to the air forced through the plenum  100  at a quicker rate than otherwise occurs when the fan  192  is operated at the first speed S 1 . This further aids in preventing the consumable holder  162  from overheating past the target temperature TT. 
     In step  258 , once the receptacle  154  has reached the target temperature TT at the third time t 3  (as shown in  FIG. 12 ), the controller  46  can direct the fan  192  to reduce speeds from the second speed S 2  to a third speed S 3 . The third speed S 3  is less than the second speed S 2 . For example, the third speed S 3  can be equal to the first speed S 1 , or can be another speed another speed below the second speed S 2 , as shown in  FIG. 13 . Step  258  can be performed while the heater  186  is maintaining the receptacle  154  at the target temperature TT. Like step  246 , operating the fan  192  at the third speed S 3  in step  258  can function to transfer excess heat to the air flowing through the plenum  100 , and thus remove some of the excess heat with the air flowing out of the air exhaust  42  of the housing  14 . 
     As described above, the biological sample analyzer  10  can include a filter  196 . If the controller  46  senses that the power consumption of the heater  186  is below expected, the controller  46  can recognize that the filter  196  may be clogged and can subsequently direct the fan  192  to operate during the temperature decay at an elevated speed that is higher than the second speed Sz. Operating the fan  192  at the elevated speed can compensate for the reduced amount of air that is entering the air plenum  100  as a result of the clogged filter  196 , which allows the biological sample analyzer  10  to continue performing heating and sensing operations as normal. As a result, the working life of the filter  196  can be extended. In addition to transitioning the fan  192  to the elevated speed when the filter  196  is clogged, the controller  46  can also produce an alert via the HMI device  54  that indicates to the operator of the biological sample analyzer  10  that the filter  196  is clogged and may require replacement. 
     Referring to  FIGS. 9 and 10 , as described above, in some instances, an operator could insert a cold consumable holder into the biological sample analyzer  10  before allowing the consumable holder to reach ambient temperature. The biological sample analyzer  10  can be configured to detect a cold consumable holder and apply additional heating to the cold consumable holder so as to heat the cold consumable holder to the target temperature for analysis.  FIG. 10  shows a method of operating the biological sample analyzer  10  that includes detecting a cold consumable holder and applying additional heating to a detected cold consumable holder so as to heat the cold consumable holder to the target temperature for analysis. The method of  FIG. 10  can be implemented as part of step  206  in  FIG. 9 . In general, the sample analyzer  10  can be configured to detect whether the consumable holder is below an ambient temperature based on a decrease in temperature of the receptacle when the consumable holder is inserted into the receptacle. Based on the detection, the analyzer  10  can be configured to 1) control the at least one heater to apply a first amount of thermal energy to the consumable holder when the controller detects that the consumable holder is not below the ambient temperature so as to heat the consumable holder to a target temperature, and 2) control the at least one heater apply a second amount of thermal energy, greater than the first amount of thermal energy, to the consumable holder when the controller detects that the consumable holder is below the ambient temperature so as to heat the consumable holder to the target temperature. 
     As described above, when an unheated (i.e., cold or ambient temperature) consumable holder  162  is inserted into the receptacle  154 , the lower temperature of the consumable holder  162  in relation to the receptacle  154  (which has been heated to the elevated temperature ET in step  202 ) will cause the temperature of the receptacle  154  to drop measurably. This temperature drop will cause an increase in the temperature error (e.g., the difference between the desired temperature and the temperature detected by the at least one heater sensor  188 ). The temperature drop for a cold consumable holder will be more rapid than that for an ambient temperature consumable holder. Therefore, the increase in temperature error will be more significant for a cold consumable holder than for an ambient temperature consumable holder. However, insertion of the cold consumable holder may take time (e.g., 5 seconds) to have an effect on the temperature of the receptacle  154  that could be used to identify the consumable holder  162  as a cold consumable holder. Eventually, as the feedback loop returns the receptacle  154  to the elevated temperature ET, the temperature error will be driven back towards zero. 
     In steps  262 - 270 , the controller  46  determines whether the consumable holder is below the ambient temperature AT and is thus a cold consumable holder. In particular, in step  262 , each of the at least one heater sensor  188  detects an initial temperature of the receptacle  154  after the consumable holder  162  is inserted into the receptacle  154 . Preferably, this initial temperature is taken after an initial period of time so as to allow effects of the cold consumable holder to be experienced by the receptacle  154 , but before the receptacle  154  returns to the elevated temperature ET. For example, the initial temperature can be measured in seconds after insertion of the consumable holder, such as one second, two seconds, three seconds, four seconds, five seconds, six seconds, seven seconds, eight seconds, nine seconds, or ten seconds after consumable holder insertion. In a preferred embodiment, the initial temperature is taken at five seconds after insertion of the consumable holder. The initial period of time can be based on the thermal time constant of the system, which is the time needed for the at least one heater sensor  188  to respond to a change in temperature. In step  266 , the controller  46  can determine an initial temperature error of the receptacle  154  based on the initial temperature taken in step  262 . 
     In step  270 , the controller  46  can compare the initial temperature error to a predetermined threshold. If the initial temperature error is within the predetermined threshold (e.g., above or below as appropriate based on how the error is calculated), then the controller  46  can determine that the consumable holder  162  is not a cold consumable holder, and the consumable holder  162  can be heated as described above in relation to the first period of time FP (step  274 ). If, on the other hand, the temperature error is outside of the predetermined threshold (e.g., above or below as appropriate based on how the error is calculated), then the controller  46  can determine that the consumable holder  162  is a cold consumable holder and can determine that additional heating is needed to heat the consumable holder  162  to the target temperature (step  278 ). In one embodiment, the predetermined threshold can be based on, for example, an expected temperature error, such as (without limitation) a maximum expected temperature, for a non-cold consumable holder at the ambient temperature AT measured by the temperature sensor  194 . If the initial temperature error is outside of a specified range of the expected temperature error (e.g., greater than 20 percent of the expected temperature error), then the controller  46  can determine that the consumable holder  162  is a cold consumable holder. In such a case, the controller  46  can optionally determine an estimate of an extended first period of time needed to heat the consumable holder  162  to the target temperature based on the initial temperature error. In one example, the estimate of the extended first period of time can be calculated as shown in Equation (4): 
     
       
         
           
             
               
                 
                   
                     E 
                     ⁢ 
                     F 
                     ⁢ 
                     
                       P 
                       E 
                     
                   
                   = 
                   
                     
                       F 
                       ⁢ 
                       P 
                       ⁢ 
                       
                         
                           T 
                           ⁢ 
                           
                             E 
                             i 
                           
                         
                         
                           T 
                           ⁢ 
                           
                             E 
                             E 
                           
                         
                       
                     
                     + 
                     FPc 
                   
                 
               
               
                 
                   ( 
                   4 
                   ) 
                 
               
             
           
         
       
     
     where: 
     EFP E  is an estimate of the extended first period of time; 
     FP is the first period of time discussed above; 
     TE i  is the initial temperature error; 
     TE E  is the expected temperature error; and 
     FP C  is a constant. 
     In step  276 , the controller  46  can optionally notify the operator that a cold consumable holder is detected. The notification can be provided to the operator via the HMI device  54 , which can produce an alert indicating this condition to the operator. In some embodiments, the controller  46  can provide the estimate of the additional heating time to the operator. The operator may choose to take manual action in response to the relative cold condition of the consumable holder  162 , if desired. 
     In step  278 , the controller  46  can apply additional heating to the receptacle  154  by increasing the thermal energy transferred to the consumable holder  162 . This increase in thermal energy transfer can aid in driving the temperature error to zero. In one embodiment, the thermal energy transferred can be increased by increasing the power provided to the heater  186 , which can cause the heater  186  to increase its temperature. However, in such embodiments, the at least one heater  186  may require significantly more wattage, which may negatively affect the cost and accuracy of the heating system. In an alternative embodiment, the controller  46  can increase the first period of time during which the receptacle  154  is maintained at the elevated temperature. For example, this increase can be up to about 60 seconds, based upon the extent to which the temperature error is outside the predetermined range. 
     Therefore, in step  278 , the controller  46  can determine an actual extended first period of time EFPA to be used to heat the consumable holder  162  to the target temperature. Further, the controller  46  can cause the at least one heater  186  to heat the receptacle  154  to the elevated temperature ET for the actual extended first period of time EFPA in lieu of the first period of time FP discussed above. The actual extended first period of time EFPA can be determined based on a summation of a set of the detected temperature errors that are detected by the at least one heater sensor  188  over time for a particular consumable holder  162  so as to provide a more accurate determination than using a single temperature error (as used in the estimated extended first period of time EFPE above). In one example, the actual extended first period of time can be calculated as shown in Equation (5): 
     
       
         
           
             
               
                 
                   
                     E 
                     ⁢ 
                     F 
                     ⁢ 
                     
                       P 
                       A 
                     
                   
                   = 
                   
                     F 
                     ⁢ 
                     P 
                     ⁢ 
                     
                       
                         Σ 
                         ⁢ 
                         T 
                         ⁢ 
                         
                           E 
                           S 
                         
                       
                       
                         Σ 
                         ⁢ 
                         T 
                         ⁢ 
                         
                           E 
                           E 
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   5 
                   ) 
                 
               
             
           
         
       
     
     where:
         EFP A  is the actual extended first period of time;   FP is the first period of time discussed above;   Σ TE S  is the sum of the detected temperature errors in the set; and   Σ TE E  is the sum of the expected temperature errors.       

     In the Equation (5), the first temperature error in the sum of detected temperature errors Σ TE S  can correspond to about the time that a consumable holder is inserted into the receptacle  154 , although other starting temperature errors can be employed. The last temperature error in the sum Σ TE S  corresponds to a temperature error has not been driven to zero (i.e., before the receptacle  154  reaches the elevated temperature ET). In one embodiment, the last temperature error in the set can correspond to a temperature error that is within a specified percentage of a detected maximum temperature error, although other ending temperature errors can be employed. For example, the specified percentage can be about 75 percent, where the last temperature error in the set would correspond to period where the temperature of the receptacle  154  is increasing and the temperature error is decreasing. The controller  46  can identify the detected maximum temperature error from the temperature errors that are accumulated over time for the particular consumable holder  162 , and determine the last temperature error of the set from the detected maximum temperature error. 
     Biological sample analyzers of the present disclosure may provide one or more benefits over conventional analyzers, including one or more of the following benefits. For example, a biological sample analyzer of the present disclosure may be capable of detecting when an inserted consumable holder is a cold consumable holder and adjusting heating of the cold consumable holder to bring the consumable holder of the desired target temperature, whereas a conventional analyzer might not be capable of compensating for a cold consumable holder. This can reduce biases or errors in results of the sample analysis that can occur due to a consumable holder not being properly heated to the target temperature. As another example, a biological sample analyzer of the present disclosure may be capable of heating a consumable holder with a given mass to a target temperature faster than a comparable conventional analyzer. This can result in shorter wait times for measurement results, and shorter wait times between biological analyses of separate consumable holders. As yet another example, a biological sample analyzer of the present disclosure may be capable of cooling its heaters quicker than a comparable conventional analyzer due to the focused air flow over the heaters through the plenum. The focuses air flow can also enable an analyzer of the present disclosure to be operated at a higher temperature than the target temperature so as to more quickly heat a consumable holder. 
     While various inventive aspects, concepts and features of the inventions may be described and illustrated herein as embodied in combination in the exemplary embodiments, these various aspects, concepts and features may be used in many alternative embodiments, either individually or in various combinations and sub-combinations thereof. Unless expressly excluded herein all such combinations and sub-combinations are intended to be within the scope of the present inventions. Still further, while various alternative embodiments as to the various aspects, concepts, and features of the inventions—such as alternative materials, structures, configurations, methods, circuits, devices and components, software, hardware, control logic, alternatives as to form, fit and function, and so on—may be described herein, such descriptions are not intended to be a complete or exhaustive list of available alternative embodiments, whether presently known or later developed. Those skilled in the art may readily adopt one or more of the inventive aspects, concepts or features into additional embodiments and uses within the scope of the present inventions even if such embodiments are not expressly disclosed herein. Additionally, even though some features, concepts or aspects of the inventions may be described herein as being a preferred arrangement or method, such description is not intended to suggest that such feature is required or necessary unless expressly so stated. Still further, exemplary or representative values and ranges may be included to assist in understanding the present disclosure; however, such values and ranges are not to be construed in a limiting sense and are intended to be critical values or ranges only if so expressly stated. Moreover, while various aspects, features, and concepts may be expressly identified herein as being inventive or forming part of an invention, such identification is not intended to be exclusive, but rather there may be inventive aspects, concepts, and features that are fully described herein without being expressly identified as such or as part of a specific invention, the scope of the inventions instead being set forth in the appended claims or the claims of related or continuing applications. Descriptions of exemplary methods or processes are not limited to inclusion of all steps as being required in all cases, nor is the order that the steps are presented to be construed as required or necessary unless expressly so stated. 
     While the invention is described herein using a limited number of embodiments, these specific embodiments are not intended to limit the scope of the invention as otherwise described and claimed herein. The precise arrangement of various elements and order of the steps of articles and methods described herein are not to be considered limiting. For instance, although the steps of the methods are described with reference to sequential series of reference signs and progression of the blocks in the figures, the method can be implemented in a particular order as desired. 
     Unless explicitly stated otherwise, each numerical value and range should be interpreted as being approximate as if the word “about,” “approximately,” or “substantially” preceded the value or range. The terms “about,” “approximately,” and “substantially” can be understood as describing a range that is within 15 percent of a specified value unless otherwise stated. 
     Illustrative Embodiments 
     The foregoing description will be understood with reference to the following illustrative embodiments. It should be understood, however, that the application is not limited to the precise illustrative embodiments discussed below. 
     Illustrative Embodiment 1: A biological sample analyzer, comprising: a housing having at least one outer wall that defines an internal cavity therein; 
     a receptacle disposed within the internal cavity, the receptacle configured to support a consumable holder containing a biological sample; 
     at least one heater configured to apply heat to the consumable holder when the consumable holder is supported by the receptacle; 
     at least one heater sensor configured to detect a temperature of the receptacle; and 
     a controller configured to 1) direct the at least one heater to heat to an elevated temperature before the consumable holder is disposed in the receptacle, and 2) direct the at least one heater to heat the consumable holder to a target temperature, less than the elevated temperature, by i) applying the elevated temperature to the consumable holder and ii) subsequently reducing an amount of heat applied to the consumable holder before the consumable holder exceeds the target temperature. 
     Illustrative Embodiment 2: The biological sample analyzer of Illustrative Embodiment 1, wherein the controller is configured to direct the at least one heater to maintain the receptacle at the elevated temperature during a first period of time after the consumable holder is disposed in the receptacle. 
     Illustrative Embodiment 3: The biological sample analyzer of Illustrative Embodiment 2, wherein the controller is configured to direct the at least one heater to reduce the amount of heat applied to the consumable holder by directing the at least one heater to decrease its temperature from the elevated temperature to the target temperature during a second period of time that is after the first period of time. 
     Illustrative Embodiment 4: The biological sample analyzer of Illustrative Embodiment 3, comprising a sensor configured to measure a characteristic of the biological sample, wherein the controller is configured to direct the at least one heater to maintain the target temperature while the sensor measures the characteristic of the biological sample. 
     Illustrative Embodiment 5: The biological sample analyzer of Illustrative Embodiment 4, wherein the controller is configured to direct the at least one heater to heat the receptacle to the elevated temperature after the sensor measures the characteristic of the biological sample and the consumable holder is removed from the receptacle. 
     Illustrative Embodiment 6: The biological sample analyzer of Illustrative Embodiment 5, wherein the at least one outer wall of the housing defines an air intake and an air exhaust, and the biological sample analyzer comprises a fan configured to force air along a path that extends from the air intake, along the receptacle, and to the air exhaust so as to cool the at least one heater. 
     Illustrative Embodiment 7: The biological sample analyzer of Illustrative Embodiment 6, comprising a temperature sensor positioned adjacent the fan, wherein the temperature sensor is configured to measure an ambient temperature of the air. 
     Illustrative Embodiment 8: The biological sample analyzer of any one of Illustrative Embodiments 6 and 7, wherein the controller is configured to operate the fan at a first speed when the at least one heater is at the elevated temperature, and at a second speed, greater than the first speed, as the temperature of the at least one heater is decreasing from the elevated temperature to the target temperature. 
     Illustrative Embodiment 9: The biological sample analyzer of Illustrative Embodiment 8, wherein the controller is configured to direct the fan to operate at the first speed when the sensor measures the characteristic of the biological sample. 
     Illustrative Embodiment 10. The biological sample analyzer of any one of Illustrative Embodiments 1 to 9, wherein the at least one heater includes a first heater attached to a first side of the receptacle and a second heater attached to a second side of the receptacle opposite the first side, and the at least one heater sensor includes a first heater sensor attached to the receptacle adjacent the first heater and a second heater sensor attached to the receptacle adjacent the second heater. 
     Illustrative Embodiment 11: The biological sample analyzer of any one of Illustrative Embodiments 1 to 10, wherein the housing defines a housing opening configured to receive the consumable holder therethrough and into the receptacle, the housing including a door configured to provide access to the receptacle, wherein the door is configured to be moved between an open position, wherein the housing is configured to receive the consumable holder through the opening and into the receptacle, and a closed position, wherein the door covers the housing opening. 
     Illustrative Embodiment 12: The biological sample analyzer of Illustrative Embodiment 11, comprising a door sensor configured to detect whether the door is open, wherein the controller is configured to produce an alert when the door sensor senses that the door is open for a specified period of time. 
     Illustrative Embodiment 13: The biological sample analyzer of any one of Illustrative Embodiments 1 to 12, wherein:
         the controller is configured to determine temperature errors over time, wherein each temperature error is based on a desired temperature and a detected temperature received from the at least one heater sensor; and the controller is configured adjust heat applied by the at least one heater to the receptacle based on the temperature errors so as to heat the receptacle to the desired temperature.       

     Illustrative Embodiment 14: A method of operating a biological sample analyzer, the method comprising: 
     causing at least one heater to heat a receptacle supported in an internal cavity of a housing of the biological sample analyzer to an elevated temperature; 
     inserting a consumable holder containing a biological sample into the receptacle such that the receptacle applies heat to the consumable holder at the elevated temperature; and 
     causing the at least one heater to reduce an amount of heat applied to the receptacle before the consumable holder exceeds a target temperature, less than the elevated temperature, so as to prevent the consumable holder from exceeding the target temperature. 
     Illustrative Embodiment 15: The method of Illustrative Embodiment 14, wherein causing the at least one heater to reduce an amount of heat applied to the receptacle comprises causing a fan to force air around the receptacle so as to cool the receptacle. 
     Illustrative Embodiment 16: The method of any one of Illustrative Embodiments 14 and 15, wherein causing at least one heater supported by the receptacle to heat the receptacle to an elevated temperature comprises adjusting heat applied by the at least one heater to the receptacle based on temperature errors, where each temperature error is determined based on a detected temperature received from at least one heater sensor supported by the receptacle and a desired temperature. 
     Illustrative Embodiment 17: The method of any one of Illustrative Embodiments 14 to 16, comprising maintaining the receptacle at the elevated temperature for a first period of time after the consumable holder is received in the receptacle. 
     Illustrative Embodiment 18: The method of Illustrative Embodiment 17, wherein reducing the amount of heat applied to the consumable holder includes decreasing a temperature of the at least one heater from the elevated temperature to the target temperature over a second period of time that is after the first period of time. 
     Illustrative Embodiment 19: The method of any one of Illustrative Embodiments 14 to 18, comprising causing a sensor to measure a characteristic of the biological sample while maintaining the at least one heater at the target temperature. 
     Illustrative Embodiment 20: The method of Illustrative Embodiment 19, comprising directing the at least one heater to heat the receptacle to the elevated temperature after the sensor measures the characteristic of the biological sample and the consumable holder is removed from the receptacle.