Patent Publication Number: US-2022228788-A1

Title: Freezing device and a method using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Taiwanese Patent Application No. 110102369, filed on Jan. 21, 2021. 
     FIELD 
     The disclosure relates to a freezing device, and more particularly to a freezing device for freezing a liquid to produce shaped solid coolant pieces and a method using the same. 
     BACKGROUND 
     In recent years, cryosurgery is commonly used to reduce the chance of a tumor recurrence after surgery. Liquid nitrogen with a temperature lower than −196° C. is used to directly contact and destroy cells surrounding an excision site. However, the rapid atomization and flowability of the liquid nitrogen can easily cause unclear surgical vision that results in large-scale necrosis of normal tissues around the excision site and other complications. 
     According to clinical research reports, malignant tumor cells can be destroyed at a temperatures below −60° C., and the use of liquid nitrogen as a medical treatment is not absolutely necessary. Instead, solid ethanol at a temperature lower than −114° C. can be used to contact and destroy the cells around the excision site. To solidify the ethanol, an ethanol-water solution is directly poured into and stirred with a low temperature liquid nitrogen until a thermal equilibrium is reached, thereby forming a solidified ethanol mixture. However, because only part of the ethanol-water solution is solidified, this method encounters difficulties in obtaining a completely solidified ethanol-water mixture. 
     SUMMARY 
     One object of the disclosure is to provide a freezing device for freezing a liquid mixture so as to produce a shaped solid coolant piece, such as a solid coolant piece for cryotherapy. 
     According to the object, a freezing device includes a container and a tray. 
     The container defines a receiving space which opens upward and has a container bottom wall underlying the receiving space. 
     The tray is removably disposed in the receiving space and has a tray plate situated above the container bottom wall in a spaced apart manner. The tray plate has an upper panel part, and a plurality of spaced-apart receptacles for receiving the liquid mixture. The upper panel part interconnects the receptacles and isolates interior spaces of the receptacles from a bottom region of the receiving space between the tray plate and the container bottom wall. 
     When liquid nitrogen is introduced into a region between the tray plate and the container bottom wall, the liquid mixture received in the receptacles is solidified by heat absorption and vaporization of the liquid nitrogen received in the receiving space. 
     Another object of the disclosure is to provide a method of freezing a liquid mixture to produce a shaped solid coolant piece, such as a shaped solid coolant piece for cryotherapy. 
     Accordingly, a method of the disclosure includes providing a container defining a receiving space which opens upward, and having a container bottom wall underlying the receiving space; positioning a tray in the receiving space, the tray having a tray plate situated above the container bottom wall in a spaced apart manner, and having a plurality of spaced apart receptacles; filling the receptacles with a liquid mixture; introducing liquid nitrogen into a region between the tray plate and the container bottom wall until the liquid nitrogen contacts the receptacles, thereby solidifying the liquid mixture. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiment with reference to the accompanying drawings, of which: 
         FIG. 1  is a perspective view of a freezing device according to an embodiment of the disclosure illustrating a cover to cover a tray connected to a container; 
         FIG. 2  is an exploded perspective view of the embodiment illustrating the tray and the container of the freezing device; 
         FIG. 3  is a sectional view of the embodiment illustrating probes disposed in the tray attached to the container of the freezing device; and 
         FIG. 4  is a perspective view of the embodiment illustrating a variant of the tray of the freezing device. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 to 3  illustrates a freezing device for separately receiving a liquid mixture  9  and liquid nitrogen  8  to solidify the liquid mixture  9  therein. In this embodiment, the liquid mixture  9  after being solidified is used for cryotherapy treatment of tumor. The liquid mixture  9  includes an ethanol water solution and liquid nitrogen; the ethanol water solution has a concentration of more than 80%; a volume ratio of the ethanol water solution to liquid nitrogen ranges from 1:1 to 1:5. By adding liquid nitrogen to the ethanol water solution, a temperature of the liquid mixture  9  can be quickly reduced to a freezing point (e.g. −110° C.). In addition, after being solidified, the liquid mixture  9  can be easily demolded. The liquid mixture  9  may also include, but not limited to, another substance, for example, iodine or isopropyl alcohol. 
     The freezing device of the disclosure includes a container  1 , a tray  2 , a top cover  3 , and a plurality of probes  4 . 
     The container  1  has a container bottom wall  10 , a container surrounding wall  11  extending upwardly from the container bottom wall  10 , and a reinforcement member  12 . The container  1  defines a receiving space  111  which opens upward to receive the liquid nitrogen  8 . The container bottom wall  10  underlies the receiving space  111 . The container surrounding wall  11  has an outer surface  113 , and a plurality of hollow members  114  formed on the outer surface  113  and respectively defining insertion holes  112 . The insertion holes  112  open at a top end of the container surrounding wall  11  and are formed outside of the receiving space  111 . In this embodiment, the container  1  is exemplified as having a depth of 4.3 cm in the receiving space  111  and a wall thickness of 2.5 mm. Each insertion hole  112  extend through top and bottom of the corresponding hollow member  114 . The container  1  is made of a thermal insulation material, e.g. a silicone rubber, having a poor thermal conductivity, so that a heat exchange rate between the receiving space  111  and an external environment can be reduced to prevent the liquid nitrogen S received in the container  1  from rapidly vaporizing and escaping. Because the container  1  is made of a thermal insulation material, frostbite of a person&#39;s skin due to contacting with the container  1  can be avoided. The reinforcement member  12  is embedded in an upper portion of the container surrounding wall  11  of the container  1  to maintain the shape of the container  1 . Particularly, the reinforcement member  12  is made of a metal material and loops around the receiving space  111  to avoid deformation of the container surrounding wall  11 . Because the reinforcement member  12  is embedded in the container  1 , a user can avoid accidentally contacting the reinforcement member  12  which is cooled to a freezing temperature by liquid nitrogen, thereby reducing the risk of skin injury. 
     The tray  2  is removably disposed in the receiving space  111 , and has a tray plate  21  situated above the container bottom wall  10  in a spaced apart manner, a tray surrounding wall  22  extending upwardly from the tray plate  21 , and a plurality of hanging hooks  23  connected to the tray surrounding wall  22 . 
     The tray plate  21  has an upper panel part  213 , and a plurality of spaced-apart receptacles  211  for receiving the liquid mixture  9 . The receptacles  211  are interconnected by the upper panel part  213 . As shown in  FIG. 3 , the upper panel part  213  has a top surface  213   a  and a bottom surface  213   b.  The receptacles  211  open at the top surface  213   a  and protrudes downward from the bottom surface  213   b.  The upper panel part  213  serves as a partition to isolate interior spaces of the receptacles  211  from a bottom region of the receiving space  111  between the upper panel part  213  of the tray plate  21  and the container bottom wall  10 . When liquid nitrogen  8  is introduced into the bottom region between the tray plate  21  and the container bottom wall  10 , the liquid mixture  9  received in the receptacles  211  is solidified by heat absorption and vaporization of the liquid nitrogen S received in the bottom region of the receiving space  111 . As shown in  FIG. 1 , each receptacle  211  is in a truncated cone shape, and is exemplified as having an opening with a diameter of 3.8 cm and a volume of 15 ml.  FIG. 4  illustrates a variant in which some receptacles  211  are formed into a rectangular parallelepiped shape. However, the shape of each receptacle  211  is not limited hereto, and the number of the receptacles  211  is not limited by this disclosure. 
     When the tray  2  is disposed in the receiving space  111 , the top surface  213   a  of the upper panel part  213  of the tray plate  21  is lower than the top end of the container surrounding wall  11  so that the bottom surface  213   b  of the tray plate  21  and the receptacles  211  are immersed in the liquid nitrogen received in the bottom region of the receiving space  111  of the container  1 . As such, a contact area between the tray  2  and the liquid nitrogen  8  can be increased to increase a cooling rate of the liquid mixture  9  in the receptacles  211  so that the temperature of the solidified liquid mixture  9  can be maintained and the solidified liquid mixture  9  cannot melt easily. In this embodiment, each receptacle  211  is exemplified as having a depth of 2 cm. When the liquid nitrogen  8  in the receiving space  111  gradually vaporize, the receptacles  211  can still be partially immersed in the liquid nitrogen  8 . Further, a wall thickness of each receptacle  211  preferably ranges between 0.5 mm and 0.8 mm. When the wall thickness of each receptacle  211  is 0.8 mm, heat transfer is facilitated but not overly fast. The wall thickness of each receptacle  211  may also be greater than 0.8 mm in order to solidify the liquid mixture  9  at a lower speed to prevent the vaporized liquid nitrogen from being wrapped into the liquid mixtures  9 . When the thickness of each receptacle  211  ranges between 0.5 mm and 0.8 mm, the liquid mixture  9  received in the receptacles  211  can be quickly solidified by heat absorption of the liquid nitrogen  8  received in the receiving space  111 , but will not produce cracks in the solidified liquid mixture  9 . 
     The tray surrounding wall  22  extends upward from and loops along an outer periphery of the upper panel part  213  of the tray plate  21  to prevent the liquid mixture  9  from overflowing outward from the tray  2  and also prevent the liquid nitrogen  8  from flowing into the receptacles  211 . When the tray  2  is disposed in the receiving space  111 , the tray surrounding wall  22  is surrounded by the container surrounding wall  11 . The tray surrounding wall  22  and the container surrounding wall  11  defines therebetween two passageways  24  for passage of liquid or gaseous nitrogen. Each passageway  24  opens at the top end of the container surrounding wall  11  and communicates the bottom region of the receiving space  111  between the tray plate  21  and the container bottom wall  10 . In this embodiment, the upper panel part  213  of the tray plate  21  has two indenting parts  213   c  respectively formed in two opposite sides of the outer periphery thereof, and the tray surrounding wall  22  has two indenting parts  222  respectively formed in two opposite sides thereof. Each indenting part  213   c  and each indenting part  222  indents inwardly to extend away from the container surrounding wall  11  so that two passageways  24  are formed between the tray surrounding wall  22  and the container surrounding wall  11 . Each passageway  24  allows the vaporized liquid nitrogen  8  in the receiving space  111  to flow outward from the container  1 . The liquid nitrogen  8  can be introduced into the receiving space  111  through the passageways  24 . In other embodiments, the number of the passageways  24  may be one or more than three. 
     In this embodiment, each of the hanging hooks  23  protrudes sideward from a top end of the tray surrounding wall  22 , passes through the top end of the container surrounding wall  11 , and then extends downward to enter a respective one of the insertion holes  112  in a removable manner so that the tray  2  is stably hung on the container surrounding wall  11 . The length of each hanging hook  23  inserted into the insertion hole  112  is arranged to correspond to the height of the container surrounding wall  11  so as to support and strengthen the container surrounding wall  11  and prevent deformation of the container surrounding wall  11 . However, the insertion holes  112  are not absolutely necessary. In other embodiments, the hanging hooks  23  can be removably and directly attached to the top end of the container  1 , and the insertion holes  112  are omitted. As shown in  FIG. 1 , the tray surrounding wall  22  is four-sided, and the hanging hooks  23  are disposed on two sides of the tray surrounding wall  22  which are opposite along one of a lengthwise direction and a widthwise direction of the tray  2 . In some embodiments, as shown in  FIG. 4 , the hanging hooks  23  are disposed on four sides of the tray surrounding wall  22 . When the hanging hooks  23  are attached to the top end of the container surrounding wall  11 , the opening of the receiving space  111  is prevented from deforming. 
     The tray  2 , in this embodiment, is made of a stainless steel which can provide good heat conduction for rapidly attaining a thermal equilibrium between the liquid mixture in the receptacles  211  and the liquid nitrogen in the receiving space  111 , and for increasing the rate of solidifying the liquid mixture. The tray  2  made of stainless steel has good corrosion and heat resisting properties and good low temperature strength. Therefore, the tray  2  can be sterilized by using high temperature heat, or disinfectants, and will not deform when contacting extremely low temperature liquid nitrogen. 
     The top cover  3  is removably disposed on the top end of the container  1  to cover the receiving space  111  of the container  1 . After the tray  2  is sterilized, it can be placed in the receiving space  111  of the container  1  and is covered by the top cover  3  to avoid exposure to an external environment which can cause contamination. The top cover  3  has a plurality of through holes  31  respectively aligned with the hanging hooks  23  so that top parts of the hanging hooks  23  can protrude outwardly and respectively from the through holes  23 , thereby allowing the top cover  3  to tightly abut against the top end of the container  1 . 
     The probes  4  are respectively and removably disposed in the receptacles  211  in an upright manner. In the drawings, only two probes  4  respectively inserted into two of the receptacles  211  are shown as an exemplification. When the liquid mixture  9  in the receptacles  211  is cooled and solidified around the probes  4 , the probes  4  are inserted into the solidified liquid mixture  9 . The probe  4  is convenient for removal of the solidified pieces of the liquid mixture  9  from the receptacles  211 . 
     In use, the tray  2  is placed in the receiving space  111 , and the hanging hooks  23  are respectively inserted into the insertion holes  112  for the tray  2  to be hung in the receiving space  111 . The liquid mixture  9 , which is premixed and pre-cooled, but not solidified, is filled in the receptacles  211  (see one of three rows of the receptacles  211  in  FIG. 1 ) in a manner that the surface of the liquid mixture  9  is not higher than the upper panel part  213  of the tray plate  21  so that the shape of the liquid mixture after being solidified conforms to that of the receptacle  211 . Subsequently, the liquid nitrogen  8  is introduced through the passageways  24  into the receiving space  111  in a manner that the tray plate is immersed in the liquid nitrogen  8  and the liquid level of the liquid nitrogen  8  is not higher than the tray plate  21 . By virtue of heat conduction of the tray  2  made of the stainless steel, the liquid mixture  9  in the receptacles  211  can quickly reach a thermal equilibrium with the liquid nitrogen  8  and is cooled to minus 114° C. and solidified. A portion of the liquid nitrogen  8  received in the receiving space  111 , which is converted into gaseous nitrogen due to heat absorption, will escape from the container  1  through the passageways  24 . After the liquid mixture  9  is solidified, the tray  2  may be removed from the container  1 , and the solidified liquid mixture  9  may be removed from the tray  2 . As the liquid mixture  9  is solidified in the receptacles  211 , it is shaped by the receptacles  211  and formed into multiple shaped solid coolant pieces. Due to the smooth surface of the stainless steel tray  2 , the shaped solid coolant pieces can be easily removed from the tray  2 . 
     The freezing device of the disclosure is capable of quickly solidifying and forming the liquid mixture into multiple shaped solid coolant pieces and therefore can be used for preparing the solid coolant pieces in an operation room for cryosurgery. As the solid coolant pieces can be quickly prepared and easily taken out from the receptacles  211 , it is not necessary to prepare the solid coolant pieces too early before cryotherapy and premature melting of the solid coolant pieces can be avoided. 
     In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiment. It will be apparent, however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. It should also be appreciated that reference throughout this specification to “one embodiment,” “an embodiment,” an embodiment with an indication of an ordinal number and so forth means that a particular feature, structure, or characteristic may be included in the practice of the disclosure. It should be further appreciated that in the description, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects, and that one or more features or specific details from one embodiment may be practiced together with one or more features or specific details from another embodiment, where appropriate, in the practice of the disclosure. 
     While the disclosure has been described in connection with what is considered the exemplary embodiment, it is understood that this disclosure is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.