Patent Application
20090113899
The present invention relates to storage of samples at ULT (ultra low temperature), typically lower than −90 degrees C.
There is an increasing need for sample storage at temperatures ranging from room temperature (20 degrees C.) down to ULT as low as −150 degrees C. In certain applications such as storing sensitive tissues and vaccines, the storage systems need to be able to reach the required low temperature, but to continuously maintain that temperature accurately and reliably since even temporary loss of cooling could weaken, damage or even destroy existing supplies of vaccines, for example. As many of such stored substances are precious not replaceable because they were derived from control studies of such vaccines, e.g. very costly and having been accumulated over a long period of time, thus requiring an extremely long time for replacement, so loss in storage could place large populations at risk.
Many refrigeration and cryopreservation systems of known art have limitations in temperature range and uniformity, capacity and reliability that would preclude their utilization in this demanding field of endeavor. Depending on their configuration, the open-door time required for loading or unloading samples could allow an unacceptable rise in temperature. Conventional ULT systems without redundant evaporators and/or highly efficient thermal insulation have a very short survival time, typically only a few hours, before loss of set point temperature, in the event of failure due to leakage of refrigerant, line blockage, motor or pump failure, electrical power outage or many other potential causes.
Systems and methods are disclosed to provide an ultra low temperature (ULT) cryogenic processor apparatus. The apparatus includes an external housing with flat sides; an inner housing coupled to the external housing to define a vacuum region there between; material disposed in the vacuum region to provide redundant insulation and structural support; and a cryogenic heat exchanger contained in the inner housing.
Implementations of the above aspect may include one or more of the following. The material can be an insulation material with one of: a silica micro balloon, polyisocyanurate. The vacuum region can be processed by removing residual water vapor and other partial pressure of contaminants. The vacuum region is evacuated to a partial pressure of approximately 0.2 milliTorr. The cryogenic heat exchanger can include one or more tubings and may include redundant tubings. The cryogenic heat exchanger can be U-shaped tubings covering at least three walls of the payload bay. The cryogenic heat exchanger can include tubings covering at least four sides of the payload bay. Alternatively, the cryogenic heat exchanger can be one or more coils positioned on the top and/or the bottom of the vessel. A port can connect to the one or more tubings to provide input and output connections thereto. A door can allow access to the payload bay, wherein the door comprises three or more materials having different thermal characteristics.
In another aspect, a method to provide ultra low temperature processing and/or storage includes providing insulation and structural support using a material disposed in a vacuum region between an external housing and an inner housing; and cryogenically processing one or more compartments contained in the payload bay.
Implementations of the above aspect may include one or more of the following. The material can be an insulation material with silica micro balloon technology. The process can remove water vapor, partial pressure contaminates and atmospheric gases from the vacuum region. The process includes evacuating the vacuum region to approximately 0.2 millitorr. The cryogenic heat exchanger can have one or more heat exchange tubings, and can include redundant tubings. The redundant tubings can be a complete set of heat exchange tubings operating in parallel with the primary heat exchange tubings. The redundant tubings can have one or more tubings branched from the primary heat exchange tubings. The cryogenic heat exchanger can also include U-shaped tubings covering at least three walls of the inner housing. The tubings can cover at least four sides of the inner housing. A door can be formed with a plurality of materials each having different thermal characteristics. A changeable rack assembly is supported in the chamber. The system can transmit energy from the payload bay into the heat exchanger through the changeable rack assembly. A negative pressure in the payload bay can be maintained through the use of pneumatic seals on the main door assembly. The cryogenics vacuum pumping via the heat exchanger can provide energy removal from the payload bay and into the heat exchanger. The surfaces of at least one of the external and inner housing can be flat surfaces.
Advantages of the preferred embodiment may include one or more of the following. The preferred embodiment provides a ULT chamber which is made in compact rectangular form, as opposed to circular or cylindrical form. The preferred embodiment also provides a substantially flat vertical door serving as the front panel of the chamber. The preferred embodiments of the ULT refrigeration system provide long term processing of biological material at ultra-low temperature, e.g. down to −90 deg.C, with an ultimate target of −150 deg.C. The embodiment provides temperature accuracy independent of ambient conditions of temperature and humidity while maintaining uniformity of temperature throughout the chamber. The embodiment has an optimal chamber size and shape and requires minimal floor space. Low operating costs are achieved through the cryogenic refrigeration method and insulation efficiency. In various embodiments, the insulation provides additional reliability in event of failure of internal tube or external refrigeration source. Components of the system can be easily accessed for maintenance purposes with minimal side effects. The design allows for ease of manufacturability and assembly. The preferred embodiments of the system can be flexibly manufactured to different sizes and requirements at a low cost.
The rigidity and high compressive strength of the Trymer insulation material serve to counteract and minimize inward bending distortion of the two opposed metal sheets due 10 stress from the internal vacuum and external atmospheric pressure. Dow Trymer insulation material, is a polyisocyanurate foam structured with small glass spheres in contact, provides sufficient compressive strength.
The insulation chamber 10B is fitted with refrigeration tubing, preferably high reliability multi-tube thermal exchange structure as disclosed in U.S. Pat. No. 6,804,976 by inventor John Dain, the content of which is incorporated by reference. As disclosed therein, reliability is greatly enhanced by providing two additional redundant lines in addition to the primary line of copper tubing along with suitable routing valve hardware.
A single three-dimensional U-shaped tubing assembly 28 can be formed to cover the region of the two sides and rear panel: this alone may suffice for some applications, however for ULT biomedical purposes, the required lower temperatures, accuracy and uniformity are attainable with addition of a flat refrigeration tubing assembly to the top and/or the bottom panel, preferably both top tubing assembly 26 and bottom tubing assembly 30 as shown in
The vacuum insulated tubing assembly 10C, shown In
In
Turning now to
The rectangular shape and proportions of the chamber provides convenient front access though the door, and may be configured internally as a stack of individual compartments (not shown in the drawings), all made independently accessible with minimal effect on other compartments, for efficient inventory control.
Negative environmental effects such air contamination and humidity can be minimized by providing positive pressurization within the ULT chamber(s), preferably with the presence of an inert gas such as nitrogen.
Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.
