Abstract:
A method of manufacturing a filter preferably for an anabolic chamber or incubator utilizing an activated carbon of the filter which has been vacuumed to remove contaminants. The assembly occurs in a clean room environment. Upon assembling the filter, vacuum sealing the filter in a bag further assures that the sterilization of the filter is maintained. Moreover, the method may subject the vacuum sealed filter to gamma radiation to kill any molds, germs and bacteria that may exist in the filter after the assembly process.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims priority to U.S. Provisional Patent Application No. 60/379,931, filed May 13, 2002, which is incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The subject disclosure relates to a method of manufacturing a filter and, more particularly to, a carbon filter fabrication process wherein the filter is free of undesirable contaminants. 
   2. Background of the Related Art 
   Filters are used for removing particulates and gases from the air and the environment of which the user intends to clean or purify. Currently most filters are manufactured or assembled in regular environmental or general assembly conditions. Such conditions will allow these filters to come in contact with particulates and gases that are present within this environment. Through this contact, the filters may retain or absorb unwanted particulates and gases that are present in the assembly environment. A particularly problematic material used during the manufacturing or assembly process is carbon which is used as an absorption ingredient. The carbon may absorb unwanted gases or volatile organic compounds (“VOC”) from the assembly environment. 
   For an additional example, particulates, unwanted VOC and other gases are absorbed into the HEPA or particulate filtering material, or additional filtering material and then introduced into the environment in which the filter is intended to clean. 
   In short, undesirable contamination occurs when the environment that you are introducing the filter to is cleaner than the filter itself or does not contain certain particulates and contaminants that may be present in the filter. In such circumstances a negative impact upon the environment results when the filter and the filtering mechanism begin to release these contaminants into the environment. This contamination defeats or at least diminishes achieving the very objective of the filter system. 
   Currently the improvement of the air within a closed environment such as an incubator or an anabolic chamber as is addressed by U.S. Pat. No. 6,013,119 to Cecchi et al. and U.S. Pat. No. 6,200,362 to Cecchi et al., each of which is incorporated herein by reference in their entirety. These patents recognize the benefits of removing VOC and chemical air contaminants from the closed environment of a cell culture incubator or chamber. 
   Despite these advantages, however, there can be inconsistency of cell and embryonic development among different lot numbers of filters and from different batches of filters that are used inside and outside the incubator or chamber due to filter contamination as noted above. Improved embryonic and cell culture development only occurs by removing nearly all volatile organic compounds and particulates from the air. 
   Moreover, the prior art does not address the separate effects of viruses, bacteria, particulates and contaminants that may attach to particulates or contaminants like mold that may exist in the assembly process environment and are transferred into the environment by the introduction of the filter which is intended to clean the environment. There is a need, therefore, for an improved method of manufacturing a filter which prevents contamination and aids in assuring adequate sterilization of the filter. 
   SUMMARY OF THE INVENTION 
   The subject disclosure relates to an improved method of manufacturing and assembling filters used in cell culture and embryonic development. 
   The filters are manufactured in an environment free from particulates or gases which may be detrimental to the intended use of the filter. The particulates may be in the form of organic materials, bacteria and viruses. The gases may be in the form of harmful, inert, volatile organic compounds or chemical air contaminants. These filters may be placed within an environment in such a way that the air circulates through these filters many times. 
   In one embodiment, the filters not only remove unwanted contaminants but keep the unwanted contaminants from entering the environment. The filters may be within the air circulation stream of an incubator, in the incoming air path from the environment outside an incubator, or in line with gas cylinders which may be used to provide specific gases, such as CO2 or nitrogen, to a closed environment within an incubator, anabolic chamber. 
   The subject disclosure is a method for handling the filter components during the assembly process, evacuating the air from the components and therefore removing unwanted gases and particulates from the filter materials. 
   Testing of these filters before and after use has also eradicated the difference in what may have been absorbed by the filters during the manufacturing and assembly process before use and after use without variance from batch to batch. 
   It is, therefore, an object of this invention to assemble a filter, which does not transmit, or discharge particulates or volatile organic compounds into the environment of which the filter is placed. 
   It is, therefore, an object of this invention to remove from the filtering material, by a specific method, the contaminants which may be absorbed by the filter material during assembly. 
   It is therefore an object of this invention to sterilize the filter assembly by gamma irradiation to suppress and eliminate mold spores, bacteria and infectious matter that may be present within the filter. 
   These and other unique features and advantages of the invention disclosed herein will become more readily apparent from the following description, the accompanying drawings and the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that those having ordinary skill in the art to which the disclosed invention appertains will more readily understand how to make and use the same, reference may be had to the drawings wherein: 
       FIG. 1  is an overview of an environment in which a filter manufactured in accordance with the subject disclosure may be used; 
       FIG. 2  is a cross-sectional view of a filter unit having a filter manufactured in accordance with the subject disclosure; and 
       FIG. 3  is a somewhat schematic flowchart illustrating an embodiment of a process for manufacturing a filter in accordance with the subject disclosure 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention overcomes many of the prior art problems associated with manufacturing filters. The advantages, and other features of the systems and methods disclosed herein, will become more readily apparent to those having ordinary skill in the art from the following detailed description of certain preferred embodiments taken in conjunction with the drawings which set forth representative embodiments of the present invention and wherein like reference numerals identify similar structural elements. 
   Referring to  FIG. 1 , a schematic diagram of a filtering system  10  for an incubator with the filter unit provided outside the incubator is shown. The filtering system  10  includes an incubator  12  for storing specimens in a controlled environment and a filter unit  16  for maintaining the cleanliness of the environment. The filter unit  16  contains a pump  22  for moving air through the filter unit and a filter  24  constructed in accordance with the subject disclosure. The filter unit  16  has an air inlet port  40  and an air outlet port  42  to receive air from the incubator  12  and return filtered air to the incubator  12 , respectively. It will be appreciated by those of ordinary skill in the pertinent art based upon review of the subject disclosure that the application of the filter may be in any situation which requires a filter such as for example, without limitation, a domestic drinking water filtration system, a automobile fuel line system, an air filter for a room and the like as would be appreciated by those of ordinary skill in the art. 
   Referring to  FIG. 2 , the exemplary filter  24  has a generally cylindrical elongated casing  98  for defining an inlet port  100  and an outlet port  108 . Tubes  102  and  104  threadably engage the inlet and outlet ports  100  and  108 , respectively, in order to facilitate connection of the filter  24  to an air inlet and outlet of the incubator  12 . The casing  98  houses a VOC filtering medium  120  and a particulate removing medium  122 . The particulate removing medium  122  surrounds the outlet port  108  and the VOC filtering medium  120  surrounds the inlet port  100  such that the gas stream passing through the filter unit  16  passes through both mediums  120  and  122 . In another embodiment, the filter  24  contains a single filtering medium. 
   Preferably, the VOC filtering medium  120  is activated carbon. In another preferred embodiment, the VOC filtering medium  120  is untreated carbon, activated charcoal, combinations of these preferred materials and the like although it is to be appreciated by those of ordinary skill in the art that other materials are capable of performing the necessary function such as filtering out VOC. Preferably, the particulate removing medium  122  is in the form of a hollow cylinder co-axial with the outlet port  108  and positioned against the casing  98 . In one embodiment, the particulate removing medium  122  is HEPA filter media although other suitable filter media may be used such as, without limitation, non-woven filter media. In a preferred embodiment, the particulate removing medium  122  is a pleated filter element having a cylindrical outer periphery  124  and an axially extending cylindrical bore  126 . 
   Referring to  FIG. 3 , the filter manufacturing process begins at step  100  when the filter material and components are initiated into the process. In the preferred embodiment, the particulate removing medium  122  is a HEPA filter material and the VOC filtering medium  120  is activated carbon. The components include casings  98 , fittings such as the tubes  102  and  104 , capsules for the activated carbon and any other component which may be required not only for filter  24  but for filter unit  16  as well. 
   At step  110 , the HEPA filter material, filter capsules and activated carbon are removed from their original packaging and inspected. Each of the steps  100  and  110  are preferably performed in a receiving area  105 . 
   At step  120 , the unpacked material is transferred from the receiving area  105  into a clean room environment  115 . In the preferred embodiment, the clean room environment  115  consists of a repeat circulating air filtration system, which is designed to remove particulates and contaminants therefrom. Each of the steps  120 - 155  are preferably conducted in the clean room  115 . 
   At step  125 , the received items are sorted into three groups for appropriate treatment as follows: capsules; activated carbon; and parts and fittings. 
   At step  130 , preferably the activated carbon is in a plastic bag as carbon is typically shipped. While still in the shipping bag, the carbon is vacuumed by using a small vacuum pump as would be appreciated by those of ordinary skill in the pertinent art based upon review of the subject disclosure. By vacuuming the activated carbon, most of the dust particulates and excess air from the shipping bag is removed, thus the particulates and VOC previously in the activated carbon and the shipping bag are removed. 
   At step  135 , the filter capsules are unwrapped from the cleaned shipping material and cleaned directly. Once the filter capsules are ready for filling, the process proceeds to step  140  where the filter capsules are filled with the activated carbon within the clean room environment. To fill the filter capsules, the vacuumed activated carbon is removed from the bag. No additional recontamination of the carbon or filter capsules occurs because the filling operation is performed in a clean room environment. 
   At step  145 , in parallel with steps  130 ,  135  and  140 , the parts and fittings are inspected, separated and cleaned. The process proceeds to step  150  where all of the necessary components to manufacture a filter  24  are assembled in an environment which prevents recontamination, i.e. a clean room. Upon assembly at step  150 , the filter  24  is properly labeled with labels which are toxic free and non-smear. 
   At step  155 , the assembled filter  24  is prepared for transport through non-clean room environments. The filter  24  is inserted into a clean bag. Preferably, the clean bag is non-breathable plastic bags from 4 to 6 mil in thickness. The extra thickness of a filter poly bag creates a barrier against leakage and contamination, and maintains the vacuum condition of the sealed filter  24 . Upon bagging the assembled filter  24 , the air is removed from the bag prior to sealing. Vacuum/heat sealing equipment creates a vacuum in the bag and seals the opening of the bag by using heat. This additional vacuum operation prior to sealing removes even more of the VOC and particulates that may be present in the filter  24  despite the manufacturing being performed in a clean room. 
   At step  160 , the assembled and vacuum packed filter  24  is transferred from the clean room  115  to a facility  165  which can gamma irradiate items for sterilization. It is envisioned that the gamma irradiation may also occur in a clean room environment although as long as the integrity of the vacuum bag is maintained, the cleanliness of the assembled filter  24  is maintained through unclean environments. The assembled filter  24  is gamma irradiated within the bag to kill any mold spores, germs, bacteria and the like which may be present as would be known to one of ordinary skill in the pertinent art based upon review of the subject disclosure. 
   At step  170 , the sterilized bagged filter  24  is transferred from the gamma radiation facility  165  to a storage facility  175 . Preferably, the filter  24  is stored in a warehouse for future shipment to a customer. In another embodiment, the filter  24  is sent directly to an end user who subsequently unwraps and installs the filter  24  for use. In another embodiment, the receiving area  105 , clean room  115 , gamma irradiation facility  165  and storage facility are all within the same location. 
   While the invention has been described with respect to preferred embodiments, those skilled in the art will readily appreciate that various changes and/or modifications can be made to the invention without departing from the spirit or scope of the invention as defined by the appended claims.