U.S. patent application number 15/750227 was filed with the patent office on 2018-08-09 for re-circulation loop in cff/tff single use path flow.
The applicant listed for this patent is GE HEALTHCARE BIO-SCIENCES AB. Invention is credited to Klaus Gebauer, Nachiket Karmarkar, Karl Axel Jakob Liderfelt, Fredrik Oskar Lundstrom, Sasi Kumar Nutalapati, Amit Kumar Sharma, Ajit S. Vernekar.
Application Number | 20180221823 15/750227 |
Document ID | / |
Family ID | 56738112 |
Filed Date | 2018-08-09 |
United States Patent
Application |
20180221823 |
Kind Code |
A1 |
Nutalapati; Sasi Kumar ; et
al. |
August 9, 2018 |
Re-Circulation Loop in CFF/TFF Single Use Path Flow
Abstract
The disclosed subject matter relates to an automated CFF/TFF
system that provides the operations of system treatment with a
system treatment solution(such as buffer) and filtration of a
solution (e.g., a biofluid) can be accomplished in succession
without having to re-configure the system (such as re-routing the
fluid conduits) that could compromise the integrity of the system.
As a result, there will be reduced contamination risk, reduced
volume of buffer required and will save time for the filtration
process.
Inventors: |
Nutalapati; Sasi Kumar;
(Bangalore, IN) ; Gebauer; Klaus; (Uppsala,
SE) ; Liderfelt; Karl Axel Jakob; (Uppsala, SE)
; Karmarkar; Nachiket; (Bangalore, IN) ; Vernekar;
Ajit S.; (Bangalore, IN) ; Sharma; Amit Kumar;
(Bangalore, IN) ; Lundstrom; Fredrik Oskar;
(Uppsala, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GE HEALTHCARE BIO-SCIENCES AB |
UPPSALA |
|
SE |
|
|
Family ID: |
56738112 |
Appl. No.: |
15/750227 |
Filed: |
August 17, 2016 |
PCT Filed: |
August 17, 2016 |
PCT NO: |
PCT/EP2016/069473 |
371 Date: |
February 5, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 2311/16 20130101;
B01D 2321/02 20130101; B01D 61/22 20130101; B01D 61/10 20130101;
B01D 2313/243 20130101; C07K 1/34 20130101; B01D 2311/25 20130101;
B01D 61/20 20130101; B01D 65/02 20130101; B01D 61/12 20130101; B01D
2315/10 20130101; B01D 2315/14 20130101; B01D 61/08 20130101; B01D
61/18 20130101; B01D 2311/08 20130101; B01D 2311/08 20130101; B01D
2311/16 20130101; B01D 2311/25 20130101 |
International
Class: |
B01D 61/22 20060101
B01D061/22; B01D 61/18 20060101 B01D061/18; B01D 61/20 20060101
B01D061/20; B01D 61/08 20060101 B01D061/08; B01D 61/12 20060101
B01D061/12; B01D 61/10 20060101 B01D061/10; B01D 65/02 20060101
B01D065/02; C07K 1/34 20060101 C07K001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 20, 2015 |
IN |
2581/DEL/2015 |
Aug 21, 2015 |
IN |
2610/DEL/2015 |
Claims
1. An automated CFF/TFF system configured to utilize flexible
tubing, comprising a cabinet having sides that define a cabinet
interior and a cabinet exterior, the cabinet including: a plurality
of pinch valves such that the portion of the valve through which
the flexible tubing passes is positioned on the cabinet exterior, a
plurality of pumps such that the portion of the pump through which
the flexible tubing passes or is connected is positioned on the
cabinet exterior, and a plurality of sensor connectors such that
when a sensor is connected thereto the portion of the sensor to
which the flexible tubing is connected is positioned on the cabinet
exterior; and an electronic data processing network at least
partially positioned in the cabinet interior, the electronic data
processing network connected to and capable of at least one of
receiving, transmitting, processing and recording data associated
with at least one of the plurality of pumps, the plurality of pinch
valves and the plurality of sensor connectors, wherein the
plurality of pumps, the plurality of pinch valves and the plurality
of sensor connectors are proximate to a path for the flexible
tubing configured to form a fluid circuitry including a reservoir
and a CFF/TFF filtration module through which a fluid stream of a
solution may be conducted through the automated CFF/TFF system, the
fluid circuitry comprising: a feed conduit to provide fluid
communication between an outlet of the reservoir and a feed inlet
of the CFF/TFF filtration module, a retentate conduit to provide
fluid communication between a retentate outlet of the CFF/TFF
filtration module and an inlet of the reservoir, a permeate conduit
to provide fluid communication with a permeate outlet of the
CFF/TFF filtration module, and a re-circulation loop conduit to
provide fluid communication between the permeate conduit and the
retentate conduit.
2. The automated CFF/TFF system of claim 1, wherein the plurality
of pumps and the plurality of valves are capable of driving and
regulating the fluid stream through the automated CFF/TFF
system.
3. The automated CFF/TFF system of claim 1, wherein the plurality
of sensor connectors when connected to a sensor are capable of
acquiring data about the fluid stream as it flows through the
automated CFF/TFF system.
4. The automated CFF/TFF system of claim 1, wherein the electronic
data processing network is capable of connecting to and determining
the performance of the CFF/TFF filtration module.
5. The automated CFF/TFF system of claim 1, wherein the fluid
circuitry further includes a second reservoir suitable for
containing the solution and having a second reservoir outlet that
is in fluid communication with the reservoir.
6. The automated CFF/TFF system of claim 1, wherein the plurality
of pumps includes a peristaltic pump or a piston pump.
7. The automated CFF/TFF system of claim 6, wherein the piston pump
is single use.
8. The automated CFF/TFF system of claim 1, wherein the flexible
tubing, the sensors, the reservoir and the CFF/TFF filtration
module are single use.
9. A method of using an automated CFF/TFF system, the method
comprising: providing an automated CFF/TFF system configured to
utilize flexible tubing comprising: a cabinet having sides that
define a cabinet interior and a cabinet exterior, the cabinet
including: a plurality of pinch valves such that the portion of the
valve through which the flexible tubing passes is positioned on the
cabinet exterior, a plurality of pumps such that the portion of the
pump through which the flexible tubing passes or is connected is
positioned on the cabinet exterior, a plurality of sensor
connectors such that when a sensor is connected thereto the portion
of the sensor through which the flexible tubing is connected is
positioned on the cabinet exterior; and an electronic data
processing network at least partially positioned in the cabinet
interior, the electronic data processing network connected to and
capable of at least one of receiving, transmitting, processing and
recording data associated with at least one of the plurality of
pumps, the plurality of pinch valves and the plurality of sensors,
wherein the plurality of pumps, the plurality of pinch valves and
the plurality of sensors are proximate to a path for flexible
tubing configured to form a fluid circuitry including a first
reservoir, a second reservoir, a third reservoir and a CFF/TFF
filtration module through which a fluid stream of a solution may be
conducted through the automated CFF/TFF system, the fluid circuitry
comprising: a feed conduit to provide fluid communication between
an outlet of the first reservoir and a feed inlet of the CFF/TFF
filtration module, a retentate conduit to provide fluid
communication between a retentate outlet of the CFF/TFF filtration
module and an inlet of the first reservoir, a permeate conduit to
provide fluid communication with a permeate outlet of the CFF/TFF
filtration module, a re-circulation loop conduit to provide fluid
communication between the permeate conduit and the retentate
conduit, a second reservoir feed conduit to provide fluid
communication between the first reservoir and the second reservoir,
a third reservoir feed conduit to provide fluid communication
between the first reservoir and the third reservoir, and a drain;
connecting a sensor to at least one of the plurality of sensor
connectors; forming the fluid circuitry using flexible tubing to
connect the first reservoir, the second reservoir, the third
reservoir, the CFF/TFF filtration module, the plurality of pinch
valves, the plurality of pumps and the plurality of sensors;
configuring the plurality of pumps and plurality of valves to
provide a system treatment solution to the first reservoir from the
second reservoir; providing a system treatment solution to the
first reservoir from the second reservoir; configuring the
plurality of pumps and plurality of valves to circulate the system
treatment solution from the first reservoir through the feed
conduit, the CFF/TFF filtration module, the retentate conduit, the
permeate conduit and the recirculation loop conduit to return to
the first reservoir; circulating the system treatment solution from
the first reservoir through the feed conduit, the CFF/TFF
filtration module, the retentate conduit, the permeate conduit and
the recirculation loop conduit to return to the first reservoir;
configuring the plurality of pumps and plurality of valves to drain
the system treatment solution from the automated CFF/TFF system
using the drain; draining the system treatment solution from the
automated CFF/TFF system using the drain; configuring the plurality
of pumps and plurality of valves to provide a solution for
filtration to the first reservoir from the third reservoir;
providing a solution for filtration to the first reservoir from the
third reservoir; configuring the plurality of pumps and plurality
of valves to filter the solution for filtration from the first
reservoir through the CFF/TFF filtration module; and filtering the
solution for filtration from the first reservoir through the
CFF/TFF filtration module.
10. The method of claim 9, further including driving and regulating
the fluid stream through the automated CFF/TFF system using the
plurality of pumps and the plurality of valves.
11. The method of claim 9, further including acquiring data about
the fluid stream through the automated CFF/TFF system using the
plurality of sensors.
12. The method of claim 9, wherein the CFF/TFF filtration module
includes sensors capable of determining the performance thereof,
connecting the electronic data processing network to the CFF/TFF
filtration module so as to at least one of receiving, transmitting,
processing and recording data associated with CFF/TFF filtration
module and determining the performance of the CFF/TFF filtration
module using the electronic data processing network.
13. The method of claim 9, wherein the drain is in fluid
communication with the permeate conduit and the recirculation loop
conduit; and draining the system treatment solution includes
circulating the system treatment solution from the first reservoir
through the feed conduit, the automated CFF/TFF filtration module,
the retentate conduit, the permeate conduit, the recirculation loop
conduit to the drain such that the flow in the retentate conduit
proceeds to the recirculation loop conduit and the flow from the
recirculation loop conduit and the flow from the permeate conduit
exit the automated CFF/TFF system through the drain.
14. The method of claim 9, wherein the system treatment solution
includes buffer.
15. The method of claim 9, wherein the solution for filtration
includes a biofluid.
16. The method of claim 9, wherein the electronic data processing
network controls the steps of: configuring the plurality of pumps
and plurality of valves to provide a system treatment solution to
the first reservoir from the second reservoir; providing a system
treatment solution to the first reservoir from the second
reservoir; configuring the plurality of pumps and plurality of
valves to circulate the system treatment solution from the first
reservoir through the feed conduit, the CFF/TFF filtration module,
the retentate conduit, the permeate conduit and the recirculation
loop conduit to return to the first reservoir; circulating the
system treatment solution from the first reservoir through the feed
conduit, the CFF/TFF filtration module, the retentate conduit, the
permeate conduit and the recirculation loop conduit to return to
the first reservoir; configuring the plurality of pumps and
plurality of valves to drain the system treatment solution from the
automated CFF/TFF system using the drain; draining the system
treatment solution from the automated CFF/TFF system using the
drain; configuring the plurality of pumps and plurality of valves
to provide a solution for filtration to the first reservoir from
the third reservoir; providing a solution for filtration to the
first reservoir from the third reservoir; configuring the plurality
of pumps and plurality of valves to filter the solution for
filtration from the first reservoir through the CFF/TFF filtration
module; and filtering the solution for filtration from the first
reservoir through the CFF/TFF filtration module, wherein the fluid
circuitry remains unchanged during the above steps.
17. The method of claim 9, wherein at least one of the plurality of
pumps is a piston pump and the piston pump, the flexible tubing,
the plurality of sensors, the first reservoir, the second
reservoir, the third reservoir and CFF/TFF filtration module are
single use.
18. An automated CFF/TFF system, comprising a cabinet having sides
that define a cabinet interior and a cabinet exterior, the cabinet
including: a plurality of pinch valves such that the portion of the
valve through which the flexible tubing passes is positioned on the
cabinet exterior, a plurality of pumps such that the portion of the
pump through which the flexible tubing passes or is connected is
positioned on the cabinet exterior, and a plurality of sensor
connectors including a sensor connected to at least one of the
plurality of sensor connectors, the portion of the sensor to which
the flexible tubing is connected is positioned on the cabinet
exterior; an electronic data processing network at least partially
positioned in the cabinet interior, the electronic data processing
network connected to and capable of at least one of receiving,
transmitting, processing and recording data associated with at
least one of the plurality of pumps, the plurality of pinch valves
and the plurality of sensors; and flexible tubing forming a fluid
circuitry including a reservoir and a CFF/TFF filtration module
through which a fluid stream of a solution may be conducted through
the automated CFF/TFF system, the fluid circuitry comprising: a
feed conduit to provide fluid communication between an outlet of
the reservoir and a feed inlet of the CFF/TFF filtration module, a
retentate conduit to provide fluid communication between a
retentate outlet of the CFF/TFF filtration module and an inlet of
the reservoir, a permeate conduit to provide fluid communication
with a permeate outlet of the CFF/TFF filtration module, and a
re-circulation loop conduit to provide fluid communication between
the permeate conduit and the retentate conduit.
19. The automated CFF/TFF system of claim 18, wherein at least one
of the plurality of pumps is a piston pump and the piston pump, the
flexible tubing, the plurality of sensors, the reservoir and
CFF/TFF filtration module are single use.
20. The automated CFF/TFF system of claim 18, wherein the
electronic data processing network is connected to and capable of
determining the performance of the CFF/TFF filtration module.
Description
BACKGROUND
[0001] The present invention relates to an automated crossflow
filtration method and system for separating a component of interest
from one or more other components in a solution. The invention is
of use in the field of purifying bio fluids including protein
separations, where specific proteins must be separated and purified
from cell lysates and cultures.
[0002] Cell culture and bioreactors and various biotechnology
processes have generated considerable interest in recent years due
to increased interest in genetic engineering and
biopharmaceuticals. Cells are cultured to make, for example,
proteins, receptors, vaccines, and antibodies that are utilize in
patient therapy, research, as well as in various diagnostic
techniques.
[0003] The separation of such molecules is of increasing commercial
interest in the chemical, pharmaceutical and biotech industries,
including, for example, the production of biological drugs and
diagnostic reagents. In particular, the isolation and purification
of proteins is of increasing importance because of advances in
proteomics (the study of the function of proteins expressed by the
human genome). Some proteins may only be present at very low
concentrations within a biological sample. As a result, development
of isolation and separation techniques is particularly important,
especially when large scale production is involved.
[0004] In general, when proteins are produced in cell culture, they
are either located intracellularly or secreted into the surrounding
culture media. Also, the cell lines that are used are living
organisms and must be fed with a growth medium, containing sugars,
amino acids, growth factors, etc. Separation and purification of a
desired protein from such a complex mixture of nutrients as well as
cellular by-products, to a level sufficient for characterization,
poses a formidable challenge.
[0005] Ultrafiltration membranes are characterized by pore sizes
which enable them to retain macromolecules. Such macromolecules may
have a molecular weight ranging from about 500 to about 1,000,000
daltons. As such ultrafiltration membranes can be used for
concentrating proteins. Ultrafiltration is a low-pressure membrane
filtration process which can be used to separate solutes up to 0.1
.mu.m in size. As a result, for example, a solute of molecular size
significantly greater than that of the solvent molecule can be
removed from the solvent by the application of a hydraulic
pressure, which forces only the solvent to flow through a suitable
membrane (usually one having a pore size in the range of 0.001 to
0.1 .mu.m). As a result, ultrafiltration is capable of removing
bacteria and viruses from a solution.
[0006] Crossflow filtration ("CFF" also referred to a "tangential
flow filtration" (TFF)) systems can be are used in industry
applications, such as, for example, manufacturing process
separations, waste treatment plants and water purification systems
where they can extend the lifetime of filtration membranes by
removing and/or preventing the build-up of contaminants and promote
consistency of the filtration process with time.
[0007] The most commonly used CFF/TFF membrane processes are
microfiltration and ultrafiltration. Such processes may be pressure
driven and depend upon the "membrane flux", defined as the flow
volume over time per unit area of membrane, across the
microfiltration or ultrafiltration membrane. At low pressures, the
transmembrane flux is proportional to pressure. As a result, by
varying the transmembrane pressure difference driving force and
average pore diameter, a membrane may serve as a selective barrier
by permitting certain components of a mixture to pass through while
retaining others. This results in two phases, the permeate and
retentate phases, each of which is enriched in one or more of the
components of the mixture. The retentate stream is recirculated in
the flow circuitry and is pumped across the membrane again in a
continuous fashion. Such CFF/TFF systems are used to significantly
reduce the volume of the sample solution as a permeate stream is
withdrawn from the system. So, the sample solution becomes
concentrated when the system is driven in a concentration mode.
[0008] CFF/TFF systems have the advantage that due to the direction
of the flow of the fluid sample, which is essentially parallel to
the membrane surface, an automatic sweeping and cleansing takes
place so that higher fluxes and higher throughputs can often be
attained with such systems in relation to corresponding normal flow
filtration systems. Further, a large fraction of sample flows
continuously over the membrane surface so that a clogging and
fouling is discouraged in such systems. With respect to these and
other advantages, CFF/TFF systems are often used in industrial
and/or biotechnological processes.
[0009] In an automated CFF/TFF system, buffer and other system
treatment solutions need to circulate through the filter and other
system components for equilibration prior or subsequent to the
separation process. Ideally, such circulation and equilibration of
buffer and other system treatment solutions is performed by an
automated method without the need for manual intervention.
BRIEF DESCRIPTION
[0010] In one embodiment, an automated CFF/TFF system configured to
utilize flexible tubing is provided. The automated CFF/TFF system
comprises a cabinet and an electronic data processing network. The
cabinet has sides that define a cabinet interior and a cabinet
exterior and includes a plurality of pinch valves such that the
portion of the valve through which the flexible tubing passes is
positioned on the cabinet exterior, a plurality of pumps such that
the portion of the pump through which the flexible tubing passes or
is connected is positioned on the cabinet exterior and a plurality
of sensor connectors such that when a sensor is connected thereto
the portion of the sensor to which the flexible tubing is connected
is positioned on the cabinet exterior. The electronic data
processing network is at least partially positioned in the cabinet
interior and is connected to and capable of at least one of
receiving, transmitting, processing and recording data associated
with at least one of the plurality of pumps, the plurality of pinch
valves and the plurality of sensor connectors. The plurality of
pumps, the plurality of pinch valves and the plurality of sensor
connectors are proximate to a path for flexible tubing configured
to form a fluid circuitry including a reservoir and a CFF/TFF
filtration module through which a fluid stream of a solution may be
conducted through the automated CFF/TFF system. The fluid circuitry
comprises a feed conduit to provide fluid communication between an
outlet of the reservoir and a feed inlet of the CFF/TFF filtration
module, a retentate conduit to provide fluid communication between
a retentate outlet of the CFF/TFF filtration module and an inlet of
the reservoir, a permeate conduit to provide fluid communication
with a permeate outlet of the CFF/TFF filtration module and a
re-circulation loop conduit to provide fluid communication between
the permeate conduit and the retentate conduit.
[0011] In another embodiment, a method of using an automated
CFF/TFF system is provided. The method includes providing an
automated CFF/TFF system comprising a cabinet and an electronic
data processing network. The cabinet has sides that define a
cabinet interior and a cabinet exterior and includes a plurality of
pinch valves such that the portion of the valve through which the
flexible tubing passes is positioned on the cabinet exterior, a
plurality of pumps such that the portion of the pump through which
the flexible tubing passes or is connected is positioned on the
cabinet exterior and a plurality of sensor connectors such that
when a sensor is connected thereto the portion of the sensor to
which the flexible tubing is connected is positioned on the cabinet
exterior. The electronic data processing network is at least
partially positioned in the cabinet interior and is connected to
and capable of at least one of receiving, transmitting, processing
and recording data associated with at least one of the plurality of
pumps, the plurality of pinch valves and the plurality of sensor
connectors. The plurality of pumps, the plurality of pinch valves
and the plurality of sensor connectors are proximate to a path for
flexible tubing configured to form a fluid circuitry including a
first reservoir, a second reservoir, a third reservoir and a
CFF/TFF filtration module through which a fluid stream of a
solution may be conducted through the automated CFF/TFF system. The
fluid circuitry comprises a feed conduit to provide fluid
communication between an outlet of the reservoir and a feed inlet
of the CFF/TFF filtration module, a retentate conduit to provide
fluid communication between a retentate outlet of the CFF/TFF
filtration module and an inlet of the reservoir, a permeate conduit
to provide fluid communication with a permeate outlet of the
CFF/TFF filtration module, a re-circulation loop conduit to provide
fluid communication between the permeate conduit and the retentate
conduit, a second reservoir feed conduit to provide fluid
communication between the first reservoir and the second reservoir,
a third reservoir feed conduit to provide fluid communication
between the first reservoir and the third reservoir, and a drain.
The method also includes connecting a sensor to at least one of the
plurality of sensor connectors; forming the fluid circuitry using
flexible tubing to connect the first reservoir, the second
reservoir, the third reservoir, the CFF/TFF filtration module, the
plurality of pinch valves, the plurality of pumps and the plurality
of sensors; configuring the plurality of pumps and plurality of
valves to provide a system treatment solution to the first
reservoir from the second reservoir; providing a system treatment
solution to the first reservoir from the second reservoir;
configuring the plurality of pumps and plurality of valves to
circulate the system treatment solution from the first reservoir
through the feed conduit, the CFF/TFF filtration module, the
retentate conduit, the permeate conduit and the recirculation loop
conduit to return to the first reservoir; circulating the system
treatment solution from the first reservoir through the feed
conduit, the CFF/TFF filtration module, the retentate conduit, the
permeate conduit and the recirculation loop conduit to return to
the first reservoir; configuring the plurality of pumps and
plurality of valves to drain the system treatment solution from the
automated CFF/TFF system using the drain; draining the system
treatment solution from the automated CFF/TFF system using the
drain; configuring the plurality of pumps and plurality of valves
to provide a solution for filtration to the first reservoir from
the third reservoir; providing a solution for filtration to the
first reservoir from the third reservoir; configuring the plurality
of pumps and plurality of valves to filter the solution for
filtration from the first reservoir through the CFF/TFF filtration
module; and filtering the solution for filtration from the first
reservoir through the CFF/TFF filtration module. In another
embodiment, an automated CFF/TFF system is provided. The automated
CFF/TFF system comprises a cabinet, an electronic data processing
network and flexible tubing. The cabinet has sides that define a
cabinet interior and a cabinet exterior and includes a plurality of
pinch valves such that the portion of the valve through which the
flexible tubing passes is positioned on the cabinet exterior, a
plurality of pumps such that the portion of the pump through which
the flexible tubing passes or is connected is positioned on the
cabinet exterior, and a plurality of sensor connectors including a
sensor is connected to at least one of the plurality of sensor
connectors, the portion of the sensor to which the flexible tubing
is connected is positioned on the cabinet exterior. The electronic
data processing network is at least partially positioned in the
cabinet interior and is connected to and capable of at least one of
receiving, transmitting, processing and recording data associated
with at least one of the plurality of pumps, the plurality of pinch
valves and the plurality of sensors. The flexible tubing forms a
fluid circuitry including a reservoir and a CFF/TFF filtration
module through which a fluid stream of the solution may be
conducted through the automated CFF/TFF system and comprises a feed
conduit to provide fluid communication between an outlet of the
reservoir and a feed inlet of the CFF/TFF filtration module, a
retentate conduit to provide fluid communication between a
retentate outlet of the CFF/TFF filtration module and an inlet of
the reservoir, a permeate conduit to provide fluid communication
with a permeate outlet of the CFF/TFF filtration module and a
re-circulation loop conduit to provide fluid communication between
the permeate conduit and the retentate conduit.
[0012] Further suitable embodiments of the invention are described
in the dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 illustrates a schematic flow diagram of a CFF/TFF
system according to one embodiment thereof.
[0014] FIG. 2 illustrates a schematic flow diagram of a CFF/TFF
system according to one embodiment thereof that shows a filling
operation before the filtration process.
[0015] FIG. 3 illustrates a schematic flow diagram of a CFF/TFF
system according to one embodiment thereof shows the filtration
process.
[0016] FIG.4 illustrates a schematic flow diagram of a CFF/TFF
system according to one embodiment thereof shows a filling
operation of system treatment solution.
[0017] FIG. 5 illustrates a schematic flow diagram of a CFF/TFF
system according to one embodiment thereof shows a circulation
operation of system treatment solution.
[0018] FIG. 6 illustrates a schematic flow diagram of a CFF/TFF
system according to one embodiment thereof shows a draining
operation of system treatment solution.
[0019] FIG. 7 illustrates a block diagram of an exemplary computing
apparatus.
[0020] FIG. 8 illustrates a cabinet for the CFF/TFF system of FIG.
1 (outside view). a) Right side panel, b) Frontal panel, c) Left
side panel.
[0021] FIG. 9 illustrates the FIG. 8 cabinet, with the panels shown
from the inside. Dashed lines indicate electrical connections.
DETAILED DESCRIPTION
[0022] In an automated cross flow filtration system the buffer
preferably re-circulates through the filter for equilibration by an
automated method without the need for manual intervention. The flow
path should be designed for this purpose in a way that can serve
the re-circulation loop for re-circulating the equilibration buffer
for filter conditioning or cleaning solution for filter cleaning
and storage. A re-circulation loop in a CFF/TFF single use flow
path will address the need for buffer re-circulation in an
automated method. This method of automated buffer re-circulation
will eliminate manual steps, save time for the filtration process
and reduce the volume of buffer or other system treatment solution
required. One benefit resulting from these advantages is reduced
cost of operating the filtration system. Another benefit resulting
from these advantages is that the sterility and/or integrity of the
fluid system is not compromised as well as risk for compromising
the sterility and/or integrity of the fluid system is greatly
reduced by eliminating manual interaction for connecting or
disconnecting fluid conduits and containers at the outlet and/or
inlet connections of the fluid system during the process.
[0023] Biofluids as used herein refers to fluids prepared by
biological or pharmaceutical methods and may contain biological
agents such as cells, molecules (particularly, valuable proteins),
suspended particles, media, buffer, carrier, reaction solution, or
other liquid component.
[0024] System treatment solutions as used herein refers to buffers
including equilibration buffers and other pre-filtration system
treatment solutions, post filtration system treatment solutions
including washing fluid and/or buffers and storage solutions placed
into the system during inactivity.
[0025] One embodiment of a CFF/TFF system 100 according to the
invention, utilizing a microfiltration membrane is shown in FIG. 1,
FIG. 8 and FIG. 9. The system may be automated and can be used to
separate components present in a solution, such as are commonly
found in biological samples including biofluids. For example,
depending upon the pore size of the membrane used, cells (such as
blood cells) can be washed with buffers prior to lysis to remove
contaminants, cellular debris can be separated from soluble
materials, and/or proteins can be purified for
characterization.
[0026] The exemplified embodiment of FIG. 1 includes an automated
system 100 that comprises reservoir 102, reservoir 104 and filter
106, for example a CFF/TFF filter or filtration module. The volume
of reservoirs 102 and 104 can, for example, range from around 1
liter to around 200 liters in volume and can be scaled to around
2000 liters or more. The reservoirs may be single use or multi-use
and can include bags or other vessels composed of suitable
material, such as, for example, glass, ceramics or stainless steel
and inert plastic material, such as flexible material including
flexible plastic material. A means for mixing or agitating the
contents of the reservoirs may also be utilized in conjunction with
the reservoirs.
[0027] The filter 106 may include a microfiltration membrane but it
will be understood that, depending upon the nature of the
separation to be effected, an ultrafiltration or other membrane
could be used. The membrane may be flat or hollow in configuration.
A microfiltration membrane may be chosen which has pore sizes such
that the component of interest (e.g., a protein) within the
solution will pass through the membrane whereas larger components
will be retained by it or such that the component of interest
(e.g., a protein) within the solution will be retained by the
membrane whereas smaller components will pass through it. The
material contained therein passing through the membrane is known as
the permeate, while the material retained by the membrane is called
the retentate.
[0028] Suitable membranes may include ultrafiltration, microporous,
nanofiltration or reverse osmosis filters formed from
polyvinylidene fluoride (PVDF), polysulfone, polyethersulfone,
polyarylsulfone, regenerated cellulose, polyamide, polypropylene,
polyethylene, polytetrafluoroethylene, cellulose acetate,
polyacrylonitrile, vinyl copolymer, polyamides (such as "Nylon 6"
or Nylon 66") polycarbonate, PFA, blends thereof or the like.
[0029] The system may also includes a plurality of pumps, valves
and sensors (sensors as used herein may also includes meters) for
driving, regulating, and acquiring data about a solution as it
moves through the system. The system may also include an electronic
data processing network capable of receiving, transmitting,
processing and recording data related to as well as coordinating
the operation of the pumps, valves, sensors and the filter. The
sensors may be used to gather information and data about the
solution passing through the system at various points therein. Such
sensors may monitor physical parameters within the system, such as,
for example, pressure, temperature, conductivity, pH, oxygen
concentration and ultraviolet light absorption as well as volume
flow and/or mass flow measurements.
[0030] The system includes a plurality of pumps to drive the flow
of solution through the system. Although pumps are preferred, other
electronically-controllable means for driving a sample solution
through such a system may also be used. Pumps used may include, for
example, high-pressure positive displacement (HPPD) pumps,
diaphragm pumps, piston pumps, centrifugal, lobe- and peristaltic
pumps as well as other pump configurations including, for example,
piezoelectric-driven, acoustically-driven,
thermopneumatically-driven and electrostatically-driven pumps.
Suitable pump flow rates may range from about 10 ml. per minute to
about 1000 liters per minute, preferably about 20 ml. per minute to
about 400 liters per minute, depending on feed volume and material
to be separated with a stipulated time period.
[0031] For certain biopharmaceutical applications in which the
biofluid under investigation has substantial and significant
protein content, forces and circumstances that can lead to the
unintended and undesired denaturation of proteins (i.e., the loss
of the physical conformation of the protein's polypeptide
constituency) should be avoided and/or mitigated. The mechanical
shear forces often produced in the operation of certain pumps,
particularly at gas/liquid interfaces (cf. e.g., bubbles), have
been linked to protein denaturation, and accordingly, should be
mitigated and/or avoided in the selection, manufacture, and
incorporation of the device.
[0032] Valves are positioned along or otherwise functionally
proximate the solution path for regulating the flow of the solution
therethrough. For example, the valves may be pinch valves that
apply a force to flexible tubing passing therethrough to regulate
the flow of the solution. The flow of solution through a valve
depends upon whether the valve is in an "open" or "closed" state or
in some circumstances in an intermediate state, the latter being
where the flow of solution is not completely "on" or "off" but in
between, thereby regulating the flow rate therethrough.
[0033] A conduits system connects reservoir 102, reservoir 104 and
filter 106 and so that they are in fluid communication and includes
a series of conduits that may also include various valves, pumps
and sensors. The filter 106 may include a CFF/TFF filter. There is
no particular limitations to the type of conduit used. Potential
conduit types include, for example, rigid pipes, flexible tubing,
and the channels and passages formed in or intrinsic to the
system's other components (e.g., filter, sensors, valves and
pumps). Other conduit systems may include "cassettes" that
integrate multiple components of the flowpath, for example. For
example, tubing networks or fluid conduit networks may be
integrated into a single device that may also include valves to
regulate the flow through the tubing network, as well as sensors,
pumps, filtration modules and other fluid treatment, control or
monitoring components. Typically, the plurality of conduits
employed in the system may include a mixture of conduit types.
Preferably, the majority of the conduits employed are flexible,
substantially biologically inert, synthetic polymeric tubing having
an internal diameter of 1-50 mm, more preferably 3-32 mm.
[0034] In the embodiment of FIG. 1 reservoir 102 is in fluid
communication with conduit 108 that is in fluid communication with
conduit 110, the latter may include valve 112. A second conduit
section includes conduit 114 and valve 116. Conduit 114 may be in
fluid communication with another reservoir (not shown) that may be
similar to reservoirs 102 and 104. Conduits 110 and 114 are both in
fluid communication with conduit 118 that may include pump 120 and
valves 122 and 124. Conduit 118 is in fluid communication with
conduit 125 that includes valve 126 and with conduit 128 that
includes valve 130.
[0035] Conduit 125 is in fluid communication with conduit 132 that
is connected to retentate outlet 134 of filter 106 and to reservoir
104. Conduit 132 also includes valves 136, 138 and 140 (such as,
for example, external tube pinch valves) as well as various sensors
including, for example, flow sensor (F) 142, conductivity and
temperature sensor (C&T) 144 and pressure retentate sensor (Pr)
146. Conduit (alternatively called a feed conduit) 148 is in fluid
communication with reservoir 104 and with conduit 132 via reservoir
104. Conduit 148 is also in fluid communication with feed inlet 150
of filter 106. Conduit 148 may include pump 152, valves 154 and 156
as well as various sensors including, for example, pressure feed
sensor (Pf) 158. Valve 160 is also in fluid communication with
conduit 148 and a drain/drain line 161 and is connected to a
drain/collection/recovery/sample container (not shown).
[0036] The embodiment may also include valves and air filters
connected thereto such that the valves are in fluid communication
with system conduits (not shown). The air filters may be open to
the atmosphere or connected to an external integrity tester. Filter
106 also includes permeate outlets 170 and 172 that are both in
fluid communication with conduit 174. Conduit 174 is in fluid
communication with conduit 176 and further with conduit 186,
forming together a permeate conduit. Conduit 176 includes valve 178
as well as various sensors including, for example, flow sensor (F)
180, conductivity and temperature sensor (C&T) 182 and pressure
permeate sensor (Pp) 184. Conduits 176 and 128 are in fluid
communication with conduit 186 and are thus in fluid communication
with each other. Conduit 186 may include valves 188 and 190 and
pump 192. Conduit 186 is also in fluid communication with drain 194
and conduit 196. Conduit 196 is in fluid communication with
reservoir 198. Reservoirs 104 and 198 may be connected to a means
of sensing the mass thereof and as such may be connected to an
electronic data processing network capable of receiving,
transmitting, processing and recording data therefrom.
[0037] A re-circulation loop formed in the flow path includes
conduit 128 (recirculation loop conduit) which can connect permeate
outlets 170 and 172 via conduits 174, 176 and 186 (the permeate
conduit) back to the retentate line/conduit (conduit 132) via
conduits 118 and 125. This additional loop is a re-circulation loop
that enables a system treatment solution (e.g., equilibration
buffer/cleaning or storage solution) to circulate in the flow path
until the user drains it via, for example, drain 194. Automated
circulation through re-circulation loop minimizes the manual steps
involved for filter and system conditioning as well as
pre-filtration treatment and post-filtration treatment. Without the
re-circulation loop, manual intervention would be needed when using
a system treatment solution due to the additional
connections/disconnections needed that would involve additional
time and threaten user interference in the sterile condition of the
system. Thus, utilizing the re-circulation loop, the sterility
and/or integrity of the fluid system is not compromised as well as
risk for compromising the sterility and/or integrity of the fluid
system is greatly reduced by eliminating the manual interaction for
connecting or disconnecting fluid conduits and containers at the
outlet and/or inlet connections of the fluid system during the
process. As a consequence, product (drug) and patient safety are
increased. Further, operator safety during production of said
products (drugs) is increased when processing potentially harmful
fluids, fluid components or product intermediates, which could be
the case during vaccine processing or production of ADC (antibody
drug conjugates).
[0038] Some of the above components may be single use or multi-use
depending on the system's usage. If components of the system are to
be used more than once, the filter, the membrane therein and other
system components can be cleaned using various washing
fluid/buffers at the end of a filtration cycle to remove any
contaminants (such as solids, particles, etc,) which may, for
example, adsorb onto the membrane surface and block the pores. In
this way, the operational lifetime of a filter, the membrane
therein and other system components can be increased and their
efficiency maintained.
[0039] The construction materials used in the system can suitably
be compatible with commonly used sterilization methods, such as
e.g. gamma irradiation and/or autoclaving. For reusable components,
stainless steel (e.g. with corrosion resistance at least equivalent
to 316 L) or engineering plastics such as polysulfone, PEEK, etc.
may be used, while for single-use components, plastics, such as,
e.g. polysulfone, polypropylene, polyethylene or ethylene
copolymers, may be used. Tubing material may comprise materials
such as silicone or TPE (thermoplastic elastomers); tubing may be
weldable. All materials used in the construction of the system
which come into contact with a solution (e.g., system treatment
solution), biofluid, retentate and/or permeate are selected to
avoid any chemical interaction and to minimize physical adsorption
with the components within the solution. Typically, the valves are
made of glass, ceramics, stainless steel or external tube pinch
valves and the tubing of an inert plastic polymer.
[0040] All product contact surfaces of the system and components
thereof are desirably, made of FDA compliant and/or USP Class VI
tested materials. The system and its components should also be
compatible with all commonly used solvents used in CFF/TFF,
including, for example, IN NaOH (at 50.degree. C.), 400 ppm NaOCl
(at 50.degree. C.), 1.1% phosphoric acid, 1.8% acetic acid, 2M HCl,
2M urea, "Triton-X" (a non-ionic detergent produced by
polymerization of octylphenol with ethylene oxide, available from
the Union Carbide Company, Danbury, Conn.), "Tween" (a
polysorbate), 30-50% hexalene glycol, 30-50% propylene glycol,
0.07% polysorbate 20, 0.01-0.02% polysorbate 80, 90% ethanol, 90%
methanol, 90% isopropyl alcohol, and 25% acetonitrile (w/v
water).
[0041] To avoid contamination of the biofluid, all system
components in contact with the biofluid should be suitably
sterilized before the filtration process starts. The system or
parts of the system may be assembled and sterilized by autoclaving
or radiation, or one or more components may be pre-sterilized and
assembled in a sterile system. To facilitate assembly, the system
parts or components may be equipped with and connected by suitable
connectors, in particular, the sterilized system parts or
components may be equipped with and connected by aseptic
connectors, e.g. of the ReadyMate type (GE Healthcare). As such,
the sterilized system parts or components and associated connectors
may be packaged in aseptic packaging. The sterilized system
parts/components may also be contained in aseptic packages and
assembled in a controlled environment, e.g., a clean room.
[0042] Typical filling operation of an automated CFF/TFF system is
exemplified in FIG. 2. Although the solution to be filtered, for
example, a biofluid, is contained during operation in reservoir
200, in typical practice, the reservoir 200 may not necessarily be
the starting point or origin of the solution. For example,
reservoir 200 can be provided with the solution from reservoir 202
through the conduit system shown in FIG. 2 driven by pump 204 with
valves 206 in an open position and valves 208 in a closed position
with the direction of flow indicated by arrows 210.
[0043] Typical filtration or concentration operation of the CFF/TFF
system is exemplified in FIG. 3. The solution to be filtered is
contained in reservoir 300 and proceeds through the conduit system
shown in FIG. 3 through filter 302 driven by pump 304 with valves
306 in an open position and valves 308 in a closed position with
the direction of flow indicated by arrows 310 for the feed, 312 for
the retentate and 314 for the permeate. Valve 316 is open and valve
318 is closed when the permeate flow is to be sent to drain 320.
Valve 316 is closed and valve 318 is open when the permeate flow is
to be sent to reservoir 322. For example, if the solution includes
a molecule of interest that is larger than the pore size of the
filter membrane, the molecule will be present in the retentate that
will be returned to reservoir 300 resulting in a greater
concentration of biomolecule present in reservoir 300 as the
operation proceeds. If, for example, the solution includes a
molecule of interest that is smaller than the pore size of the
filter, the molecule will be present in the permeate for
collection, for example, in reservoir 322.
[0044] Prior to proceeding with the filtration operation, the
system may need to treated with equilibration buffer or other
pre-filtration treatment solutions to prepare the system for the
filtration process. One of the purposes of equilibration buffer and
other pretreating solutions may be to prepare the filter and
membrane included therein as well as other system components for
the fluid containing, for example, a desire biological product
(e.g., a protein) by, for example, raising the salt concentration
and other fluid physical parameters of the system including the
filter, the membrane and other system components to match that of,
for example, a bacterial lysate that will be put through the
system.
[0045] Subsequent to the filtration process, if components of the
system are to be used more than once, the filter, the membrane
therein and other system components can be cleaned using various
washing fluid/buffers at the end of a filtration cycle to remove
any contaminants (such as solids, particles, etc,) which may adsorb
to the membrane surface and block the pores.
[0046] Buffer equilibration and use of other pre-filtration
treatment solution as well as use of post filtration washing
fluid/buffers and storage solutions (all of which are referred to
herein as system treatment solutions) is accomplished by the
exemplified embodiment as shown in FIGS. 4, 5 and 6. In FIG. 4, the
exemplary embodiment undergoes the step of system treatment
solution fill in which reservoir 400 may provided with the system
treatment solution from reservoir 402 through the conduit system
shown in FIG. 4 driven by pump 404 with valves 406 in an open
position and valves 408 in a closed position with the direction of
flow indicated by arrows 410.
[0047] In FIG. 5, the system treatment solution from reservoir 500
is circulated through the conduit system shown in FIG. 5 and filter
502 driven by pump 504 with valves 506 in an open position and
valves 508 in a closed position with the direction of flow
indicated by arrows 510. Re-circulation is important to the
filtration process. For example, buffer needs to recirculate
through the filter for filter conditioning at a particular flow for
stipulated time and in the same way for the filter cleaning and
storage. Conditioning will improve filter efficiency. Suitable pump
flow rates during this process may range from about 0.1 liter per
hour to about 5000 liters per hour, preferably about 1 liter per
hour to about 1000 liters per hour, more preferably 2-300 liters
per hour. The conditioning circulation process can take place from
about 10 minutes to about 6 hours, however, the time can vary
depending on such parameters as, for example, filtration area,
filter membrane type, filter condition and process condition.
[0048] In FIG. 6, after system treatment solution circulation is
completed, the system treatment solution is drained from reservoir
600, filter 602 and the conduit system. The draining process is
driven by pump 604 with valves 606 in an open position and valves
608 in a closed position with the direction of flow indicated by
arrows 610 and to drain 612.
[0049] In at least one aspect of the disclosed embodiments, the
systems and methods disclosed herein may be executed by an
electronic data processing network including, for example, one or
more controllers, computers or processor-based components under the
control of one or more programs stored on computer readable medium,
such as a non-transitory computer readable medium. FIG. 7 shows a
block diagram of an exemplary controller or computing apparatus 700
that may be used to practice aspects of the disclosed embodiments.
In at least one exemplary aspect, the system control circuitry,
data acquisition circuitry, data processing circuitry, operator
workstation and other disclosed devices, components and systems may
be implemented using an instance or replica of the controller or
computing apparatus 700 or may be combined or distributed among any
number of instances or replicas of computing apparatus 700.
[0050] The controller or computing apparatus 700 may include
computer readable program code or machine readable executable
instructions stored on at least one computer readable medium 702,
which when executed, are configured to carry out and execute the
processes and methods described herein, including all or part of
the embodiments of the present disclosure. The computer readable
medium 702 may be a memory of the controller or computing apparatus
700. In alternate aspects, the computer readable program code may
be stored in a memory external to, or remote from, the apparatus
700. The memory may include magnetic media, semiconductor media,
optical media, or any media which may be readable and executable by
a computer.
[0051] Controller or computing apparatus 700 may also include a
processor 704 for executing the computer readable program code
stored on the at least one computer readable medium 702. In at
least one aspect, computing apparatus may include one or more input
or output devices to allow communication among the components of
the exemplary imaging system, including, for example, what may be
generally referred to as a user interface 706, such as, the
operator workstation described above, which may operate the other
components included in the imaging system or to provide input or
output from the controller or computing apparatus 700 to or from
other components of the imaging system. The controller or computing
apparatus 700 may be connected to the pumps, valves, sensors and
other components of the system (as illustrated in FIG. 9) for
coordinating the operation thereof as well as receiving,
transmitting, processing, and recording data from the pumps,
valves, and sensors.
[0052] Preferably, the embodiment of FIG. 1 is a single use system
that maximizes maintaining the sterility or integrity of the system
during system operation such that the environment outside the
system does not contaminate or violate the environment inside the
system as well as vice versa. Such operation includes the process
of treating the system with system treatment solutions (e.g.,
buffer, particularly equilibration buffer) and the filtration
process itself. In order to maintain the integrity of the system,
the embodiment may include a cabinet having sides that define a
cabinet interior and cabinet exterior. Some of the components shown
in FIG. 1 may be single use and mounted to the cabinet and may be
partially exposed to an external side of the cabinet so as to
provide easy access for installation and removal. As a result of
utilizing single use components, the system can be set-up and
system operation conducted automatically (e.g., utilizing
electronic data processing network) without having to change or
alter the path of system components that could affect the integrity
of the system from the outside or allow components of solutions in
the system (e.g., viruses, proteins and other components of a bio
fluid) to escape the system that could, for example, potentially
cause harm to human operators.
[0053] Preferably, the complete flow path in fluid contact is
provided as a single use flow path unit that is exchangeable in
between different processes and production runs. Single-use
technology helps reduce time-consuming device preparations, such as
cleaning and cleaning validation, and helps reduce a risk for
cross-contamination, which is important in applications such as
vaccine manufacturing, for example. For example, GE Healthcare Life
Science's READYTOPROCESS.TM. platform provides disposable, scalable
fluid processing solutions. For example, the AKTA ready.TM. single
use chromatography system provides an integrated disposable fluid
processing conduit system (Flow Kit) with tubing, sensors, pumps
and other fluid treatment, control and monitoring components that
comprises all system components in fluid contact aimed for exchange
and disposal after processing with biofluids. The Flow Kit is
manufactured in a controlled environment and subjected to a
bioburden reduction by gamma irradiation.
[0054] External to the cabinet, for example, in FIG. 1 and the
frontal 101, left 103 and right 105 side panels of the cabinet as
shown in FIGS. 8 and 9 (back side panel not shown) may be
reservoirs, conduit tubing, tubing connectors (e.g., aseptic
connectors, such as the ReadyMate type (GE Healthcare)), sensors
and intersection points to which the conduit tubing encounters
other system components, for example pumps and a filter module. For
example, some, if not all, of the conduit tubing is flexible
tubing, preferably, single use tubing, (e.g., conduits 108, 110,
114, 118, 128, 132, 148, 174, 176, 186 and 196 in FIG. 1) external
to the cabinet, including some flexible tubing mounted to an
exterior side of the cabinet and other components such as valves,
sensors and pumps positioned thereon. The reservoirs, preferably,
single use reservoirs, (e.g., reservoirs 102, 104 and 198 in FIG.
1) may be mounted to the cabinet or separate therefrom. The CFF/TFF
filter, preferably, a single use CFF/TFF filter, (e.g., filter 106
in FIG. 1) may be mounted to the cabinet such that the portion of
the filter connected to the flexible tubing is external to the
cabinet, for example, positioned on an external side of the
cabinet. The sensors, preferably, single use sensors, (e.g.,
sensors 142, 144, 146, 158, 180, 182 and 184 in FIGS. 1, 8 and 9)
may be mounted to the cabinet such that the portion of the sensor
connected to the flexible tubing is external to the cabinet, for
example, positioned on an external side of the cabinet. The valves
(e.g., valves 112, 116, 122, 124, 126, 130, 136, 138, 140, 154,
156, 160, 178, 188 and 190 in FIGS. 1, 8 and 9) may be pinch valves
mounted to the cabinet such that the portion of the valve through
which the flexible tubing passes is external to the cabinet, for
example, positioned on an external side of the cabinet. The pumps
(e.g., pumps 120, 152 and 192 in FIGS. 1, 8 and 9) may be
peristaltic pumps mounted to the cabinet such that the portion of
the peristaltic pump through which the flexible tubing passes is
external to the cabinet, for example, positioned on an external
side of the cabinet. If another type of pump is utilized (e.g.,
pump 152 of FIG. 1), for example, a piston pump, the components of
the pump that will encounter the solution passing through the
system (e.g., inlet, outlet, chamber and parts contained therein,
check valve, etc.) may be single use or replaced for each use as
well. Furthermore with a piston pump, it may be mounted to the
cabinet such that the portion of the piston pump connected to the
flexible tubing is external to the cabinet, for example, positioned
on an external side of the cabinet. An electronic data processing
network including a controller or computing apparatus 700 connected
to the pumps, valves, sensors and filter and capable of receiving,
transmitting, processing and recording data related to as well as
coordinating the operation thereof may be partially or completely
internal to the cabinet.
[0055] As a result, the operations of system treatment with a
system treatment solution and filtration of a solution (e.g., a
biofluid) can be accomplished in succession without having to
re-configure the system (such as re-routing the fluid conduits)
that could compromise the integrity of the system.
[0056] Furthermore, an electronic data processing network can
direct the other components of the system (e.g., pumps and valves
as well as sensors and filter) to proceed with the operations of
system treatment and filtration of a solution automatically and
without human intervention.
[0057] This written description uses examples as part of the
disclosure, including the best mode, and also to enable any person
skilled in the art to practice the disclosed implementations,
including making and using any devices or systems and performing
any incorporated methods. The patentable scope is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they have structural elements that do not differ
from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
* * * * *