WEIGHT MEASUREMENTS OF LIQUIDS IN FLEXIBLE CONTAINERS
Articles and methods for measuring weight of a liquid in a disposable bag bioreactor are presented. In certain embodiments, bioreactor systems described herein include a supported container (e.g., a flexible bag in a reusable housing) for containing a liquid, and at least two pressure indicating sensors operatively associated with the container. A first pressure indicating sensor can be placed near the bottom of the container to measure the total downward force within the container, including the liquid head in the container and the gas pressure above the liquid. The second pressure indicating sensor can be placed near the top of the container to measure only the pressure at the top of or above the liquid. Signals from the pressure indicating sensors can be directed to a control system that receives the signals and calculates a difference between the signals. This difference can be used to determine a volume or a weight of the liquid in the container. Advantageously, real-time weight measurements can be obtained while the system is in operation and continuous flow processes can be monitored. Moreover, in some embodiments, the pressure indicating sensors are isolated from contact with any fluid (e.g., liquid) in the container and, therefore, do not require cleaning after processing of each batch of reactants. Contamination of the process fluid by contact with the pressure indicating sensors can also be avoided.
1 . A bioreactor system comprising:
a flexible container for housing a liquid, the container;
a reusable support structure for surrounding and containing the flexible container;
a first pressure or force indicating sensor operatively associated with the flexible container but not in fluid contact with any fluid in the flexible container, the pressure or force indicating sensor configured to measure a parameter indicative of a first pressure in the flexible container;
a second pressure or force indicating sensor operatively associated with the flexible container, the pressure or force indicating sensor configured to measure a parameter indicative of a second pressure in the flexible container; and
a control system configured to receive input from the first and second pressure or force indicating sensors indicative of the first and second pressures and to calculate a difference between the first and second pressures.
2 . A bioreactor as in claim 1 , further comprising determining a volume or a weight of a liquid in the flexible container using the difference between the first and second pressures.
3 . A bioreactor system as in claim 1 , wherein the flexible container is configured to be removable from the reusable support structure.
4 . A bioreactor system as in claim 3 , wherein the flexible container is in the form of a disposable bag.
5 . A bioreactor system as in claim 4 , wherein the disposable bag is sterile prior to use.
6 . A bioreactor system as in claim 1 , wherein the flexible container includes at least one inlet port and at least one outlet port.
7 . A bioreactor system as in claim 1 , wherein the control system is configured to receive signals from the first and second pressure or force indicating sensors, the signals comprising the input indicative of the first and second pressures.
8 . A bioreactor system as in claim 1 , wherein the first and/or second pressure or force indicating sensors comprises a measuring cell for sensing a force or pressure and an electronic circuit to process a signal from the measuring cell.
9 . A bioreactor system as in claim 1 , wherein the first and/or second pressure or force indicating sensors comprises a piezoelectric sensor.
10 . A bioreactor system as in claim 1 , wherein the first pressure or force indicating sensor senses a force applied to the flexible container by a liquid in the flexible container.
11 . A bioreactor system as in claim 1 , wherein the first pressure or force indicating sensor is positioned at a bottom of the flexible container.
12 . A bioreactor system as in claim 1 , wherein the first pressure or force indicating sensor is positioned at an inner surface of the reusable support structure and the inner surface is in contact with the flexible container.
13 . A bioreactor system as in claim 1 , wherein the first pressure or force indicating sensor is mounted flush at a bottom surface of the reusable support structure.
14 . A bioreactor system as in claim 1 , wherein the first and/or second pressure or force indicating sensor is not in contact with a liquid in the flexible container.
15 . A bioreactor system as in claim 1 , wherein the first and/or second pressure or force indicating sensor is not in contact with a gas in the flexible container.
16 . A bioreactor system as in claim 1 , wherein the flexible container forms a closed system.
17 . A bioreactor system as in claim 1 , wherein the flexible container forms an open system.
18 . A bioreactor system as in claim 4 , wherein the disposable bag is substantially deflated prior to being filled with a liquid.
19 . A bioreactor system as in claim 1 , further comprising a gauge guard positioned between the second pressure or force indicating sensor and the flexible container.
20 . A bioreactor system as in claim 1 , further comprising a mixer.
21 . A bioreactor system as in claim 20 , wherein the mixer comprises an impeller positioned inside the flexible container.
22 . A method comprising determining a weight and/or volume of the liquid in the flexible container of claim 1 .
23 . A method as in claim 22 , further comprising determining a status of a vent filter operatively associated with the bioreactor system of claim A using one or more measurements from the first and/or second pressure or force indicating sensors.
24 . A bioreactor system comprising:
a flexible container for housing a liquid in the container;
a reusable support structure for surrounding and containing the flexible container;
a first pressure or force indicating sensor operatively associated with the flexible container and configured to measure a parameter indicative of a first pressure in the flexible container;
a second pressure or force indicating sensor operatively associated with the flexible container and configured to measure a parameter indicative of a second pressure in the flexible container; and
a control system configured to receive input from the first and second pressure or force indicating sensors indicative of the first and second pressures and to calculate a difference between the first and second pressures.
25 . A bioreactor as in claim 24 , further comprising determining a volume or a weight of a liquid in the flexible container using the difference between the first and second pressures.
26 . A bioreactor system comprising:
a flexible container for housing a liquid in the container;
at least one pressure or force indicating sensor operatively associated with the flexible container but not in contact with any fluid in the flexible container, the pressure or force indicating sensor configured to measure a parameter indicative of a pressure in the flexible container, and
a control system configured to receive input from the at least one pressure or force indicating sensor indicative of the pressure, the control system configured to determine from the input a volume or a weight of a liquid in the flexible container.