System and methods for control of pumps employing electrical field sensing
First Claim
1. A system for pumping a fluid comprisinga pump chamber, a flexible diaphragm on the pump chamber and responsive to applied fluid pressures to convey fluid through the pump chamber, an electrode in the pump chamber in electrical conductive contact with the fluid in the pump chamber and coupled to an electrical source to generate an electrical field in the pump chamber that varies according volume of fluid in the pump chamber, and a sensing circuit coupled to the electrode to register variations in the electrical field as fluid is conveyed through the pump chamber.
6 Assignments
0 Petitions
Accused Products
Abstract
Systems and related methods pump fluid through a pump. The pump comprises a pump chamber, which is responsive to applied pressures to convey fluid. The systems and methods place an electrode in the pump chamber which, in use, is coupled to a current source. The electrode generates an electrical field in the pump chamber that varies according volume of fluid in the pump chamber. The systems and methods register variations in the electrical field as fluid is conveyed through the pump chamber.
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Citations
59 Claims
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1. A system for pumping a fluid comprising
a pump chamber, a flexible diaphragm on the pump chamber and responsive to applied fluid pressures to convey fluid through the pump chamber, an electrode in the pump chamber in electrical conductive contact with the fluid in the pump chamber and coupled to an electrical source to generate an electrical field in the pump chamber that varies according volume of fluid in the pump chamber, and a sensing circuit coupled to the electrode to register variations in the electrical field as fluid is conveyed through the pump chamber.
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15. A system for pumping a fluid comprising
a pump chamber having a known stroke volume, which is essentially constant, a flexible diaphragm on the pump chamber and responsive to applied fluid pressures to convey fluid through the pump chamber, a fluid pressure actuator interacting with the flexible diaphragm during a stroke interval to pump fluid through the pump, an electrode in the pump chamber in electrical conductive contact with the fluid in the pump chamber and coupled to an electrical source to generate an electrical field within the pump chamber that varies according volume of fluid in the pump chamber, a sensing circuit coupled to the electrode to register variations in the electrical field as fluid is conveyed through the pump chamber, and a controller coupled to the sensing circuit and including a control function operating to command a desired flow rate by deriving an actual flow rate based upon the variations in the electric field over a sample time period and adjusting the stroke interval so that the desired flow rate is achieved.
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20. A system for pumping a fluid comprising
a pump chamber having a known stroke volume, which is essentially constant, a flexible diaphragm on the pump chamber and responsive to applied fluid pressures to convey fluid through the pump chamber, a fluid pressure actuator interacting with the flexible diaphragm during a stroke interval to pump fluid through the pump, an electrode in the pump chamber in electrical conductive contact with the fluid in the pump chamber and coupled to an electrical source to generate an electrical field within the pump chamber that varies according volume of fluid in the pump chamber, a sensing circuit coupled to the electrode to register variations in the electrical field as fluid is conveyed through the pump chamber, and a controller coupled to the sensing circuit and including a diagnostic function operating to detect abnormal operating conditions based upon variations in the electrical field and to generate an alarm output.
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25. A system for pumping a fluid comprising
a pump chamber, a flexible diaphragm on the pump chamber and responsive to applied fluid pressures in a draw cycle to draw fluid into the pump chamber and in an expel cycle to expel fluid from the pump chamber, an electrode in the pump chamber in electrical conductive contact with the fluid in the pump chamber and coupled to an electrical source to generate an electrical field in the pump chamber that varies according volume of fluid in the pump chamber, and a sensing circuit coupled to the electrode operating to register changes in capacitance due to variations in the electrical field during draw and expel cycles, the capacitance having a high signal magnitude when the pump chamber is filled with liquid, a low signal magnitude when the pump chamber is empty of fluid, and has a range of intermediate signal magnitudes when the pump chamber is neither full nor empty of fluid.
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34. A blood processing system coupled to a blood separation device comprising
a cassette containing a preformed, pneumatically actuated pump chamber, a preformed fluid flow path, and a pneumatically actuated valve in the fluid flow path, an electrode in the pump chamber in electrical conductive contact with fluid in the pump chamber, and connectors to couple the electrode to an electrical source to generate an electrical field in the pump chamber that varies according volume of fluid in the pump chamber.
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35. A blood processing system coupled to a blood separation device comprising
a cassette containing at least one pneumatically actuated pump station comprising a pump chamber having a known stroke volume, which is essentially constant, a pneumatic actuator to hold the cassette and selectively apply pneumatic force to the pump station during a stroke interval to pump fluid through the pump chamber, an electrode in the pump chamber in electrical conductive contact with the fluid in the pump chamber and coupled to an electrical source to generate an electrical field in the pump chamber that varies according volume of fluid in the pump chamber, and a sensing circuit coupled to the electrode to register variations in the electrical field as fluid is conveyed through the pump chamber.
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40. A method for conveying fluid through a pump comprising a pump chamber and a flexible diaphragm on the pump chamber and responsive to applied fluid pressures to convey fluid through the pump chamber, the method comprising the steps of
placing an electrode in the pump chamber in electrical conductive contact with the fluid in the pump chamber and which, in use, is coupled to an electrical source to generate an electrical field in the pump chamber that varies according volume of fluid in the pump chamber, and registering variations in the electrical field as fluid is conveyed through the pump chamber.
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55. A method for conveying fluid through a pump comprising a pump chamber having a known stroke volume, which is essentially constant, and a flexible diaphragm on the pump chamber and responsive to applied fluid pressures to convey fluid through the pump chamber, the method comprising the steps of
placing an electrode in the pump chamber in electrical conductive contact with the fluid in the pump chamber and which, in use, is coupled to an electrical source to generate an electrical field in the pump chamber that varies according volume of fluid in the pump chamber, placing the pump chamber into association with a fluid pressure actuator that interacts with the flexible diaphragm during a stroke interval to convey fluid through the pump, registering variations in the electrical field as fluid is conveyed through the pump chamber, and commanding a desired flow rate by deriving an actual flow rate based upon the variations in the electric field over a sample time period and adjusting the stroke interval so that the desired flow rate is achieved.
Specification