Sheathed particle flow controlled by differential pressure
AssigneeBecton, Dickinson and Company
InventorHoward L. North, Jr.
Life of this patent
Estimating the term…
Abstract
A flow apparatus for the analysis of particles passing substantially one at a time through an analysis region includes a flow rate control responsive to changes in the pressure used to drive the particles through the analysis region. The flow rate control automatically regulates the flow to a preset value throughout the analysis by adjusting the particle driving pressure to be uniform even though the sheathe liquid supply is depleted during the analysis. A method for controlling the flow of a supply of particles to be analyzed includes steps of sensing differential pressure and regulating the differential pressure to a preset reference.
Claims12
A sample flow control for a flow cytometer comprising:
- a body member having a passageway therethrough for the passage of particles which are to be analyzed, said passageway including an analysis portion, a pre-analysis portion and a post-analysis portion;
- a differential pressure transducer in fluid communication with a sheath liquid supplied to said pre-analysis portion of said passageway and adapted for fluid communication with the test tube containing a sample of particles connected to said pre-analysis portion of said passageway for providing a differential pressure input signal equivalent to the pressure difference therebetween;
- comparator means connected to receive said input signal and a preset reference signal for providing an operative control output comprising the difference between the signals;
- and
- regulating means powered by said operative control output to maintain the pressure applied to the sample test tube for driving particle flow therefrom at a preestablished flow value.
A method for controlling the flow rate through a particle analysis apparatus transporting a sample of particles carried in a liquid by regulating air pressure applied to the liquid including the follow steps;
- sensing a pressure difference between air driving a sample of particles and liquid to ensheath the sample,
- developing an electrical signal relative to the pressure difference sensed,
- providing an electrical reference signal of a pre-selected value relative to a desired sample flow rate,
- comparing the electrical reference signal and the pressure difference signal to generate an error signal,
- using the error signal to operate a pressure regulator, and
- effecting a control function of the pressure regulator for at least one of the differential pressures sensed.
Dependencies are inferred from the claim text.