Timing and/or phase adjustment of the separation and/or charging of drops from a fluid stream in a flow cytometer
AssigneeBio-Rad Laboratories, Inc.
InventorEdward Marquette
Life of this patent
Estimating the term…
Abstract
Disclosed is a system for setting the timing or phase of the separation of droplets from a fluid stream in a flow cytometer, or the timing or phase of a charge pulse generator, based upon the collected charge of charged droplets. In one embodiment, a conductive mesh can be used to collect the charged droplets that are either deflected or not deflected by the deflection plates. In another embodiment, the charge can be collected from metal plates in the waste collection device. In addition, a defanning device is disclosed that allows substantially uniform deflection of charged cells.
Claims12
A method of adjusting the timing or phase of a charge pulse signal for charging droplets from a fluid stream of sheath fluid in a flow cytometer, the method comprising:
- forming a fluid stream by flowing the sheath fluid through a nozzle, wherein the fluid stream separates into droplets after exiting the nozzle;
- applying the charge pulse signal to the nozzle during a calibration phase, wherein each droplet that separates from the stream when the charge pulse signal causes a charge to be applied to the nozzle becomes a charged droplet and each droplet that separates from the stream when the charge pulse signal does not cause a charge to be applied to the nozzle remains an uncharged droplet;
- receiving the charged and uncharged droplets in a charge collector during the calibration phase;
- collecting charges during the calibration phase from the charged droplets for a plurality of timing or phase settings using an electrometer that is connected with the charge collector;
- measuring the charges collected from the charged droplets for each of the timing or phase settings to create a plurality of collected charged droplet signals that are each indicative of an accumulated charge signal produced by the electrometer;
- determining a collected charged droplet signal of the plurality of collected charged droplet signals that has the greatest magnitude;
- and
- operating the flow cytometer with a timing or phase setting of the plurality of timing or phase settings that corresponds to the collected charge droplet signal that has the greatest magnitude.
A method of adjusting the amplitude of a charge signal that is applied to droplets formed from a fluid stream in a flow cytometer to create a substantially uniform charge on the droplets in a fluid stream comprising:
- controlling a charge pulse signal to impart a positive charge, a negative charge, or a neutral charge to each droplet generated during a calibration phase to produce a plurality of calibration charge series, each calibration charge series including a sequence of droplets;
- subjecting each calibration charge series to an electric field to cause the droplets in that calibration charge series having a positive charge imparted to them by the charge pulse signal to be collected in a first conductive droplet collector, the droplets in that calibration charge series having a negative charge imparted to them by the charge pulse signal to be collected in a second conductive droplet collector, and the droplets in that calibration charge series having a neutral charge imparted to them by the charge pulse signal to be collected in a third conductive droplet collector;
- detecting accumulated charges in the first conductive collector, the second conductive collector, and the third conductive collector for one or more instances of each calibration charge series
- determining, for each calibration charge series and based on the accumulated charges for the first conductive collector for that calibration charge series, the accumulated charges for the second conductive collector for that calibration charge series, and the accumulated charges for the third conductive collector for that calibration charge series, an average measured charge magnitude for each droplet of that calibration charge series,
- adjusting an amplitude of the charge pulse signal used to impart positive, negative, or neutral charges to each droplet of a first charge series based on the average measured charge magnitude for droplets in the calibration charge series that corresponds with the first charge series.
A system for adjusting a charge amplitude of a charge pulse signal that is applied to droplets formed from a fluid stream in a flow cytometer to create a substantially uniform charge on said droplets comprising:
- a charge pulse generator that generates said charge pulse signal in response to a control signal, that has a charge magnitude that charges droplets just prior to separation from said fluid stream to obtain charged droplets;
- at least one conductive collector that collects said charged droplets and accumulates a charge having a charge magnitude;
- an electrometer connected to said at least one conductive collector that detects said charge magnitude and generates a charge magnitude signal;
- a processor that receives said charge magnitude signal and generates said control signal, said control signal producing a plurality of charge series of said droplets that produces affected droplets that have a charge that has been affected by electric fields of preceding droplets and non-affected droplets that have not been affected by electric fields of preceding droplets, and compares said charge magnitude signal for said affected droplets and said non-affected droplets for said plurality of charge series to alter said charge magnitude of said control signal, which charges said droplets to a uniform magnitude during operation of said flow cytometer.
Dependencies are inferred from the claim text.