Method and apparatus for flow cytometry

A flow cytometer comprising:

• a source of stream fluid to establish a stream;
• a stream exit point where the stream is emerges from the flow cytometer;
• a droplet break off point where the stream breaks off into droplets;
• a first sensor to determine an approximate speed of the stream at a first position along the stream;
• a second sensor to determine an approximate speed of the stream at a second position along the stream;
• and
• a computer to utilize the approximate speed of the stream at a first position along the stream and the approximate speed of the stream at a second position along the stream in order to determine a stream characteristic by modeling the speed of the stream in a region occurring between the stream exit point and the droplet break off point as decaying approximately exponentially relative to distance.

A method of flow cytometry comprising:

• establishing a stream comprising a flow of particles, the stream having a droplet break off point;
• creating a first droplet, the first droplet having an electrical charge;
• capturing an image of the stream;
• creating a second droplet in proximity to the first droplet;
• determining an effect that the electrical charge on the first droplet will have on the second droplet;
• generating a signal for the flow cytometer based on the determined effect;
• and
• charging the second droplet to counteract the determined effect that the charge on the first droplet will have on the second droplet.

A method of controlling a flow cytometer, comprising the steps of:

• establishing a stream comprising a flow of particles, the stream having a droplet break off point;
• capturing an digital image of the stream to determine a drop delay time for a particle in the stream;
• and
• generating a signal for the flow cytometer, wherein a time of generation of the signal is adjusted based on the determined drop delay time from the captured image.

A flow cytometer comprising:

• a source of stream fluid;
• a source of particles for suspension in the stream fluid;
• a stream comprising the stream fluid and the particles;
• a nozzle through which the stream is established;
• a break off point of the stream at which point the stream breaks off into droplets, said droplets centered about the break off point;
• a camera that captures an image of the stream;
• an analyzer that analyzes the image of the stream to determine the effect that a first charged droplet has on a second droplet;
• and
• a signal generator to generate a signal based on the determined effect that the first charged droplet has on the second droplet.

A flow cytometer comprising:

• a source of stream fluid;
• a source of particles for suspension in the stream fluid;
• a stream comprising the stream fluid and the particles;
• a nozzle through which the stream is established;
• an exit point at which said stream emerges from said nozzle;
• a break off point of the stream at which point the stream breaks off into droplets, said droplets centered about the break off point;
• a camera that captures a digital image of the stream;
• an analyzer that analyzes the digital image of the stream to determine a drop delay time for a particle in the stream;
• and
• a signal generator to generate a signal, for the flow cytometer wherein a time of generation of the signal is adjusted based on the determined drop delay time.

A method comprising:

• establishing a stream in a flow cytometer;
• capturing a first image of the stream established in the flow cytometer;
• creating a first digital representation of the stream based on the first image;
• capturing a second image of the stream established in the flow cytometer;
• creating a second digital representation of the stream based on the second image;
• comparing the second digital representation of the stream to the first digital representation of the stream;
• and
• determining whether a property of the stream has changed based on the comparison of the first digital representation of the stream with the second digital representation of the stream.

A flow cytometer apparatus comprising:

• a stream source used to establish a stream;
• a camera to capture images of the stream;
• an imaging means for creating digital representations of the stream;
• a memory to store a first digital representation of the stream;
• a comparator to compare the first digital representation of the stream with a second digital representation of the stream;
• and
• a signal generator to generate a signal to the flow cytometer based on the comparison of the first digital representation of the stream with the second digital representation of the stream.