Flow cytometry system with stepper flow control valve

A flow cytometry system, comprising:

• a first scatter channel to detect a first light scatter generated by a particle passing through a first laser beam, wherein the particle flows in a flow channel of a sample fluid;
• a second scatter channel to detect a second light scatter generated by the particle flowing in the flow channel of the fluid sample and passing through a second laser beam, wherein the first laser beam and the second laser beam are separated by a first predetermined distance;
• a flow cell to receive a flow of the sample fluid and a flow of a sheath fluid, wherein the flow of the sample fluid is surrounded by the flow of the sheath fluid;
• and
• a linear resistance stepper valve to apply a physical fluid resistance to the flow of the sheath fluid, wherein the physical fluid resistance regulates a flow rate of the sheath fluid and thereby regulates a flow rate of the sample fluid, the linear resistance stepper valve comprising internal walls that form a piston bore;
• an inlet port to receive sheath fluid into the piston bore;
• an outlet port to send sheath fluid out of the piston bore;
• and a piston configured to travel a length into the piston bore.