Definition: Step resolution or (advance per microstep) is the sensitivity parameter of the syringe pump.

Theory: Chemyx syringe pumps are driven via stepper motors. A stepper motor (or step motor) is a brushless synchronous electric motor that divides a full rotation into a large number of fixed steps.

When the motor moves, it moves a certain angle driving the lead screw a fixed distance. This fixed distance is the "step resolution." The smaller the step resolution the more sensitive the pump - until you reach the sensitivity of the syringe itself. Chemyx syringe pumps engage in "micro-stepping" and the step resolution given is for the smallest movement of the motor.

Application: For most applications on the market a step resolution of 0.200 microns is more than enough.

For micro and nanofluidics is more complicated due to instantaneous accuracy requirements. For instance, microdialysis require little instantaneous accuracy since collecting samples over time smoothes out flow fluctuations. Nano ESI injections require very high instantaneous accuracy due to spray requirements.

Step resolutions under 0.010 microns have no impact on instantaneous accuracy because the pump is going below the syringe sensitivity.

Chemyx has products with both high and low instantaneous accuracy requirements please see the applications section in the web site.