SCYM (ASCP) EXAM SUMMARY GUIDE 2026 100% CORRECT

Hydrodynamic Focusing Most modern flow cytometers tightly position the sample for optical analysis via hydrodynamic focusing. Here, a carrier fluid called the sheath fluid is used to position the sample of cells into a single file for optical interrogation. Hydordynamic focusing and sheath fluids The central stream (sample stream) is focused and surrounded by the secondary slower stream (sheath fluid). The shape and size of the flow cell is crucial to hydrodynamic focusing, and traditionally the cell is nozzle shaped. ... In a flow cytometer, the sheath fluid pressure is constant while the sample fluid is adjusted Sample Pressure and the Sheath Pressure The difference between the sample pressure and the sheath pressure is the differential pressure. This controls the width of the core stream and the total number of cells passing the laser intercept. differential pressure based flow cytometers Differential pressure based flow cytometers currently dominate the market. These systems have two pressure regulators. The first is at a constant pressure that sets how fast the fluids runs at. The second is regulated by the investigator (like on this LSR-II control panel). Generation of differential pressure (syringe pump, pressure based) Low differential pressure allows the cells to move past the interrogation point one at a time. .... One kind involves generating pressure using a pump and regulator system ... Differential pressure based fluidic system. ... peristaltic and/or syringe pumps to deliver the sample into the instrument. Characterization of syringe-pump-driven induced pressure In syringe-pump-driven microfluidic systems, pressure fluctuations are observed in an elastic microchannel. The syringe pump is driven by an electrical stepper motor, from which mechanical oscillations are expected to generate flow-rate fluctuations and in turn leads to the pressure fluctuations in the channel flow. Optical Filters Filters are pieces of glass coated on both sides that allow light of a certain collection, or band, of wavelengths to pass through while absorbing or interfering with photons of other wavelengths. These come in bandpass, longpass, and shortpass flavors Band Pass Optical Filter A filter that allows light between a set wavelength to pass through and reflects light above and below the set wavelength. For example, a bandpass filter with a wavelength of 550/40nm would allow light between 530nm and 570nm to pass through, but reflect light below 530nm and above 570nm. Longpass Filter