Luminex 200 System User Manual - Manual (Page 21)

Theory of Operation
Luminex xMAP technology is based on flow cell fluorometry with Luminex-developed
innovations. The fluidics, optics, robotics, temperature control, software, and xMAP
microspheres work together to enable simultaneous analysis of up to 100 analytes in a single
test sample. Assay analysis requiring temperature control is provided through the Luminex
XYP instrument heater block.
There are two fluidics paths in the Luminex 200 analyzer. The first path involves a syringe-
driven mechanism that controls the sample uptake. This mechanism permits small sample
uptake volumes from small reaction volumes. The syringe-driven system transports a
specified volume of sample from a sample container to the cuvette. The sample is injected
into the cuvette at a steady rate for analysis. Following analysis, the sample path is
automatically purged with Luminex xMAP Sheath Fluid by the second fluidics path. This
process removes residual sample within the tubing, valves, and probe. The second fluidics
path is driven by positive air pressure and supplies sheath fluid to the cuvette and sample
path.
Luminex xMAP Sheath Fluid is the delivery medium of the sample to the optics component.
The analysis sample is acquired using a sample probe from a 96-well microtiter plate via the
Luminex XYP instrument and injected into the base of the cuvette. The sample then passes
through with sheath fluid at a reduced rate resulting in a narrow sample core to ensure that
each microsphere is illuminated individually. The sample injection rate is such that the xMAP
microspheres are introduced to the optics path as a series of single events. The Luminex SD
system lets you run samples continuously without refilling sheath bottles. It automatically
draws sheath from a non pressurized bulk sheath container to constantly maintain a reservoir
of pressurized sheath fluid. A single 20 liter sheath container provides enough fluid for 48
hours or more of normal operation.
The optics assembly consists of two lasers. One laser excites the dye mixture inside the
xMAP microspheres and the second laser excites the fluorophore bound to the surface of the
xMAP microspheres. Avalanche photo diode detectors measure the excitation emission
intensities of the color coding classification dye mixtures inside the xMAP microspheres and a
photomultiplier tube detects the excitation emission intensity of the reporter molecule bound
to the surface of the xMAP microspheres. High speed digital signal processors and advanced
computer algorithms provide analysis of the xMAP microspheres as they are processed
Chapter 2: The System
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