 | APD: Avalanche photodiode detector DD: Doublet discriminator channel, discriminates single beads from aggregated beads CL1: Classify channel, allows multiplexing, detects dye inside beads RP1: Reporter channel, quantitates assay in this channel |
Bio-Plex assays are bead-based assays that can be performed in a mixed array (multiplexed). The reader combines two lasers, fluidics, and real-time digital signal processing to distinguish up to 100 different sets of color-coded polystyrene beads, each bearing a different assay. The Bio-Plex array reader is an essential tool that performs the key functions of this multiplex technology:
- Fluidics — The Bio-Plex array reader detects individual beads by flow cytometry. The fluidics system of the reader aligns the beads into single file as they enter a stream of sheath fluid and then enter a flow cell. Once the beads are in single file within the flow cell, each bead is individually interrogated for bead color (analyte) and assay signal strength (PE fluorescence intensity)
- Lasers — The Bio-Plex array reader is a dual laser system. The 532 nm Nd-Yag laser (green "reporter" laser) is used to excite the PE dye of the assay, for example, streptavidin-PE used for sandwich immunoassays. The 635 nm solid state laser (red "classify" laser) is used to excite the dyes inside the beads to determine their "color" or "region" and is also used for doublet discrimination by light scatter
- Optics — The Bio-Plex array reader contains an optics bench with four detection channels. Details are shown below. The dual lasers are precisely focused to excite an individual bead within the quartz flow cell. Upon excitation, the fluorescent signal emitted from the bead travels though the optics paths to the individual detectors
- Detectors — The Bio-Plex array reader has four detectors, one for each of the optical paths shown in the figure below. A high-sensitivity photomultiplier tube (PMT) detector is used for the reporter channel. Photodiodes are used for the stronger signals of the classify CL1 and CL2 and doublet discrimination channels
The Bio-Plex 200 system offers simplified needle height adjustment, improved array reader and microplate platform alignment, a robust, quiet air compressor, and other significant advantages, including:
- Simplified startup, shutdown, control, and maintenance routines
- Streamlined data analysis with no need to export or import files
- Automated installation and operational qualification (IQ/OQ)
- Integrated system validation and calibration logs for a record of system performance
- Superior curve fitting and statistics reporting
- Calibration capabilities for both broad range and low range standard dilutions
