Imaging Systems



Following electrophoresis, the gels can be imaged and analyzed using a variety of imaging systems. The electrophoresis patterns (called electropherograms) are digitized by dedicated image acquisition devices, and data are analyzed with sophisticated software. Once the gels are digitized, the raw data can be stored for further reference. This section provides an overview of the suite of gel imaging systems that Bio-Rad offers and highlights their features.

The selection of which image acquisition device to use for the digitization of electrophoresis gels depends on the staining technique used (see Table below):

Related Topics: Image Analysis Software.


Densitometers are based on high-performance document scanners utilizing visible light for analysis of electrophoresis gels and blots stained with visible dyes. Bio-Rad's GS-900™ Calibrated Densitometer can be used to image both gels and blots and has a linear response up to 3.0 optical units in gray levels.

GS-800 calibrated densitometer

GS-900 Calibrated Densitometer.

Charge-Coupled Device (CCD) Cameras

Charge-Coupled Device (CCD) cameras operate with either trans-illumination provided by UV or visible light boxes positioned underneath the gel or blot for imaging a variety of stains (Coomassie, silver, fluorescence) or epi-illumination detected using colormetric or fluorescent techniques. Supercooled CCD cameras reduce image noise, allowing detection of faint luminescent signals. Bio-Rad's Gel Doc™ EZ system provides four application-specific trays: a UV tray (for ethidium bromide staining of DNA gels and fluorescence imaging), a white tray (for Coomassie, copper, silver, and zinc stains), a blue tray (for nondestructive nucleic acid imaging), and a Stain-Free tray for direct visualization, analysis, and documentation of protein samples in polyacrylamide gels without staining, destaining, or gel drying (see sidebar). Bio-Rad's ChemiDoc™ MP system has the ability to image colorimetric and fluorescently stained gels and blots to detect chemiluminescent and other low light and multiplex or multiplex fluorescent samples.

Gel Doc EZ system
Gel Doc XR+ system
ChemiDoc XRS+ system
ChemiDoc MP system
Gel Doc EZ system Gel Doc XR+ system ChemiDoc XRS+ system ChemiDoc MP system

Laser-Based Scanners

Laser-based scanners offer the highest sensitivity, resolution, and linear dynamic range. They are powerful image acquisition tools for electrophoresis gels and blots stained with fluorescent dyes like Flamingo™ fluorescent gel stain. Lasers can be matched to the excitation wavelengths of a multitude of fluorophores. Bio-Rad's PharosFX™ systems use multiple lasers, which enhance application flexibility and allow optimal excitation of single and multicolor fluorescent samples to enable detection of almost any fluorescent dye or label.

PharosFX system
PMI system

PharosFX™ system

PMI™ system

Bio-Rad Gel and Blot Imaging Systems Selection Guide

Application ChemiDoc™ MP Gel Doc™ EZ GS-900™ Densitometer Gel Doc XR+ ChemiDoc™ XRS+ PharosFX™ PharosFX Plus Personal Molecular Imager™
Nucleic Acid Detection
Ethidium bromide stain 5 4 4 4 5 5
SYBR® Green I stain 5 4 4 4 5 5
SYBR® Safe stain 5 4 4 4 5 5
Fast Blast DNA stain 4 4 5 4 4
Protein Detection, 1-D Gels
Stain-free gels 5 5
Coomassie Blue stain 4 4 5 4 4 2 2
Silver stain 4 4 5 4 4 2 2
SYPRO Ruby protein gel stain 4 4 4 4 5 5
Flamingo™ fluorescent gel stain 4 3 4 4 5 5
Oriole™ fluorescent gel stain 5 4 5 5
Protein Detection, 2-D Gels
Coomassie Blue stain 4 2 5 3 3 2 2
Silver stain 4 2 5 3 3 2 2
SYPRO Ruby protein gel stain 4 3 3 3 5 5
Flamingo fluorescent gel stain 4 2 3 3 5 5
Oriole fluorescent gel stain 5 3 3 3 3
Pro-Q stain 4 2 2 2 5 5
Cy2, Cy3, Cy5 label 4 5 5
Blot Detection
Stain-free blots 4 5
Coomassie Blue stain 4 5 4 4 2 2
Silver stain 5 5 4 4 2 2
SYPRO Ruby protein blot stain* 5 5 5
Immun-Star™ chemiluminescence 5 4
Chemifluorescence* 5 1 1 4 4
Quantum dot* 5 2 2 2 5 5
Multiplex fluorescence 5 5 5
Micro- and Macroarray** Detection
Radiolabel 5 5
Fluorescence 5 2 2 5 5
Immun-Star chemiluminescence 5 4
Colony Counting
Colorimetric detection 5 4 4 3 3
Fluorescence detection 5 4 4 5 5
Isotopic Detection
Radiolabel 5 5
X-ray film 4 4 5 4 4 3 3

— Not recommended; 1–5, recommendation level (5 = highest).
* Optimal with low fluorescence PVDF membrane.
** With spot diameters >400 µm.

Related Content

Trans-Blot® Turbo™ System vs. Traditional Blotting Techniques
This video demonstrates how the Trans-Blot Turbo system measures up against traditional blotting techniques both interm of equipement and supplies needed and speed.
Installing the Molecular Imager® Gel Doc™ XR+ System
This tutorial guides you through installing the Gel Doc XR+ system and provides troubleshooting techniques for common problems. Information is provided for new installations on both PC and Macintosh systems.
Gel Doc EZ System Tour
In this interactive demonstration you will be able to test drive the Gel Doc EZ imager and dig deaper into the instrument's capabilities, specifications and features.
Number Description Download
5888 Bio-Rad Imaging Systems Family Brochure, Rev E Click to download
5989 Imaging Fluorescently Stained Gels with Image Lab Software Quick Start Guide, Rev A Click to download
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