What are fluorescent microspheres?

Invisible Microspheres - Activated to Yellow-Green by a UV Light (Black Light)
Invisible Microspheres - Activated to Yellow-Green by a UV Light (Black Light)

Fluorescent microspheres are round spherical particles that emit bright colors when illuminated by UV light. Ability to emit intense color under UV (black light) illumination provides contrast and visibility of microspheres relative to background materials. In addition to the benefits of conventional high quality microspheres, such as sphericity, smoothness and spreadability among others, fluorescent spheres offer extra sensitivity and detectability for analytical methods. For example, fluorescent microbeads are often used as traces to simulate spread of viruses in medical research.

What are applications of fluorescent microspheres?

Typical applications of fluorescent spheres include: testing of filtration media and systems, vial and container cleaning studies, flow tracing, flow visualization, and fluid mechanics studies, medical imaging and flow cytometry, fluorescence microscopy and photography, as well as biomedical technology research, qualification and validation of medical devices, biomedical diagnostics, process troubleshooting and process flow among others. Specifically fluorescent microspheres are often used for water- and air-flow testing and bead-based diagnostic applications. New unique applications of fluorescent spheres are being discovered daily.

What is unique about fluorescent microspheres?

Fluorescent spheres have a unique ability to appear translucent(clear) and practically invisible under ordinary light and to emit intense vsible color when energized by ultraviolet (UV) light. This effect allows scientists and engineers to design blind tests and controlled experiments (e.g. simulate spread of viruses) where the microspheres are invisible to the operator doing the procedure until after the fact, therefore, eliminating any operator bias and uncertainty in the validity of experiment. This unique feature of fluorescent microspheres has numerous applications in biomedical research and process troubleshooting.

What is fluorescence?

Fluorescence occurs when a molecule absorbs energy in the form of light and then immediately releases this energy again in the form of light.

  • Excitation wavelength - characteristic wavelength that molecule absorbs
  • Emission wavelength - characteristic wavelength that molecule emits
  • Stokes shift - difference between excitation and emission wavelength
  • Quantum efficiency - ratio of emitted energy to absorbed energy

What are colored fluorescent microspheres?

Currently fluorescent microspheres in a variety of excitation wavelength and emission wavelength are available which allows the differently colored microspheres to represent different experimental variables/conditions and be separated on the basis of either their excitation or their emission spectra.

What types of fluorescent microspheres are available?

Fluorescent Bright Blue Microspheres, Microparticles, Spherical Powder
Fluorescent Bright Blue Microspheres, Microparticles, Spherical Powder

There are several different types of fluorescent polymer microspheres on the market that are manufactured from different materials and manufacturing processes, making them suitable for a variety of applications. UV fluorescent microbeads vary based on size: submicron, 1-5 micron, 10-15 micron and 20 micron – 1000 micron (1mm). Color under daylight conditions and UV (black light) illumination conditions can be optimized for each application to either color-match with the background or provide high contrast. Specific density of the fluorescent microparticle can be important if the spheres need to be suspended in a fluid and desired buoyancy is required. In addition, stability of a specific fluorescent colorants under environmental effects and photobleaching varies and may be important. Typically microspheres that are heavily loaded with fluorescent colorants are the most highly visible with the strongest fluorescent response. Those processes that embed the colorant into the polymer matrix of the sphere, rather than just providing the coating on the surface, usually result in the most stable fluorescing properties minimizing the possibility of leaching of the colorant into the fluid. The products can be stored at room temperature and can be dispersed in aqueous media or air without degrading their fluorescent properties.

How are Cospheric Fluorescent Microspheres unique?

Cospheric microspheres are different from other commercially available fluorescent microspheres in several ways:

  1. Cospheric is the only global supplier offering fluorescent polyethylene microspheres where the fluorophore is fully embedded into the polymer matrix and will not degrade or leach out into solution (unless the polyethylene matrix gets dissolved).
  2. Cospheric polyethylene fluorescent microspheres are offered in size ranges from 10micron to 1.2mm.
  3. Cospheric polyethylene fluorescent microspheres are produced in of precision densities ranging from 1.00g/cc to 1.3g/cc. Custom density product is avaialble on request.
  4. Some grades of Cospheric fluorescent microspheres are produced with precision density suitable for making density gradients.

Contact Cospheric Technical Support for a product recommendation.

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