Everything about Microspheres
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  • Fluorescent Glass Microspheres

    Fluorescent Red Coated Soda Lime Glass MicrospheresSolid glass microspheres hemispherically coated with fluorescent coatings,  a fluorescent coating is precisely applied to half of the core sphere,  making the glass spheres appear colorful and fluorescent at daylight and exhibit bright fluorescent response under UV light.  Fluorescent coatings are available in seven standard colors, with three options for glass cores available for customers who require a fluorescent tracer of a specific emission spectra and density.  Fluorescent coatings can also be applied to other microsphere cores on special request, exact size range options vary by material.  For PIV applications that typically use green lasers (530nm) as excitation sources, we recommend utilizing our fluorescent red coating in conjunction with a 570-580nm high pass filter so only the fluorescent particles will be visible during imaging.

    Three standard core densities are:

    Borosilicate Glass Core – Density ~2.2g/cc
    Soda Lime Glass Core – Density ~2.5g/cc
    Barium Titanate Glass Core – Density ~4.5g/cc

    Seven standard fluorescent color coating options on glass with broad spectrum responses:

    Fluorescent Blue Glass (445nm peak emission) at 407nm excitation
    Fluorescent Green Glass (515nm peak emission) at 414nm excitation
    Fluorescent Yellow Glass (525nm peak emission) at 485nm excitation
    Fluorescent Orange-Yellow Glass (594nm peak emission) at 460nm excitation
    Fluorescent Orange Glass (606nm peak emission) at 577nm excitation
    Fluorescent Red Glass (607nm peak emission) at 585nm excitation
    Fluorescent Violet Glass (636nm peak emission) at 584nm excitation

  • PIV Seeding – Microparticle Recommendations

    Flow Visualization can best be accomplished with colored or fluorescent tracing particles of the same density as the fluid being studied.Particle image velocimetry (PIV) is the term used for imaging the fluid flow using colored tracer particles.  Through high speed particle imaging the velocity of the particles can be obtained and mapped.

    Photo Courtesy of Wiki-CommonsFor PIV experiments in water there are a wide variety of 1g/ml microspheres available as seeding particles, Cospheric offers polyethylene seeding particles in a variety of colors (fluorescent and non-fluorescent) and sizes from 10-20um, on up to 1mm.

    Particle size selection is important to ensure that observations can be accurately made.  For imaging systems without any magnification or unaided human observation it is recommended to use micro-spheres that are larger than 200um.   Human eyes can resolve features down to about 75um, at 200um+ the particles will be large enough to be discernible.

    Correctly seeding the system is also important.  For most applications loadings of 0.1-0.3% are sufficient.  This is the equivalent of about 1 gram of particles per gallon of fluid in systems of 10-50 gallons (40-200 liters) .  Exact loading levels will depend on the individual experiment requirements.

    For aqueous systems, polyethylene micro-particles will require a surfactant to wet properly.  For general flow studies pre-wetting the PE microspheres with Simple Green concentrated cleaner works well.  For biological systems a bio-compatable surfactant such as Tween 20 or Tween 80 is recommended.

    Seeding particle color selection is important to ensure that sufficient contrast is achieved during testing.  Very bright fluorescent micro-particles are available in densities of 1g/cc  these offer not only bright testing under daylight conditions, but also the option of illumination with lasers or uv lights for increased system contrast.

    The recommended PIV seeding particles are available from Cospheric.

    For green lasers (530nm)  we recommend UVPMS-BR
    For dark backgrounds: UVPMS-BY, UVPMS-BG, BLPMS, ORGPMS, BSPMS, or WPMS
    For light backgrounds: GRYPMS, VIOPMS, UVPMS-BR, UVPMS-BO

  • Density Marker Beads

    Cospheric recently added density marker beads in aqueous solution to their range of products.   Available in densities from 1.02 g/ml to 1.13 g/ml.

    The beads come in a variety of colors and densities and ship within one business day.   These beads are small microspheres of very specific particle density that are used to visualize density gradients.  Commonly used in Percoll gradients these beads offer a fast visual indicator for scientists.

    Density Markers Beads are:
    DMB-FGRN-1.02 Fluorescent Green at 1.02g/cc
    DMB-FORG-1.04 Fluorescent Orange at 1.04g/cc
    DMB-RBLU-1.08 Blue at 1.08g/cc
    DMB-FRED-1.09 Fluorescent Red at 1.09g/cc
    DMB-FBLU-1.13 Fluorescent Blue at 1.13g/cc

    Cospheric Density Marker Beads are provided at a 20% concentration in an aqueous solution in 2.5ml vials. Unlike density marker kits which used to be manufactured by GE Healthcare and have been discontinued, the Cospheric’s colored microspheres are ready for use right out of the vial, don’t need to be swollen, will work with any media, do not expire, and do not change density over time.

    Resources on Creating Density Gradients:

    Biotechnology: Theory and Techniques, Volume I (Jones and Bartlett Series in Biology) by Jack Chirikjian and Chirikjian (Jan 1, 1995)
    Pages 45-50 on Density Gradient Centrifugation.

  • Microparticles for simulating fish egg dispersion and recruitment

    Understanding survival and mortality of fish in the early life stages has been a fundamental issue in biology and a central problem in fisheries oceanographic study for more than a century. It has been argued that most marine fishes begin life as an egg that floats in the sea, and, during their evolutionary history, the early life of fishes has surely been shaped to ensure the “continued existence of species” by the sheer pressure of natural selection, and stated that a fish to survive must deal with and exploit its physical and biological environments. However, although we are now in the 21st Century, there still remains a lot to be made scientifically clear in the early life of fishes. In the present lecture, I will talk about fundamental issues in the isolated floating eggs of marine fish, which many pelagic species spawn in thousands, millions, or sometimes almost billions during a life of an individual female. The topics contain description and discussion on the egg size, buoyancy and rising speed. Measurements on the eggs naturally spawned in aquaculture systems are firstly introduced. Several examples of egg vertical distribution, accumulation and dispersion observed through field surveys will be shown to consider how the egg size and buoyancy are adaptive to survive in the pelagic environment.1

    UVPMS-BG 180-212um - 40x MagnificationScientists who study fish require artificial micro-particles to simulate fish eggs and their dispersion behavior in water. In order to accurately simulate the dispersion of fish eggs it is important to use particles of the proper size and buoyancy/density. Particles with accurate size ranges and densities are now available from Cospheric LLC. Densities from 1.00g/cc up to 1.12 g/cc are available in size ranges from 10-27um on up to 0.85-1.0mm. Sea water particles of 1.025g/cc (UVPMS-BG-1.025), and fresh water beads of 1.00g/cc are in stock and available for quick delivery.

    Most fish eggs are in the size of 0.5-5mm1 with the typical size of 1mm being the most common.   Salt water fish eggs tend to be slightly less dense than medium saltwater at a density of about 1.020g/cc1.

    Continue reading “Microparticles for simulating fish egg dispersion and recruitment” »

  • Neutrally Buoyant in Water – Microspheres with Specific Gravity of 1g/cc

    Cospheric offers polymer microspheres with specific gravity of 1g/cc are specifically designed to match the density of water for optimal suspension of particles. Suspension of microspheres in water enables the visualization and characterization of fluid flow and testing the capability of devices to withstand particulate matter in the fluid stream, ensuring that microspheres do not settle and do not float on the surface.  Most of these polymer microspheres are at least moderately opaque and clearly visible in water, clear or translucent liquids.

    Many Colors are available in sizes from 10um up to 1180um,  of polyethylene microspheres are available with specific density of 1g/cc, designed for optimum suspension in water for fluid flow visualization.  Colors include Violet, Orange, Yellow, Fluorescent, Grey, Pink, Blue, and many fluorescent colors.

    600-710um violet PE microspheres250-300um ORANGE PE Microspheresblue microspheres 355-425um Yellow microspheresGrey Microspheres PE