Everything about Microspheres
RSS feed
  • Negatively-charged Yellow Microparticles – Back in Stock

    Highly Negative Charged Microspheres - Polyethylene, Selection of Sizes 5 to 500um

    Highly Negative Charged Microspheres - Polyethylene, Selection of Sizes 5 to 500um, 1.0g/cc

    Cospheric’s neutrally-buoyant highly charged yellow microspheres have a strong negative charge and are used by scientists in medical technology, biotechnology, applied physics and research. Precise particles with known density of 1.0g/cc that behave in a known way are useful as a model particles in simulation experiments.  Particles in a range of diameters from 5micron to 500micron(0.5mm) are currently back in stock.

    Bright yellow polymer microparticles of high sphericity are spherical polyethylene beads that are specifically designed with density ~1.0g/cc for suspension in fresh water,  serving as seed or tracer particles and enabling flow visualization and Particle Image Velocimetry PIV analysis of fluid flow in a device. It is often advantageous to color code the particles by size to better understand which part of the process the spheres of the specific size were able to pass through, or where the contamination in the process is coming from. Microspheres are supplied in dry powder form and are color stable in solution. No solvents are used in the manufacturing process. Polyethylene is inert to most solvents.

    Cospheric also offers unique capability to manufacture Bichromal janus microspheres and microparticles with partial coatings and potentially dual functionality. Currently half-shell or hemispherical coatings can be applied to any sphere (glass, polymer, ceramic) in sizes 45micron in diameter and higher. Coatings can be customized for any color and coverage of between 20% to 60% of the sphere. Each coating is custom formulated for color, charge, magnetic, electric, and surface properties, and solvent resistance per customers’ needs. Hemispherical coatings of less than 1 micron with tolerances as low as 0.25 micron have been routinely demonstrated.  Color combinations are truly unlimited. White, black, silver, blue, green, red, yellow, brown, purple as well as transparent microspheres have been made. Sphericity of greater than 90% and custom particle size ranges are offered.

    It would be interesting to combine these highly charged yellow microspheres with a partial paramagnetic black coating and investigate the behavior of these spheres in electromagnetic field.

  • Silane and Fluorochemical Coated Glass Spheres

    Solid glass imparts visual and material benefits that cannot be replicated when spheres are made of other materials such as ceramics or polymerics, aluminum oxides, or silicas and mineral fillers. Solid glass refracts [bends] and reflects light. Most ceramics [with exceptions] do not transmit light or exhibit specular [mirror-like] reflection due to their internal crystalline structures and surface irregularities. Instead of being reflected back, the light is “trapped” in the structure and emitted as diffuse or scattered reflectance, which is not as strong or direct as light transmitted through glass, which produces mirror-like reflectance.  Prizmalite glass spheres distributed by Cospheric offer off the shelf pre-coated spheres for enhancing these effects.

    Silane coated solid glass spheres with increased hydrophobicity are offered to improve the dispersion of spheres throughout paints and coatings.  Silane coated spheres are not recommended for pure water solutions as the spheres will be too hydrophobic to wet.

    Fluorochemical Coating is available for paint and coating applications where it is desired to bring the spheres to the top of the surface of the coating.  This is best used in applications where retro reflectance is desired.

    The following products are offered in both Silane and Fluorochemical Coating.
    P2011SL  3-6um mean diameter solid soda lime glass
    P2015SL  8-12um mean diameter solid soda lime glass
    P2050SL  35-45um mean diameter solid soda lime glass
    P2075SL 65-75um mean diameter solid soda lime glass
    P2453BTA 40-60um mean diameter solid barium titanate glass with aluminum shell.

    Solid Glass Spheres:

    • Act as mini-magnifying glasses to deliver visually truer color
    • Clarify and magnify the visual impact of pigments and metallic flakes
    • Create a richer, wetter, deeper look
    • Visually extend expensive color-shift pigments to create cost-effective new looks
    • Prop up other pigments, mica and aluminum flakes
    • Increase exposed surface area and visual impact
    • Facilitate even dispersion of colorants and reflectors
    • Are anti-mottling agents that enhance visual consistency
    • Act as mini-ball bearings to improve material flow and reduce flow lines
    • Provide color consistency from all viewing angles
  • BioCompatability of Metal Coated Spheres

    For those scientists who are looking to use silver coated materials such as silver coated microspheres in biomedical applications, it is important to understand whether they are bio-compatable.  A selection of abstracts and article references related to the biocompatability of silver follow:

    The Biocompatibility of Silver2

    The experiments reported have referred to some of the characteristics of the biocompatibility of Ag. Silver has been shown to display interactions with albumin, as an example of a plasma protein, quite different from those of most metals. Such studies shed further light on the complex issue of protein adsorption on biomaterials. It has also been demonstrated that Ag at concentrations < 1 ppm exerts a considerable influence on the activity of lactate dehydrogenase, this effect being reversed in the presence of albumin. A significant but transient increase in blood levels of Ag following intramuscular implantation of the metal has been observed. This is not reflected in any raised urine level. It is proposed that the richly vascular tissue immediately surrounding the implant in the acute phase of the response gives rise to the transient increase, but a subsequent decrease in vascularity reduces this possibility. It appears that Ag released from implants following this initial period substantially remains in the local area.2

    Lack of toxicologocial side-effects in silver-coated megaprostheses in humans1

    Deep infection of megaprostheses remains a serious complication in orthopedic tumor surgery. Furthermore, reinfection gets a raising problem in revision surgery of patients suffering from infections associated with primary endoprosthetic replacement of the knee and hip joint. These patients will need many revision surgeries and in some cases even an amputation is inevitable. Silver-coated medical devices proved their effectiveness on reducing infections, but toxic side-effects concerning some silver applications have been described as well. Our study reports about a silver-coated megaprosthesis for the first time and can exclude side-effects of silver-coated orthopedic implants in humans. The silver-levels in the blood did not exceed 56.4 parts per billion (ppb) and can be considered as non-toxic. Additionally we could exclude significant changes in liver and kidney functions measured by laboratory values. Histopathologic examination of the periprosthetic environment in two patients showed no signs of foreign body granulomas or chronic inflammation, despite distant effective silver concentrations up to 1626 ppb directly related to the prosthetic surface. In conclusion the silver-coated megaprosthesis allowed a release of silver without showing any local or systemic side-effects.1

    Specific Article References for the biocompatability of silver are below: See the References

  • High Index of Refraction Retroreflective Glass Microspheres

    Retro-reflective MicrospheresBarium Titanate Glass Microspheres are excellent for use as a functional retro reflective additive  to paints and coatings.  Spheres with sizes of about 50 micron (~0.002 inches) mean diameter provide a small enough size for most coatings while offering a large enough size to reflective a significant amount of light.  Barium Titanate Glass Spheres are offered in both partially aluminum coated retro-reflective version for addition into transparent coatings, or as uncoated glass spherical powder for uses in colored paints.

    Barium Titanate Glass microbeads offers one of the highest indexes of refraction with an IR greater than 1.9 which provides high intensity retroreflectivity from these spheres.

    For those applications calling for a high density filler, barium titanate glass spheres offer a density of 4.5g/cc, that is almost double that of the more common soda lime glass spheres.   In addition to a high density, barium titanate glass spheres have a hardness of about 55-65 on the Gardner scale and a crush strength of over 30,000 psi (207 Mpa) making these spheres very durable in high wear environments.

    The spheres offered by Cospheric as product ID:  BTGMS (uncoated ) and P2453BTA (aluminized) are produced in the USA, and are Lead free.

  • Silica Microspheres – 6 micron mean Diameter

    Silica Microspheres 4-8um Mean Diameter  200x MagnificationProperties

    Silica is a chemically stable inorganic synthetic material.   It has the benefit of providing no irritation to human skin.  Silica is essentially transparent, colorless and promote a high degree of slip in products.  The skin feel is generally lubricious in nature.   Spherical silica imparts exceptional lubricity to loose and pressed powder products. The effect is increased ‘play time’ and a luxurious feel.  Spherical products with mean particle size between 3 to 10 micron will scatter light on the surface of its particle, ie which are transparent, but give natural coverage.

    • Properties :
      - Hollow and porous spherical powder
      - Uniform size distribution
      - Excellent dispersibility
      - Good oil absorbancy
      - Good fluidity
    • Applications :
      - Emulsion products
      - Makeup products
      - Anticaking agent
      - Additive carrier and perfume carrier
    • Available with Optional Silicone Coating (Dimethylpolysiloxane)
      - Increases Hydrophobicity
      - Transparent
      - Resistant to acid, alkalis, UV and moisture

    Silica Microspheres are available for purchase at Cospheric in R&D quantities or bulk.