High Index of Refraction Retroreflective Glass Microspheres

Barium 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.

Advantages of Borosilicate Glass Microspheres in 0.03mm to 0.2mm sizing

BSGMS 63-75 micron at 40x magnification

High quality glass microspheres for research and development are always in high demand.  In an effort to better serve scientists Cospheric recently added a complete line of high quality borosilicate microspheres, and microbeads.

Borosilicate glass offers  advantages over standard soda lime glass microbeads.

• Roundness is >90%   (Soda lime >85%)
• Density is the lowest of most glasses at 2.2g/cc  (Soda Lime 2.5g/cc)
• Very low thermal expansion coefficient  32×10^-7/°C   (for 30-300°C)   (Soda Lime:  90×10^-7/°C)

The high roundness, and low thermal expansion make borosilicate spheres an excellent candidate for use as spacers in epoxy bond lines, or other applications which require stability over a wide temperature range.

Borosilicate glass spheres are now offered in narrow size ranges from 0.03mm to 0.2mm with greater than 90% of the particles in range.

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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.

Microspheres for Medical Devices – MDDI Magazine – January 2011

The Microsphere of Influence

Published: January 2011, MDDI

Find more content on: Feature, Nano and Microtechnology, Technology, Testing and Inspection

Microspheres come in many different grades and sizes, and are usually solid particles that are composed of polymers, glass, and ceramics. All images courtesy of COSPHERIC LLC

Microspheres are round microparticles that typically range from 1 to 1000 μm in diameter. In the pharmaceutical and cosmetics industry, microspheres are well known for their ability to deliver active materials. This process usually involves the microencapsulation of a drug or an active cosmetic ingredient to protect it from the deteriorating effects of the environment or for optimal release and performance in the final product. Active ingredients are released by dissolution of the capsule walls, mechanical rupture (rubbing, pressure, or impact), melting, or digestion processes. Solid microspheres are widely used as fillers and spacers in a variety of industries.

Microspheres used to manufacture and test medical devices are typically solid particles that are made from robust and stable raw materials such as polymers, glass, and in some cases, ceramics. Different types and grades of microspheres are available and selected based on specific application requirements.

They are often used as tracers and challenge particles in medical devices. In these situations, it is beneficial to use larger microspheres with sphere diameters greater than 50 μm that are vividly colored (red, blue, black, yellow, or green), since they provide contrast with the background material and visibility to the naked eye in daylight. Colored microspheres are typically used in the testing of filtration media and systems, vial and container cleaning evaluations, flow tracing and fluid mechanics, centrifugation and sedimentation processes, pharmaceutical manufacturing, and contamination control.

Fluorescent microspheres are recommended for applications that require the use of particles that emit distinctive colors when illuminated by UV light and offer additional sensitivity for observation through the use of microscopes, lasers, and other analytical methods. Examples include microcirculation and biological research, imaging, and flow cytometry. Fluorescent microspheres can be excited and detected by a wide range of methods and are useful as experimental particles for acoustical and optical analytical systems.

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Microspheres: Technologies and Global Markets

An extensive market research report titled Microspheres: Technologies and Global Markets was recently published by BCC Research marketing firm. The microspheres report examines the spherical microparticles used as components in many advanced materials and composites, in the healthcare and personal care industries, and in many specialty research and development applications. The report estimates the size of the microsphere industry worldwide and makes predictions on a 5-year compound annual growth rate of the microsphere market.

The global market for microspheres in 2010 is estimated to be $2 billion and growing at a 5–year compound annual growth rate (CAGR) of 11.6%, reaching global sales of $3.5 billion by 2015.