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  • 12th International Symposium on Particle Image Velcoimetry

    Posted on July 13th, 2017 Daniel D. Stuart

    Particle Image Velocimetry and Seeding Particles

    I recently attended the 12th International Symposium on Particle Image Velocimetry in Busan, Korea on behalf of Cospheric, a company that specializes in precision microspheres. With the hope of learning more about seeding particles involved in PIV research and what advancements in microsphere technology would benefit the work being done in flow visualization. Through conversations with many attendees I was able to gather information on some of the important factors involved in tracer particle and their ideal capabilities. An interesting addition to seeding particles brought up by several individuals was temperature sensitive spheres which could potentially provide temperature field information.

    Below is an example of neutrally buoyant microspheres which are used as flow tracers in PIV applications.

    Fluorescent Red Polyethylene Microspheres

    The venue, Haeundae Grand Hotel, was spectacular with multiple large halls available for the over 200 presentations. The surrounding city was a maze of markets and skyscrapers nestled between the mountains and coast. Wonderful weather graced us, even rivaling that of Santa Barbara. Which was not something I had considered possible. I had the pleasure and displeasure of trying many unique foods. With bibimbap from a shop near the beach and shrimp dumplings from a small business steeped in the steam used to cook their dumplings being definite highlights. While the eel which I am still unsure whether was cooked or not falling on the other side of the spectrum. I am still processing the wealth of information from ISPIV 2017 and will express my conclusions as it manages to leak from my head.

  • Use of Polyethylene Spheres for Analyzing Microplastic Transport in Correlation with Earthworm Presence

    Posted on July 12th, 2017 Daniel D. Stuart

    Work by Matthias C. Rillig, Lisa Ziersch, and Stefan Hempel at Freie Universität and Brandenburg Institute of Advanced Biodiversity Research in Berlin has been published in an article titled Microplastic transport in soil by earthworms. This article investigates earthworms effect on microplastic movement into subsurface soil layers.

    Polyethylene Microplastic

    With the increase in plastic usage in recent decades the issue of how this discarded plastic will affect marine environments has been studied extensively. However, effects of microplastics on soil environments have not been tested to the same extent. Scientists have begun testing microplastic movement into lower soil layers by analyzing how differing sized polyethylene beads moved in a 21-day period with and without earthworm facilitation.

    The experiment was designed to confirm the assumption that earthworms would aid in particle movement. Results found earthworms to have a significant positive effect on transporting polyethylene particles from the soil surface. While particle size was also an important factor on the level of transportation into subsurface environments. With polyethylene spheres in the size range 710-850um being significantly more likely to move into the lowest layer when earthworms were present.

    With this experiment showing the ability of earthworms to transport microplastics into subsurface layers more research needs to be done to determine the effects this may have on the soil environment and the worms themselves. Including the multitude of other organisms that could also facilitate similar transportation. As well as the possibilities of microplastics reaching ground water where problems similar to those realized in marine systems could occur.

  • Fluorescent Glass Microspheres

    Posted on May 19th, 2016 Microsphere Expert

    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

  • Janus (Micro) Particles – From 45um to 1mm+

    Posted on April 24th, 2015 Microsphere Expert

    Black and White Jansum particles (1mm diameter)Cospheric offers unique capability to manufacture Janus microspheres and micro-particles with partial coatings and dual functionality. Currently half-shell or hemispherical coatings can be applied to any sphere (glass, polymer, ceramic) in sizes 45micron in diameter on up to 1mm and higher. 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 in both fluorescent and non-fluorescent have been made. Sphericity of greater than 90% and custom particle size ranges are offered.

    Fluorescent Red on Silver Coated Glass 50um

    Fluorescent Red on Silver Coated Glass 50um

    The custom coating capability offers customers the ability to create fluorescent glass micro-spheres of the specific size and emission/excitation needed. As the micro spheres and coating are solvent resistant

    they work ideally as fluorescent tracers or highly visible targets. We can overcoat clear glass or silver coated glass for the effect needed.

    For those needing very large Spheres Cospheric can coat spheres of 1mm and larger.

    Janus microparticles are now available as either dry powder or in a diellectric oil.

  • Stainless Steel Microspheres

    Posted on April 24th, 2015 Microsphere Expert

    300 Series stainless steel is well known for its corrosion resistant properties. Now Scientists are demanding high quality spherical stainless steel microspheres which offer high density (7.8g/cc), high sphericity (>90% round) and corrosion resistance (300 series stainless steel).

    A full range of precision sizes are now available from 1-22um on up to 1.0-1.2mm.

    Stainless Steel 250um (0.25mm) Spheres

    Stainless Steel 250um (0.25mm) Spheres

    Applications for Stainless steel spheres include.
    1) Conductive Spacers
    2) High Density Projectiles
    3) Charge Transport
    4) Shock Absorbtion

    Research vial quantities are listed, many sizes have kg quantities in stock for larger project needs.