Everything about Microspheres
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  • Black Paramagnetic Spheres and Micropsheres 10micron to 1.4mm

    Black polyethylene paramagnetic microspheres are now available in wide selection of particle sizes ranging from 10 micron to 1.4 millimeters. The particles are supplied in dry powder form. No solvents are used in the manufacturing process. Black paramagnetic polymer microspheres have a strong response to magnetic fields and can be manipulated with a magnet. Highly opaque particles with maximum hiding power.

    Paramagnetic microspheres have the ability to increase in magnetization with an applied magnetic field and loose their magnetism when the field is removed. Neither hysteresis nor residual magnetization is observed and that provides the end use two very practical advantages:

    • When the filed is removed, the microspheres demagnetize and re-disperse easily. This property allows efficient washing steps, low background and good reproducibility.
    • The behavior of the microspheres is always the same whatever the magnetization cycles may be. Such behavior is a key point for automated instrument.

    According to Wikipedia, paramagnetic materials have a small, positive susceptibility to magnetic fields. These materials are slightly attracted by a magnetic field and the material does not retain the magnetic properties when the external field is removed. Paramagnetic properties are due to the presence of some unpaired electrons, and from the realignment of the electron paths caused by the external magnetic field.

    Encyclopedia Britanica defines paramagnetism as a kind of magnetism characteristic of materials weakly attracted by a strong magnet, named and extensively investigated by the British scientist Michael Faraday beginning in 1845. Most elements and some compounds are paramagnetic. Strong paramagnetism (not to be confused with the ferromagnetism of the elements iron, cobalt, nickel, and other alloys) is exhibited by compounds containing iron, palladium, platinum, and the rare-earth elements.

    Paramagnetic microparticles are used in numerous applications where they can be manipulated with a magnet, observed and cleaned-up for reuse.

    • Solid Phase Immunoassays
    • Bacteria Detection
    • High Throughput screening
    • Rapid Tests
    • Cell Sorting
    • Biosensors
    • Nucleic Acids Technology
    • Microfluidics
  • Bichromal Janus Particles, Microspheres, Microbeads – Stock selection or Custom-made

    Bichromal (half-white half-black or any other color) Microspheres, Janus Particles

    Bichromal (half-white half-black or any other color) Microspheres, Janus Particles. In this picture - Paramagnetic black microspheres with partial white coating - Magnification 40x.

    Cospheric offers unique capability to manufacture Janus microspheres and microparticles 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 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.

    Half-coated glass microspheres - Partial coating on glass particles

    Half-coated glass microspheres - Partial coating on glass particles. In this picture - Soda lime glass microspheres with partial red coating - Magnification 40x.

    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.

    We have successfully coated solid and hollow glass microsphere, including soda-lime, borosilicate, and barium titanate glass microspheres. We have also coated on silver.

    Half-coated Microspheres

    Half-coated Microspheres

    Optically anisotropic spheres and janus particles with magnetic half-shells have been originally developed for applications in electronic displays, such as e-paper, but are now widely used in numerous applications in diagnostics, medical research, microscopy and biotechnology, as well as electronics, due to their ability to orient themselves in response to electromagnetic field and show a visual response. This is achieved by making spheres both bipolar and bichromal, with dipole precisely aligned with two differently colored hemispheres. As the spheres align themselves, the viewer will observe the color of one hemisphere, while the other hemisphere will be hidden from view, providing an obvious strong visible indication of the presence of the field or other stimuli.  In alternating electromagnetic field, these microspheres have been proven to spin at hundreds of times per second.

  • Electrostatic-based DNA Microarray Offers Medical Diagnostics Capabilities

    The uses for microspheres continue to grow, a recent article published by UC-Berkley shows how DNA sequencing can be achieved through the use of statically charged microspheres.   The key breakthrough is that they have been able to achieve a visible result through using the electrostatic repulsion of the microspheres.   A copy of their announcement follows:

    Groves,  and members of his research group Nathan Clack and Khalid Salaita, have published a paper on their technique in the journal Nature Biotechnology, which is now available online. The paper is entitled “Electrostatic readout of DNA microarrays with charged microspheres.Continue reading “Electrostatic-based DNA Microarray Offers Medical Diagnostics Capabilities” »