Microspheres Online

Everything about microspheres and research utilizing precision spherical particles.

Matching the Density of Particle and Fluid for PIV Applications

Product Code: UVPMS-BG-1.00 (Cospheric LLC) Fluorescent Microspheres Precision Density of 1.00g/cc

Density of particle vs. density of fluid in particle image velocimetry: Many flow visualization experiments are done in water but there are a variety of other liquids and even water-based solutions that will have differing densities whose velocity fields are being mapped or will be in the future. Therefore, having seed particles to match these … Read more

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:

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Patent Review: Process for forming hollow glass spheres up to 5mm

A process for forming hollow glass micro-spheres with walls of controllably variable thickness in a size range of 50 to 5,000 microns, embodying (1) preparation of a water slurry of finely particulated, high temperature and low temperature glass formers; (2) prilling the slurry in a vertical spray drying tower; (3) separating and supporting the individual prilled feed material; (4) heating the feed material to glassification of the high temperature glass former while maintaining appropriate geometry and shell thickness and (5) cooling the finished product. The high temperature glass former is preferably a naturally occurring soda feldspar. The process is particularly adapted to form thicker walled micro-spheres of larger size and high quality.

Metal-Coated Microspheres – Conductive Coating

Metal-Coated Microspheres - Hollow Glass

Electrically conductive microspheres are produced by applying a metallic silver coating to the surface of the microspheres, thus giving the advantages of a metal particle with the additional properties of the core microsphere. Typically hollow glass microspheres are silver coated as this offers the combination of a low density filler and a conductive particle. Coatings with EMI shielding of greater than 45db have been produced by adding as little as 20% by weight of M-18 silver coated microspheres.

What is a Microsphere? Definition and Explanation.

Sourcing Microspheres - Monodisperse Silica
Conductive Bondline Spacer - Silver-Coated Silica Spheres
Conductive Bondline Spacer – Silver-Coated Silica Microspheres (Cospheric Product ID: SiO2MS-Ag)

Definition of a Microsphere:

There is a lot of confusion and uncertainty in the academic community as well as the industry on exactly what is a microsphere. Below is the definition of “microsphere” that we use, because it is clear and straight-forward:

Microsphere is a term used for a small solid spherical particle, with diameter in the micrometer range (typically 1 micron to 1000 micron (1mm)).

What a Microsphere is Not:

A microsphere is not the same as a microcapsule, because microcapsules typically consist of a flexible (deformable) shell encapsulating a fluid, which might be liquid or gas. Microspheres always have a solid shell. Even if the microsphere is technically hollow (containing gas inside), its shape is not significantly flexible or deformable.

A microsphere is not the same as a microparticle, because microparticle is a general term that refers only to the size of the granular material and does not provide information on the shape. Microspheres are always round and spherical. There are no sharp edges, oblong shapes, or debris.

What are Nanospheres? Silica Nanospheres
Monodisperse Silica Nanospheres (Cospheric Product ID: SiO2MS)

A microsphere is not the same as a nanopshere, because nanospheres have diameters on the nanoscale (typically between 1 nanometer and 1000 nanometers (1 micron)). Nano-diameters present a complete different characteristics, behaviors, and functionalities.

What are Microsphere Materials:

Microspheres are manufactured from various natural and synthetic materials. Glass microspheres, polymer microspheres, and ceramic microspheres are commercially available. Solid and hollow microspheres vary a lot in density and, therefore, are used for different applications. Hollow microspheres are typically used as additives to lower the density of a material. Solid microspheres have numerous applications depending on what material they are constructed of and what size they are.

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