Janus (Micro) Particles – From 45um to 1mm+
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.
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
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.
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.
Large Polystyrene Spheres Available
High Quality precision Large Polystyrene Spheres now available.
Sizes of 2mm and 4.4mm.
Having a density of 1.05g/cc size ranges as narrow as CV=0.2% these are excellent for research applications
Glass Microspheres Used in Studying Self-Cleaning Gecko-Inspired Adhesives
Researchers from Carnegie Melon University and Karlsruhe Institute of Technology have recently published an article in Journal of the Royal Society titled Staying Sticky: Contact Self-Cleaning of Gecko-Inspired Adhesives that presents the first gecko-inspired adhesive that matches both the attachment and self-cleaning properties of gecko’s foot on a smooth surface.
Using glass microspheres to simulate contamination the scientists created a synthetic gecko adhesive that could self-clean and recover lost adhesion. Real world applications of self-cleaning adhesives are reusable adhesive tapes, clothing, medical adhesives (bandages) and pick-and-place robots, among others.
Everyday challenge with traditional adhesives is that they loose their stickiness once contaminated. Geckos have been intriguing researchers for decades because of their unique and striking capability to maintain the stickiness of their toes through contact self-cleaning. They can travel up the walls and ceilings in a wide variety of “dirty” settings retaining adhesion.
Upon experimentation, scientists discovered that the critical variable is the relative size of microfibers that make up the adhesive compared to the diameter of contaminant particles. Glass microspheres were used in diameters from 3 to 215microns. Glass microspheres were packed in air and used as supplied. Contamination of the samples was achieved by brining each sample in contact with a monolayer of glass microspheres with specific speeds under predetermined compressive loads. The cleaning process involved a load-drag-unload procedure.
Best self-cleaning results were obtained with the largest contaminants (glass microspheres), with the size of the adhesive fiber much smaller than the contaminating particle. This information is important to know when designing self-cleaning adhesives—make the adhesive fibers much smaller for improved adhesion recovery. This cleaning mechanism requires unloading particles by dragging. The other extreme of contaminating microspheres being much smaller than the adhesive fibers has advantages in some situations, even though it works by a different mechanism. Smaller microspheres tended to become embedded into the adhesive material. Particle embedding is a temporary cleaning process but might be sufficient in some applications.
Silica Nanospheres as Photonic Nanostructure Found in the ‘Disco’ Clam Ctennoides Ales
Scientists from UC Berkeley have recently discovered that a strange naturally occurring bright display of the ‘disco’ or ‘electric’ clam Ctenoides ales is actually a photonic display created by a layer of silica nanospheres. The display functions solely by reflecting light.
An article was published in the Journal of The Royal Society titled “A Dynamic Broadband Reflector Built from Microscopic Silica Spheres in the ‘Disco’ Clam Ctenoides Ales“, where the researchers shared their findings.
Laboratory elemental analysis of the reflective nanospheres showed that they are indeed composed of amorphous silica. Both the outer shells and the cores are composed of silica. Silica nanospheres are secreted by the animal and used as a light scattering structure in a behavior modulated reflective photonic display.
The measurements show that the diameter of the silica nanospheres is at around 300nanometers, an optimal particle size for scattering visible light, especially the shorter blue-green wavelengths of 400-500nm that predominate at 3-50m underwater, which is typically the clam’s habitat. In addition to the diameter, the highly organized packing structure of the nanospheres aid in the scattering of the visible light at the shorter wavelengths.
The display is so bright that it has been mistakenly thought of as bioluminescent, but the findings show that it is actually based on light scattered by photonic nanostructures.
Silica has a high index of refraction at n=1.43 at 589nm.
This study is extremely interesting to scientists in many different fields because it opens their minds up to many creative uses of silica nanospheres that have not been known before. The findings show a practical way to manipulate light in low light situations. Among its other advantages, silica, similar to glass, is a very durable material, with high melt point. Using silica nanospheres in tightly packed arrays to create photonic nanostructures seems like a great idea.
Highly precise and spherical silica nanospheres with narrow size distribution, diameters around 300nm and sphericity of greater than 99% in dry powder from can be purchased from CosphericNano—a new website specializing in precise silica nanospheres.