Glass microsphere

About: Glass microsphere is a research topic. Over the lifetime, 2111 publications have been published within this topic receiving 24777 citations.

Polymer compositions exhibiting a PTC property and methods of fabrication

Abstract: Various embodiments of the invention provide polymeric compositions including PTC composites that exhibit highly non-linear PTC effects together with extremely rapid, repeatable switching within a predetermined temperature range. In one embodiment, the polymer composite includes a polymer base material with dispersed conductive particles that have very low densities and very low thermal conductivity properties. The conductive particle component can comprise hollow glass microspheres to provide low mass and low thermal conductivity properties together with a nanoscale conductive cladding of silver or gold. The conductively clad microspheres have a core portion with a bulk density of less than about 2.0 g/cm 3 and a mean thermal conductivity of less than about 5.0 W/m-° K.

Adhesion Forces between Glass and Silicon Surfaces in Air Studied by AFM: Effects of Relative Humidity, Particle Size, Roughness, and Surface Treatment

Abstract: Using the atomic force microscope (AFM), the pull-off forces between flat glass or silicon surfaces and silicon AFM tips or glass microspheres of different sizes have been extensively studied as a function of relative humidity (RH) in the range 5−90%, as model systems for the behavior of cohesive powders. The glass and silicon substrates were treated to render them either hydrophobic or hydrophilic. All the hydrophilic surfaces gave simple force curves and pull-off forces increasing uniformly with RH. Small contacts (R ∼ 20 nm) gave pull-off forces close to values predicted by simple Laplace−Kelvin theory (∼20 nN), but the values with microspheres (R ∼ 20 μm) fell well below predictions for sphere−flat or sphere−sphere geometry, due to roughness and asperity contacts. The hydrophobic silicon surfaces also exhibited simple behavior, with no significant RH dependence. The pull-off force again fell well below predicted values (Johnson−Kendall−Roberts contact mechanics theory) for the larger contacts. Hydroph...

Fiber-coupled microsphere laser.

Abstract: We demonstrate a 1.5-mm-wavelength fiber laser formed by placement of glass microsphere resonators along a fiber taper. The fiber taper serves the dual purpose of transporting optical pump power into the spheres and extracting the resulting laser emission. A highly doped erbium:ytterbium phosphate glass was used to form microsphere resonant cavities with large gain at 1.5 mm. Laser threshold pump powers of 60 mW and fiber-coupled output powers as high as 3 mW with single-mode operation were obtained. A bisphere laser system consisting of two microspheres attached to a single fiber taper is also demonstrated. © 2000 Optical Society of America

Optical super-resolution by high-index liquid-immersed microspheres

Abstract: It is experimentally shown that barium titanate glass microspheres with diameters (D) in the range 2–220 μm and with high refractive index (n ∼ 1.9–2.1) can be used for super-resolution imaging of liquid-immersed nanostructures. Using micron-scale microspheres, we demonstrate an ability to discern the shape of a pattern with a minimum feature size of ∼λ/7, where λ is the illumination wavelength. For spheres with D > 50 μm, the discernible feature sizes were found to increase to ∼λ/4. Detailed data on the resolution, magnification, and field-of-view are presented. This imaging technique can be used in biomedical microscopy, microfluidics, and nanophotonics applications.