When the contact angle of a drop in a surface is over 90° the surface is referred as hydrophobic, which refers to poor wetting. When the angle is below 90° the surface is referred as hydrophilic. Contact angle is often used to measure cleanliness, roughness, absorption, surface heterogeneity, among other properties.
Auger electrons emitted from the surface are drawn into a spectrometer that ultimately measures their kinetic energy distribution. The technique is inherently surface sensitive because the Auger electrons typically have low kinetic energies (<3kv). The Auger spectra contain information about the concentration and (sometimes) the chemical environment of surface and near-surface atoms. Greater depths (up to a few microns) can be probed by coupling the technique with ion milling. Lateral distributions of elements can be measured with sub-micron resolution.
An Atomic Force Microscope (AFM) provides 3-dimensional topographic information about a sample by probing its surface structure with a very sharp tip. The tip is scanned laterally across the surface, and the vertical movements of the tip are recorded and used to construct a quantitative 3-dimensional topographic map. The lateral resolution of the image can be as small as the tip radius (typically 5-15 nm), and the vertical resolution can be on the order of angstroms.
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By reconfiguring neural networks in artificial intelligence (AI) devices, a multi-institute team that included Penn State researchers facilitated AI systems to continually learn and adapt new data and tasks in ways that were not possible or practical before.
Self-powered sensors are key to more accurate, continuous health monitoring
Researchers are developing novel biomaterials to target post-stroke immune response and promote new blood vessel and axon — the part of the neuron that carries nerve impulses away from the cell’s processing center — formation at the site of the stroke.
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By Gabrielle Stewart
Metamaterials, made up of small, repeated structures engineered to produce desired interactions with light or sound waves, can improve optical devices used in telecommunications, imaging and more. But the functionality of the devices can be limited by the corresponding design space, according to Lei Kang, assistant research professor of electrical engineering at Penn State.
