numerical aperture (NA) of an optical system is a dimensionless number that characterizes the range of angles over which the system can accept or emit light. Phase shifting masks – selectively altering phase to take advantage of destructive interference Soft shifters – molybdenum silicide layer Hard shifters – etch quartz mask Immersion Lithography – increasing …
Category Archive: Techniques
Endocytosis
Endocytosis – process by which cells absorb material from outside the cell by engulfing it with their cell membrane. Nanoparticles can transport drugs into cells using this method. After entering the cells, the physical forces that hold together the self-assembled nanoparticle no longer exist, so the nanoparticle falls apart and the drugs entrapped within are …
Nano Electric Lithography
Nano Electric Lithography (NEL) – can pattern 10 nm nanoparticle assembly with high throughput. A nanoscale lithographic method in which a reusable conductive mask, having a pattern of conductive surfaces and insulating surfaces, is positioned upon a substrate whose surface contains an electrically responsive resist layer over a buried conductive layer. When an electric field …
Biomedical applications of nanotechnology
Fluoresent reportor – an incident photon of high enough energy can be absorbed raising an electron to the excited state. The electron can recombine with a hole in the valence band and emit a photon (fluorescent light). Fluorescence Resonance Energy Transfer – When a fluorophore or QD is close to a quencer (<10 nm), the …
How Polymerase Chain Reaction Works
Polymerase Chain Reaction (PCR) – method to generate millions of copies of a DNA sequence. PCR uses thermal cycling, with repeated cycles of heating and cooling. Heat physically separates the two strands in the DNA double helix, and lower temperatures each strand is used as a template. Primers (short DNA fragments) with sequences complementary to …
DNA
DNA: Genes provide instructions for proteins to build new copies of a cell, or repair damage. Each protein is a specialist that only does one particular job, so every time a cell wants to do something new, it has to produce a new protein. Proteins are made from 20 different amino acids. One type of …
Nano Composites
Nano Composites – reinforcing material called fiber and a continuous matrix material. The reinforcement material can be: Particulates: 0D Fibers: 1D, could be rods or whiskers Platelets: 2D Pressure Molding – a composite sheet material made by sandwiching chopped fiberglass between two layers of thick resin paste. To form the sheet, the resin paste transfers …
Near Field Scanning Optical Microscopy (NSOM)
Near Field Scanning Optical Microscopy (NSOM) – allows for optical resolution beyond the diffraction limit. The probe is an optical fiber with a sharp tip. The sidewall is coated with metal to improve reflection. Light can only enter at the sharp tip. The resolution is not limited by diffraction, but by the size of the …
How Plasmons Work
Plasmons – a metal cube is placed in an external electric field pointing to the right. Electrons accumulate on the left side, and positive ions on the right side. When the electric field is switched off, the electrons and positive ions oscillate back and forth at the plasma frequency. Light of frequency higher than the …
How Lasers Work
Laser – a photon with equal energy to the recombination energy can cause recombination by stimulated emission, which generates another photon of the same frequency travelling in the same direction and polarization and phase as the first photon.