Electromagnetic interference films

Electromagnetic interference shielding effectiveness of about 18 dB was achieved with 10 vol% MWCNT-PMMA film which was found to be primarily an EMI absorbing composite material. Figure 7.15 shows the variation of EMI shielding effectiveness due to reflection... 

Fiber optic chemical and biological sensors, based on SPR in continuous metallic films deposited on optical fibers, have been previously reported. " Sensors based on optical fibers have advantages like high response times, ability to be remotely interrogated, and low electromagnetic interference. In our study, fiber optic devices were developed based on excitation of LSPs in gold nanoparticles, deposited on the surface and tip of different optical fiber stractures. As refractive index of the medium around the sensors was varied, or biological molecules attached to the nanoparticles, a shift in the plasmon resonance related dip in the transmission spectram was observed. 

J. Joo, C. Y. Lee, High Frequency Electromagnetic Interference Shielding Response of Mixtures and Multilayer Films Based on Conducting Polymers. 7 Appl Phys 2000,88, 513. 

The effects of chemical structure on polymer film properties and applications were reviewed. The uses of conductive polymers in the bioanalytical sciences and in biosensor applications were investigated. Synthesis, characterization, and applications of CPs were reported, and the main aspects of CPs in chemical sensors and biosensors were covered. The advantages and limitations of conductive polymers for different biomedical applications like tissue engineering, biosensors, drug delivery, and bioactuators were reported. Different preparation methods for conductive polymers and the use of conductive pol5miers for electromagnetic interference (EMI) shielding applications were reviewed. ... 

Properties affected Attraction of (especially) lightweight plastics (films, fibres, etc.) to each other and to other materials improved operation of high-speed machinery (e.g. for packaging) shielding equipment against electromagnetic interference reduction/elimination of spark hazard in handling electronics, chemcials. medical equipment. 

Metal Foils. Most common is aluminum, less common are copper and lead. Snch tapes are quite conformable and are used to seal against moisture and water. Tapes with aluminum foils or aluminum-coated films can shield surfaces against thermal radiation. Copper and aluminum foils and vapor-coated films also can be used to shield against electromagnetic interference. 

Li Y., Chen C., Zhong S., Ni Y, and Huang J., Electrical conductivity and electromagnetic interference shielding characteristics of multiwalled carbon nanotube filled polyacrylate composite films. Applied Surface Science 2008, 254, 5766-5771. 

This section aims at providing a clear illustration as to what extent CNT length and quality can impact the electrical conductivity of polymer nanocomposites. The latter strongly determines for which applications, for example, electromagnetic interference (EMI) shields and electrostatic discharge (ESD) coatings, or thin-film field-emitters and (at low CNT concentrations) transparent conductors, the final materials are suitable (see Figure 7.1). 

Joo, J. and Lee, C.Y. (2000) High frequency electromagnetic interference shielding response of mixtures and multilayer films based on conducting polymers./oumoJ of Applied Physics, 88, 513-518. 

If measurements are made in thin oxide films (of thickness less than 5 nm), at highly polished Al, within a small acceptance angle (a < 5°), well-defined additional maxima and minima in excitation (PL) and emission (PL and EL) spectra appear.322 This structure has been explained as a result of interference between monochromatic electromagnetic waves passing directly through the oxide film and EM waves reflected from the Al surface. In a series of papers,318-320 this effect has been explored as a means for precise determination of anodic oxide film thickness (or growth rate), refractive index, porosity, mean range of electron avalanches, transport numbers, etc. 

The inner reference cylinder can be moved vertically and maintained concentric with the outer section. With the inner cylinder raised, a metal him can be evaporated to form the outer cylinder of the capacitor. The reference surface is prepared by coating the outside of the glass cylinder with a mixture of stannous oxide+1% antimony pentoxide. For most evaporated films, the condenser has a capacity of 30 pf. It is essential to screen effectively from electromagnetic and electrostatic interference. This is done by earthing the filament, an inner stannous oxide coating and an outer coating of liquid platinum. 

---