As a result, the liquid completely filled the microchannels, after which the solvent evaporated. A coating of the preceramic material was then left inside the PMMA structure. One difficulty with this process is that the ceramic material becomes somewhat cracked during the heating process, partly because of shrinkage during the transforming reaction. Clearly because of the way the preceramic layer was formed, the cylindrical structures are also hollow, which adds to their fragility. Researchers are currently trying to improve their understanding of the dielectric constant and how it can be altered.
Solid line shows the measured transmission of radiation by wave number.
The dotted line shows a comparison taking the real part of the dielectric constant as 4. According to Michalis Sigalas of the Ames Laboratory and Department of Physics and Astronomy at Iowa State University, more recent experiments have used the same types of ceramic structure, but filled them with metal. Theoretical analysis predicts that defects in these metal structures will cause transmission peaks, but extremely narrow ones, thus making the devices useful as bandpass filters. Sunny Bains is a scientist and writer based in the San Francisco Bay area.