Three-dimensional all-dielectric metamaterial solid immersion lens for subwavelength imaging at visible frequencies

Although all-dielectric metamaterials offer a low-loss alternative to current metal-based metamaterials to manipulate light at the nanoscale and may have important applications, very few have been reported to date owing to the current nanofabrication technologies. We develop a new “nano–solid-fluid assembly” method using 15-nm TiO₂ nanoparticles as building blocks to fabricate the first three-dimensional (3D) all-dielectric metamaterial at visible frequencies. Because of its optical transparency, high refractive index, and deep-subwavelength structures, this 3D all-dielectric metamaterial-based solid immersion lens (mSIL) can produce a sharp image with a super-resolution of at least 45 nm under a white-light optical microscope, significantly exceeding the classical diffraction limit and previous near-field imaging techniques. 

                                

Theoretical analysis reveals that electric field enhancement can be formed between contacting TiO₂ nanoparticles, which causes effective confinement and propagation of visible light at the deep-subwavelength scale. This endows the mSIL with unusual abilities to illuminate object surfaces with large-area nanoscale near-field evanescent spots and to collect and convert the evanescent information into propagating waves. Our all-dielectric metamaterial design strategy demonstrates the potential to develop low-loss nanophotonic devices at visible frequencies.

 Souece: http://advances.sciencemag.org/content/2/8/e1600901.full

                                                            

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Scientists develop dissolving battery

Scientists have developed a self-destructing battery capable of dissolving when exposed to heat or liquid.

It delivers 2.5 volts and can power a desktop calculator for 15 minutes.

It could power medical devices in patients' bodies before degrading, or keep military secrets confidential.

Iowa State University mechanical engineering professor Reza Montazami said it was the first practical transient battery.

Researchers have been examining how batteries could dissolve harmlessly within the human body, and prevent the pain of removal, for several years.

Prof Montazami developed the lithium-ion battery with a team of scientists who recently published details of their discovery in the Journal of Polymer Science, Part B: Polymer Physics.

It measures 5mm in length, is 1mm thick and 6mm wide, and is similar to commercial batteries in terms of its components, structure and electrochemical reactions.

How it works

It contains an anode, cathode and an electrolyte separator within two layers of polyvinyl alcohol-based polymer.

When dropped in water, the battery's polymer casing swells and the electrodes are broken apart, causing it to dissolve. However, it contains nanoparticles which do not degrade, meaning it does not dissolve entirely.

The entire process takes around half an hour.

"Unlike conventional electronics that are designed to last for extensive periods of time, a key and unique attribute of transient electronics is to operate over a typically short and well-defined period, and undergo fast and, ideally, complete self-deconstruction and vanish when transiency is triggered," the scientific paper stated.

While it would be possible to create a more powerful battery, it would take longer to break down.

Saving the planet?

Dissolvable batteries could play a part in helping to reduce the waste caused by discarded electronics.

Researchers at the University of Illinois at Urbana-Champaign are working on electronic circuit boards capable of dissolving in water.

Once in a landfill site, the boards could break down within three to six months, according to the University's prof John Rogers.

Source/Reference:by http://www.bbc.com/news/technology-37021474

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