Posted in chemistry, engineering, physics

Carving colors into gold nanoparticles

From the MIT Technology Review Physics ArXiv blog. Apparently it has been traditionally hard to get metals to offer up anything other than their natural color; you could only create different colored metals by mixing different metals with it, for example…

But now there’s another way thanks to some interesting work by Jianfa Zhang at the University of Southampton and a few pals. Their idea is to carve a different type of repeating pattern on to the surface of a metal.

These patterns are smaller than the wavelength of visible light. Instead of causing the light to interfere, they work by changing the properties of the sea of electrons in the metal–in particular its resonant frequency. This alters the frequency of light it absorbs and reflects.

This is the same technique that researchers have been using for some time to build invisibility cloaks . The idea is that by carefully building repeating patterns of subwavelength structures, researchers can tailor the way a “metamaterial” can steer light.

But instead of creating 3D structures that steer light as it passes through the material, Zhang and Co. carve the relevant structures onto the surface to control the way light is absorbed and reflected.

Visit the ArXiv blog for more details…

All I keep thinking is I’m glad there are lasers now that can do that for you; doing it the old-fashioned way would be waaaay too tedious for even the most skilled metal craftsman.

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Posted in biology, chemistry, communication and networking, medical imaging, Optics

Technology Review: Sensor Detects Emotions through the Skin

So this isn’t directly art-related. But measuring and gauging emotions has always been considered a “touchy-feely” kind of activity. Well, now it is very touchy-feely, with specific measurements! And the armband conducts more of a stress-test rather than a mood ring, but it is still cool. From Technology Review:

A new device developed by Affectiva, based in Boston, detects and records physiological signs of stress and excitement by measuring slight electrical changes in the skin. While researchers, doctors, and psychologists have long used this measurement–called skin conductance–in the lab or clinical setting, Affectivas Q Sensor is worn on a wristband and lets people keep track of stress during everyday activities. The Q Sensor stores or transmits a wearers stress levels throughout the day, giving doctors, caregivers, and patients themselves a new tool for observing reactions. Such data could provide an objective way to see what affects an autistic person positively and negatively, says Rosalind Picard, director of the Affective Computing Research Group at MIT and cofounder of Affectiva.

If this works, it’d be a great tool not only for autistic kids, as the article suggests, but for anyone who is worried about panic attacks, stress-induced heart trouble, or anything like that

more via Technology Review: Sensor Detects Emotions through the Skin.