Harvard has invented a new device that can instantly identify an unknown liquid! The device, which fits in the palm of a hand and requires no power source, exploits the chemical and optical properties of precisely nanostructured materials to distinguish liquids by their surface tension. http://venitism.blogspot.com
The device offers a cheap, fast, and portable way to perform quality control tests and diagnose liquid contaminants in the field. Digital encryption and sensors have become extremely sophisticated these days, but this is a tool that will work anywhere, without extra equipment, and with a very wide range of potential applications.
Akin to the litmus paper used in chemistry labs around the world to detect the pH of a liquid, the new device changes color when it encounters a liquid with a particular surface tension. A single chip can react differently to a wide range of substances; it is also sensitive enough to distinguish between two very closely related liquids.
A hidden message can actually be written on a chip, revealing itself only when exposed to exactly the right substance. Dipped in another substance, the chip can display a different message altogether. http://venitism.blogspot.com
This highly selective wetting would be very difficult to achieve on a two-dimensional surface. The optical and fluidic properties Harvard exploits are unique to the 3-D nanostructure of the material.
The Watermark Ink, or W-Ink, concept relies on a precisely fabricated material called an inverse opal. The inverse opal is a layered glass structure with an internal network of ordered, interconnected air pores. Harvard has recently perfected the production process of large-scale, highly ordered inverse opals.
Two factors determine whether the color changes upon the introduction of a liquid: the surface chemistry and the degree of order in the pore structure. The more ordered the structure, the more control you can have over whether or not the liquid enters certain pores by just changing their surface chemistry.
Harvard discovered that selectively treating parts of the inverse opal with vaporized chemicals and oxygen plasma creates variations in the reactive properties of the pores and channels, letting certain liquids pass through while excluding others.
Allowing liquid into a pore changes the material's optical properties, so the natural color of the inverse opal shows up only in the dry regions. Each chip is calibrated to recognize only certain liquids, but it can be used over and over.
With the hope of commercializing the W-Ink technology, the researchers are developing more precisely calibrated chips and conducting field tests with government partners for applications in quality assurance and contaminant identification.
If you want to detect forgeries, you can tune your sensor to be acutely sensitive to one specific formulation, and then anything that's different stands out, regardless of the composition. http://venitism.blogspot.com
One immediate application would allow authorities to verify the fuel grade of gasoline right at the pump. Another application is a chip that tests bootleg liquor for toxic levels of methanol.
The W-Ink technology also would be useful for identifying chemical spills very quickly. A W-Ink chip that was calibrated to recognize a range of toxic substances could be used to determine, on the spot, whether the spill required special treatment. If you want something in the field that requires no power, easy to use, and gives you an instant result, then the W-Ink is exactly what you need. http://venitism.blogspot.com
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