In this month's collection of interesting news from the world of research and development we've got a pressure-sensitive artificial skin based on optical sensors, energy harvesting from a wider range of frequencies, and bendy yet robust antennas.
A Light Touch
Researchers Jeroen Missinne and Bram Van Hoe with the CMST, Electronics and Information Systems Department at Ghent University, have developed an artificial optical skin that could be used to provide tactile feedback for robots and to surgeons performing robot-assisted or laparoscopic surgery. The skin uses two layers of polymer waveguides separated by a thin layer of soft silicone. The waveguide layers are oriented so that the guides in the bottom layer are rotated 90° from those in the top layer and light is piped into the bottom layer of waveguides. When a pressure is applied to the skin, the top layer of waveguides is pushed toward the bottom layer; exerting a force on a waveguide crossing point couples light from the input waveguide to an output waveguide; the applied pressure determines the amount of coupled light. The skin is flexible, its resolution depends on the number of polymer waveguides running through it, and because it is light-based, it avoids problems with EMI. For a longer discussion of the project, read "Optical pressure sensors give robots the human touch," in New Scientist.
Tweaking Vibration Energy Harvesting
Led by Dr Stephen Burrow, Lecturer in Aircraft Systems in the Department of Aerospace Engineering at Bristol University, researchers are developing vibration energy harvesters that work over a wider range of frequencies. Similar to existing vibration energy harvesters that use a mass and a spring to transform vibrations into voltages; the new devices use a mass and a nonlinear spring. This combination allows the device to resonate over a wider frequency range than is possible with linear springs. (More detail is available in the article, "Pickin' up good vibrations to produce green electricity" courtesy of Bristol University.
Future antennas may be significantly stretchier than existing ones, if the researchers from North Carolina State University have anything to say about it. Graduate students Ju-Hee So, Jacob Thelen, Amit Qusba, and Gerard J. Hayes and professors Michael D. Dickey and Gianluca Lazzi (who is now at the University of Utah) have created shape-shifting antennas that use a gallium indium alloy injected into thin channels within a carrier material. The alloy is a liquid at room temperature; once injected into a channel, the surface of the alloy oxidizes to form a skin. Because the resulting wire is still a liquid (albeit held in place by the oxide skin), it takes on the mechanical properties of the carrier material. When the researchers injected the alloy into a silicone elastomer, they got an antenna that would bend and stretch. As Dickey says in the article, "Shape Shifters: NC State Creates New Breed Of Antennas," "This flexibility is particularly attractive for antennas because the frequency of an antenna is determined by its shape. So you can tune these antennas by stretching them." (Go read the article. The picture of the antenna is amazing.)