Georgia Institute of Technology’s pressure sensor. (via Georgia Institute of Technology)
We interact with pressure sensors almost on a daily basis, especially when shopping for products, as using a credit or debit card requires signing a pressure sensitive pad (unless those stores still use paper). The problem with checkout pads is that they degrade through repeated use becoming scratched, which requires more pressure to obscurely sign your name. A new development in sensor technology may hold the solution to that problem as well as a host of others, including sensitive skin for robots. Researchers at Georgia Institute of Technology have designed a new pressure-sensitive sensor that mechanically converts pressure directly into light signals that can be optically processed.
The process of turning pressure into light is known as piezo-phototronics, which generate a charge polarization when under stress. GIT researchers incorporated that process into their newly developed pressure sensor by using thousands of individual zinc oxide nanowires that are chemically grown on top of a gallium-nitride film. When subjected to pressure, the wires produce visible light on the opposite side of the film and the amount of pressure determines the amount of perceived light. When the wires are under strain, they create a piezoelectric charge at both ends of the wire that alters the wires band structure allowing the electrons to remain at the ends of the wire longer. When the nanowires are grouped, they create a form of pixelated light that creates an electroluminescent signal, which can then be read with on-chip photo-optics and transmitted to a computer that can process that information. The incredible thing about their sensor is that it can create up to an astoundinlyg high resolution of 6,300 dpi when using their method of growing the nanowires in a pixelated pattern! The researchers tested their sensor by pressing letters into the top of the film, which in turn displayed the same letters on the opposite side of the film and found it had a response rate of only 90 nanoseconds.
All of the nanowire emitters were able to be seen simultaneously from both sides, which were then tested for 25 on/off cycles in an effort to look for any light degradation and found that the sensor fluctuated in intensity at only 5% of the overall base signal. While the researcher’s sensor is an amazing accomplishment unto itself, the team is already looking for ways to refine their design and upping the resolution even more, which they say could be done by reducing the thickness of the nanowires. This would allow more of the wires to be grown on the film using a higher temperature fabrication process. Besides using their sensor pad for biometrics or signatures at checkout lines, it could be adapted for use as a type of e-skin for robotics that could provide an artificial sense of touch as well as providing a new level of human-machine interface. GIT surmises that the technology could be made commercially available in the next 5 to 7 years, which isn’t very long considering the technology is still in its infancy.
C
See more news at:
