Smart cities and Tech Evolution - V Leveraging on Sensors (b)

Response patterns for three different solvents on a 17 element sensor array. The pattern type identifies the vapor and the magnitude of the pattern signals is linearly proportional to the analyte concentration. Credit: Lewis Research Group Caltech

Any device connected to the Internet is -in one way or another- a sensor. In the Smart City area the forecast is for a tremendous growth of connected devices as show in the figure. Credit: MEMS&Sensors Industry Group

  • Radiation sensors detect particles emitted from atoms, alpha, beta and gamma particles and for a long time have been of interest to physicists only. After the terrorist attacks of 9/11 several cities in the US have started deploying radiotion sensors in coordination with the US Environmental Protection Agency. These sensors are part of the RadNet system (covering all 50 US states) and have been deployed in major US cities although in 2015 an article in the WSJ has revealed that many beta-radiation detectors do not work as expected because of interference with cellular towers and have been switched off. The gamma sensors seems to work fine. Technology is now providing alternative ways for detecting radiation. A US start up, Aerochromics, is selling shirts (and fabric) that can detect radiation level. Imagine having people (like the one working in waste pick up and disposal) wearing this type of shirts and moving around in the city. They would provide, at a glance, an indication of potential hazards due to radiation. We can expect more progress in material science (as I will point out in the next post) to address detection and monitoring aspects in our cities.
  • Chemical sensors can detect specific chemical compounds. There are now many technologies enabling more and more types of molecules, chemical noses as a matter of fact that are way better than our nose and are approaching, and for certain chemicals, bettering our dog’s nose, one of the best chemical sensors in the world. Chemical sensors are usually based on an array of individual sensors containing molecules that bind on specific molecules present in the environment and when the binding occurs an electrical signal is generated. This signal reveals the presence of a specific chemical and its quantity. The analyses of the signals produced by the array identifies a substance containing those individual molecules in that specific percentage. Hence an electronic nose can detect the type of wine not just its individual components. At a city level chemical sensors are been deployed to monitor drinkable water quality, pollution levels and substances in the air, waste detection and more. In NYC a network of 150 chemical sensors placed on light poles monitors air quality.
  • Mechanical sensors detect movements and proximity. They have been used even before the age of electronics and found widespread applications in the industrial revolution (in looms, lathe and many other tools).Modern mechanical sensors are coupled with electronics, optical and electromagnetic components that are increasing their sensitivity. Also, precision tooling has led to micro systems: MEMS Micro ElectroMechanical Systems, that have found application in micro sensors. These have achieved an amazing sensitivity and can be found in our smartphones, in lifts, in digital cameras,… actually almost everywhere. Cities can leverage on these MEMS sensors placing them in the tarmac, on sidewalks, on public transportation vehicles…
Author - Roberto Saracco

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