The Age of Sensors
By Stanley Trout
Often we describe a specific time in human history as an age, such as the age of reason, the bronze age or the middle ages. Many people call the time we live in today the “Information Age” because of the rise and dominance of computers in our lives, and I would agree that it is an apt description. However, I would like to discuss another name that may well describe the time we live in, especially the future, and that is the “Age of Sensors”.
Why sensors? It really is a natural consequence of our heavy use of computers. Computers give us a great tool for handling data of all kinds: the names and addresses of all our contacts may be organized in Outlook, our checkbook may be organized by Quicken and all our correspondence may be stored as Word files. Computers handle all this data and much more with ease. In fact, if we think about how we interact with the computer, by keyboard, mouse, scanner, web cam, etc., they are all just ways to enter information into the computer. With such a useful tool at our fingertips, I think that the challenge of our time, our new frontier, is finding more and better ways to bring information to computers and that is why I say we live in the age of sensors. Let me offer just one simple example.
I had the opportunity this summer to rent a Toyota Prius for a week. It is a great example of modern automotive technology. The actual fuel economy numbers are really impressive and significantly better than the new EPA mileage ratings. (see www.fueleconomy.gov) I drove almost 1600 miles and consumed a little over 30 gallons of gasoline, for an average of just over 52 miles per gallon. (The metric numbers are 2500 km, 115 liters and 4.5 l/100 km.) But my initial interaction with this car was of a much more mundane matter. I had a low tire pressure warning. Checking with my tire gauge revealed the pressure in one of my tires was just 22 psi (1.5 x 105 Pa), well below the 35 psi (2.4 x 105 Pa) recommended by Toyota, yet not low enough to be readily noticeable to someone just looking at the tire. In this case, a small sensor from the tire was giving me the warning. Technically, this is a difficult sensing problem. It must be done wirelessly since the tire must be free to rotate, yet this technology is available on most cars these days.
This example gives us a clue about how much sensing technology has improved in the last few decades. Our automobiles are now a vast collection of sensors, continuously feeding a wide variety of information to the onboard computer about the condition of the car, its passengers and its environment. Sensors give us the ability to optimize the performance of the car, provide troubleshooting information to our mechanic and improve our personal comfort as we drive. Over time we can expect the number, the sophistication and the benefits of sensors to increase.
What is at the heart of a sensor? The simplest sensors are merely switches, that turn on and off in response to a particular stimulus. The automotive crash sensor is a good example of this idea, and since it is a magnetic sensor, it is one of my favorites. Here the sensor is normally off, but under the proper conditions – the rapid acceleration of a crash – the sensor switches on, deploys the air bag and may even initiate an automatic call to OnStar® for help. This sensor is an example of excellent engineering, since the sensor must activate with absolute certainty during a crash, and never at any other time. Not deploying during a crash is dangerous for the passengers and a false deployment is expensive and also potentially dangerous.
More complicated sensors are proportional, meaning that the response to a stimulus varies with the magnitude of the stimulus. A photosensor in a camera is a good example of this technology. The exposure is adjusted in response to the ambient light. The less available light the longer the exposure and the greater the aperture opening.
There are two great challenges on the horizon for sensors. One is coming up with new materials to make new sensing devices. This is an active area of research operating at the intersection of physics, chemistry, materials science, electrical and mechanical engineering. The goal of this research is to find new ways to take advantage of some unusual material characteristics to measure some parameter. That parameter could be almost anything, speed, time, temperature, distance, pressure, etc. While many sensors have some sort of magnetic connection, not all sensors are based on magnetic phenomena.
The other challenge is learning to apply the sensor technologies we already have to solve some nagging control problems. Advances in this technology have brought us vehicles that are far more efficient, less-polluting and safer than they were just a decade or so ago. They allow us to control rush hour traffic by adjusting traffic signals in response to the prevailing traffic pattern, to control the temperature and lighting of our homes, to monitor our factories remotely, for example. All we need is a sensor, a computer and some software. But we should expect wider deployment of sensors in all facets of our daily lives, as we learn more about how to use sensors. This means that if you have a device that you would like to control, either a system already exists, or it will be available soon.
This is why I am so optimistic about this technology and believe that we are in the “Age of Sensors”.
More information about Stanley Trout can be found at http://www.spontaneousmaterials.com/.