The Mobile Phone – The Ultimate Sensor of Choice

When I entered my undergraduate school, we had a punch card system. The next year we moved to Digital’s VAX system. Not a mainframe by any standards, but the punch cards were replaced by terminals, and a new age began. At that time, mainframes were “big iron” some like to say. The machine sat in an air-conditioned room on shock absorbing floors with a round the clock staff to tend to its every need.

Fast forward 23 years to today. I now type on a PC and I can’t help but think that the desktop computers of today are the new “big iron” machines. The envelope of technology is now a hand-held device called the mobile phone. Computational power, battery life, ruggedness, display visibility, handheld form factor all make it an ideal platform for virtual instrumentation applications.

One view of the mobile phone is as a sensor itself. Even standard phones come with sensors such as accelerometers and with a little tweaking could be retrofitted with optical, temperature, wireless, vision, and other sensors. Imagine walking up to the machine and placing the phone on the machine. After reading a few cycles, the phone gives a readout of pass/fail based on order analysis routines reading the vibrations from the machine.

Imagine taking temperature measurements in a park and then coupling the temperature reading with the GPS-position, and a date/time stamp. The result is then sent to a server pushing the results to a web-site so others can read it.

In addition to the wireless capability of sending the data back through Wi-Fi or a cellular system to a central database or server, the mobile phone also reduces the cost of collecting the data. Imagine using the SMS text messaging feature to send data back to a central server. As the cost of data collection drops, so the number of applications increases. There are many data collection applications that are never performed because the cost of collecting the data outstrips the budget or costs more than the benefit of having the data.

Even if the phone you have in your pocket right now is not ideal for a measurement or automation application think of the cost drivers behind it that would let you build a sensor collection device suitable to your application. Millions of phones sold each year drive down the cost of the components. The last time we saw this was the PC in the late 80s and early 90s, when the soaring number of PCs drove down the cost of memory, displays, storage, and more. Here’s an article that’s almost a year old placing the cost of the phone at around $25 for cost-sensitive regions. Compare that to the cost of a full-blow computer for measurement and automation and there’s a compelling proposition.

Best regards,
Hall T.