LCD to Touch-screen Monitor in just $5

Researchers at Ubiquitous lab (University of Washington) have designed a sensor costing merely $5. This sensor can turn any household LCD into a touch-screen monitor. The sensor plugs into a wall and uses technology called uTouch.

When the user’s hand moves close to or touches the screen, it causes electromagnetic interference (EMI). uTouch is capable of measuring EMI. The electricity running through every house has its unique electromagnetic signature. The power company, through the nearby substation, provides the “carrier wave”. The electromagnetic signature is modulated by each kink and switch till it becomes unique. This EM signature is changed by every electronic device that is plugged in. Modulations in the unique electromagnetic signature are the actual cause of electromagnetic interference. A television set, for instance, does not only suck power from your house but also changes your house’s EM signature.

Once the EMI sensor is plugged into the wall, the EM signature can be read and the changes in it can also be measured. Obvious changes in the EM signature can be detected when electronic devices are switched on and off. Simply moving your hand near an LCD also causes slight changes in the EM signature.

Researchers at the Ubiquitous lab of The University of Washington have been able to design sensors that can detect the movement of a single finger near an LCD across the house.

How it works:

Its working is similar to the working of a normal touch-screen. Every pixel of a LCD monitor is connected to a matrix of wires. The monitor’s row rate governs the row by row updating of these pixels. Touching or coming close to these row wires causes the capacitance (voltage) to change thus causing the row monitor’s driver to work harder. This in turn produces EMI at a specific frequency.

uTouch can perceive and distinguish between five different gestures:

  1. a)      Full hand touch
  2. b)      Five finger touch
  3. c)       Pushing
  4. d)      Pulling
  5. e)      Hovering above the screen

The average detection rate is 96.4% which has been brought down by the hover and push gestures which are extremely hard to detect. Detection of these gestures becomes harder because the EMI caused by these gestures is infinitesimally small.

The Ubiquitous Computing lab at the University of Washington has the ultimate goal of making everything around us interactive in the most economical and the easiest way possible. uTouch technology has been developed keeping this aim in mind. It has not been designed to be used in standard desktop monitors or laptops. And it will probably never be used for such purposes. But, it could be used in places where large and expensive display screens need to be converted into touch-screens. Some of these places are living areas, libraries, museums and other commercial spaces. This technology has the power of converting non-interactive and dumb spaces into highly engrossing and interactive ones in just $5.

Unfortunately, The Ubiquitous Computing Lab does not intend to make uTouch a commercial product. But, uTouch can be recreated easily by any commercial entity using the available algorithms.

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