The Latest in Semiconductor Technology: Imaging a Body in Space Is Not Science Fiction

What do you get when you cross a physicist's musical experiment with a semiconductor provider dedicated to making everyday things smarter and safer? A semiconductor chip that may soon change the car, home and workplace.

What began as an experiment done for cellist Yo-Yo Ma evolved into a collaborative development between Massachusetts Institute of Technology's (MIT) Media Lab's Center for Bits and Atoms, Elesys North America and Motorola's Semiconductor Products Sector. The resulting electric-field imaging chip from Motorola is now enabling contact-less sensing and imaging of low-level electric fields for a variety of systems and products, from automobile air bag controllers to wheelchairs.

Electric Fields

Nearly every object encountered in daily life contains charged atoms that can move in an electric field (e-field). The charge can be sensed and three-dimensionally imaged showing how one object relates to another object or to its environment. E-field sensing builds on the strengths of many alternative technologies, such as optical and acoustic sensing, while avoiding several of their weaknesses, such as not being able to detect objects that are not in the line of sight.

Information gleaned from e-field sensing and imaging can be used to trigger functions such as turning switches on or off, disabling features, or setting off alarms to indicate dangerous situations. The applications of low-level e-field imaging are vast, but, until recently, have been restricted by the difficulty in implementing practical systems.

Uses for Electric Field Imaging

Motorola's e-field imaging chip, the MC33794, together with electrodes and a microcontroller can help embedded systems designers readily implement three dimensional (3D) sensing and imaging applications. The ability of this combination to detect touch can be used in a wide range of applications from automobiles to consumer electronics.

For example, an automatic on/off feature can easily be implemented in home appliances. A few electrodes embedded in the body a hair dryer would allow the device to turn on when picked up and turn off when set down. A few more electrodes would allow the user to control the temperature or speed by merely touching a defined location on the barrel of the dryer.

Other applications that could be simple to implement include liquid level detection, spill detection or moisture sensing. For example, stoves with flat tops could be programmed such that when liquids boil over, the heat would be automatically reduced or tuned off.

A more sophisticated application is a touch panel input in which an array of electrodes embedded in glass or behind a non-metallic surface could be sensed in a matrix fashion similar to contact switch inputs. This method eliminates membrane switches or expensive multi-layer resistive touch pads. Because the input is sensed without requiring a contact mechanism, problems of wear, dirt, and corrosion are eliminated. This is especially beneficial in harsh environments.

Using e-field imaging, a virtual computer touch pad can act as a computer mouse. With electrodes built in or under a desk, the touch pad could sense hand or finger positions on or above a desktop.

With advanced software techniques, the position of an object in 3D space can be determined. An example of this is an automobile occupant detection system, such as the one offered by Elesys North America (formerly NEC Technologies Automotive Electronics Division), a leading provider of automotive electronic safety systems.

Electric Field Imaging: Helping to Save Lives Today

Elesys uses Motorola's MC33794 e-field imaging chip in its SeatSentry™ occupant protection system. This system uses low-level e-fields to detect a passenger's head and proximity to the side airbag, and then stops airbag deployment if the passenger's head is determined to be too close to the airbag. Currently, the SeatSentry system is installed in all Honda and Acura vehicles with side airbags.

“While simple capacitance measurement is one of the most mature kinds of sensing, working with Motorola and Elesys we found that tiny arrays of charging currents can be used to determine real three-dimensional geometries,” said Professor Neil Gershenfeld, director of the MIT Media Lab's Center for Bits and Atoms. “Motorola and Elesys have brought this exciting capability to the market in a form that could help save lives today, and that promises to enable many new kinds of unobtrusive and responsive computer interfaces tomorrow.”

Video content: Footage includes a laboratory demonstration of electric-field detection, exotic fish, entertainer Penn Gillette of Penn & Teller, M.I.T. campus, Motorola campus, circuit boards, semiconductor chips and a child in a car seat. Soundbites from: Phil Rittmueller, vice president of Elesys North America, Inc.; Dr. Neil Gershenfeld, director of the M.I.T Media Lab's Center for Bits and Atoms; Joshua Smith, PhD., Escher Group; and, Dan Leih, analog products marketing manager in Motorola's Semiconductor Products Sector.

Additional product features are listed at: www.motorola.com/analog.

About Motorola
Motorola, Inc. (NYSE:MOT) is a global leader in wireless, automotive and broadband communications. Sales in 2002 were $27.3 billion. Motorola is a global corporate citizen dedicated to ethical business practices and pioneering important innovations that make things smarter and life better, honored traditions that began when the company was founded 75 years ago this year. For more information, please visit www.motorola.com.

###

Media Contact

Motorola Semiconductor Products Sector
Brian Thorsen
+1-480-413-5209
brian.thorsen@motorola.com

MOTOROLA and the Stylized M Logo are registered in the U.S. Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2003.

Editors Note:
Broadcast-quality video of Motorola "E-Field Imaging Technology" can be requested by calling MultiVu Media Relations, +1-800-653-5313 EXT. 3, or by sending an e-mail to dubrequest@multivu.com. Please include the following information with your request:
Name
Station Call Letters
Address 1
Address 2
City
State
Zip
Phone number (this is required by the shipping company)
E-mail address
Video Title
Comments