Materials Science Corp. (MSC), a $250 million coatings company with expertise in metal coils and plates, is hoping to gain a toehold in the electronic components arena.
The company is coming to market with a field-effect sensing device that promises more durability and responsiveness than the membrane switches commonly used on control panels of consumer appliances. Called the Mirus detector cell, the flat panel switch, which acts as a proximity detector, uses a small, radiated electromagnetic field to register a state change.
"It's a clever capacitive sensor," said Mike Taylor, engineering team leader for MSC's Electronic Materials and Devices Group, Elk Grove, Ill.
The capacitance between two electrodes changes when an object, like a finger, penetrates their low-level field. The field is created by a 100MHz oscillator.
The technology, covered by several U.S. and overseas patents, is licensed from TouchSensor Technologies LLC., Wheaton, Ill. The device uses 4- to 10uA in standby from a 5V supply, or 16uA when triggered. Typical response time is 160microseconds.
The device is similar to a field-effect sensor from Motorola Inc.'s Semiconductor Products Sector. In one of its first attention-getting automotive applications, the Motorola E-Field sensors are wired as an antenna array into the cushions and seatback of a passenger car seat.
Connected to a microprocessor look-up table, the sensor array will determine whether an adult, a child, or a bag of groceries occupies the passenger seat, and will use that information to modify the force with which a passenger-side airbag pops open in an accident.
Taylor said the Motorola sensor depends on coils and a higher capacitance to detect a field change. MSC's device, which targets the same type of applications, depends on two small-area electrodes, and requires no microprocessor.
Markets targeted by MSC include automotive and consumer appliances, according to Taylor, who added that the company's primary competition is not Motorola, but manufacturers of membrane switches.
Because the field-effect switches can be protected behind stiff glass or plastic panels and require no actual pressure to actuate, the mean-time-between-failures is much higher for touch panels than switches. In addition, the conductive films used by membrane switches have a tendency to stick together and to peel from their plastic membranes, shortening their utility, Taylor claimed.
He acknowledged, however, that the MSC field-effect device will cost more to implement.