By Candace Stuart
Small Times senior writer

The auto industry has found a new way to make vehicles safer and more energy efficient, but it’s not in the vehicles. It’s underneath them — in the tires and wheels, where small technologies can be imbedded or installed without hindering performance.

Tire makers such as Michelin and Goodyear are aligning with international giants and small-town entrepreneurs to offer technologies ranging from puck-sized pumps that keep tires properly inflated to monitoring systems that alert drivers when tire pressure is dangerously low. The nerve center in each is a MEMS device that measures pressure and temperature. Other MEMS and microsystems relay that information to a dashboard display or an intelligent air pump.

Although the technology has existed for years in niche markets, it’s now poised to become standard fare, much as airbags did in the 1990s. Many airbags also rely on MEMS devices to detect motion, which triggers deployment

“We’ve been advocating for 10 years that tire monitoring would be the next safety issue,” said Charlene Krepiakevich, a spokesperson for the Canadian company SmarTire. SmarTire provides tire monitoring systems to auto suppliers, industrial trucks and the motorsport industries from its headquarters in Richmond, British Columbia.

Underinflated tires are dangerous because they build up heat that can damage the inside tire structure. Undetected, that strain can cause potentially fatal blowouts. Vehicles with underinflated tires also need more fuel, so proper inflation can improve fuel economy and reduce emissions.

The American market for tire monitors is expected to boom in the wake of last year’s revelation that the treads on some Ford Explorer tires would separate, especially when the tires were underinflated. The report of the flaw and deaths associated with it led to a massive recall by Bridgestone/Firestone, the maker of the tires, and prompted Congress to create the TREAD (Transportation Recall Enhancement, Accountability and Documentation) Act.

The TREAD Act calls for a tire monitor standard to be established by November. By the fall of 2003, all new vehicles must include a tire monitor that meets that standard.

All tires gradually lose pressure. The most basic tire monitors use a MEMS sensor mounted in the wheel or imbedded in a tire valve to measure air pressure within the tire. A signal is sent to a dashboard display, which warns the driver when pressure drops below the recommended level. It also alerts a driver about leaks and punctures.

Most sensors also measure temperature, which can indicate internal wear and an imminent blowout. Other MEMS and microsystems can be added as communication components or to make the device more sophisticated.

Krepiakevich says SmarTire is well positioned to serve the American market, thanks to its alliance with the Norwegian MEMS supplier SensoNor. SensoNor, which was created in 1985 to make MEMS devices for aerospace applications, expanded first into the airbag market and later into tire sensors.

SensoNor has devised a pressure sensor that is robust enough to survive the tough conditions of real-world driving, where dust and other contaminants can gum up the sensors. Its pressure sensor is based on a triple stack method with a silicon diaphragm sandwiched between two layers of glass. The layers are vacuum sealed and customized to include metal conductors, electrical connections and any other components a client needs.

Pressure changes force the diaphragm to bow, producing a mechanical strain that other components can measure. The layering, vacuum sealing and a special transfer molding technique help protect the parts from moisture and corrosion.

“Packaging is a key element,” said Hans Petersen, SensoNor’s vice president of business development. “We have a sealed vacuum cavity where all the active parts fit inside. Others have to put the active components on the diaphragm and then coat it.”

The devices range from three to 25 microns and production is fully automated. A production line of two to three people at the company’s fabrication center in Horten, Norway, can produce about 100 units a minute, Petersen said.

SensoNor began producing its first tire pressure monitoring sensors in 1997 for the European car market. Its sensors are now used in Mercedes, Porsche, BMW and Volkswagen vehicles, and the international supplier Siemens Automotive will begin using sensors in its systems.

Japanese carmaker Toyota also uses SensoNor monitors in its 2001 Lexus models in Japan.

Petersen said drivers in Europe and Japan embraced the technology for safety reasons, but also because it improves a vehicle’s fuel efficiency, an incentive in countries where fuel costs are high. Efficiently running cars also create less air pollution, which is a priority in Japan.

SmarTire and SensoNor joined forces in the late 1990s to develop tire microsystems for passenger cars and light trucks. They plan to roll out a more sophisticated product in the next two months that can detect changes in each individual car tire and relay that using radio frequency transmitters to the driver. SensoNor provides the sensors and SmarTire specializes in wireless transmitters.

Michigan-based TRW Automotive Electronics signed a deal with SmarTire and SensoNor to use their products to develop tire monitor systems for auto manufacturers. TRW also is working with Michelin to promote the systems. Michelin is both an automotive supplier and retailer.

Cycloid Co., a small company in Cranberry, Pa., has taken a different tack to improve tire safety. Cycloid houses a SensoNor pressure and temperature sensor within an air pump that nestles in the wheel. The sensor checks air pressure through a tube in the tire valve. If air pressure is not optimal, the pump automatically adds air through the valve using an air compressor that is powered by the rotating wheel.

“It adds enough to compensate for normal loss or a small leak,” said Tom Zdanowski, director of electronics at Cycloid. “One pump can handle a Neon or a Navigator.”

The company started marketing the pump to the heavy truck industry in the late 1990s and it has been installed on more than 6,000 trucks. Cycloid is working with Ford Motor Co. to include the pump on future Windstar minivans and other high-end vehicles.

Goodyear Tire and Rubber Co. has a minority stake in the company but the pump will be compatible with all tires, Zdanowski said.

SensoNor is not the sole MEMS pressure sensor company. Lucas NovaSensor, a Fremont, Calif.-based MEMS pioneer that now is under the umbrella of TRW, provides pressure sensors for Schrader Electronics. Schrader incorporates the sensor and a RF transmitter into tire valves. Its system has been used by Corvette, Peugeot, Cadillac, Renault and Chrysler.

Schrader is based in Antrim, Northern Ireland, and is part of Tomkins PLC in London.

Other competitors include Motorola Co. and the Taiwanese company Pacific International Co. Chicago-based Motorola has worked on a pressure monitoring microsystem for use in run-flat tires. The system warns a driver of any extreme tire pressure loss, while an inner wall in the run-flats allow a vehicle to continue driving for 50 miles. Pacific also supplies the run-flat market.

Tire pressure monitors will be good for consumers, according automotive industry analyst Rod Lache, but not for the tire makers. “Over the long term, it will be a negative,” said Lache, a vice president at Deutsche Banc Alex. Brown in New York.

Proper inflation can extend the life of the tire significantly, he pointed out. Consumers will get more for their money, but retailers will see their tire replacement business slowing down, he predicted.