MEMS technology refers to the integration of mechanical elements, sensors, and electronics on a common silicon substrate through the utilization of microfabrication technology. While the electronics are fabricated using Integrated Circuit (IC) process sequences, the micromechanical components are fabricated using compatible "micromachining"processes that selectively etch away parts of the silicon wafer or add new structural layers to form the mechanical and electromechanical devices. In addition, MEMS technology is attractive because sensors can be manufactured hundreds at a time on silicon wafers using proven manufacturing techniques developed for silicon chip production.

The main difference between electromechanical devices and solid-state sensors is that the latter has all of its electrical and mechanical components built into a single piece of silicon. When a washing machine tub is filling with water before the wash cycle, electromechanical sensors will signal only when the appropriate water level is reached. On the other hand, a solid-state sensor sends a continuous signal while the tub fills. If the water flow should happen to cease, this sensor indicates the actual water level. Therefore, the added intelligence translates into user convenience.

The Sensors Market

The overall sensors industry has experienced many improvements in the technology, which in return, has reduced the average selling price of most of the sensing devices and has helped them broaden their competitive position in untapped markets. As shown in Figure 1, in 2001 the total North American pressure sensors and accelerometers market generated revenues of U.S. $1.2 million with a growth rate of 13.1 percent. MEMS pressure sensors represented the majority (approximately 83 percent) of the total revenues due to their smaller size, lower cost, and lower power consumption. However, it is anticipated that accelerometers’ revenues will continue to increase as more manufacturers introduce low-cost and accurate sensing devices.

The total North American pressure sensors and accelerometers market revenues are projected to reach revenues of $1.5 million in 2008 at a compound annual growth rate (CAGR) of 10 percent. Moreover, pressure sensors and accelerometers in the home appliance market generated revenues of approximately $60 million with a growth rate of 21.7 percent in 2001. During 2001 and 2002, growth rates experienced a harsh decline primarily due to the U.S. economic downturn of 2001, which had a high impact on this particular market. Nevertheless, revenues slightly increased to $62.7 million in 2002 and are expected to settle at $74.9 million by 2003 with a CAGR of 15 percent.

The migration in the appliance industry from mechanical, through electro-mechanical, to full electronic control, has been ongoing for several years with the microcontroller proving the intelligence to electronic solutions. Amongst some of the main factors driving the adoption of electronics are reliability, cost, and improved energy efficiency. According to the U.S. Department of Energy, clothes washers can consume between 350-500 W of power, while clothes dryers' power consumption is higher ranging from 1,800-5,000 W. A vacuum cleaner consumes around 1,000-1,400 W of electricity, and finally, dishwashers between 1,200-2,400 W (using the drying feature greatly increases energy consumption). Therefore, smart sensors or microcontrollers can drastically reduce power consumption as well as cost of home appliances, which makes them more attractive for the consumer.

This information is provided by Daniela L. Carrillo, Frost & Sullivan, Research Analyst Sensors Group, e-mail: dcarrillo@frost.com.