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issue: December 2003 APPLIANCE Magazine

Sensors: Statistics
Sensors: Bringing the World of Tomorrow...Today

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by Michael Rasche, industry research manager, Frost & Sullivan

We live in a world that is starving for information. We want it immediately, in greater detail, and in higher volumes. Through the wonders of sensors, the 21st century promises to make information about our homes, and what is happening within it, more readily available and easier to access.

While the home appliance market is subject to many outside factors and can be characterized as cyclical, it has certainly benefited from the U.S. government's attempts to jump-start the economy. Low interest rates have allowed new home constructions to remain strong, growing at more than 6 percent in 2002 and have sustained growth in 2003. In addition, appliance purchases are expected to continue the upward trend started in 2001.

Sensors in the Appliance Market

Our homes are filled with sensors. They are in every major appliance, from our washing machines, clothes dryers, and dishwashers to water heaters, refrigerators, freezers, stoves, ovens, and microwaves ovens. They are a major component in home security and safety systems as well as in lighting and environmental controls. Figure 1 lists the major home applications and the types of sensors used in them.

Figure 1: Type of Sensor by Home Appliance Type, 2003

Appliance	Temp	Pressure	Level	AVV	Mag/Prox	Turb	Hum	Motion
Dishwasher	X	X	-	X	X	X	-	-
Washing Machines	X	X	X	X	X	X	-	-
Clothes Dryers	X	X	-	X	X	-	X	-
Stoves/Ovens	X	X	-	-	-	-	-	-
Microwaves	X	X	-	-	X	-	X	-
Vacuum Cleaners	-	X	-	-	-	-	-	-
Refrigerators	X	X	X	-	X	-	X	-
Freezers	X	X	-	-	X	-	-	-
Water Heaters	-	X	X	-	-	-	-	-
Indoor/Outdoor Lighting	-	X	-	-	-	-	-	X
HVAC	X	X	-	-	-	-	X	X
Home Security	X	X	-	X	X	-	-	-
Pools/Hot Tubs	X	X	X	-	X	-	-	-

Temp = Temperature
AVV = Acceleration, Vibration, Velocity
Turb = Turbidity
Hum = Humidity

Source: Frost & Sullivan

Major Trends Affecting the Sensors Market

Chart 1 - CLICK for large graphic.

There are three key trends that are affecting the sensors market.

First, there is an emphasis on the use of MEMs (micro-electromechanical systems, also known as silicon micromachined) technologies. Aside from allowing for the miniaturization of sensors, it permits the integration of the sensing element with microelectronic functions within a compact unit. Additionally, since MEMs are fabricated using integrated circuit batch-processing techniques, it is possible to mass-produce them at a minimal cost, while still improving functionality and reducing size.

The second major trend is the development of smart sensors. Smart sensors improve the reliability and durability of the sensors and make them more easily adaptable to new functions and conditions. Smart sensors also offer self-diagnostic features that allow the sensor to calibrate and adapt itself as conditions change.

Chart 2 - CLICK for large graphic.

The final important trend within the sensors market is the development of communication features allowing for data transmission over a network or into a control system. Using a standard interface, it will be possible to link sensors to a network quickly and easily. Chart 2 shows the percent of revenues for the major types of sensors being used in the appliance industry for 2003.

Growth in the sensors market in home appliance applications is being fueled by end-user demand for smaller and smarter products. One strategy being used by appliance makers to meet this demand and to ensure the safety of their customers is to utilize more accurate, smaller, and efficient sensors. Appliance makers, which primarily used mechanical sensors in their products, are shifting to electronic sensors. These sensors provide superior readings on the environment surrounding appliance as well as supply faster and more reliable data on the operating conditions of the appliance. Finally, the electronic sensors are less expensive, smaller, and provide better interfaces with modern control systems. This not only makes the appliance easier to operate, it also prepares them to be Internet compatible.

Chart 3 - CLICK for large graphic.

Chart 3 provides the revenues for sensors being sold into the appliance industry through 2003 and forecasts revenues for 2004.

One of the biggest areas of focus has been on the use of MEMS, particularly for sensing pressure. These sensors rely on a simple principle where a diaphragm is placed in contact with the medium for which the pressure is to be measured. The sensor is built out of a silicon-based substrate upon which the diaphragm rests. As the medium to be measured exerts pressure on the diaphragm, embedded resistors exhibit a change in resistance. Electronics in the sensor converts this signal into a voltage, which is then interpreted as a pressure reading. Aside from measuring pressure, MEMS-based sensors can be used to measure liquid levels (in washing machines), acceleration (typically for balance control of washing machines and clothes dryers), and advances in radio frequency allow MEMS sensors to provide wireless communication capabilities.

This last aspect is an area of great interest (and perhaps concern) because it is expected that in the near future our appliances will become Internet-ready. By tapping into the wireless broadband systems that are unobtrusively permeating our homes, appliances will be able to send manufacturers warranty information and provide notification about needed maintenance and impending unit failures.