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If you believe the hype, small technology will eventually find its way into everything but the kitchen sink. In the white goods category, this may not be too much of an overstatement. Over the next several years, “intelligent” appliances tricked-out with microscale sensors and actuators will hit home.
I’m not talking about an accelerometer-laden Rosie the House-Cleaning Robot, although she may be on deck soon, too. I’m talking about newfangled washing machines, dishwashers, vacuum cleaners, ovens and even refrigerators that will ease the pain of some household chores while keeping your utility bill in check.
Consider the costliest white good you probably own: your washing machine. Hopefully, your model is Energy Star qualified, meaning that it meets a certain level of energy efficiency. Clothes dryers eat up 3.5 times more power than washers, though. So one way manufacturers increase the energy efficiency of dryers is to make them not have to work so hard. Increasing the spin speed of the washer means that the clothes aren’t as wet when they go in the dryer. But high spin speeds often cause loads to become unbalanced. And there’s no bigger buzz-kill on laundry day than the earth-shaking rattle of an unbalanced load.
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Some modern washing machines already take advantage of sensing systems that detect unbalanced conditions. From mechanical switches that monitor drum displacements to systems that measure motor torque or velocity, the complexity and sensitivity of the systems vary with the price of the appliance. And according to Christophe Lemaire of Analog Devices’ Micromachined Products Division, “None of these solutions can handle vibration detection over the entire rate range of high-speed washing machines.”
But MEMS accelerometers, like those manufactured by Analog Devices, Motorola and others, are made for these kinds of measurements. The ultrasensitive accelerometers can provide constant feedback to the washing machine to create an “intelligent spin” cycle, says Rod Borras, a market development engineer for Motorola’s Sensor Products Division.
“The machine can increase the speed of the spin cycle and, if it notices that it’s getting close to knocking, it will slow it down a bit,” Borras says.
Eventually, he adds, advanced algorithms built into the control system could affect the rotation to automatically shift the clothes inside the dryer to maintain a high-speed spin without any human intervention. The high-end Sensotronic Plus washing machine from Bosch, also a MEMS supplier, lists this functionality, but a spokesperson for the company says that MEMS are not utilized in any of its products. Oddly, though, a new sensor-based automobile brake technology developed jointly by Bosch and Mercedes-Benz is also branded with the “Sensotronic” name.
A bit further down the road, appliance manufacturers may pull increased functionality from MEMS pressure sensors, already used to monitor water dynamics inside washing machines. By measuring the speed at which the fabric absorbs water, advanced MEMS pressure sensors may automatically determine the filth of your gym clothes or whether the load of unmentionables you just threw in should be washed on a “delicate” setting. Your laundry worries might be further quelled with an iron containing a MEMS accelerometer and a simple line of code: If the iron is horizontal, and not moving, then it probably should be shut off.
Indeed, the proliferation of MEMS pressure sensors in home appliances is following the industry trend from electromechanical toward total electronic control. Borras points out that MEMS pressure sensors in vacuum cleaners can alert the user when a bag is a full, whether the tube is blocked, or adjust the suction when you move from a wood floor to the shag carpet in the living room.
MEMS are also making forays into the kitchen. MEMS pressure sensors can increase the efficiency of dishwashers by monitoring and carefully adjusting the water level during a cycle. Meanwhile, companies like GE Industrial Systems’ Thermometrics and Melexis manufacture tiny thermopiles used to sense temperatures in ovens via infrared. General Electric also has demonstrated a cooking range outfitted with a MEMS acoustic sensor to “listen” for certain frequencies indicating that liquid in a utensil is boiling so, er, you don’t have to watch the pot.
So when will this stuff hit Sears?
Whirlpool’s director of Advanced Electronic Applications, Marco Monacchi, says that MEMS prices still aren’t quite low enough to fully edge out their electromechanical predecessors. In fact, Whirlpool blamed cost for its decision to remove MEMS gas sensors from a line of ovens that used the devices to control self-cleaning operations. Monacchi says the appliances offer the same function-ality with smart software at a lower price.
In fact, none of the MEMS suppliers I spoke with were authorized to disclose their end-customers. But the word on the street is that Europe is the first region where true small tech-augmented appliances are hitting stores. Surprisingly, it seems that in the United States we’re only willing to pay so much for convenience. Even when faced with doing our own dirty work.