cell-phone sensors have great potential for monitoring pollution

Some problems are better suited to cell phones for sale sensing than others. For example, cell-phone sensors have great potential for monitoring pollution, which usually concentrates in densely populated areas—where cell phones abound.

"The action is where the people are," says Honicky, now a senior software engineer at Tarana Wireless.

Honicky has already tested a prototype cheap cell phones containing a carbon-monoxide sensor capable of sniffing out the lethal gas and thus saving lives. To help measure air pollution, other researchers at Berkeley have succeeded in miniaturizing a MEMS particulate matter sensor—normally the size of a shoebox—so that it fits inside a cell phone.

Elsewhere, researchers have focused on using cell phones with sensors to create an early-warning system for modeling and predicting the spread of tuberculosis in South Africa, and using cell phones in tandem with water quality sensors to monitor village water supplies.

The potential applications extend beyond the developing world. Honicky says sensors in cell phones could control temperature in homes and offices; detect emergencies, such as an elderly person's fall or a lack of motion; and "slurp up" data stored in delay-tolerant networks as a 2dffREs3 person walks past a nearby node, with the cell phone functioning as a data mule.

And as smartphones become even smarter, experts say they will come loaded with even more sensors, such as altimeter sensors that can tell you what floor you're on in a building, and sensors that can detect perspiration to monitor your excitement level and mood, which could become incorporated in video games that will factor in emotion during gameplay.

For now, the cell phones for sale-as-sensor approach is still largely in the idea stage, due in part to issues of size, cost and energy use. Honicky says sensors need to be small enough that they can fit inside increasingly sleek phones without adding bulk, cheap enough that they don't send phone costs soaring, and energy efficient enough that they don't drain a phone's power. All of these challenges will be solved in time, Honicky says.

More problematic, he says, are the massive privacy issues that will come with embedding sensors in smartphones that, arguably, already know and transmit too much personal information.