Wireless sensors: a new computing era

Soon you will begin to hear about wireless sensor networks used everywhere in Asia, from farms to factories. What are they?

A wireless sensor network is formed by very small computers called 'motes' - tiny, self-contained, battery-powered computers with radio links. The radio links enable the motes to self-organise into a network, communicate with each other and exchange information about the physical world.

Wireless sensor technology is just beginning to be embraced by businesses that could not conceive of going wireless in the past. Think about companies that provide heavy machinery and construction equipment rental: these companies can now use wireless sensor nets at active construction sites to monitor and manage the company's tractors. For example, at the site of a new residential complex, one of the rented tractors had a small tuning problem, resulting in an irregular vibration of the engine. The irregular vibration is a warning sign of engine breakdown that will result in disruption of work. Through the wireless sensor technology that this company has in place, a sensor picked up on the irregularity in a matter of seconds and sent an email to the company's mechanic. Within moments, he arrived and fixed the problem before it became serious and before his customers were even aware that a tune-up was needed.

Intel, along with the University of California at Berkeley, is leading the research on mote technology. The researchers have created fully functional sensors that can compute, sense and communicate even though they are only the size of a bottle cap. Imagine the possibilities of sensors this small. They could be placed in paint and used to monitor structural integrity in buildings after an earthquake!

How sensor nets work

These sensors connect to each other in the same way that wireless laptops, desktops and PDAs around the world are connected to the internet. They require very little power and, as their price decreases in the coming years, are designed to be disposable. They are distributed like seeds around a physical location, talk to one another and essentially monitor an environment or collect information. Sensor networks can tell you when motors need maintenance, watch buildings or forests for fire or warn whether an old dam is failing in areas where motes are used.

These sensors are the next step forward towards 'proactive computing', where hundreds of small computers work together to anticipate the needs of humans. "Today, computers are either waiting for us or we're waiting for them," says Intel Research Director David Tennenhouse. "In a proactive world, the computers are anticipating your needs, and sometimes acting on your behalf."

More real-life examples

In San Francisco, 200 networked motes are already positioned on the Golden Gate Bridge. The motes measure how much the bridge sways from side to side, which can be as much as several feet in a strong wind. When a mote senses movement, it relays this information through the network of tiny computers. The information is eventually relayed to a more powerful computer for data analysis. Any strange readings that don't match current weather conditions might indicate a weakness in the bridge, alerting engineers to make repairs that will keep the bridge safe in case of an earthquake or other natural disaster.

Motes can be used to measure light, temperature, humidity, acceleration, magnetism, movement and other physical conditions. There are several obvious applications for motes in industrial production and manufacturing. In the same way that a car engine sounds 'right' when it is tuned properly, heavy equipment has a signature vibration when it is in normal operation. Intel is currently testing a wireless network of 210 sensors installed on 40 machines in one of its factories. There are about 3000 machines in each of its semiconductor fabrication plants that could eventually benefit from such a mote monitoring system. This same concept could work on almost any assembly line, or any engine. This drastically reduces the cost of overseeing equipment and, because problems are caught early, reduces downtime, increases efficiency and prolongs the life of equipment.

Possible applications reach beyond machinery. A study at the University of Rochester shows that these computers can even be leveraged for medical research. Scientists used wireless sensors to create a 'Smart Medical Home', essentially a five-room apartment where human research subjects will be involved to test medical concepts and prototype products. Motes are used in the Smart Medical Home to measure occupants' vital signs (blood pressure, pulse and respiration), sleep patterns and movement, 24 hours a day. The data collected will be used for further medical research purposes.

The sensor nets also have applications in hazardous work environments. Employees on oil rigs, nuclear power plants and assembly lines can now be constantly monitored. These motes could tell you about the people who are at your work site, what they are doing and how safe they are.

Agriculture is another important area where motes can be used. To explore this possibility, Intel created one of the first wireless vineyards in Oregon. Motes were placed around the vineyard, taking soil temperatures every minute to ensure that the grapes grow healthily, ensuring precision harvesting. Soon the researchers will implement a system that monitors the amount of moisture at each mote, or the number of pests in the region. They are even placing motes on farm animals, such as dogs, so they can collect information as they patrol the fields. This will allow for targeted irrigation and pesticides, lowering costs and making farms more efficient.

Although the technology is still in its early stages, motes will likely be widely available and affordable in as soon as five years. Crossbow Technologies was the first to offer motes commercially. Their latest generation of devices holds a microprocessor, memory, storage and an internal analog-to-digital converter, all integrated into a device roughly the size of a coin. These motes can measure acceleration, magnetism, light, temperature and other factors. Motes currently cost around US$50 a piece. As demand for them increases and processors become cheaper, this price may decrease dramatically.

It is clear that the applications for these minicomputers are limited only by the imagination and will likely pop up through Asia over the next few years.