Smart Dusts. EE453 Project Report submitted by. Chanz Murata Fall 2008

Transcription

1 Smart Dusts EE453 Project Report submitted by Chanz Murata Fall 2008

2 Smart dusts are many small wireless devices that form a network of microelectromechanical sensors (MEMS). These sensors have a wide range of uses from sensing the temperature in a room to exploring the surfaces of unexplored planets. The idea for these devices was first introduced in a science fiction book The Invincible, published in 1964 [3]. It was not until 1997, when a professor at UC Berkeley, Kristofer Pister began research in this area [9]. Solar powered mote with an acceleration and light sensor. It is around 11.7 mm 3. Courtesy of Nanotechnology Now. The individual devices are called motes, which consists of a sensor, power supply, processor, and wireless communication. The targeted size for these devices is around 1mm 3. Current devices are around 5mm 3 [7]. This has posed many problems for researchers in this area. To make the motes smaller, one technique proposed is to fuse the MEMS and the electronics onto a single chip [7]. Since many of the applications of smart dusts require each mote to be very small, advances in nanotechnology fabrication techniques have helped to shrink the size. The communication protocol of the smart dusts is one of its major advantages. Since it relies on a mesh networking protocol, it is not as susceptible to failures of other point to point communication schemes [10]. For example, if one of the motes were to fail, communication between nearby motes would not be cutoff. Smart dusts were designed to provide reliable communications and sensing while allowing for many failures and losses of individual motes. 2

3 Individual parts of a mote. Courtesy of Computer World. Pictures of the individual motes. Courtesy of UC Berkeley. One of the main problems associated with the shrinking of the motes are the power supply. As the motes get smaller and smaller, it becomes more difficult to find an adequate power supply. The solution for this problem is to reduce power consumption and/or find a better source of power. To reduce power consumption researchers have been focusing on low power ad hoc routing protocols. This will reduce the amount of energy required to communicate between the motes since they do not need to communicate individually over long distances. 3

4 Another way to reduce power consumption is to combine the separate semiconductors on the chip into a single semiconductor. To increase its power supply, there are several different options researchers are focusing on. Fuel cells could be used that have the capability to gather power from its surroundings by converting energy from vibrations or light [7]. Power could be gathered from living organisms, like spinach, sugar, slugs, and flies [9]. The power is gathered by using Adenosine TriPhosphate molecules which store energy similar to muscles in living organisms (Wikipedia). Nuclear micro batteries could also be used to power the motes. At the University of Wisconsin, researchers have experimented with the idea of a nuclear battery that produces electricity from the decrease in the number of radioactive nuclei [5]. Smart dusts have many uses in safety. One use is that they could be used in buildings as temperature and humidity sensors. They could also be put into the concrete in buildings to monitor the structural integrity of the building. Hospitals could use smart dusts to monitor the location and status of patients [2]. Outdoors, they could be used to alert others of the location of survivors during a disaster. Cities could use smart dusts to monitor available parking spaces. Smart dust could be embedded into the road surface and detect when a car is parked in a stall. Cars could then have a monitor installed which would alert drivers of open parking spots. Parking meters could also have sensors embedded to monitor activity. Currently, San Francisco and Los Angeles have systems installed. In the commercial space, smart dusts can be used for inventory monitoring. If each package in a warehouse is outfitted with a sensor, it can communicate with the smart dust to help identify its location. It could be used to easily monitor inventory levels and the condition of each package. This would help increase productivity and decrease downtime from unknowingly running out of a product. Factories could use larger versions of smart dusts as remote monitors. They could monitor all parts of the factory and send an alert to the control room in the event of equipment failure. Their sensors could also be used to detect problems with equipment before they fail. Since the motes are wireless, they can be placed in many areas that could not be reached by wired sensors. One of the companies that produce such devices is called Dust Networks. It is a company that was founded to commercialize the concept of smart dusts. 4

5 In the military, smart dusts have many applications. Soldiers could deploy smart dusts in an area to track enemy movement or locate a specific individual. Since the smart dusts have sensors, they could detect poisonous gases or radioactive material and alert the soldier of its danger without exposing the soldiers [9]. An extreme application of smart dusts is the exploration of other planets. In theory, motes could be deployed on a planet s surface. For example, on Mars, smart dusts can be carried by wind. The motes would be encased in a plastic sheath which could alter its shape when a small voltage is applied to it [7]. This would allow the mote to steer itself and stabilize itself within a swarm of motes. It has been shown through simulations that wrinkling the surface of the mote would increase its drag and cause it to gain altitude. Flattening its surface will allow it to decrease its altitude. The wireless communication between motes would allow them to be aware of its surroundings and allow them to spread out evenly. They can then record data and send information back to a nearby space probe for communication back to Earth. Since the mote size required for this application would be less than 1mm 3, current chemical sensors are too large to be properly implemented in smart dusts for this application [7]. Therefore, as nanotechnology and miniaturization techniques advance, they will be able to produce smaller sensors that will be able fit on a mote around the size of a grain of sand. Current concerns about smart dusts are environmental concerns about whether or not spreading a bunch of tiny electronics into the atmosphere will have a negative impact on the environment. There are also privacy issues of having miniature sensors that could be used to spy on people. Kristofer Pister, the main researcher behind smart dusts believes that they are too small to have any significant impact on our environment [6]. He also says that there is always a dark side to everything and it is how we use these technological advancements that matters [6]. 5

6 Works Cited 1. Bonasia, J., and Doug Tsuruoka. "Sweeping Changes Coming With Smart Dust." Investors.com. 5 Dec Dec < 5>. 2. Hoffman, Thomas. "Smart Dust." Computerworld Mobile and Wireless. 24 Mar Dec < 3. "The Invincible." Wikipedia. 6 Dec < 4. Knight, Will. "Shape shifting 'smart dust' may explore alien worlds." NewScientist. 18 Apr Dec < shapeshifting smartdust may explore alien worlds.html>. 5. "Nuclear Micro Battery." Wikipedia. 6 Dec < battery>. 6. Pister, Kris. "Smart Dust." UC Berkeley. 6 Dec < 7. Rincon, Paul. "'Smart dust' to explore planets." BBC News. 18 Apr Dec < 8. "SmartDust & Ubiquitious Computing." Nanotechnology Now. 29 Mar Dec < now.com/smartdust.htm>. 9. "Smartdust." Wikipedia. 6 Dec < 0>. 10. "Technology." Dust Networks. 6 Dec < 6