Autonomous sensing and communication in a cubic millimeter
Supported by the DARPA/MTO MEMS program
This project finished in 2001, but many additional projects have grown out of it. Among these are
The two figures above represent where we are and where we’d like to be.
On the left is where we hope to be in July of ’01 – a cubic millimeter device with a sensor, power supply, analog circuitry, bidirectional optical communication, and a programmable microprocessor. Click on the figure to get more detail.
On the right is where we are now (July ’99) – a (currently) non-functional mote with a volume of about 100 cubic millimeters. There are two silicon chips sitting on a type-5 hearing aid battery. The right chip is a MEMS corner cube optical transmitter array – it works. On the right is a CMOS ASIC with an optical receiver, charge pump, and simple digital controller – it doesn’t work (we violated some of the design rules in the 0.25 micron process, but the next one should work).
- Laser communication from a cubic millimeter
- Mote Delivery
- Micro Air Vehicles
- Micro Rockets
- Silicon maple seeds and silicon dandelion seeds
- Sub-microWatt Electronics
- Power Sources
- Macro Motes (COTS Dust)
- Using commercial-off-the-shelf (COTS) components, we’ve built some really wonderful little “macro motes“. Some the features:
- temperature, humidity, barometric pressure, light intensity, tilt and vibration, and magnetic field sensors all in a cubic inch package, including the bi-directional radio, the microprocessor controller, and the battery!
- 20 meter communication range
- one week lifetime in continuous operation, 2 years with 1% duty cycling
- 21 km laser communication (Coit Tower and Twin Peaks in San Francisco to Cory Hall at UC Berkeley)
- Using one of the micro-weather stations, we stripped off the radio and wired in a laser pointer. This went to SF. In my office at Cal we had a video camera hooked up to a frame grabber in my laptop. The software looked for (and decoded) flashing lights in the image, and gave us the weather information 21 km away.
- Large angle MEMS beam-steering
- The laser motes above need to be aimed. We’ve made a sub-millimeter mirror coupled to two motors on the same silicon chip. The motors can scan a reflected laser beam tens of degrees in either direction.
- Micro Air Vehicle endurance record
- Sub-contractor Steve Morris of MLB Co has built an 8″ radio controlled plane which flys 60mph for 18 minutes and can carry a color video camera with a live video feed.
- Silicon maple seeds
- Using a honeycombed layer of silicon only 0.1 mm thick we have made a 3×10 mm winglet. With a cubic millimeter of silicon attached, these wings auto-rotate as they fall, just like a maple seed. The next generation will have solar cells built right in. (ok this generation had the solar cells too, but they didn’t work!)
The science/engineering goal of the Smart Dust project is to demonstrate that a complete sensor/communication system can be integrated into a cubic millimeter package. This involves both evolutionary and revolutionary advances in miniaturization, integration, and energy management. We aren’t targeting any particular sensor, in fact there is no direct funding for sensor research in the project (but we’ve got quite a few to choose from based on a decade or two of outstanding MEMS work at Berkeley and elsewhere).
We’re funded by DARPA, so we will demonstrate Smart Dust with one or more applications of military relevance. In addition, we’re pursuing several different applications with commercial importance, and we’ve got a long list of applications to work on if we only had the time. Here’s a sampling of some possible applications, in no particular order:
- Defense-related sensor networks
- battlefield surveillance, treaty monitoring, transportation monitoring, scud hunting, …
- Virtual keyboard
- Glue a dust mote on each of your fingernails. Accelerometers will sense the orientation and motion of each of your fingertips, and talk to the computer in your watch. QWERTY is the first step to proving the concept, but you can imagine much more useful and creative ways to interface to your computer if it knows where your fingers are: sculpt 3D shapes in virtual clay, play the piano, gesture in sign language and have to computer translate, …
- Combined with a MEMS augmented-reality heads-up display, your entire computer I/O would be invisible to the people around you. Couple that with wireless access and you need never be bored in a meeting again! Surf the web while the boss rambles on and on.
- Inventory Control
- The carton talks to the box, the box talks to the palette, the palette talks to the truck, and the truck talks to the warehouse, and the truck and the warehouse talk to the internet. Know where your products are and what shape they’re in any time, anywhere. Sort of like FedEx tracking on steroids for all products in your production stream from raw materials to delivered goods.
- Product quality monitoring
- temperature, humidity monitoring of meat, produce, dairy products
- Mom, don’t buy those Frosted Sugar Bombs, they sat in 80% humidity for two days, they won’t be crunchy!
- impact, vibration, temp monitoring of consumer electronics
- failure analysis and diagnostic information, e.g. monitoring vibration of bearings for frequency signatures indicating imminent failure (back up that hard drive now!)
- temperature, humidity monitoring of meat, produce, dairy products
- Smart office spaces
- The Center for the Built Environment has fabulous plans for the office of the future in which environmental conditions are tailored to the desires of every individual. Maybe soon we’ll all be wearing temperature, humidity, and environmental comfort sensors sewn into our clothes, continuously talking to our workspaces which will deliver conditions tailored to our needs. No more fighting with your office mates over the thermostat.
- Interfaces for the Disabled (courtesy of Bryndis Tobin)
- Bryndis sent me email with the following idea: put motes “on a quadriplegic’s face, to monitor blinking & facial twitches – and send them as commands to a wheelchair/computer/other device.” This could be generalized to a whole family of interfaces for the disabled. Thanks Bryndis!
- The dark side
- Yes, personal privacy is getting harder and harder to come by. Yes, you can hype Smart Dust as being great for big brother (thank you, New Scientist). Yawn. Every technology has a dark side – deal with it. [this was my original comment on “dark side” issues, but it made a lot of people think that we weren’t thinking about these issues at all. Not true.]
- As an engineer, or a scientist, or a hair stylist, everyone needs to evaluate what they do in terms of its positive and negative effect. If I thought that the negatives of working on this project were larger than or even comparable to the positives, I wouldn’t be working on it. As it turns out, I think that the potential benefits of this technology far far outweigh the risks to personal privacy.
A lot of people seem to be worried about environmental impact. Not to worry! Even in my wildest imagination I don’t think that we’ll ever produce enough Smart Dust to bother anyone. If Intel stopped producing Pentia and produced only Smart Dust, and you spread them evenly around the country, you’d get around one grain-of-sand sized mote per acre per year. If by ill chance you did inhale one, it would be just like inhaling a gnat. You’d cough it up post-haste. Unpleasant, but not very likely.
Consider the scale – if I make a million dust motes, they have a total volume of one liter. Throwing a liter worth of batteries into the environment is certainly not going to help it, but in the big picture it probably doesn’t make it very high on the list of bad things to do to the planet.