Ubiquitous Sensors and the Evernet

Stephen DeAngelis

April 6, 2007

Talk about big brother watching you — Michael Peck reports how “someday the paint on your wall may spy on you.” [“Sensors in Your Paint?” Defense News, 19 March 2007]. Peck’s article focuses on the possibility that nanotechnology could change how we monitor everything, including people. Tom Barnett calls this kind of 24/7 connectivity the “Evernet.” What some hold as the promise of the future, others see as the bane of the future. Peck writes:

Nanotechnology inhabits a netherworld of objects just larger than individual atoms. A nanometer is one-billionth of a meter — or 10 hydrogen atoms lined up in a row. The period at the end of this sentence is about 1 million nanometers in diameter. Nanotech focuses on objects that are smaller than 100 nanometers and larger than a single molecule. They are not just smaller versions of the macro world, like you would get if you chopped a sheet of metal into tiny fragments. Objects behave differently at the nano level.”

This different behavior at the nano level is what generates both the hope and fear of nanotechnology. On the beneficial side, nano sensors, because they operate on a molecular scale, can detect harmful agents before they reach lethal concentrations. Peck reports:

Nanomaterials can sense small quantities of materials, such as nerve agents. ‘They are more sensitive because, by making the sensing regions very small, a smaller number of analyte [the substance being analyzed] molecules is required to change the properties of the sensing region,’ said Stergios Papadakis, a nanotech researcher at the Applied Physics Laboratory at Johns Hopkins University. ‘It is really that simple.’ Papadakis and Johns Hopkins are working on sensors for agencies such as DTRA [Defense Threat Reduction Agency], the Office of Naval Research and the Defense Intelligence Agency. The overall goal is sensors the size of a wristwatch or shoe box and can be manufactured cheaply. Papadakis is working on sensors containing nanowires that will be tens of nanometers in diameter, and with an active sensing region that will be less than 10 nanometers long.”

Peck goes on to talk about the two different nanotechnology research tracks being pursued. The first track focuses on nanotechnology techniques that can change or create materials used in products (like sensors). The second, and more difficult, track focuses on creating nanomachines. This latter track is the one that incites the most excitement and concern.

The easier track, which will probably bear fruit in the next five or 10 years, is incorporating nanotech sensor cores into existing macro-sized sensors to produce equipment with better range and sensitivity. The harder track is to create complete nanomachines. ‘Imagine a PDA connected to thousands of nanosensor systems, and each sensor system is unique to each type of material we’re interested in,’ Wong said. ‘Can that be imagined? It certainly can. We can’t do that now because our systems are too big to put in such a small space.’ Wong foresees a nano-sized machine that could instantly read the DNA sequence of a biological agent, rather than having to send a sample to a lab for incubation. Or, ultradense but ultra-light armor made with nanomaterials. … A more exotic — and expensive — technology on the horizon is nanoelectromechanical systems (NEMS). Papadakis likens it to attaching a mass to a spring. ‘When a molecule sticks to that part of the device, it changes the mass of the vibrating element. Since the spring constant doesn’t change, the resonance frequency changes. It is this resonance frequency shift that signals detection of the molecule. Obviously, the vibrating part of the device has to be small enough that the molecules which land on it change the mass significantly.’ Or, put another way, the challenge is that ‘if it’s going to be small enough to be sensitive to a virus, it basically has to be the mass of a virus.’ Another type of NEMS uses chemicals. ‘Imagine a cantilever that is very thin and is coated on one side with a selective chemical,’ Papadakis said. ‘When an analyte coats that side of the cantilever, the cantilever bends due to a change in the surface energy on one of its surfaces. Obviously, the cantilever must be very thin for this to work.’ Nanotech will not replace macro-sized sensors. Wong and Papadakis are careful to say that nanotech isn’t better than macrotech, it’s just different. For example, Wong dismisses the notion of nanoexplosives as having too small a yield. For that matter, he says he is unaware of any research in nanoweapons.'”

What nanotechnology will eventually achieve remains unclear, but most futurists believe that it will play a significant role in a variety of human activities. It’s an area where science will race ahead of both policy and ethics generating gaps in the rule sets that must eventually be adopted to control how nanotechnology should be used and controlled. Some things are certain. A lot of money and jobs are at stake and nanotechnology will be an economic driver in the decades ahead.