This section was edited by Associate Editor Jeffrey Winters.

INSTRUMENTATION AND CONTROL

PRECISION TO SPARE

Measuring the location of objects to within one atom is an everyday miracle. But research recently reported by the National Institute of Standards and Technology promises something really startling: a laser ranging system that can pinpoint an object with nanometer precision over distances of up to 60 miles. Such accuracy in ranging could lead to advances in nanoscale manufacturing, the scientists said, or assist astronomers looking for Earth-like planets orbiting distant stars.

The LIDAR system (the acronym stands for “light detection and ranging”) sends a light beam through the air and utilizes the reflected light to measure distance. Such systems have been in use for some time, but can suffer from an ambiguity in the distance measured, due to the use of light waves as the measuring tool. When determining a distance by comparing the differences in the phase of two light waves, a technique known as interferometry, large errors in distance can creep in even when the precision is accurate to within a  fraction of a wavelength of light.

To eliminate both large and small errors, the NIST LIDAR system measures distances in two ways. Two laser pulses at slightly different wavelengths are sent out. One pulse is partly reflected from a stationary point nearby; the time it takes for the rest of the pulse to reflect off the target and return to the sensor can be measured to provide a crude measurement of distance. The interference pattern made by the light waves of the two laser beams as they hit the target provides for a precision refinement of the distance.

The team, led by NIST physicist Nathan Newbury, suggests that such a system could find application in automated manufacturing, which relies on great precision. Also, LIDAR could be used to help determine the location of space telescopes flying formation; combining the light received from mirrors separated by a great distance could increase the resolution of an image enough to spot an extraterrestrial planet.

HANDHELD ULTRASOUND

MODERN MEDICINE IS DRIVEN BY IMAGING: ULTRASOUNDS, CAT SCANS, AND MRIS SEEM TO BE USED TO VERIFY EVERY DIAGNOSIS. In the U.S., that isn’t a too much of a problem, since those tools have become ubiquitous in American hospitals. But advanced imaging is less common in developing nations and virtually impossible in field conditions.

That situation could soon change thanks to a collaboration between a pair of engineers at Washington University in St. Louis. William D. Richard and David Zar have invented a system that mates an ultrasound probe with a smart phone to create a handheld medical imaging system that can be taken anywhere.

Ultrasound images can be read on a smart phone or sent to a radiologist in a remote location for diagnosis.

While magnetic resonance imaging still requires an enormous and expensive piece of equipment, advances in ultrasound over the past decade have translated into smaller machines. Indeed, most of the “brains” for the ultrasound system now reside in the probe—the wand-like gadget that both produces the sonic signal and receives the waves that bounce back from the body’s tissues.

Richard and Zar adapted an existing ultrasound probe that could be powered from a conventional USB port. The adapted probe can connect with a smart phone that runs a special version of the Windows operating system. Special software and firmware was then written to operate the ultrasound probe via the smart phone and enable the phone to view the images.

The work was funded in part by a $100,000 grant from Microsoft.

The system is in the process of undergoing field trials in developing nations, where medical imaging of this sort and the specialists trained to interpret such imaging are in short supply. Technicians could obtain the data in the field and then send the images via the phone link to doctors in a central facility, who would read the results and send back a diagnosis.

Smart-phone enabled ultrasound imaging could also find its way into ambulances and into the military. Medics could use ultrasound to find bits of shrapnel and remove them in the field, or evacuate the wounded soldier to a rear hospital if the shrapnel is deeply and dangerously embedded.

NICKEL NOSE

Nickel oxide is a substance that has gotten a lot of attention from materials scientists lately. They’ve been investigating its potential use in batteries and fuel cells, for example. But researchers at the Ohio State University in Columbus believe they have discovered another, potentially more critical use for the substance—as a means for detecting toxic chemicals in the air.

The key is creating ultrapure particles of the oxide. The Ohio State researchers, led by engineering professor Patricia Morris, have found a method for creating 5-nanometer nickel oxide particles by keeping raw ingredients heated to 225 °C for 12 to 24 hours and then rinsing the material in a solvent. When particles this size are deposited on the tip of a silicon microsensor, they attract large molecules floating in the air; the attracted chemicals change the oxide’s electrical conductance in a way that is easy to detect.

Different chemicals affect the change in conductance differently, so the distinctive signal should provide a reliable measurement of what’s in the air.

Not only are the nickel oxide nanoparticles made through this method relatively cheap—about $5 a gram—but they can be applied to the microsensor with a modified inkjet printer that deposits drops about a billionth of a milliliter in volume.

Such sensors could one day be common enough to be part of a fireman’s equipment or a soldier’s uniform.

EFFICIENT COLORS

Monitor screens have replaced old-fashioned dials and gauges in many sensor applications. The reasons for this are obvious: display screens are more flexible than older technologies and capable of conveying different kinds of information. And the computer software that processes data coming from sensors is often already optimized for sending information to a screen.

There is an unforeseen drawback to this monitor mania, however. Display screens draw quite a bit of power. The small screen on a typical cell phone, for instance, consumes as much as half the handset’s power.


Compared to the standard red-green-blue image on the left, the energy-efficient image
on the right can be made with 40 percent less power.

To cut down on that power draw, a team of researchers from Simon Fraser University in British Columbia and the University of Stuttgart in Germany have devised a set of colors for displays that save as much as 40 percent of the energy used by screens.

The problem is that the eye is not as sensitive to some colors as it is to others. To compensate for this, colors such as blue must be displayed more brightly than colors like yellow in order to read at the same level. That isn’t as much of a problem in technologies such as liquid crystal diode displays, which use backlighting to provide brightness, as it is in old cathode ray tubes and newfangled organic light emitting diode screens, in which each pixel generates light.

The key, the researchers found, is to find colors that are sufficiently different from one another at equal brightness. Combining standard data of human color perception with the energy it takes to create a red, blue, or green pixel, the team, led by Johnson Chuang at Simon Fraser, found colors that required the same amount of energy to produce while being easiest to distinguish from each other.

The results look somewhat muted to those used to the bright blues and reds of traditional computer graphics. The palette is heavy on subtle greens, oranges, and purples. But because each color is selected to be distinct from the other, the resulting images are still clear.

Of course, while such colors are good at providing efficiency and legibility, they are somewhat less successful at being startling. It’s unlikely, then, that we’ll start seeing “tomato-orange alerts” anytime soon.

DNA GOES DIGITAL

MOORE’S LAW, WHICH WAS REALLY JUST AN OBSERVATION BY INTEL CO-FOUNDER GORDON MOORE, STATES THAT NUMBER OF TRANSISTORS THAT CAN BE PLACED ON AN INTEGRATED CIRCUIT DOUBLES EVERY TWO YEARS OR SO. Thanks to advances in photolithography, which etches the pattern for the circuits with a focused beam of light, the computer industry has been able to match this progress for more than 40 years.

But with circuit size reaching the limit dictated by the wavelength of light, Moore’s Law may be repealed—a prospect that would affect not only the computer industry, but also makers of MEMS devices and sensors that make use of silicon wafer technology. In a bid to get around this light-based limit, researchers at IBM’s Almaden Research Center in San Jose and the California Institute of Technology in Pasadena have developed a method for using DNA to make nanoscale patterns on silicon wafers.

Folded strands of DNA litter an etched silicon wafter
(above). When special anchor points were put on the
wafer, the DNA lined up on those points.

Strands of DNA can be folded into fairly complex shapes through a method known as DNA origami. In that technique, a single strand of DNA is folded into a precise shape through use of short bits of DNA known as “staple strands.” Folded in this way, the DNA strands can be transformed into nanoscale squares, triangles, and stars. Though the resulting shapes can have very small features—as small as 6 nm—the DNA has to be in a water-based solution, which renders exact placement on a silicon chip close to impossible.

The researchers have found a way to more precisely place the DNA origami by etching anchor points onto a wafer though use of electron beam technology. These anchor points attract the DNA shapes and bind them to the wafer.

The hope is that in time, the DNA origami can be used to create a scaffold to help guide the assembly of circuits made from carbon nanotubes, nanoscale wires, or other material. Circuits made from such stuff would be able to have features much smaller than the 45 nm limit of current techniques. And that might keep Moore’s Law in force for another couple of years.

LOOKING FOR CATARACTS

The old saying that one shouldn’t go looking for bad news doesn’t apply to cataracts. Once the lens of an eye begins to take on the disease’s characteristic cloudiness, it’s too late to treat through medicines or lifestyle changes. Doctors and researchers at the National Eye Institute and NASA’s Glenn Research Center in Cleveland have developed a new method that uses a fiber-optic probe to non-invasively detect cataracts in their earliest stages.

The technique, called dynamic light scattering, was first developed to analyze protein crystals in a weightless environment such as the International Space Station. The fiber-optic probe shines low-power laser light into the lens of the eye; the scattering of light due to abnormalities in the lens is recorded for later analysis.

Researchers were most interested in measuring the levels of a protein called alpha-crystallin, which binds to damaged proteins and keeps them from clumping together. It’s this clumping of damaged proteins that forms cataracts.

The light collected from the eye lens was compared to the signature of light scattering off alpha-crystallin proteins. In data collected from the eyes of 380 volunteers, researchers found that as the measured levels of the protein decreased, lenses became increasingly cloudier. The researchers believe they can use this technique to track the virtually unnoticeable early stages of cataracts that are undetectable using currently available technology.

While people with early stages of cataracts can try to slow its onset through such measures as stopping smoking and limiting exposure to the sun, NASA is quite interested in finding ways to prevent cataracts. The space agency is concerned that, should it send astronauts on interplanetary missions, the elevated levels of radiation the astronauts would be exposed to could cause cataracts in addition to other health problems. Learning how to mitigate or prevent damage to the eyes could be a critical element in a mission’s success.

DASHBOARD PROPELLER

Heads-up displays are great for providing data to drivers or pilots who can’t afford to take their eyes off what they’re doing. Unfortunately, such displays require a specially designed windshield to project the image against. But now a small company in Indiana has developed a heads-up display for small planes that gets around the windshield problem by projecting its images on an unlikely spot: the propeller.

VirtualHUD, headquartered in Lawrenceburg, launched production of the device of the same name in July. The portable device plugs into a cigarette lighter and provides information such as attitude, heading, and speed. That data is fed to a projector and beamed through the windshield onto the propeller. The image reflects off the spinning propeller, enabling the pilot to see the display when he is looking straight ahead.

Of course, such a set-up works only on single-engine, front-propeller planes where the pilot sits along the center axis; pilots of twin-engine planes and jets are out of luck.