This section was edited by Associate Editor Alan S. Brown.
Calling Doctor Roboto
Robot developer Adept Technology Inc., of Livermore, Calif., will collaborate with the United Kingdom's Prosurgics Ltd. to develop robots to perform image-guided and navigated neurological and soft tissue surgery. This unusual combination marries Adept's knowledge of industrial robots and vision systems with Prosurgics' experience in surgical operating rooms.
Hospitals are increasingly interested in using robotic systems to perform minimally invasive procedures. Surgeons currently do this by inserting an endoscope—a snakelike device that contains a light, lens, and surgical instruments—through a small incision in the body. The surgeon then uses the images from the endoscope to view and manipulate tissue and organs.
Surgical robots enable surgeons to work with larger-than-life, three-dimensional images of body parts. As the surgeons manipulate their tools on the screen, the robot smooths their motions and scales them down to the size of the actual body on the operating table.
 High tech, small incision: A da Vinci surgical system performs an operation in St. Pierre, Ore. Adept Technology has entered a partnership with a British company to put another robotic surgical system into the field.
Engineers introduced robots to the operating room in the late 1990s, but they got off to a bumpy start, said Adept chief technology officer David Pap Rocki. "They introduced a lot of technology at once and failed to take into account operating room workflow, sterilization, and even how much space was available," he explained. Yet 3-D surgical navigation systems continued to improve, and eventually the robots began to catch up.
Prosurgics hopes to take advantage of Adept's experience with industrial robots. "Packaging and medical robots have different constraints and goals," explained Pap Rocki. "In packaging, you want high speed and repeatability. In surgical, you need controlled motion and accuracy. But the underlying science and engineering is very similar."
Pap Rocki said that Adept will focus on robotic vision systems, controlled motion, mechanical design, and servo control to build a next-generation surgical robot.
The new system, for example, will use filters to remove microtremors in surgeons' hands, so robotic motions are smooth yet precise. Adept will also adapt its vision technology for surgery. The system currently registers parts moving on a conveyor belt against a template so a robot can determine their quality and orientation before manipulating them.
"With a surgical robot, we want to register the pre-operative image with the patient and the surgeon's instruments—all in an area you can't see—and maintain that registration if the patient moves."
The deal positions Adept in a fast-growing market. Another pioneer in the field, Intuitive Surgical Inc., has sold 700 of its million-dollar da Vinci surgical systems since 1999. Adept believes that robots now perform more than half of all prostate removals in the United States, and points to a study by BCC Research that estimates a market for $2.5 billion surgical robots by 2011.
Hot Bolt Powers Sensors
A German company, Micropelt GmbH, has developed a prototype bolt that screws into a hot machine and harvests the waste heat as electricity. Based on thermoelectric thin films, the TE-Power-Bolt generates 0.2 to 15 milliwatts of power and uses an integrated dc-dc converter to set voltage between 1.2 and 5 volts.
So what can you do with such a small trickle of power? Micropelt's vice president, Burkhard Habbe, points to wireless sensor nodes. By connecting tiny autonomous sensors wirelessly, manufacturers create distributed networks to track material flow and monitor machinery. The network gives managers a precise picture of production status. A single plant could use dozens, hundreds, or even thousands of sensor nodes.
Today, batteries power those devices. Habbe points to a survey by San Diego-based market research firm ON World Inc. that sees global deployment of 128 million wireless sensor nodes within two years. The same survey found that 75 percent of industry experts named batteries as a critical issue because they require constant monitoring and replacement.
 Thermoelectric generator: This bolt contains a thermoelectric generator that can produce enough power to run a wireless sensor node without a battery, powering a multinode factory network.
Micropelt's solution is to replace batteries with TE-Power-Bolts. The bolts are self-sustaining power supplies that never need replacement. Their low power output is ideal for sensors that take and report intermittent measurements (as opposed to critical sensors that must operate all the time).
The sensors themselves consist of two different types of semiconductors that produce a current when there is a temperature gradient between them. The semiconductors and power conditioning devices sit on the head of an M24 steel screw.
The screw transmits heat from a hot machine or a pipe carrying fluids to the semiconductors. One of the semiconductors is connected to a 1.5- inch-diameter aluminum heat sink above the bolt head that draws away heat. As long as the hot surface is 10 to 20°C warmer than ambient temperature, the TE-Power-Bolt will generate power.
"We are supporting two basic scenarios," Habbe said. "One is an external energy supply, as represented by TE-Power-Bolt, where a short wire connects to the sensor node, which may not sit on a warm surface but has one nearby. The second is an integrated thermal energy source, functioning like a built-in battery, which would never run out. It is good for sensors sitting on warm or hot surfaces of any type."
The TE-Power-Bolt was designed to show how an energy harvester based on the company's thin film thermoelectric technology might look. Micropelt would like to license the technology, and Habbe says some companies are already evaluating the prototype.
Diamonds Are a Pump's Best Friend
Diamonds are not just beautiful, but also rank with the best engineering materials. They are the hardest of all natural substances, more slippery than Teflon, and conduct heat better than copper. Diamond would make an outstanding wear surface, and someone has finally figured out how to do it.
Advanced Diamond Technologies Inc. of Romeoville, Ill., has launched a new family of ultrananocrystalline diamond seals that promise to extend pump lifetimes significantly. The company's accelerated wear tests on pumps with extremely poor lubrication caused conventional silicon carbide seals to fail and leak. Under the same conditions, the diamond seals showed only negligible wear.
 Diamond ring: Diamond seals promise to prolong pump life and reduce operation costs through reductions in friction at costs that are competitive with silicon carbide.
The reason is friction. High-performance pumps are designed with a hydrodynamic fluid layer that runs between the two seal faces. "If there were no fluid, the seal faces would heat up and fly apart," company president Neil Kane explained.
"The fluid lubricates the faces and also removes heat. Seals also wear out due to normal abrasion, and even faster if the fluid contains particulates. These forces cause grooving, and eventually the seal fails," Kane said.
In poorly lubricated pumps, diamond survives because it removes heat far more effectively, produces 75 percent less friction, and is significantly harder than silicon carbide. Kane said that pumps could cut energy use by 20 percent by optimizing their design to use low-friction diamond seal faces. He also believes that diamond faces will enable pumps to last longer between maintenance intervals.
Compared with the cost of a pump, diamond-coated surfaces are cost-effective enough to compete with conventional silicon carbide, Kane claims. This is a big breakthrough for synthetic diamond films, which have been around since the 1980s.
The first diamond films were made by chemical vapor deposition, a technique that breaks down hydrocarbons in a vacuum chamber at extremely high temperatures. The films had grain sizes measured in micrometers. This produced a surface that was relatively rough, which is why the largest use of diamond films is currently abrasive cutting tools. Applications like seals were unthinkable because it was so expensive to polish diamond.
Then Argonne National Laboratory developed a process to make grains in the 3- to 5-nanometer range. While this is not as smooth as glass, it is easily smooth enough for pump faces. Advanced Diamond Technologies licensed the technology and spent two years making it reliable and economical. "Argonne used to make one seal at a time," said Kane. "We make dozens, and that's how we achieve the economics."
Sleep on a Nanotube Sheet
A three-year-old New Hampshire start-up, Nanocomp Technologies Inc., has produced the largest cohesive nanotube structures ever, a series of 3-foot-by-6-foot sheets made entirely of carbon nanotubes. Not only is the structure big, but the way Nanocomp made it opens the door to new types of nanotube composites and fibers as well as nanotube wiring, aircraft lightning protection, and high-performance heat sinks.
Nanocomp's breakthrough lies in its ability to make nanotubes about 1 millimeter long. This may not sound like a lot, but given the small size of most nanotubes (a few nanometers in diameter, perhaps 100 to 200 micrometers long), it is equivalent to building a 10-foot-diameter tube nearly 180 miles high. Production takes place in a tube furnace. Nanocomp injects a hydrocarbon gas and iron catalyst on one end and pulls off nanotubes on the other.
 A new nanoscale: This 3-foot-by-6-foot sheet is the largest coherent nanotube structure ever created. The technology could be used for lightweight electrical wires in aircraft and satellites.
To make large sheets, it simply captures the exiting nanotubes on a rotating belt. The mutual attraction of the nanotubes, long a problem when it came to dispersing them evenly in other materials, proves an advantage here. The randomly arranged nanotubes stick together so strongly, they exhibit tensile strengths of 200 to 500 megapascals.
"Aluminum breaks at 500 megapascals," said company CEO Peter Antoinette. "We can also relax and partially align the tubes, which raises the breaking strengths for these sheets to 1.2 gigapascals, which is around that of carbon steel. What is most significant is that our sheets have densities of 0.2 to 0.5 grams per cubic centimeter. Aluminum is 2.8 grams per cubic centimeter and steel 7.8 grams per cubic centimeter. The strength-to-weight ratio for our sheets is a key benefit."
Of course, nanotubes are not ready to take on traditional metals in most applications. But Antoinette says if he can scale the process, he should be able to get costs down to about $400 per kilogram or less. That sounds like a lot, but on a volume basis it is well within the range of high-end carbon fibers.
Antoinette has his markets picked out as well. "When you say 'aircraft' and 'nanotubes,' most people think fuselages or wings. I say, 'Think about lightning strike protection, wiring, or ground planes for electrical equipment.'"
His argument is simple. When he aligns nanotube sheets, he turns them into outstanding conductors of electricity and heat along their length. The millimeter-long nanotubes are also large enough to wrap around each other to form conductive yarns.
"The aerospace industry is very interested in these applications, as our products are so much lighter-weight than the copper-based wiring harnesses used today," he explained. "The wires actually weigh less than the insulation around them."
Copper, he notes, accounts for about one-third the weight of most satellites. A large satellite that weighs 10,000 pounds would contain more than 3,000 pounds of copper wiring. He claims that nanotube wiring could save more than 1 ton of weight. "It costs between $10,000 and $30,000 per pound to launch to orbit, thus the interest," said Antoinette.
The same reductions in weight might interest airframe builders. For example, the new Airbus A380 jumbo jet uses 350 miles of copper wiring. Slashing cabling weight would lower fuel costs, especially when multiplied over the 30-year service life of the aircraft. Airframers might also consider conductive nanotube sheets to protect composites from lightning strikes and for lightweight ground planes for electrical devices.
Antoinette also sees applications for heat sinks in cell phones and other mobile devices. "It outperforms any metal," he said. Oriented sheets would also transfer heat in the direction engineers want it go. Nanocomp is getting ready to announce nanotube yarns for reinforcement, ballistics, and other applications. Meanwhile, Antoinette will focus on getting production rates up and cost down.
Stainless Tools Take on Corrosion
Anyone who works with stainless-steel screws eventually finds out that, yes, they do rust. Corrosion may occur after a single season on boats that sail the salty seas, or after several years on window and door frames.
The reason, according to Wera Tools of Wuppertal, Germany, is that assemblers almost always use carbon steel or other non-stainless-steel tools to tighten stainless hardware. Simply turning a screw or a hex nut generates enough force to break off microscopic particles of tool steel. These particles will corrode. Left in a damp-enough environment, corrosion will eventually attack the stainless fastener. At best, the screw will bleed rust; at worst, it could start to pit and deteriorate.
 Contamination from carbon steel tools can cause corrosion on stainless-steel fasteners such as these.
The solution sounds like it should be obvious: Switch to stainless-steel tools, which generate stainless particles that resist corrosion. The problem is that stainless, by itself, is too soft for high-volume factory work. Past attempts to harden stainless steel make tools too brittle for regular use. This is why stainless screwdrivers are usually reserved for medical and small-scale hardware.
Wera spent two years attacking the problem. Its solution includes a final cryogenic tempering step that supercools its stainless-steel tools in a vacuum chamber. The resulting material achieves a Rockwell hardness of 58, hard enough to compete with carbon steel. The company scores its screwdriver tip with a laser to improve its grip and uses oversize contact zones to reduce notching on its hex drivers.
One caveat, though: Stainless-steel tools are only for stainless-steel fasteners. Tighten a carbon steel tool with them, and it will require autoclaving to remove the contamination. | 
