The hand-held laser painlessly removes the upper layer of the skin to permit
liquid drugs such as insulin and the local anaesthetic lidocaine to enter the
body.

The surface layer of human skin, the stratum corneum, is up to 20 micrometres
thick and prevents most drugs from reaching the tissue beneath. “It’s the
primary barrier to topically applied drugs, impermeable to just about
everything,” says Stephen Flock, director of the Medical Sciences Research
Center at the University of Arkansas at Little Rock.

Developed by Flock together with Venisect of Little Rock and LaBarge of St
Louis, Missouri, the transdermal instrument is a hand-held, battery-operated,
erbium laser. It emits pulses of infrared light to remove the stratum corneum
from a spot 2 millimetres in diameter. “You don’t feel it,” says Flock. “You’re
not hitting any tissue with nerves.” Once the barrier layer has gone, liquid
drug will penetrate the skin.

Initial studies on human volunteers suggest that the system is an effective
way of delivering drugs and has no side effects. In studies with lidocaine, the
skin was completely anaesthetised within three minutes. And within six minutes,
the anaesthesia had reached a depth of 2.5 centimetres—deep enough to
permit minor surgery.

Needle-free anaesthesia would be a step forward for clinical medicine, says
Flock. “It would let us get past the problem of needle phobia, and also reduce
biohazardous waste,” he says. “If we can eliminate some needle usage, it will
decrease the odds of healthcare workers getting stuck with contaminated
needles.” The system is now undergoing clinical trials in the US.

The High Energy Transient Experiment (HETE) satellite, built for NASA by the Massachusetts Institute of Technology, was supposed to study gamma-ray bursts, mysterious explosions of energy that come from all parts of the sky at a rate of about one a day. The bursts were first detected in 1973.

HETE was launched by a Pegasus XL rocket. The craft’s companion was the Scientific Applications Satellite-B (SAC-B), the result of a collaboration between NASA and Argentina’s National Commission of Space Activities, which was designed to observe the Sun and other stars.

The problem came after the third stage of the Pegasus rocket, which is launched from beneath an aircraft, reached the planned orbit. The explosive device which should have released the satellites failed to ignite, sending the rocket and satellites tumbling in an orbit that is expected to decay within months, leaving the spacecraft to burn up in the atmosphere.

HETE was unable to deploy its solar arrays and lost battery power within hours. After deployment of the SAC-B solar array, scientists initially thought that four of the five SAC-B instruments would work, but the tumbling motion and shadowing by the rocket’s third stage prevented the array generating enough power to keep SAC-B’s batteries charged. Less than 24 hours after launch, both satellites were dead.

The loss of HETE is particularly disappointing as scientific review panels have ranked the project as second in importance only to the Hubble Space Telescope. HETE’s instruments were more sensitive than those on other gamma-ray satellites, and the spacecraft would have analysed X-rays and any ultraviolet radiation accompanying the bursts. It would also have been able to scrutinise the source of the bursts almost immediately after each event. This may have allowed astronomers to identify the objects responsible for the bursts.

The failure is also bad news for Orbital Sciences of Dulles, Virginia, which makes Pegasus. Three out of 14 Pegasus launches have failed. Nevertheless, both Orbital Sciences and NASA remain optimistic about the prospects for the rocket, which can launch satellites more cheaply than ground launchers. It can also be used anywhere in the world, allowing satellites to be launched into orbits that are inaccessible from the northern hemisphere.

“If you look back at the history of early expendable launch vehicles, the failure rate is not all that unusual,” says Donald Miller, a NASA official who is responsible for launch systems.

“It was a failure from the customer point of view in that we were not able to service the mission as planned,” says Orbital Sciences spokesman Barron Beneski, “but from our own internal perspective it reaffirmed that the Pegasus programme is very good at delivering the satellites into their proper orbit.”

NASA has suspended launches of payloads aboard Pegasus XL until the fault has been identified and corrected. Orbital Sciences and NASA have both set up investigations into the failure. One possible cause is a loss of power in the electronics responsible for firing the explosive release mechanism. “We’re fairly confident we can locate [the failure] to just a few elements of the vehicle,” says Miller.

Integrated circuits are usually manufactured by photolithography, in which the circuit pattern is printed onto the chip in a process similar to creating stencil designs. The “stencil” is a polymer resist that protects certain regions of the underlying layers from etching, coating or implanting operations. Resists are made by cutting away areas of the protective layer using ultraviolet light, which limits the smallest size of any feature to about 100 nanometres, or half the wavelength of the light.

To print smaller features, manufacturers could turn to X-rays, which have a shorter wavelength. Unfortunately, compact, high-energy X-ray sources are not yet available and polymer resists for use with X-rays are still being developed. So until now, the only alternative has been electron-beam lithography, in which a tightly focused electron beam “writes” the pattern onto the surface like a pen. But this approach is expensive and time-consuming and is not suitable for high-volume manufacturing.

Now researchers at Harvard University and the US National Institute of Standards and Technology have shown that a beam of atoms can be controlled by lasers to create tiny patterns on a resist. They have cut features as small as 40 nanometres and hope to reach the 10 nanometre mark.

Atoms are normally stable when their electrons are in the lowest energy state. In atoms known as neutral metastable atoms, however, electrons can get trapped in higher energy states, from which they cannot decay. When such an atom lands on a surface it deposits its spare energy. The researchers have developed a resist made of a material that is damaged by the energy from neutral metastable argon atoms. When the damaged segments are etched away, a pattern remains.

The resist is a layer of alkanethiolate only one molecule thick applied over a thin gold film. The argon atoms are energised into a metastable state by an electrical discharge and directed by an interference pattern produced by laser beams.

Beams of light interfere with each other in the same way as water waves, creating peaks and troughs of energy. When the light meets the argon atoms, it quenches their internal energy in the brightest regions. The light’s magnetic field also exerts a force on the atoms, pushing some into the minimum energy regions. The atoms then create a corresponding pattern in the resist.