Active Control Experts (ACX) is a company in Cambridge, Massachusetts, which specialises in piezoelectric materials and their use in various “smart” structures. ACX teamed up with K2, America’s largest manufacturer of alpine skis, to develop the smart skis.

The skis are designed to absorb vibrations where they tend to originate, which is around a point just in front of the bindings that anchor the skier’s feet. Curbing the vibrations at that point should minimise them along the entire length of the ski.

Piezoelectric materials can turn mechanical energy into electrical energy and vice versa. ACX has embedded a small card made of a piezoelectric, lead-based ceramic in the skis at the crucial point. The ceramic card also contains an electronic control circuit that acts as the smart ski’s “brain”.

During skiing, vibrations in the piezoelectric ceramic generate electrical signals in the card. These are interpreted by the control circuit, which in turn sends pulses of electrical energy into the piezoelectric material to change its stiffness and damp the vibrations. This prevents the skis from changing shape and gives the skier a smoother ride.

ACX says its smart structures technology could be used to damp vibrations on aircraft wings. The company is researching a system for damping the wings of F-18 supersonic fighter planes. It also sees potential applications for curbing vibrations in cars and machine tools.

The skis appeared on the US market in December. They are available in three sizes, and are selling for around $625.

ThermoTrex Corporation of San Diego, California, calls its new system Lasercom. Traditional systems transmit information by bouncing radio waves off satellites and down again to receiving stations. Lasercom will rely on a satellite-to-satellite approach, passing laser signals around the planet bet ween orbiting relay modules known as transceivers. The signals will only come down to Earth at their destination.

The transceivers are about the size of a desktop computer and could be carried “piggy back” on multipurpose satellites at a fraction of the cost of launching purpose-built communications satellites. ThermoTrex estimates that each transceiver will cost between $50 000 and $100 000. Relaying information in space also minimises the number of ground-based receivers that would be needed.

The idea of passing information between satellites is not unique. For example, Motorola plans to have its Iridium constellation of satellites – which will carry mobile phone conversations – in place by 2000. But the Iridium satellites will communicate using microwaves, which cannot carry as much data as lasers.

As well as carrying more information than radio or microwaves, infrared lasers should be more secure. The signal travels in a tightly focused beam, rather than scattering like radio signals, so laser transmissions are more difficult for unauthorised receivers to intercept. “We have improved the engineering on the transceivers to the point where we now feel all the technical hurdles have been passed,” says Scott Bloom, the Lasercom project manager.

In order to pass information reliably between satellites, the on-board transceivers must be able to track each other. Lasercom aims to achieve this with the help of beacons. The transmitting satellite will look for the beacon of the satellite next in line. To cut down interference from ambient light, principally sunlight, ThermoTrex has developed an optical filter that only admits light at the precise wavelength of the beacons. According to Bloom, this will allow the transmitting satellite to track the receiving satellite in broad daylight.

While the lasers should transmit clearly in space, their beams may not be able to penetrate thick cloud cover as the signal passes to and from the Earth at each end of its journey. One option is to rely on radio links between the satellites and the ground. Although they would be slower than laser links, Bloom says that the system can be configured to prevent the radio links from becoming information “bottlenecks”.

Each satellite will have as a many as four laser transceivers, enabling it to communicate with several others simultaneously. If a satellite or a transceiver is disabled, the network could be rapidly reconfigured to keep the information flowing.

Earlier this year, ThermoTrex conducted an Earth-based test of Lasercom when it broadcast several video teleconferences simultaneously by laser between the Naval Research and Development Laboratory on Point Loma in the San Diego bay and the San Diego Convention Center 10 kilometres away. ThermoTrex is now negotiating with Teledesic, a company founded by Bill Gates of Microsoft, about launching the transceivers aboard Teledesic’s satellites.

Virginia Brooks, a satellite technology analyst at the Aberdeen Group in Boston, is optimistic about the prospects for laser technology in space. “It could be a cost-effective alternative to fibre optics, given that it is expensive to lay wires,” she says. “And since infrared is harder to penetrate than radio waves, it does offer clear security advantages. What remains now is to see if the technology can compete with other technologies, such as ISDN.”

The next planned test for Lasercom will be in 1997 when transceivers will be launched aboard US military satellites.

One of the costliest and most common operations performed in the US
is angioplasty – the unblocking of arteries, especially the coronary arteries,
by inserting a catheter that can be blown up like a balloon. The problem
with the technique is that between 30 and 50 per cent of patients suffer
from restenosis, in which the arteries begin to block up again. This then
requires either an additional angioplasty or bypass surgery. But the new
hydrogel is able to keep the arteries open while they heal. And with almost
500 000 angioplasties, each costing about $10 000, performed each year in
the US, eliminating just one-third would cut more than $1 billion from
the health care bill.

A team from the University of Texas at Austin has developed the hydrogel,
which consists of 90 per cent water, with polyethylene glycol, lactic acid
and acrylate. After a standard angioplasty it is delivered to the treated
area by a catheter or needle. Light piped through optical fibres is used
to solidify the gel, leaving a slippery surface on the artery walls which
prevents platelets, white blood cells and other blood constituents from
sticking to it.

The polymer provides structural support for the treated arteries, keeping
them open until they heal. It is then hydrolysed naturally and absorbed
by the body after seven to 10 days. Trials in animals have found that it
leaves less scarring than other surgical methods used to keep the arteries
open.

The polymer is also expected to be useful after obstetric and gynaecological
surgery, spinal surgery and appendicectomies. After an appendicectomy it
would provide support to keep the intestine open, preventing intestinal
walls sticking together, which can be dangerous.

One problem that the scientists are addressing is that as the material
begins to break down it could create side effects such as inflammation,
thrombosis or hypersensitivity.

Use of the hydrogel has been licensed to Focal, a company based in Cambridge,
Massachusetts, which specialises in biodegradable polymers and ‘minimal
invasion’ products.

Jeffrey Hubell, one of Focal’s founders, who as a professor at the university
helped to invent the gel, has noted from trials that preventing restenosis
has been ‘one of the toughest challenges’ in developing the product.

Clinical trials are expected to begin later this year in the US and
Europe.