Autonomous robots, micro-scale air vehicles, and prosthetic limbs are all supposed to operate for long periods without recharging or refuelling, making efficient energy supply crucial.
Nature's choice is to provide chemical power for natural actuators like muscles. Human engineers have typically taken another route, relying on converting electrical energy into mechanical energy using motors, hydraulic systems, or piezoelectric actuators.
This is much less efficient, meaning even the most athletically capable robot must be wired to a stationary power source for much of the time.
The ideal solution is an artificial muscle that can convert chemical energy directly and efficiently into mechanical energy, says Ray Baughman a physicist at the NanoTech Institute at the University of Texas in Dallas, US.
Baughman says he has built such a device made of a "shape memory" alloy of nickel and titanium. The metal is coated with a platinum catalyst and placed in a device that allows methanol to be drawn along the surface.
Exposing the surface to air causes the methanol to be oxidised, which heats the alloy and makes it bend in a pre-determined way. Cutting off the methanol supply lets the alloy cool and causes the alloy to its original shape.
Baughman says the device can generate stresses 500 times greater than human muscle and believes further significant improvements should be possible.
"The integration of electronic components into clothing is becoming an increasingly important area in the field known as wearable computing," says the electronics giant Philips in one of its latest patent filings.
The textile industry can today produce threads that are highly conductive and as flexible as regular fabric so that sensors in garments can measure biometric characteristics, like the wearer's temperature or heart rate. Such garments could have important applications in medicine and sports.
The trouble is that weaving sensors into these textiles is tricky. Threads not only need to be highly durable to survive the weaving process but, because fabrics are woven on a large scale and then cut to size, it is hard to ensure they will end up where they are needed in the garment. This fabrication method also limits the choice of sensors that can be used.
So Philips is pioneering another approach. This involves making a fabric that acts like a flexible circuit board to which any variety of sensors can then be attached. The company suggests weaving a fabric out of both conducting and non-conducting fibres, and then cutting the garment to size.
Sensors can be pinned to the garment where they are needed, with the conducting wire providing power but also communications between different sensors. The resulting fabric can easily be tailored to any size and can carry a variety of sensors for monitoring the wearer's body.
The long sightedness that afflicts people in their 40s and 50s is known as presbyopia, and is caused by a gradual stiffening of the lens in the eye. This is the result of the continual generation of new cells on top of older ones on the lens, a process that makes it stiffer and thicker.
In practice, this inflexibility prevents people focusing on near objects and means they must rely on reading glasses instead.
Now Szymon Suckewer, a mechanical engineer and laser specialist at Princeton University, New Jersey, US, says it may be possible to remove excess cells in the lens by using short laser pulses to vapourise them.
The process is entirely different from current laser treatments for vision, which change the shape of the cornea. Instead, it should make the lens fully flexible again, giving sufferers back their near vision.
However, Suckewer makes no mention in his a patent application of any tests involving animal or human subjects. So best wait and see how well the idea works before throwing those reading glasses away.
