The medical hypodermic syringe is a shotgun. It injects a gram or so of drug solution, which then diffuses wastefully through the whole body. Daedalus is now refining it. His ‘microdermic syringe’ has a needle a micrometre or so across, smaller than a typical cell diameter. It will nose its way between the cells of the body without hurting or doing damage. It will pass harmlessly through organs and blood-vessels, and even through the microporosity of bone. It will deliver a drug to its precise target, however deep.

The ideal microdermic needle would simply be a giant multi-layered carbon nanotube — far stronger and stiffer than steel. Carbon technology is advancing so fast that large nanotubes with thick enough walls should soon be available. For microdermic use, a nanotube should be treated with fluorine. This would coat its outer surface with slippery graphite fluoride, minimizing the friction of its insertion. Of course, such a long fine needle could not just be pushed into the skin; it would buckle. It must be driven from the skin surface itself, perhaps by tiny traction rollers. Daedalus even hopes that it could be drawn in by repeated ultrasonic pulses sent down it, and reflected at its tip as tensile pulls (a scheme he has proposed for driving nails). If that tip were angled, the pulses would tend to draw it in along a gentle curve. The needle could then be steered into the body by rotating it from the surface, so as to vary the direction of that curve. Much of the arcane know-how of the oil-drilling industry might be scaled down for the job. Some sort of imaging system would be needed to guide the needle to its destination. The ultrasonic pulses radiating from its tip could locate it in sonar-fashion.

An aqueous solution would take ages to flow down such a fine bore. So Daedalus will dissolve the drug in a supercritical solvent, with its low viscosity and high pressure. In supercritical carbon dioxide under 73 atmospheres of driving pressure, it will traverse the needle far faster. At the site of delivery, the few micrograms of carbon dioxide will dissolve harmlessly in the body's fluids. The drug will act exactly where it is wanted, and nowhere else; side-effects will vanish. The needle could be even be left in place. A tiny sub-dermal pressure-capsule could leak the drug continuously into the target till the trouble was fully cleared, by maybe a millionth of the usual dose. The drug companies would be furious.