Spider webs are truly a marvel of nature. Their construction uses techniques and materials that our greatest engineering minds have never matched — until now.
Researchers from Germany have built a microfluidics system (a type of miniature plumbing set-up) for spinning short strands of artificial spider silk. They are still some way away from making a spider’s web though, because the strands are less than half a millimetre long and their strength and elasticity remains untested.
Other researchers have created longer strands that come close to the properties of spider silk, designed for weaving into lighter bullet-proof vests or artificial tendons and ligaments. But even short strands may have a place in medical procedures such as brain surgery.
The German researchers studied artificial dragline silk, which spiders use to hang from ceilings and to outline their webs. The researchers based their silk on that of Araneus diadematus, the European garden spider. Genuine dragline silk can hold over 280 million kg/m2 without breaking, making it stronger than steel in weight for weight terms.
It is difficult to farm spiders for their silk, because of their propensity for eating each other, so the team inserted a pair of dragline silk genes into bacteria to produce their raw material. They managed to eject the resultant fluid, in a spider-like manner, through a constriction measuring roughly 10µm wide at a speed of 600µL per hour (equivalent to a flow rate of less than 10 fl oz per minute through a garden hose).
There is still some way to go before matching some of the spider world’s best spinners, which can produce up to 2,000ft of silk continuously.
While still in the spider’s gland the secretion is a water soluble viscous fluid. But upon being drawn through spinnerets, its molecular arrangement changes and it becomes insoluble and 10 times more dense than in the fluid state.
