Before you have arachnophobic nightmares, these microspiders are for helping the body heal.
(New Scientist)- A new spider-like micromachine could swim through a person's blood vessels, healing damaged areas and delivering drugs as it goes.
Ayusman Sen of Pennsylvania State University in University Park and his colleagues have created the self-propelling microspiders using spheres less than a micrometre wide. Each sphere is made up of two halves – one hemisphere is gold, the other silica – and looks like a gold-and-silver Christmas bauble.
To turn the spheres into motors, the group attached a Grubbs catalyst – a molecule that builds long chains of smaller molecules – to the silica side. When Sen drops his spheres into a solvent containing the chemical norbornene, the catalyst spins a polymer from molecules of the chemical. Eventually there are far more unpolymerised single molecules of norbornene around the gold side of the sphere than the silica side , creating an osmotic gradient, as fluids will always move from a region with lots of particles to a region with fewer particles. The solvent rushes toward the gold side of the sphere, causing the whole sphere to move.