Lasers blow cells over microwalls

Scientists have used the unusual curving properties of laser beams to hurl microparticles and cells over walls.
Jörg Baumgartl at the University of St Andrews, UK, and colleagues used non-diffracting laser beams to transport particles between microwells. Baumgartl likens the laser beams to micrometre-sized snowblowers. The microparticles and cells are attracted to the bottom of the chip and then 'blown' upwards in an arc by the laser , he says.
Normal laser beams travel in a straight line and their light spreads out over distances. 'For instance, the beam emitted by a laser pointer would have the size of several hundred kilometres were it to reach the Moon,' explains Baumgartl. However, the non-diffracting laser beams he used travel in a curve without spreading out.

In most microfluidic studies, scientists move particles between chambers using a liquid flow. 'Our method opens an alternative route to transport, mix or sort microparticles and cells within the same microfluidic chip,' says Baumgartl.
'This is an important step forward in increasing the functionality of microfluidic environments by allowing particles to be transferred between different media,' says Ewan Wright, an expert in optical sciences and physics at the University of Arizona, Tucson, US. 'It is a wonderful example of how, over time, fundamental research, here on novel laser fields, can bring about highly innovative results in applied science.'
Baumgartl anticipates the method will lead to high-throughput, automated chips that will mix and sort microparticles and cells or mediate chemical reactions. It could be used to study cell processes and selectively expose cancer cells to drugs, he adds.