Laser/electrical combination separates particles by size

The development could lead to a potential lab-on-a-chip system and the theory behind the technology, rapid electrokinetic patterning (REP), has been described in technical papers published between 2008 and 2011.

Now researchers in the US have used the method for the first time to collect bacteria and fungi, said Steven T Wereley, a Purdue University professor of mechanical engineering.

According to a statement, the technology could bring innovative sensors and analytical devices for lab-on-a-chip applications, or miniature instruments that perform measurements normally requiring large laboratory equipment. REP is a potential new tool for applications, including medical diagnostics; testing food, water and contaminated soil; isolating DNA for gene sequencing; crime-scene forensics; and pharmaceutical manufacturing.

‘The new results demonstrate that REP can be used to sort biological particles but also that the technique is a powerful tool for development of a high-performance on-chip bioassay system,’ Wereley said.

The technology works by using a highly focused infrared laser to heat fluid in a micro-channel containing particles or bacteria. An electric field is applied, combining with the laser’s heating action to circulate the fluid in a microfluidic vortex to isolate specific types of particles based on size.