Laser tweezers are finding application in many research disciplines, but they restrict the user to manipulating single objects. Now a team at St. Andrews University in the UK has demonstrated that tweezers employing lasers with a Bessel beam profile can trap several particles along the beam's axis in separate sample cells.

In the Sept. 12 issue of Nature, the scientists describe how adding an axicon to the setup enables the central maximum of the beam to re-form beyond an obstruction. Using both inverted and standard tweezers configurations, they trapped and manipulated microparticles in up to three sample cells millimeters apart.