Special issue on optical micromanipulation

Abstract

Few would have predicted the impact the laser has had across all of the natural sciences. Laser technology in tandem with microscopy has fuelled a revolutionary advance in biology and chemistry. Microscopic methods permit imaging of cells, nanoparticles, atoms and single molecules. Without doubt, biophotonics has emerged in many guises as a major player on the international arena, and has spawned an industry with an explosive growth rate. Notably, the influence of light is not restricted to passive imaging—it may also move, trap and manoeuvre objects from single atoms right through to the size of a large cell with no damage whatsoever. Given the well-known uses of high power lasers in surgery and industrial cutting, this sounds like science fiction, but at the size scale of these objects it is science fact: it is the area of optical micromanipulation that is the subject of this special issue. The field of optical micromanipulation has continued to impact right across the sciences in an unprecedented fashion, since its inception in the late 1960s. Excitingly the field has made an exceptional impact in single molecule biophysics and the physics of non-equilibrium systems largely due to the fact that an optical trap is an elegant and powerful force transducer. The field is also branching out into new directions: cell biology is benefiting from this advance. Trapping and microfluidics is an exciting combination within the broader remit of the field of optofluidics: methods of multiple traps using diffractive optics are permitting cell sorting, traps are aiding local viscosity measurements and novel biological studies are being performed. Combining traps with other spectroscopic methods and imaging modes is an interesting theme that poses interesting challenges but promises exciting new knowledge. All these areas are represented in this special issue, along with a number of contributions to quantitative modelling of optical fields suitable for trapping and of the motion of particles in these traps. The increasing sophistication and accuracy of these models allows for the optimization of the trapping process and shows how more and different information can be obtained. Light certainly has taken hold!