Studies of droplet manipulation in optical traps

We discuss the application of optical trapping techniques to droplets, both in air (aerosols) and in fluid (emulsions). We show the holographic optical manipulation of aerosols and how this can be used to transfer orbital angular momentum to airborne particles. We demonstrate new types of traps for aerosols in the form of dual beam fibre traps and compare the trapping efficiency of IR and visible lasers. We discuss some of the interesting dynamics that can be observed when trapping airborne particles and how this appears to differ from conventional liquid based devices. We also examine how holographic optical trapping can be used to facilitate droplet manipulation in another liquid phase. We conclude with a discussion of the difficulties associated with trapping particles in air and possible solutions and well as look at some of the anticipated applications of such work, in particular in digital microfluidics.