Trapping and manipulation of bubbles with holographic optical tweezers

A methodology to manipulate bubbles and measure adhesion forces is presented and validated. Holographic optical tweezers are employed to establish a circular array of high intensity points to effectively trap a gas bubble within a liquid medium. This approach includes an efficient calibration protocol based on a theoretical framework for the calculation of optical forces using a ray tracing algorithm, which allows enhancing the versatility of optical manipulation to micro-objects with a lower refractive index than the surrounding medium. As an initial application, the adhesion force between two stable bubbles at different sizes is measured, finding a minimum when they have the same diameter.