A Microfluidic Approach to Producing Gravitational Masses for an Optically Levitated Force Sensor

Recent experiments have used optically levitated microspheres in high vacuum to study fundamental forces with novel precision. We describe our search for non-Newtonian gravity at the micron scale using such a force sensor. In particular, we report on our development of a microfluidics-based method for producing a controlled gravitational field. This method yields a monodisperse, mesoscopic emulsion of low-density oil droplets in a higher-density aqueous phase. We report both on our control of this system, as well as our precision limits in optically measuring it in vacuum.