Cavity optomechanical transduction sensing of single molecules

We report narrow linewidth optomechanical oscillation of a silica microsphere immersed in a buffer solution. Through a novel optomechanical transduction sensing approach, single 10-nm-radius silica beads and Bovine serum albumin (BSA) protein molecules with a molecular weight of 66 kDalton were detected. This approach predicts the detection of 3.9 kDalton single molecules at a signal-to-noise ration above unity.