Modulated optical nanoprobes (MOONs) are microscopic (spherical and aspherical) particles designed to emit different fluxes of light in a manner that depends on particle orientation. When particle orientation is controlled remotely using magnetic fields (MagMOONs) it allows modulation of fluorescence intensity in any selected pattern including square and sinusoidal waves. The broad range of sizes over which MOONs can be prepared allows them to be tailored to applications from intracellular sensors using submicron MOONs to immunoassays using larger MOONs (1–10μm). In the absence of external fields, or material that responds to external fields, the particles tumble erratically due to Brownian thermal forces. These erratic changes in orientation cause the MOONs to blink. The temporal pattern of blinking contains information about the local rheological environment and any forces and torques acting on the MOONs.