Methods of exerting magnetic forces to separate magnetic particles disposed in a portion of subsurface vasculature using a wearable device are provided. The magnetic forces can act to attract, slow, speed, or otherwise influence the magnetic particles in various applications. In some examples, different magnetic forces are exerted on respective sets of magnetic particles to separate the respective sets of magnetic particles. In some examples, similar magnetic forces are exerted on sets of magnetic particles, and separation of the sets of magnetic particles is related to properties of the sets of magnetic particles and/or of the environment of the sets of magnetic particles. In some embodiments, the magnetic particles are configured to bind to an analyte of interest. The separation of the magnetic particles can enable detection of one or more properties of the analyte, modification of the analyte, and/or extraction of the analyte bound to the magnetic particles.
