Abstract: Technologies are generally described to detect hydration using a shielded ring resonator structure. In some examples, a shielded ring resonator structure configured to be attached to a subject for hydration detection may include a ring resonator, one or more feed structures that couple signals into and out of the ring resonator, and a conductive shield structure that covers gaps between the ring resonator and the feed structure(s). The shield structure may be disposed between the gaps and the subject to reduce capacitive coupling between the gaps and the subject, thereby reducing current flow between the subject and the ring resonator and/or feed structure(s).