A protected resonating sensor may include at least one resonating sensor unit, each sensor unit has one or more vibratable members. The protected sensor includes at least one body of gel for protecting the vibratable member(s) of the sensor. The gel may be disposed on or attached to the sensor unit(s) covering the vibratable member(s) of the sensor unit(s). The gel may also be disposed in an open housing including one or more sensor units, and may cover vibratable members of different sensor units. The sensor unit may be any resonating sensor unit having a resonance frequency that depends on the value of a physical variable in a measurement environment. The protected sensor may also be attached to or included in or formed as part of any suitable device or sensor anchoring device and may also be implanted or inserted into a body or an organism. Methods are described for constructing the gel-protected sensor. The gel may have modified surface properties and may contain one or more drugs or therapeutic agents or other releasable substances. The gel may be formulated to retard or reduce diffusion of substances from the measurement environment into the gel and their deposition on the vibratable member(s).