Methods for analyzing a fluid sample can include providing a sensor comprising a non-conductive housing and having a first face and an electrode array mounted in the first face. The method can include disposing the first face of the housing into a fluid sample to be analyzed, selecting a mode of operation, and initiating sensor operation. Modes of operation can include electrochemical operation and conductivity analysis, and can be selected via positioning a switch. The method can include receiving information from the sensor regarding at least one parameter of the fluid. Such parameters can include a concentration of a target constituent in the fluid sample, combined concentrations of different species within the fluid sample, and/or information indicative of the conductivity of the fluid sample.