Osmolality and osmolality sensors and methods utilizing electrochemical impedance to detect changes in impedance to varying salinity concentrations. By way of example, the impedance reported at the specified frequency varies logarithmically with the concentration of sodium chloride subject to the sensor surface. Measurements obtained by the sensors and methods herein are utilized, for example, to differentiate between the clinical stages of dry eye disease (290-316 mOsm/L) to complement the current diagnostic procedures. Blood serum, urinalysis, and saliva also may be tested and the corresponding osmolarity or osmolality level evaluated for indications of a disease or condition.