A demonstration of acquiring specific concentration data by variations in the operating conditions of a non-specific sensor
A method for determining separate ion concentrations using a conductivity sensor was developed and tested. While a single electrical conductivity measurement in a solution does not give information on the present ion types, a range of measurements at various electrolyte temperatures does. Since the temperature dependency of the mobility of an ion is unique for that ion, it appeared to be possible to fit ion concentrations from a set of conductivity measurements while heating the electrolyte. For the calculation of the ion concentrations from conductivity vs, temperature sweep, an estimation algorithm is introduced based on the linear minimum mean square of the error. Errors in the measured conductivity will propagate through the algorithm into errors in the fitted ion concentrations. For the validation of the estimation method, this propagation of errors is also evaluated. The example given merely shows the feasibility of obtaining specific concentration information from an intrinsically non-specific type of measurement, electrolyte conductivity, by using the unique temperature dependence of ionic mobility. (C) 2000 Elsevier Science B.V. All rights reserved.
ion concentration electrical conductivity temperature parameter estimation