Abstract: A method for in situ monitoring of a membrane of a membrane separation system comprises measuring a complex impedance of the membrane at a plurality of frequencies to provide an indication of the electrical conduction and electrical polarization properties of the membrane. The membrane based separation system for removing or reducing the concentration of materials carried in a fluid including a separation membrane has a first pair of electrodes separated by the membrane and arranged for measurement of the complex impedance of the membrane at a plurality of frequencies to provide the indication of the membrane properties. There may also be a second pair of electrodes separated by the membrane for injecting the stimulus current such that the injecting and monitoring functions are separated.

Abstract: A measurement system is provided for measuring a complex transfer function of a system under test. The measurement system comprises a signal source for generating an input signal to be applied to the system under test, a signal detection device for detecting a response signal of the system under test in response to the input signal; and a signal analyzing system for determining the gain and phase shift of the system under test by comparing the response signal to the input signal. The signal analyzing system includes phase adjustment means to adjust a relative phase difference of the detected response signal and input signal; and curve fitting means to identify a phase difference adjustment of the phase adjustment means which gives the best fit of the response signal to the input signal. The phase measurement of the response signal is determined from the best fit phase difference adjustment.

Abstract: A measurement cell provides electrochemical characterization of a sample. The cell includes a container in which a sample is located, the container having walls and a base defining an interior region for containing a conductive media. A base electrode is located adjacent a base of the container, a counter electrode is spaced from the base electrode and a reference electrode is located between the base and counter electrodes. Samples that may be characterized include the conductive media, an element forming the base electrode or a surface of the base electrode, an element in contact with the conductive media, or any two or more of these. The reference electrode contacts the conductive media between the base electrode and the counter electrode such that electrical paths are is established through the sample between the base electrode and the counter electrode and between the base electrode and the reference electrode.