Instrumentation for Simultaneous Measurement of Double-Layer Capacitance and Solution Resistance at a Qcm Electrode
by Paul, D. W.; Clark, S. R.; Beeler, T. L.
Double-layer capacitance and solution resistance are two parameters that can be used to indicate dynamic changes occurring near the surface of an electrode. Here, we report the development of instrumentation that simultaneously monitors data from the quartz-crystal microbalance (QCM) sensor and the electrica] double-layer without the use of a potentiostat. The development of this instrumentation is reported along with some preliminary data. Early indications are that the capacitance responds to structural changes in the electrical double-layer. Changes in resistance reflect changes in the solution anywhere between the two electrodes. The frequency shifts of the QCM originate in structural changes that occur not only in the electrical double-layer but also farther out into the solution.