Crystals reveal the answer: Detecting drugs with a quartz crystal microbalance Balancing in the heat A novel type of high temperature quartz crystal disc could make the perfect detector for small, portable gas chromatography (GC) systems, say US researchers. Such quartz crystal discs form the centrepiece of quartz crystal microbalances (QCMs), which are widely used Read more about Detecting Drugs with QCM[…]
Article now available at Springer by A. Robert Hillman Abstract In its simplest manifestation, the electrochemical quartz crystal microbalance (EQCM) is a relatively new device for executing a classical technique, electrogravimetry. The advantages it brought were in situ applicability (notwithstanding prior misconceptions regarding damping by a contacting fluid), exceptional sensitivity and dynamic capability, thereby Read more about The EQCM: electrogravimetry with a light touch[…]
Gamry Instruments is pleased to announce the publication of a manuscript highlighting the capabilities of the Gamry eQCM 10M. The project entitled “Application of the combined electrochemical quartz crystal microbalance and probe beam deflection technique in deep eutectic solvents” uses the EQCM/PBD method for the first time applying to metal deposition/dissolution processes in deep eutectic Read more about Combined EQCM and Probe Beam Deflection in Deep Eutectic Solvents[…]
This Application Note is intended to provide the reader with a general framework for characterization of an electroactive polymer film. Electropolymerization is a convenient way to control film growth either through repeated cycling, potential steps, or current steps. Examination of the film redox behavior in monomer-free, fresh electrolyte provides insight on doping and dedoping of these polymer films.
Polybithiophene films were assembled by cycling an Au-coated 10 MHz quartz crystal between 0 and 1.5 V in the presence of 1 mM bithiophene solution containing 100 mM tetrabutylammonium perchlorate (TBAP) in acetonitrile (MeCN). Potentials are reported against a Ag/Ag+ pseudo-reference electrode. The Teflon® cell was outfitted with a Teflon o-ring to prevent swelling from the acetonitrile and placed inside a VistaShield™. The cell was connected to an eQCM 10M™ which was coupled to a Reference 600™. Both instruments were connected to a computer running Resonator™ version 5.67. Bithiophene, electropolymerizes via a two-electron oxidation at potentials greater than ~1.25 V versus a Ag/Ag+ pseudo reference electrode.
Figure 1 shows two cycles of film growth. Cycle 1 (blue curve) shows only background (non-Faradaic) current until the potential is greater than 1.25 V. Cycle 2 shows additional Faradaic current beginning at approximately 0.75 V due to oxidation of the polymer film. Polymerization still happens at potentials greater than 1.25 V. The small spike at 1.1 V is related to an irreversible film rearrangement since subsequent cycles (seen when thicker films were prepared) show no current spike.