The leading supplier of cutting edge technology

QCM100 and QCM200 Quartz Crystal Microbalance

  • Electronic oscillator design with automatic gain control circuit
  • Simultaneous series resonance frequency and resistance outputs
  • Simplified shunt capacitance cancellation
  • Transformer isolated crystal face for EQCM measurements
  • Compatible with highly loaded crystals (up to 5 kΩ) including viscous liquids and viscoelastic films
  • No network or impedance analysis necessary
    •
Specifications

The QCM100 is a highly accurate quartz crystal microbalance used for mass and viscocity measurements. It provides outputs related to the series resonance frequency and resistance of the crystal oscillator and it is specially designed to handle heavily loaded crystals (up to 5 ΩW) making it ideal for applications involving lossy films and highly viscous liquids.

The QCM100 comes complete with analog controller, crystal oscillator electronics, quartz crystal and holder. All you need is a frequency counter and a voltmeter to complete the QCM measurement setup. Replacement crystals, oscillator and crystal holders are also available.

The analog controller provides power to the crystal oscillator electronics and has outputs (BNCs) for frequency and conductance. It also has a potentiometer for canceling shunt capacitance. Proper capacitance cancellation is required to assure true series resonance operation of the crystal oscillator, and eliminate frequency and resistance errors.

The QCM100's capacitance cancellation adjustment is extremely simple. There are no complicated tuning steps and no special tool requirements ¾ just a single 10-turn pot and an LED display that shows you which way to turn the knob and when to stop. The achievable capacitance cancellation is 0.01pF ¾ an order of magnitude better than competitive models.

The crystal oscillator electronics are designed around a unique automatic gain control (AGC) circuit instead of the traditional phase lock oscillator (PLO). The AGC provides the quartz crystal resonator with the necessary gain to overcome viscoelastic losses and achieve series resonance, while providing a signal that monitors the energy dissipated by the sensor (i.e. related to the series resonance resistance). The crystal oscillator will reliably drive crystals with resistance up to 5 kΩ. For example, it will maintain oscillation in viscous aqueous solutions containing over 88 % glycerol (w/w %).

The QCM100 uses a 5 MHz, 1 inch diameter, AT-cut, quartz crystal. All quartz crystals are designed specifically for operation in liquids, and are available in a variety of electrode materials and finishes. The crystal holder is designed so that only the front electrode is exposed to the gas or liquid under test, as required in EQCM experiments. A conductive metallic pad (wrap-around electrode) allows connection to the front electrode from the back of the crystal. This feature, combined with transformer isolation between the crystal electrodes and the oscillator circuit makes the QCM100 ideal for electrochemical research, and compatible with virtually all potentiostats.

The QCM100 offers improved measurement capabilities, simplified capacitance cancellation and better value than any other controller of its kind.


1mM CuSO4 in 0.1 M H2SO4

Cyclic voltammogram and massogram data for Cu deposition on a Au electrode. The frequency/potential diagram shows a frequency decrease with the deposition of Cu metal on the crystal's surface.

Schematic of EQCM apparatus based on QCM100 and potentiostat. A frequency counter and digital voltmeter provide the frequency and resistance measurements.

Df and DR versus glycerol weight percentage (in water) as predicted by theory and as measured with QCM100 and a 5MHz polished crystal.