What is QCM-D?
Quartz crystal microbalance with dissipation monitoring (QCM-D) is a surface-sensitive technique that measures mass changes and viscoelastic properties of thin films at a solid-liquid interface in real time without labels. It is widely used in biosensor research, drug delivery, polymer science and membrane biophysics.
The Principle
A QCM-D sensor is a thin quartz crystal disk. Because quartz is piezoelectric, applying an oscillating voltage causes it to vibrate at its resonant frequency. When molecules adsorb onto the surface, the frequency decreases in proportion to the added mass (Sauerbrey equation). When the drive is switched off, oscillation decays: rigid films decay fast (low dissipation), viscoelastic films decay slowly (high dissipation). Simultaneous measurement of frequency shift (delta-F) and dissipation shift (delta-D) provides both mass and mechanical property information.
What QCM-D Measures
- Adsorbed mass with sensitivity down to 1 ng/cm2
- Adsorption and desorption kinetics in real time
- Viscoelastic properties: shear modulus, viscosity and thickness of soft films
- Structural changes in adsorbed layers upon exposure to different conditions
- Water content trapped in hydrated films
Key Applications
- Protein adsorption – kinetics and conformation changes at biosensor surfaces
- Lipid bilayer formation – monitoring supported bilayer assembly for membrane studies
- Polymer brush characterization – swelling and collapse of responsive polymers
- Nanoparticle-surface interactions – quantifying nanoparticle binding and layer structure
- Corrosion and passivation – monitoring oxide film growth and inhibitor adsorption
- Drug-membrane interactions – studying how drug molecules interact with model membranes
QCM-D vs SPR
QCM-D and surface plasmon resonance (SPR) are complementary label-free surface techniques. SPR measures the optical mass of adsorbed layers and is more sensitive to protein mass. QCM-D measures the coupled water mass in addition to the biomolecule mass, giving information about hydration and viscoelastic properties not accessible by SPR. Using both techniques together allows the water content of adsorbed films to be determined independently.
Instrument Selection
QSense QCM-D systems from Biolin Scientific are the industry standard, available in single-channel (QSense Analyzer) and multi-channel (QSense Pro) configurations with optional electrochemical, optical and microfluidic modules. NewRoad distributes QSense systems with full local application support.
