Resonant mass measurement is a technique used in an innovative way by Archimedes to detect and count sub visible and submicron particles in a sample, and to measure their size and mass and distributions of size and mass. At the heart of Archimedes is a MEMS (micro Electro-Mechanical Systems) sensor, containing a resonating cantilever with a microfluidic channel embedded in its surface. When a particle of between 50nm - 5µm flows through the fluidic channel, it alters the resonating frequency of the cantilever which indicates the buoyant mass, and also the dry mass and size of the particle.

The sensor is also able to provide information on sample concentration, viscosity, density, and volume, and can detect and measure both negatively and positively buoyant particles within a sample. The detection of positively buoyant particles is extremely useful, for example, to distinguish between protein aggregates and contaminating silicone oil droplets in a biopharmaceutical formulation.

The use of resonant mass measurement by the Archimedes offers the following advantages:

  • Quick, accurate, reproducible and reliable particle counting, and determination of particle mass and size in the 50nm - 5µm range.
  • Mass determination 350ag.
  • Little or no sample preparation required.
  • Minimal sample consumption (100µL).
  • High concentration (109 particles/mL).
  • High viscosity (100 cP).
  • Differentiation between positively and negatively buoyant particles.
  • Fast, NIST-traceable calibration.