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, mass and sample concentration. 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 60nm - 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 viscosity, density, and volume, and can detect and measure both negatively and positively buoyant particles within a sample when 2 different material types are present. 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 or to confirm the presence of bubbles in an ultrasound contrast agent 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 60nm - 5µm* range.​
  • Limit of mass detection 2000ag.​
  • Differentiation between positively and negatively buoyant particles.​
  • High concentration (108 particles/mL).​
  • Little or no sample preparation required.​
  • Does not require specific sample carrier fluid.​
  • Compatible with many sample fluids.​
  • Minimal sample consumption (100µL).​
  • High viscosity (50cP).​
  • Fast, NIST-traceable calibration

*Accessible size range is sample and sensor dependent.



Sizing from Buoyant Mass

More details
Measurement type
Particle size
Protein aggregation
Particle size range 0.05µm - 5µm
Resonant Mass Measurement (RMM)