Method and apparatus for measuring particle characteristics through mass detection

Inventors

Babcock, Kenneth • Burg, Thomas • Godin, Michel • Manalis, Scott

Assignees

AFFINITY BIOSENSORS LLC • Massachusetts Institute of Technology

Abstract

Method for measuring a target particle property. A suspended microchannel resonator is calibrated to determine the relationship between a detected mass and a resonance frequency shift of the resonator. The target particle is suspended in a fluid and introduced into the resonator, and the resonator frequency shift due to the particle is measured. Target particle mass is calculated from the resonator frequency shift, the target particle density, and the fluid density. A target particle property such as size or volume is determined from the calculated target particle mass.

Core Innovation

The invention provides methods using a suspended microchannel resonator (SMR) to measure properties of target particles based on resonance frequency shifts. A target particle is introduced into the SMR and the shift in resonance frequency is measured. The SMR is calibrated to determine a relationship between the resonance frequency or shift in resonance frequency and detected mass due to the presence of a particle inside the resonator, enabling calculation of particle properties from the resonance frequency shift.

The invention includes determining particle density by introducing the target particle in a first fluid and measuring the resonance frequency shift, introducing the target particle in a second fluid having a different density and measuring the resonance frequency shift, and determining the fluid density that would produce zero resonance frequency shift as the target particle density. It also extends to measuring mean density of a population by measuring time averages or mean resonance frequency shifts for particles in first and second fluids and determining the fluid density that would produce zero mean shift as the mean density of the particle population.

The invention further includes identifying the type of an individual particle among two possible types distinguished by distinct mean densities by suspending the particle in a fluid with a density between the two types, introducing the fluid and particle into the SMR, monitoring the resonance frequency shift as the particle passes through the resonator, and identifying the particle with the corresponding type. In addition, it provides methods for measuring a fluid density using SMR calibration and seeded particles of known mass and density, and methods for measuring particle volume, diameter, and linear size from resonance-frequency shift via density-correction relations using the relationship between detected mass and the shift in resonance frequency.

Claims Coverage

The independent claims cover density measurement of a target particle and a particle population, particle-type identification between two density-distinct types, fluid-density measurement via SMR calibration and seeded particles, and particle property measurement from resonance frequency shifts using density-correction relations. In total, the claims emphasize SMR calibration to relate detected mass to resonance frequency shift and calculation of particle properties from that relationship, including zero-shift and zero mean shift density determination methods.

The claims center on calibrating a suspended microchannel resonator to relate resonance frequency or resonance frequency shift to detected mass, then using that relationship to determine particle properties, densities, and fluid density via zero-shift and density-correction relations. Additional coverage includes measuring population properties and identifying an individual particle type among two density-distinct types.

Stated Advantages

Documented Applications