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
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Publication Number
US-9027388-B2
Publication Date
2015-05-12
Expiration Date
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 calibrates a suspended microchannel resonator to determine the relationship between resonance frequency of the resonator and detected mass due to the presence of a particle inside the resonator. The calibration is performed using at least one of particles of known mass and density and fluids of known density. After calibration, resonance frequency shifts are converted to detected mass, and then to a property of a single target particle.
A single target particle is introduced into the resonator along with a fluid at a particle/fluid volume concentration near or less than 1/(resonator volume). The method measures the shift in resonance frequency created by the presence of the single particle. A property of the single target particle is calculated from the resonance frequency shift using the calibrated relationship.
The described approach includes calculating a property as particle mass and/or particle volume and/or particle diameter/size, based on density relationships between particle density and fluid density. Extensions include distinguishing particle types by sign or magnitude of SMR response in fluids of intermediate density, measuring particle density via two-fluid interpolation/extrapolation to zero response, and measuring fluid density by seeding with known particles. In multi-particle regimes, mean properties are obtained from time-averaged signals.
Claims Coverage
The patent includes one independent method claim. Across dependent claims, it specifies inventive features for computing particle mass, particle volume, diameter/size, or linear size from the resonance frequency shift after calibrating the suspended microchannel resonator and operating at a particle/fluid volume concentration near or less than 1/(resonator volume).
Calibrated resonance-to-detected-mass conversion in a suspended microchannel resonator
Calibrating a suspended microchannel resonator to determine the relationship between the resonance frequency of the resonator and the detected mass due to the presence of a particle inside the resonator using at least one of particles of known mass and density and fluids of known density.
Single target particle introduction at near-or-less-than 1/(resonator volume) concentration and resonance frequency shift measurement
Introducing a single target particle into the resonator along with a fluid at a particle/fluid volume concentration near or less than 1/(resonator volume) and measuring the shift in resonance frequency.
Single-particle property calculation from resonance frequency shift
Calculating a property of the single target particle from the shift in resonance frequency.
Mass calculation using a density-based detected-mass relationship
Calculating the particle mass from the detected mass using an equation particle mass = detected mass/(1 − fluid density/particle density).
Volume calculation using a density-based detected-mass relationship
Calculating the particle volume from the detected mass using an equation particle volume = detected mass/(fluid density − particle density).
Diameter determination using a cube-root relationship from detected mass and densities
Determining the property diameter using a relationship diameter = CubeRoot(6 × detected mass/(Pi × (fluid density − particle density))).
Linear size determination using selected shape volume-to-size relationships
Determining a property defined as linear size by relating volume to linear size for selected shapes.
Droplet-in-emulsion target particle
Where the target particles are droplets in an emulsion.
The claims cover a method that calibrates a suspended microchannel resonator to convert resonance frequency shifts into detected mass and then calculates single-particle properties from that shift. The dependent claims narrow the computed property to mass, volume, diameter/size, or linear size, and further narrow the target particle type to droplets in an emulsion.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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