Electrophoresis device and method for separating objects
Inventors
Assignees
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Publication Number
US-8262884-B2
Publication Date
2012-09-11
Expiration Date
Abstract
An electrophoresis method is provided for separating objects in a fluid contained in a separation channel. The method comprises: applying an electric field along the separation channel, the electric field having a field profile, and thereby causing at least some of the objects to move relative to the fluid; varying the applied electric field so as to adjust the field profile relative to the separation channel, thereby causing the objects to separate into bands under the combined influences of an electric force due to the electric field and a hydrodynamic force due to the fluid.
Core Innovation
The invention relates to an electrophoresis method for separating objects in a fluid contained in a separation channel. The method applies an electric field along the separation channel, where the field profile has a spatial variation in the magnitude of the electric field along at least a portion of the separation channel, causing at least some of the objects to move relative to the fluid. The fluid and the separation channel are substantially stationary with respect to one another.
The method further varies the applied electric field to adjust the field profile relative to the separation channel, thereby causing the objects to separate into bands. Each band comprises objects with like electrical and hydrodynamic properties, under the combined influences of an electric force due to the electric field and a hydrodynamic force due to the fluid. The electric field profile is shaped such that the net force experienced by each object results in a width of each separated band that remains substantially constant with time.
In device form, the invention includes a separation channel, means for applying and varying an electric field along the separation channel, and a controller adapted to apply and vary the applied electric field to adjust the electric field profile. The device provides an electric field profile shaped such that the net force experienced by each object results in each separated band undergoing substantially zero spatial diffusion, while the fluid contained in the separation channel is substantially stationary relative to the separation channel.
As described, the separation can be achieved using a time-varying electric field having a spatially varying profile with a moving field profile relative to the channel, where the moving field profile causes band formation with substantially constant width over time. The description associates the approach with making bands share substantially equal constant terminal velocity and reducing diffusion-based resolution loss, including support for stationary gels or sieving matrices and controlled band spacing, position, and resolution.
Claims Coverage
The independent claims are directed to an electrophoresis method and an electrophoresis device that separate objects into bands using a spatially varying electric field profile whose relative position to the channel is adjusted, with additional shaping so band width remains substantially constant or diffusion is substantially zero. Across the two independent claims, the main inventive elements are the moving or adjusted field profile relative to a stationary fluid and channel and net-force shaping to control band broadening under combined electric and hydrodynamic forces.
Moving field profile for band formation with substantially constant band width
Applying an electric field along the separation channel with a field profile in which the magnitude varies spatially along at least a portion of the separation channel, thereby causing at least some objects to move relative to the fluid; varying the applied electric field to adjust the field profile relative to the separation channel so that the objects separate into bands based on electrical and hydrodynamic properties; shaping the electric field profile such that the net force experienced by each object results in the width of each separated band remaining substantially constant with time; wherein the fluid and the separation channel are substantially stationary with respect to one another.
Controller-adjusted field profile with substantially zero spatial diffusion
A separation channel containing a fluid and the objects to be separated; means for applying an electric field along the separation channel with a field profile in which the magnitude varies spatially along at least a portion such that objects move relative to the fluid; a controller adapted to apply and vary the applied electric field to adjust the electric field profile relative to the separation channel so objects separate into bands based on electrical and hydrodynamic properties under electric force and hydrodynamic force; wherein the controller applies an electric field profile shaped such that the net force experienced by each object results in each separated band undergoing substantially zero spatial diffusion; and wherein the fluid contained in the separation channel is substantially stationary relative to the separation channel.
Both independent claims require band separation created by a spatially varying electric field profile that is adjusted relative to a substantially stationary fluid and channel, with the electric-field profile shaped so that band broadening is controlled by net-force effects under combined electric and hydrodynamic forces, substantially constant band width with time in the method, and substantially zero spatial diffusion in the device.
Stated Advantages
Eliminating the need for constant fluid flow or pumping, since the fluid and separation channel are substantially stationary with respect to one another.
Reducing diffusion-based resolution loss by shaping the electric field profile so band width remains substantially constant with time or bands undergo substantially zero spatial diffusion.
Supporting stationary gels or sieving matrices as a basis for separation.
Enabling fast high-resolution separation with controlled band spacing, band position, and resolution.
Documented Applications
Label-free DNA sequencing using sequential injections and detected bands, with predicted resolution improvements for closely spaced DNA lengths.
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