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Small volume liquid manipulation, method, apparatus and process

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20120298512 patent thumbnailZoom

Small volume liquid manipulation, method, apparatus and process


An apparatus, a method and a process to achieve manipulation of particles and/or solutions through the use of electrokinetic properties are disclosed. The manipulation is performed using a disposable device positioned on top of a stage for purposes of powering the electrodes. The fluidic solution is brought into contact with the active part of the device and then manipulated.

Browse recent The Regents Of The University Of California patents - Oakland, CA, US
Inventors: Igor Mezic, Frederic Bottausci, Jason S. Spievak, Peter J. Strand
USPTO Applicaton #: #20120298512 - Class: 204627 (USPTO) - 11/29/12 - Class 204 
Chemistry: Electrical And Wave Energy > Apparatus >Electrophoretic Or Electro-osmotic Apparatus >Barrier Separator (e.g., Electrodialyzer, Etc.)

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The Patent Description & Claims data below is from USPTO Patent Application 20120298512, Small volume liquid manipulation, method, apparatus and process.

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CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. Section 119(e) of co-pending and commonly-assigned U.S. Provisional Patent Application Ser. No. 60/917,796 filed on May 14, 2007, by Igor Mezic et al., entitled “SMALL VOLUME LIQUID MANIPULATION, METHOD, APPARATUS, AND PROCESS,” attorneys\' docket number 30794.235-US-P1 (2006-673-1), which application is incorporated by reference herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

This invention was made with Government support under Grant No. DMS-0507256 awarded by the NSF. The Government has certain rights in this invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates in general to the field of manipulating fluid flow and/or particle motivating force and is related to separation, concentration, transport, reaction and mixing apparatus, method and process. More particularly, the present invention relates to improved manipulation by bringing the present invention in contact with the solution. Moreover, the invention can be embedded into existing liquid-containing vessels such as well-plates and microarrays.

2. Description of the Related Art

(Note: This application references a number of different publications as indicated throughout the specification by one or more reference numbers within brackets, e.g., [x]. A list of these different publications ordered according to these reference numbers can be found below in the section entitled “References.” Each of these publications is incorporated by reference herein.)

Devices using electrokinetic properties (electrophoresis, dielectrophoresis, electroosmosis and electrothermal convection) have been used to manipulate fluids and particles.

Electrophoresis is a technique for manipulating components of a mixture of charged molecules (proteins, DNAs, or RNAs) in an electric field within a gel or other support. Under AC electric field, uncharged particles suspended in a dielectric media can be polarized and further manipulated. If the field is spatially inhomogeneous, it exerts a net force on the polarized particle known as dielectrophoretic (DEP) force [1]. This force depends upon the temporal frequency and spatial configuration of the field as well as on the dielectric properties of both the medium and the particles. Single frequency electric fields can be used to transport and separate particles.

Fluid motion can also be induced by applying an electric field onto a solution. The force driving the fluid thus originates in the bulk (buoyancy, electrothermal effect) or at the interface between the fluid and the device containing the fluid (electroosmosis).

The buoyancy generates a flow because of a density gradient. It can be produced by internal or external heating. An electric field is often used as internal energy source. Applied to a solution, part of the electric energy dissipates in the fluid by Joule effect and locally heats the fluid. Furthermore, local heating creates gradients of conductivity and permittivity. The fluid can then move under the influence of an electrothermal flow [2, 3, 4].

Under certain conditions (material properties, conductivity and permeability of the fluid and the device containing the fluid), ion layers develop at the fluid-surface interface due to chemical associations or dissociations and physical adsorption on or desorption from the solid surface. Ion layers can also be generated at the surface of electrodes where a potential is externally imposed. Appling an electric field with a tangential component to the layers moves the ions which carry the fluid along by viscous force. This process produces a bulk flow [2, 3, 4].

Coupled with an electrohydrodynamic flow, several electrode geometries have been designed as a tool to manipulate fluids and particles. Interdigitated castellated electrodes are, for instance, designed to trap and separate particles [5, 6]. Polynomial electrodes [7], planar electrodes [8, 9], quadripolar electrodes [27] or more complex geometries [10] have also been proposed.

Micro Technology Applied to Biological Problems

Massively parallel hybridization [11-13] improves the way many biological and medical analyses are performed both in research and clinical applications, but there is still a lack of an efficient multipurpose device. As sample volumes used in massive parallel systems become smaller and smaller (micro- to nanoliter or even smaller) it is more challenging to manipulate the fluids since the fluid viscosity dominates any convection. Multiple reports have shown that micromixing, transport or concentration improves hybridization reaction [14-16,17,18]. Micromixing can be achieved by ultrasonic agitation (the nucleation of bubbles creates small jets that enhance the mixing) [19] or by vortexing or agitating the solution and creating convection [20]. Micromixing can also be produced by surface wave generation [21] for instance.

What is needed then are improved methods, processes and general apparatus to efficiently and accurately mix, separate, concentrate, and transport small volume of fluids with or without particles (e.g., atoms, molecules, cells in biological and chemical assays) using combined fluid flow and/or electrokinetic methods. The present invention satisfies that need.

SUMMARY

OF THE INVENTION

The present invention discloses an apparatus, a method and a process to achieve manipulation of particles and/or solutions in a container. The invention uses electrokinetic properties. The manipulation is performed by bringing the fluidic solution into contact with the active part of the device. For the purpose of this document, a “vessel” will denote specifically either a microtiter plate (microplate or well-plate) well or more generally any volume containing liquid solution. The invention includes a process where one or more vessels with built in electrodes (made of any applicable material) are filled with one or more fluids or one or more fluids and one or more types of particles for the purpose of manipulating fluid(s) and/or particles. The manipulations can include concentration, separation, transport or mixing.

A device composed of two parts comprising vessels containing electrodes capable of inducing electrokinetic (including electroosmotic and electrothermal) fluid flow inside vessels (including microplates or well-plates) and a connecting plate (the vessels bloc being a separate entity from the connecting plate).The electrodes contacts or pads are accessible from outside the vessels. The electrodes are energized through the connecting plate by bringing into contact the electrodes contacts or pads with the connecting plate. The electrodes are built into the vessel, itself. The device can be used for general manipulation of fluids and particles inside the vessel, including concentration, separation, transport or mixing. The device is tunable, so that by applying different DC and/or AC voltages, different flow effects can be induced and adapted to efficiently manipulate the fluids and particles contained inside the vessel. The device can perform one or more particle manipulation operations.

A method where more than one frequency of AC field is used to induce fluid flows sequentially in time or simultaneously to induce fluid flow and electromagnetic field for the purpose of manipulating particles (including concentration, separation, transport or mixing of the particles). The flow and electromagnetic field can be applied by electrodes built into the device (thus being an integral part of the device) or applied externally. A device for manipulating fluidic solutions in accordance with the present invention comprises a vessel for containing a fluidic solution, and a plurality of electrodes, coupled to the vessel, the plurality of electrodes being arranged in an array and each applying an electric field to the fluidic solution, wherein the plurality of electrodes manipulate at least one of a flow of the fluidic solution and a separation of particles in the fluidic solution, the manipulation using electrokinetic properties resulting from the applied electric fields, wherein the fluidic solution comprises a total volume of fluid on the order of microliters.

Such a device further optionally comprises the electrokinetic property is at least one of electrothermal convection and electroosmosis, at least a first electrode in the plurality of electrodes being made from a first material and at least a second electrode in the plurality of electrodes being made from a second material, the array being a periodic array, each electrode in the periodic array being controlled independently, at least a first electrode in the plurality of electrodes having a first shape and at least a second electrode in the plurality of electrodes having a second shape, and the electric field inducing a time-dependent electrohydrodynamic fluid flow.

A method in accordance with the present invention comprises forming at least one recurrent circulating fluid flow within the fluid, introducing at least one particle motivating force to the fluid having the recurrent circulating fluid flow, and manipulating the at least one particle motivating force using electrokinetic properties, the particle motivating force comprising at least applied electric fields, wherein the fluidic solution comprises a total volume of fluid on the order of microliters.

Such a method further optionally comprises at least one particle motivating force directionally interacting with the at least one recurrent circulating fluid flow in a tangential orientation relative to the recurrent circulating fluid flow, the at least one particle motivating force directionally interacting in a tangential orientation at a periphery of the at least one recurrent circulating fluid flow, collecting the particles, and applying a time-dependent electrohydrodynamic fluid flow.

Another device in accordance with the present invention comprises a vessel for containing the fluid to be mixed, a plurality of electrodes, inside the vessel, and a plurality of connectors, coupled to the plurality of electrodes, the plurality of connectors being electrically coupled to a plurality of applied electric fields, wherein the plurality of electric fields electrically excite the electrodes thereby creating a flow within the fluid.

Such a device further optionally comprises the plurality of electric fields generating at least one of electrothermal convection and electroosmosis within the fluid, at least a first electrode in the plurality of electrodes being made from a first material and at least a second electrode in the plurality of electrodes being made from a second material, the plurality of electrodes being arranged in a periodic array, each electrode in the periodic array being controlled independently, at least a first electrode in the plurality of electrodes having a first shape and at least a second electrode in the plurality of electrodes having a second shape, and the electric field inducing a time-dependent electrohydrodynamic fluid flow.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings in which like reference numbers represent corresponding parts throughout:

FIG. 1 illustrates an example of the arrangement of the electrode arrays inside a vessel. The electrodes connectors are on the bottom of the vessel.

FIGS. 2(a) through 2(c) illustrate examples of the vessels (with embedded electrodes) arrangement to form a wells plate. FIG. 2(a) shows the vessels on top of the holding plate with the electrodes connectors on the backside on the plate. FIG. 2(b) shows the vessels inserted into the holding plate with the electrodes connectors on the bottom of the vessels. FIG. 2(c) shows the electrodes directly inserted into the holding plate with the electrodes connectors on the backside of the plate.

FIG. 3 illustrates an example of a connecting plate. In this example, each row can be controlled separately. The electrode pads (shown in detail in FIG. 4) are wired to link the electrode pads to an external controller. The wires are drawn on the backside of the plate in this example but can by on any side of the plate.

FIGS. 4(a) and 4(b) illustrates an example of a vessel with electrodes from a side view (a) and a connection on the electrodes array (b). The connectors of the array have conic shape with flexible conductive flaps designed to enable reliable contacts.

FIG. 5 is a drawing of a vessel with embedded electrodes with a streamline of the flow once the electrodes are energized.

FIG. 6 is a block diagram that illustrates examples of the arrangement of the electrode inside a vessel. FIG. 6(a) is a drawing of aligned cylindrical electrodes, FIG. 6(b) is a drawing of cylindrical electrodes arranged in staggered row, FIG. 6(c) is a drawing of cylindrical electrodes with different length arranged in staggered row, FIG. 6(d) is a drawing of cylindrical and circular electrodes, and FIG. 6(e) is a drawing of curved cylindrical electrodes. The electrodes can also be mounted on the plate without a container around them.

FIG. 7 is a graph that shows the velocity field in the plane orthogonal to the electrodes for the electrode configuration shown in FIG. 6(a). The velocity field is measured par Particle Image Velocimetry at mid height of a cell measuring 570 μm high, 2 mm wide and 2 mm long. The fluidic solution was water with conductivity σ=0.6 S·m−1 seeded with 0.71 μm fluorescent particles. The signal applied was 530V·cm−1 at 700 KHz.

FIG. 8 is a process chart in accordance with the present invention.

DETAILED DESCRIPTION

OF THE INVENTION

In the following description of the preferred embodiment, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration a specific embodiment in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

Overview

The impact of the manipulation of fluids and/or particles induced by electric fields is described theoretically and experimentally herein. By means of a microfluidic device comprising a periodic array of microelectrodes, fluid(s) and/or particles manipulations are shown including concentration, separation, transport or mixing using electrokinetic properties. The theoretically predicted dynamical phenomena are demonstrated experimentally.

This invention could be used, for example, to improve the mixing of microliter or nanoliter volume protein solutions analyzed in high throughput screening assays. Electrokinetic micromixing improves the time and reliability for protein expression by rapidly homogenizing the small volume solution. Current methods require extensive.human or robotic operations and generally lack the required sensitivity to meet reliability testing standards. Other possible applications could be the separation and detection of small populations of pre-cancerous cells from body fluids (blood, sputum, urine) or the concentration of DNA particles inside a Polymerase Chain Reaction (PCR) apparatus for improved DNA detection.

Technical Description

The present invention discloses an apparatus, a method and a process to achieve manipulation of particles and/or solution in micro- to nanoliter volumes. Volumes on the order of microliters means that the total volume of the fluid is less than one milliliter, but the device can be used with total volumes greater than one milliliter if desired. The device of this invention uses electrokinetic properties. The manipulation is performed by positioning vessels onto the electrodes arrays for purpose of powering the electrodes, bringing the fluidic solution considered into contact with the active part of the device in the vessels and applying precise and carefully chosen electric fields combinations. The purpose of the active part of the device is to manipulate the flow and/or particles using an electric field.

Electric fields induce a force on charged particles in solutions, moving the particles towards either the cathode or the anode depending on the sign of the charged particles [22]. Such a particle motion in liquid phase is called electrophoresis. If the particle is uncharged, applying AC-electric field to the medium containing the particles creates a dipole on the particles. The orientation of the dipole depends on the conductivity and permittivity of both the particles and the medium. For dielectric particles, the expression of the time average force is given by

=2πα3εmRe[K(ω)]∇|E|2

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stats Patent Info
Application #
US 20120298512 A1
Publish Date
11/29/2012
Document #
13562011
File Date
07/30/2012
USPTO Class
204627
Other USPTO Classes
204648
International Class
/
Drawings
7



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