Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
  • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
  • G01N27/416—Systems
  • G01N27/447—Systems using electrophoresis
  • G01N27/44756—Apparatus specially adapted therefor
  • G01N27/44791—Microapparatus
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
  • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
  • G01N27/416—Systems
  • G01N27/447—Systems using electrophoresis
  • G01N27/44704—Details; Accessories
  • G01N27/44752—Controlling the zeta potential, e.g. by wall coatings

Definitions

• electrophoresis and in particular to a device for controlling the movement of fluids in
• a capillary channel used in chemical systems for separations, reactions, or analysis.
• Microdevices for fluids Movement of fluids on microchips has been
• valves have not been fabricated on the micron to sub-micron scale
• Electroosmosis is the most important flow-generating mechanism
• the ⁇ -potential is
• the cationic counter ions (H 3 O + , Na + typically) entrained in the diffuse layer are free to migrate towards the
• Electroosmosis also termed electroosmotic flow
• electroosmosis as a propulsion mechanism is that both the flow rate and the
• Electroosmosis is also an important component of capillary zone
• the flow generated is usually large enough to force all species present
• Electroosmosis directly influences the efficiency
• Electroosmosis can be altered in a variety of ways. Examples of
• EAF electroosmotic flow
• capillary for fused silica capillaries used in conventional capillary electrophoresis
• Radial voltage flow control Radial voltage flow control, a method to
• heterogeneous (-potential caused by radial fields in the partially covered capillaries.
• radial voltage flow control could be done at lower voltages in a silica capillary of up
• micrometer inside diameter having an inner capillary of 75 micrometer outside
• micrometer inside diameter channel cross section 2 x 10 " ° square meters
• section 2 x 10 "9 square meters) and 370 micrometer outside diameter, in which radial voltages of up to 30 kilovolts were applied across the capillary to control
• channel inner wall surfaces were 62 and 160 micrometers, respectively.
• micrometer inside diameter channel cross section 0.3 x 10 "9 square meters
• radial voltage electrode and the channel inner wall surface was 62 micrometers.
• invention is to provide a device and method for monitoring uniform electroosmotic
• an integrated external electrode positioned microscopically close to a capillary
• ultrasmall cross section of the capillary channel reduces the voltage required for
• the present invention is directed to a capillary
• electrodes are positioned at the immediate ends of the channel to apply a longitudinal
• This embodiment permits independent control of the
• the present invention is directed to a capillary
• dielectric constant is positioned between the integrated external electrode and the capillary wall to inject charge to the capillary channel inner wall surface when voltage
• a plurality of channels are combined in a device.
• the present invention is directed to a
• capillary channel device as described above, further comprising a means to monitor
• Fig. 1 illustrates an example of a device for ultrasmall volume flow
• Fig. 2 illustrates the physical parameters of geometry of a device for
• Fig. 3 illustrates a plot of model capillary inner wall surface charge
• Fig. 4 illustrates an example of a microchip device for ultrasmall
• Fig. 5. illustrates a plot of fluorescent intensity of a dye migrating
• Fig. 6. illustrates an example of a device for ultrasmall volume flow
• integrated external electrode we mean an electrical conductor
• the perpendiclar voltage field provides control of
• the present invention provides a practical device for controlling
• Fluid flow is provided in a capillary channel 170 defined by
• control electroosmotic flow is applied perpendicularly across a capillary channel
• a voltage to the integrated external electrode is provided.
• a voltage to the integrated external electrode is provided.
• electrodes 110 are provided at the immediate ends 180 of the capillary channel to
• longitudinal electrodes can be electrically connected to nodes 100 for connecting to a
• the longitudinal electrodes 110 can be adjacent to, and in electrical contact
• This device will find application, for example, with capillary zone
• electrophoresis Another example is any fluid movement within microinstrumentation
• the device can be made as a microchip, as shown in Fig. 2.
• capillary channel 170 is again defined by the substrate 160, and can have ultrasmall
• Integrated external electrodes 120 can be positioned
• the device can be a ceramic, silica, fused silica, quartz, a silicate, a titanate, a metal oxide,
• nitride silicon, titanium dioxide, and the like, or a polymer, a plastic, a
• polydimethylsiloxane or a polymethylmethacrylate.
• the applied voltages may be lower in
• the first issue is structural integrity.
• electrode or conductor, more accurately
• electrode could be placed very near (nanometers to
• Fig. 4 wherein a microchip capillary channel device is illustrated.
• substrate 160 defines a capillary channel 170.
• Two integrated external electrodes 120 are integrated external electrodes 120
• a material of high dielectric constant 130 can be
• Ultrasmall capillary channel cross section A fused silica capillary
• tube may be modeled as a cylindrical capacitor, as described in Keely, et al., Chromatogr. A 1993, 652, 283-289. Without intending to be bound by any one
• capillary channel wall can also improve the control of flow. They can increase the
• a material with high dielectric constant such as titanium
• the typical substrate material quartz (or fused silica) has a
• ⁇ material are ceramics, a silicate, a titanate, a metal oxide, a nitride, titanium dioxide,
• the direction in which the electric charge is transferred can be any direction in which the electric charge is transferred.
• the charge will be preferentially injected towards the channel.
• the device is a combination of capillary channels each with
• perpendicular voltage flow control as shown in Fig. 6, controlling the direction of
• the distances can be 100 or more, and the ratio of the dielectric constants can be as
• the surface must retain low surface charge density in the presence of the
• aqueous buffers typically used in capillary electrophoresis as described in Poppe, et
• the surface charge density should be insensitive to pH
• the silicate surface is labile to acid and base
• organosilanes forms an uncharged, stable surface, as described in Pesek, et al., Chromatographia 1997, 44, 538-544, which is hereby incorporated by reference in its
• the organosilane coating on the titanium dioxide does not require hindered
• buffer/wall interface must be minimized to extend radial voltage flow control to
• Polymers have been covalently bound and physically adsorbed to the inner wall
• triorganosilane treatments have demonstrated stability to acidic and basic buffers and
• This information is used as a feedback mechanism to confirm or to
• monitoring device is that the materials and fluid within the channel must remain
• the monitoring system must be non-invasive
• the flow may be calculated from the elution time. This technique is limited to
• One method to directly measure EOF is to weigh the mass transferred
• conductivity across the capillary is proportional to a weighted average of the
• Patent No. 5,624,539 which is hereby incorporated by reference in its entirety.
• channels, or selected channels, allow introduction of an electric field selectively
• these longitudinal electrodes provide
• Bulk flow can be directly changed by the applied longitudinal voltage field, or by changes in the (-potential caused by perpendicular
• Electrophoretic migration may be changed by varying the longitudinal
• Lucifer yellow was prepared (1 mg/mL) using NaH 2 PO 4 buffer. All
• a capillary channel microdevice was designed in-
• This device consisted of a long capillary channel, used for electrophoretic separation,
• the substrate was Corning 0211 glass
• the side channels were off-set by 500 micrometers.
• Integrated external electrodes were positioned parallel to the main channel, separated
• the effective perpendicular voltage field strength was determined by first
• the effective perpendicular voltage field was the
• Image acquisition was performed with an RSI 70 CCD camera (CSI
• the device was approximately 40 times
• Peak elution times varied by as much as 16 ⁇ 3 seconds over a 5 mm separation distance, as shown in
• modified yellow-green fluorescent (505 nm excitation/515 nm emission) latex microspheres (Molecular Probes, Eugene, Oregon) were used as received. All
• NaH 2 PO 4 buffers were prepared to 100 mM concentration and adjusted with 100 mM
• the device was interfaced by placing the cathodic buffer reservoir in a
• buffer reservoir was fashioned from plexiglas material to form a container where the
• a substrate of Corning 0211 glass is fabricated defining a capillary
• An integrated external electrode is positioned parallel to the channel separated by
• a layer of titanium dioxide, a high dielectric material, is positioned between the integrated external electrode and
• the channel extending longitudinally 0.2 cm in both directions from the longitudinal
• a voltage is applied to the integrated external electrode to

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• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Dispersion Chemistry (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Sampling And Sample Adjustment (AREA)
• Electrostatic Separation (AREA)
• Flow Control (AREA)

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• 1999
  • 1999-11-10 EP EP99958906A patent/EP1129345A1/de not_active Withdrawn
  • 1999-11-10 CA CA002348864A patent/CA2348864A1/en not_active Abandoned
  • 1999-11-10 JP JP2000581444A patent/JP2002529235A/ja not_active Withdrawn
  • 1999-11-10 WO PCT/US1999/026724 patent/WO2000028315A1/en not_active Ceased

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