Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Means for analyzing gas sample
Reexamination Certificate
2000-12-13
2004-09-07
Warden, Jill (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Means for analyzing gas sample
C422S105000, C204S601000, C204S451000, C204S450000, C204S600000, C134S16700R, C134S16700R, C134S171000, C134S16600C, C134S172000
Reexamination Certificate
active
06787111
ABSTRACT:
TECHNICAL FIELD
The invention relates in general to molecular separation technology utilizing microchip substrates and in particular to an apparatus and method for filling and cleaning microchannels and inlet ports of microchip substrates for use and reuse in the molecular separation of samples.
BACKGROUND ART
In the past ten years or so, parallel capillaries have been used extensively for molecular separations, such as by means of electrophoresis. Capillary electrophoresis has been used for the analysis of DNA and proteins, and for the separation of small ions, small molecules, bacteria, and viruses. Different separation media have been used in the capillaries including solutions, gels, and polymers. In each technique, the mobility of the target can be measured.
Capillaries have been applied both to DNA fragment length analysis and to DNA sequencing. The study of nucleotide sequences relies upon the high resolution separation of polynucleotide fragments. Each fragment in a family of fragments is tagged with fluorescent markers and the differences in the molecular migration in a capillary channel are observed. Fragments having differences of only a single base pair are routinely separated with fluorescent detection.
To increase the throughput, many capillaries can be used in parallel. Parallel capillary electrophoresis allows many samples to be analyzed simultaneously and can result in high throughput rates.
Recently, several groups have implemented capillary electrophoresis in microchannel formats (A. T. Wooley, G. F. Sensabaugh and R. A. Mathies, “High-Speed DNA Genotyping Using Microfabricated Capillary Array Electrophoresis Chips”,
Anal. Chem.,
69:2181-2186 (1997); A. T. Woolley and R. A Mathies,
Anal. Chem.,
67:3676-3680 (1995); A. T. Woolley, P. C. Simpson, S. Liu, R. Johnston, G. F. Sensabaugh, A. N. Glazer, and R. A. Mathies, “Advances in Microfabricated Integrated DNA Analysis Systems”,
HPCE
98 (1998); P. C. Simpson, D. Roach, A. T. Woolley, T. Thorsen, R. Johnston, G. F. Sensabaugh, and R. A. Mathies, “High-throughput genetic analysis using microfabricated 96-sample capillary array electrophoresis microplates”, Proc.
Nat'l. Acad. Sci. USA,
95:2256-2261 (1998)). This approach uses microchannels etched or molded into a substrate as the separation channels in place of capillaries (R. M. McCormick, R. Nelson, M. G. Alonso-Amigo, D. J. Benvegnu and H. H. Hooper, “Microchannel electrophoretic separation of DNA in injection-molded plastic substrates”,
Anal. Chem.
69:2626-2630 (1997); U.S. Pat. No. 5,376,252, issued 1994 to B. Ekstrom, G. Jacobson, O. Ohman and H. Sjodin). The resulting device is commonly called a microchip, even though the physical size of the entire substrate can vary from microchip size, i.e. dimensions of a few millimeters on a side, to wafer size, i.e. dimensions similar to semiconductor wafers (10-20 centimeters diameter) to microchannels in 48 cm long “macrochips” (C. Davidson, J. Balch, L. Brewer, J. Kimbrough, S. Swierkowski, D. Nelson, R. Madabhushi, R. Pastrone, A. Lee, P. McCready, A. Adamson, R. Bruce, R. Mariella and A. Carrano, “Development of a Microchannel Based DNA Sequencer”,
DOE Human Genome Program Contractor
-
Grantee Workshop VI,
Santa Fe, N.M. (1997)). The determining factors in microchip size are the complexity of microchannel routes and the lengths of the separation channels. The length of the channels must allow for sample input, sample migration and a measurement zone. The channels are typically of dimensions from 8 to 40 micrometers deep and 20 to 150 micrometers wide. The small channels resolve DNA fragments in significantly shorter times than capillaries with larger cross-sectional areas.
Beyond providing parallel capillaries, some advances in speed of analysis have been achieved by providing parallel sample wells and providing automated optical detectors and software analyzers.
In spite of these advances, fine separations are still a time consuming and labor intensive process, particularly when it comes to the preparation of the microchip substrate. Such preparations involve injection of separation media and solutions in the microchannels of the microchip substrate, filling inlet ports with solutions needed for analysis of samples, and cleaning the microchannels and inlet ports of the microchip substrate.
Prior art methods of filling and cleaning the microchannels and inlet ports of the microchip substrates involve a completely manual process. Matrix or other separation media is injected by syringe into common openings called anodes leading to the microchannels of the microchip substrate. The pressure of the matrix injected into the common anodes forces the old matrix out of the microchannels into a plurality of inlet ports on the microchip. Next, a pipette tip attached to a vacuum source is used to suction out solution or old matrix from the inlet ports one at a time. Sometimes, it is necessary to first add water to each of the individual inlet ports in order to dissolve any dry matrix so that it may be suctioned. Not only is this method time consuming, matrix in some of the microchannels may dry before all of the microchannels have been injected with new matrix. A dry matrix does not provide the electrically conductive path or the sieving characteristics necessary for proper separation of samples and is difficult to remove. Washing out the chip for storage involves a similar process in that each inlet port and all microchannels must be washed and dried individually. Although more microchannels present in the microchip substrate allow for more samples to be analyzed simultaneously, the preparation time of the entire microchip substrate increases.
An object of the invention was to devise an apparatus and method for efficient filling and cleaning of microchannels and inlet ports of microchip substrates for use in molecular separation and chemical analysis of samples. A further object was to automate the preparation of microchip substrates and to integrate the apparatus with the apparatus for the automatic handling and presentation of specimens into the microchips for parallel high throughput analysis in microchannels.
SUMMARY OF THE INVENTION
The above objects have been achieved with an apparatus for simultaneously cleaning and filling a large number of inlet ports and channels of a microchip substrate for use in molecular separations and chemical analysis of samples.
The microchip has macroscale inlet ports leading to the microchannels. The inlet ports are spaced apart to match the size and spacings of pipettors in an array of ganged pipettor tips.
The microchannels provide microscopic volumes, much less than a microliter, in which analysis is carried out. The instrument features a microchip handler, with relative motion of the microchip with respect to a pipettor, electrodes, and detector. In some instances the microchip is moved, while in other instances, the other components are moved. There is a sequence of automatic operations involving placing a sample-free microchip on a chuck, loading samples with a pipetting device into the microchip, contacting microchannels in the microchip with electrodes, injecting samples into the separation microchannels, running an electrophoretic separation, detecting and measuring the separation, and then removing the microchip. In a preferred embodiment, a microchip, pre-filled with matrix or other separation media but not sample, is held in a vacuum chuck which is movable with high precision on a first Y-axis track from a sample loading station to a sample analysis station.
In a preferred embodiment, the microchannels of the microchip are filled beforehand with matrix or other separation media that acts as a sieve to enhance sample separation. If the microchip substrate has already been used for molecular separation and chemical analysis and is in need of cleaning, an apparatus is used to clean and vacuum the inlet ports and to pump out the old matrix within the microchannels to the inlet ports for vacuuming before filling the microchip with new matrix. If the microchip sub
Armstrong Thomas M.
Harris Dennis W.
Johnston Richard F.
Jovanovich Stevan B.
Loder, Jr. Robert T.
Amersham Biosciences (SV) Corp.
Quan Elizabeth
Schneck David M.
Schneck Thomas
Warden Jill
LandOfFree
Apparatus and method for filling and cleaning channels and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for filling and cleaning channels and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for filling and cleaning channels and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3211053