Abstract: Methods and systems that employ hybrid fluid flow profiles for optimized movement of materials through channel networks. These systems employ hybrid pressure-based and electrokinetic based flow systems for moving materials through interconnected channel networks while maintaining interconnection among the various channel segments. In particular, the invention is generally directed to channel networks where flow in a first channel segment is driven by pressure flow with its consequent parabolic flow profile, while flow in an interconnected channel segment is dominated by electrokinetic flow with its consequent plug flow profile. The invention also provides channel networks wherein fluid flow in channel segments is driven by both pressure and electric field and the multiple species contained in a fluid plug are separated by altering the applied pressure and electric fields in the various channel segments of the channel networks.

Abstract: Methods for monitoring time dependent reactions that comprise providing a flow channel, typically microscale in dimension, flowing at least two reagents into the flow channel and varying the flow rate of the mixture through the flow channel. By increasing and/or decreasing the flow rate of the reagent mixture from the point of mixing to the point of detection, one alters the amount of reaction time, allowing monitoring reaction kinetics over time.

Abstract: Microfluidic devices, systems, and methods measure viscosity, flow times, and/or other flow characteristics within the channels, and the measured flow characteristics can be used to generate a desired flow. Multi-reservoir pressure modulator and pressure controller systems, electrokinetic systems and/or other fluid transport mechanisms can generate the flow, controllably mix fluids, and the like.

Abstract: Methods for monitoring time dependent reactions that comprise providing a flow channel, typically microscale in dimension, flowing at least two reagents into the flow channel and varying the flow rate of the mixture through the flow channel. By increasing and/or decreasing the flow rate of the reagent mixture from the point of mixing to the point of detection, one alters the amount of reaction time, allowing monitoring reaction kinetics over time.

Abstract: Methods of concentrating materials within microfluidic channel networks by moving materials into regions in which overall velocities of the material are reduced, resulting in stacking of the material within those reduced velocity regions. These methods, devices and systems employ static fluid interfaces to generate the differential velocities, as well as counter-current flow methods, to concentrate materials within microscale channels.

Abstract: Microfluidic devices, systems, and methods measure viscosity, flow times, and/or pressures. other flow characteristics within the channels, and the measured flow characteristics can be used to generate a desired flow. Multi-reservoir pressure modulator and pressure controller systems, electrokinetic systems and/or other fluid transport mechanisms can generate the flow, controllably mix fluids, and the like.

Abstract: Microfluidic devices and systems having enhanced detection sensitivity, particularly for use in non-fluorogenic detection methods, e.g., absorbance. The systems typically employ planar microfluidic devices that include one or more channel networks that are parallel to the major plane of the device, e.g., the predominant plane of the planar structure, and a detection channel segment that is substantially orthogonal to that plane. The detection system is directed along the length of the detection channel segment using a detection orientation that is consistent with conventional microfluidic systems.

Abstract: Microfluidic devices and systems having enhanced detection sensitivity, particularly for use in non-fluorogenic detection methods, e.g., absorbance. The systems typically employ planar microfluidic devices that include one or more channel networks that are parallel to the major plane of the device, e.g., the predominant plane of the planar structure, and a detection channel segment that is substantially orthogonal to that plane. The detection system is directed along the length of the detection channel segment using a detection orientation that is consistent with conventional microfluidic systems.

Abstract: Methods, apparatus and systems are provided for introducing large numbers of different materials into a microfluidic analytical device rapidly, efficiently and reproducibly. In particular, improved integrated pipettor chip configurations, e.g. sippers or electropipettors, are described which are capable of sampling extremely small amounts of material for which analysis is desired, transporting material into a microfluidic analytical channel network, and performing the desired analysis on the material.

Abstract: Methods of concentrating materials within microfluidic channel networks by moving materials into regions in which overall velocities of the material are reduced, resulting in stacking of the material within those reduced velocity regions. These methods, devices and systems employ static fluid interfaces to generate the differential velocities, as well as counter-current flow methods, to concentrate materials within microscale channels.

Abstract: Improved microfluidic devices, systems, and methods allow selective transportation of fluids within microfluidic channels of a microfluidic network by applying, controlling, and varying pressures at a plurality of reservoirs. Modeling the microfluidic network as a series of nodes connected together by channel segments and determining the flow resistance characteristics of the channel segments may allow calculation of fluid flows through the channel segments resulting from a given pressure configuration at the reservoirs. To effect a desired flow within a particular channel or series of channels, reservoir pressures may be identified using the network model. Viscometers or other flow sensors may measure flow characteristics within the channels, and the measured flow characteristics can be used to calculate pressures to generate a desired flow. Multi-reservoir pressure modulator and pressure controller systems can optionally be used in conjunction with electrokinetic or other fluid transport mechanisms.

Abstract: Methods for monitoring time dependent reactions that comprise providing a flow channel, typically microscale in dimension, flowing at least two reagents into the flow channel and varying the flow rate of the mixture through the flow channel. By increasing and/or decreasing the flow rate of the reagent mixture from the point of mixing to the point of detection, one alters the amount of reaction time, allowing monitoring reaction kinetics over time.

Abstract: An improved echelle spectrometer comprises a slit in light blocking plate, an echelle grating, and a detector array. The slit is shaped and oriented to align an image of a light beam projected through the slit, onto the echelle grating and onto the detector in a desired orientation and shape relative to the detector array. Precise adjustment of the shape and orientation of the slit is dependent on the orientation of the detector with respect to the dispersion direction of the echelle grating. The echelle spectrometer provides high detector resolution with reduced read-out time.

Abstract: A solid-state detector for use in an atomic spectrometer comprises a plurality of arrays of sensing elements, or pixels, each of the arrays being positioned along and on the locations of spectral signals on a focal plane of an echelle grating spectrometer. The sensing elements are positioned along the many diffraction orders presented on a two-dimensional echelle grating focal plane so that at least one element is located at each and every resolution element regardless of global x-y coordinate positioning of the elements or with reference to each other. The result is a series of skewed lines of sensing elements, those lines being in the same shape as the series of diffraction order lines which comprise an echelle spectrum. The solid-state detector is particularly useful in an atomic spectrometer wherein an echelle grating is used to diffract incident radiation such that the various components of the radiation may be observed.

Abstract: On-column optical detection apparatus and method for use with capillary separation columns are shown. The apparatus and method minimize the adverse effects of light scattered from the walls of the column, thereby improving detection sensitivity and providing greater dynamic range. Light from a conventional source is focussed onto a column. Spatial filter means are positioned in front of the column to prevent at least some light from striking the column wall. Another spatial filter is positioned in front of a light collecting means which gathers light emanating from the column. In a specific embodiment, a unique monolens design is shown comprising collecting and focussing lens formed as an integral unit with a bore for a capillary column.

Abstract: The method for improving sample concentration in capillary electrophoresis by extracting the sample buffer from the capillary column using the electro-osmotic flow while the sample components are stacked into the support buffer utilizes a system for this technique. The system has a separation column 11, sample introduction means 16 for injecting the sample solution, an injection detector means 20 for detecting the volume of injected sample solution, a separation detector means 21 for detecting the sample components, power supply means 17 for applying a high voltage along the separation column 11 for reversing the direction of the electro-osmotic flow thereby causing extraction of the sample buffer from the separation column and afterward providing the separation sample into its components.

Abstract: An improved electroinjection method of introducing a sample having positive and negative ions into a capillary column for CE or CZE process by introducing a short plug of a low concentration buffer before introducing the sample into the column which results in increasing amount of charged ions of the sample introduced in the capillary column due to increasing the electric field at the injection point. A method for efficiently introducing both positive and negative ions is also shown.