Influence of channel position on sample confinement in two-dimensional planar microfluidic devices.

We report enhanced sample confinement on microfluidic devices using a combination of electrokinetic flow from adjacent control channels and electric field shaping with an array of channels perpendicular to the sample stream. The basic device design consisted of a single first dimension (1D) channel, intersecting an array of 32 or 96 parallel second dimension (2D) channels. To minimize sample dispersion and leakage into the parallel channels as the sample traversed the sample transfer region, control channels were placed to the left and right of the 1D and waste channels.

Electrokinetic fluid control in two-dimensional planar microfluidic devices.

We present microfluidic device designs with a two-dimensional planar format and methods to facilitate efficient sample transport along both dimensions. The basic device design consisted of a single channel for the first dimension which orthogonally intersected a high-aspect ratio second-dimension channel. To minimize dispersion of sample moving into and through the sample transfer region, control channels were placed on both sides of the first-dimension channel, and the electrokinetic flow from these control channels was used to confine the sample stream.

Detection of nitrated benzodiazepines by indirect laser-induced fluorescence detection on a microfluidic device.

Recently there has been concern regarding the use of flunitrazepam and other low-dose benzodiazepines in drug-facilitated sexual assault. These compounds are placed in drinks of unsuspecting victims and produce a sedative effect with anterorgrade amnesia. Chip-based microfluidic systems can provide a quick and disposable procedure for the detection of flunitrazepam and other nitrated benzodiazepines used in these crimes.

Micellar electrokinetic chromatographic screening method for common sexual assault drugs administered in beverages.

Recently, much attention has been given to benzodiazepines and gamma-hydroxybutyric acid (GHB) related compounds owing to their alleged widespread use as date-rape drugs. Toxicologists would greatly benefit from a screening method that allows for the simultaneous detection of both groups of substances. A new capillary electrophoresis (CE) method has been developed in the micellar mode to accomplish this separation in under 16 min using a sodium dodecyl sulfate (SDS)/sodium tetraborate/boric acid buffer with an acetonitrile organic modifier.