[nanoPost] Devices and Methods for Improving the Injection of Liquid Samples

University USA

Background:
Separation and detection of substance in fluids require injection of a plug of sample fluid into a separation column. Chip-based injections of samples for chemical and biological analysis have traditionally relied on open channel geometries like double-T and double-L methods to define the injection zone or upon isoelectric focusing (IEF), also called pinched injection. The double-T and double-L injections result in injection of sample plugs of greater axial extent than the width of the sample introduction channel resulting in sample loss. In IEF injection, the sample is isoelectrically confined to control the initial distribution of the analyte in an open intersection, giving sharp bands. While the focusing potentials reduce the injection sample volume, they pinch the sample with electroosmotic flows from two arms of a separation channel. The current methods thus result in undesirable asymmetry and sample loss as well as reduced quality in the actual measuring of the samples.

Novel technology:

The invention presents a new way, using microfluidic electrokinetic systems, to introduce rectangular zones of sample for analysis. The technology uses a structure that produces anisotropic flow under an applied electric field which reduces the sample loss and also increases the possible resolution in the analysis itself. The invention is furthermore amenable to any material from which microfluidic chips are made, and should be very easily incorporated into existing microfluidic chip designs.

Commercial Applications:

The technology is valuable in any situation where controlled injection of fluids is of importance. This is especially the case in drug discovery systems, high-throughput chemical analysis and other forms of chemical synthesis and analysis.

Advantages:

Delivers a rectangular injection sample which results in higher resolution

Minimizes sample loss

The method can make injections of narrow bands which creates higher resolution

Easy to use