Development of Microfluidic Chip Technology for Spatial Three-Dimensional Liquid Chromatography

Multidimensional liquid chromatographic separations strategies are advancing towards higher separation performances, driven by the analysis of contemporary life-science samples used in biomarker discovery studies. These samples are typically characterized by a large sample complexity (often containing ~1,000,000 compounds) and broad dynamic range, requiring separation technology which provides the resolution required for the identification and quantification of all compounds present in a complex sample mixture.
A microfluidic device for spatial three-dimensional LC holds the promise to provide ultra-high peak capacities. In spatial 3D-LC chromatography components are separated inside the microchannels of the device with each peak being characterized by its X, Y, and Z coordinates in the separation body. Furthermore, due to parallel developments of all fractions in the second- and third-dimension separations, the analysis time is greatly reduced compared to conventional column-coupled multi-dimensional LC approaches. The different design aspects to create spatial multi-dimensional chip technology will be discussed, including flow distributor design and channel layout. During the different developments in X-, Y-, and Z-direction, the analytes and therefore also the flow should not convolute in other dimensions. Aspects of flow control mechanisms, which includes the use of physical barriers to achieve flow control, and implementation of polymer-monolithic stationary phases, will be discussed. We extended an earlier introduced concept, in which active flow confinement is achieved by applying a rotating interface. To allow for automated process operation, mechanisms applying advanced robotics have been successfully integrated on-chip. Furthermore, approaches to integrate functionalized monolithic stationary phases inside the microfluidic device have been realized, which are essential to realize a spatial 3D-LC separation.