IMEC and Vrije Universiteit Brussel (VUB) built and demonstrated an on-wafer liquid phase chromatograph using sub-micron micromachining at last week's IEEE International Electron Devices Meeting. The device shows a five- to 10-fold increase in speed of analysis and an improved separation capacity compared to macroscopic chromatographs, according to an IMEC release Liquid phase chromatography is used to separate and identify molecules. Biochemistry labs, for example, use it to separate proteins. The molecules, which are suspended in a liquid, are separated when forced through macroscopic columns filled with micron-sized, randomly packed spherical particles. IMEC and VUB's sub-micro chromatograph validates fluid dynamic computations that predict that injecting molecules though a submicron maze of perfectly ordered structures will increase the separation speed of liquid phase chromatography. The device, which was implemented on a 200-mm Si wafer, has 56 separation channels with a length of 4 cm, a width of 50-150 µm, and a depth of 5-18 µm. The channels are packed with vertical micro-cylinders. These pillars are 1-5 µm thick, are separated by gaps of 1-0.1 µm, and have an identical shape, size, and distance within individual channels. Its performance was tested by injecting a fluid with tracer molecules in the chromatograph and following the velocity and width of the resulting tracer band. Researchers found that in the sub-micro chromatograph — unlike in macro-chromatographs — the separation does not degrade with higher velocities of molecule transport.