A micromachined system for the separation of molecules using thermal field-flow fractionation method

All silicon-glass micromachined thermal field-flow fractionation (TFFF) microsystem has been developed and presented for the first time. The device consists of seven layers of double side, deep, selectively etched silicon and glass substrates, bonded anodically. The built-in fluidic heater and cooler allows producing the high thermal gradient. In the 30 mum deep, 2 mm wide and 50 mm long separation channel, the temperature gradient 1.5 x 10(6) K/m, has been obtained for relatively low heating agent temperature (similar to343 K). The TFFF microsystem has been equipped with two integrated, three-electrodes conductivity detectors. Some basic separation properties have been evaluated for low concentrated KCl test samples in water. It has been found that retention time of 0.6 mul sample of 0.01 M KCl in water, for 293/321 K (cooling/heating agents) compared to 0.9 X 10(6) K/m, is almost two times longer than it has been obtained in the device during the absence of the temperature gradient. (C) 2003 Elsevier B.V. All rights reserved.