A new polymer microchip is presented in this paper for separation and particle sorting in flowing suspensions. It includes a microchannel where a fluid-sample containing particles flows in parallel with another liquid. The working principle is based on an ultrasonic actuation on the cross-section of the chip, which behaves as a multilayer system. That part of the wave established within the channel includes a node of pressure strategically located within the collector fluid path, where the target particles collected to be extracted from their host sample. The use of a polymer as the constitutive material of the chip, new in this type of devices, allows a channel width somewhat larger than a quarter of a wavelength, which does not fit any of the conventional models but it represents an intermediate situation. The device has been fabricated by standard SU-8 photolithography using PMMA as substrate. In the experiments, polystyrene particles of 20 μm in diameter have been extracted from aqueous suspensions containing 6-μm sized particles by a strategic application of ultrasonic waves. A high efficiency of particle separation, over 95%, at different concentrations and flow rates, prove the feasibility of the device to carry out sorting processes on flowing suspensions.
Bibliographical noteFunding Information:
This trial was performed partly within the Transversal Cancer Action approved by the Council of Ministers on October 11, 2007, in accordance with an agreement between the Carlos III Health Institute and the Biomedical Research Foundation of Hospital of Elche. Part of this research was performed within a National Research Project BIO2008-06843-C04 funded by the Science and Innovation Ministry of Spain.
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- Mass transfer