Production of micro-channels with an integrated porous membrane by ultrasonic hot Embossing

Abstract

[ES] Currently, a polymer chip (Fig. 1.1) is being developed for the analysis of cells together with the University of Kaiserslautern. It is about a micro total analysis system (μTAS) which will integrate the functions of a lab on a chip just in a few centimetres. This chip consists of micro-channels with an intermediate porous membrane, a micro reactor, optical fiber for the coupling into a spectrometer and a gold surface for detecting the electrical conductance. For the analysis, a cell is introduced into the micro reactor and then gets destroyed by an ultrasonic impulse. The remains of cell are filtered by a membrane and can be analyzed. This work focuses on the production of a system of two micro-channels with an intermediate porous membrane. These micro systems were produced by ultrasonic hot embossing and ultrasonic welding out of polycarbonate (PC) and polyvinylidene fluoride (PVDF). Once a micro-channel had been created, the porous membrane was welded on top. It then was closed by welding another micro-channel on top. The produced micro-systems were tested regarding their leakproofness and permeability. In the production of PC micro-channels systems, this test was made using 10 micro-systems and was obtained that 40 % of them worked properly getting an error between 10% and 40%, while 60% of them obtained an error between 68% and 89 %. Ten PVDF micro-channels systems were produced. Five of them worked properly. Protein permeability tests were carried out to verify if proteins can pass through the micro-system. The test was made with a PVDF micro-system and using serumalbumin (BSA) and α-Lactalbumin as proteins. The 61 % of BSA passed through the membrane, but it should no pass because it has the size 66 kDa, while the pore size of the Membrane was 40 kDa. α-Lactalbumin has the size of 14 kDa. Therefore the 90 % passed through the membrane.