Continuous extraction of proteins with a miniaturized electrical split-flow cell equipped with suspended splitters fabricated by dry film lamination

This article describes the development of an electrically driven Split-Flow Thin microsystem suitable for continuous-flow protein purification or concentration. We used a technology based on dry film resist, Ordyl SY 355, to realize 3D suspended structures in a microchannel (150 µm), including patterned Cr/Pt electrodes. The device developed for this research is the first electrical miniaturized dry film SPLITT system including suspended splitters and represents a good miniaturization effort of the ideal SPLITT cell, thus expanding the possibilities of realizing split-flow fractionation microfluidic network based on dry film technology. A suitable design and fabrication process for the realization of such a kind of device is reported. The purification/concentration performances of the system have been tested by infusing a Bovine Serum Albumin solution (0.1 weight percentage) through the inlets and evaluating the protein content at the outlets after the application of a pulsed electric potential. Experimental conditions have been changed during the testing phase, by varying the applied potential and the duty cycle of the square wave and the flow rate to find suitable conditions for protein extraction. The best-achieved purification/concentration rate was around 60%, measured as concentration difference between the two output channels normalized on the input concentration, thus confirming the viability of device for protein enrichment or purification for sample preparation. The device has a potential for integration in micro-TAS, thanks to its reduced dimensions, for applications involving protein analysis or bio-sensing in matrices including proteins interfering with the measurement.