Category: Micro- and Nanotechnologies
The fabrication of microfluidic devices using low-cost alternative materials has received great attention for applications in several fields including clinical, bioanalytical, environmental, and forensic analysis. This study describes for the first time the fabrication and application of a fully disposable ($ 0.30) polyester-based microfluidic device for flow injection analysis with screen-printed graphite electrodes coupled with amperometric detection. The device was assembled using three layers of polyester films, which are often used for laminating. The bottom layer was used as base and support for graphite electrodes. The middle, or intermediate, layer was cut with using a cutting printer (Silhouette Cameo 3) to create the microfluidic channel. Finally, the upper layer was used to promote the sealing of the microfluidic channel leaving the fluid inlet and outlet holes open as well as the point of injection of the sample. The three layers of polyester were aligned and laminated at 160 °C through thermal laminator. The electrodes were made from a mix of graphite powder and enamel base, and then screen-printed on the surface of the bottom layer through a cut-out mask in the chosen configuration (1.5 cm × 1.0 mm and spacing 1.0 mm). The device was designed in a straight microfluidic channel with 6 cm length. The channel width ranged from 300 to 700 μm keeping constant the channel depth equal to 175 μm. To promote the fluid in and out, Syringe needles were glued to the upper layer of the device to promote the connections between the device syringe pumps for handling the solution inside microchannels. The sample introduction was performed hydrodynamically through an electronic pipette coupled to the upper layer of the device at distance of 1.5 cm from the electrolyte inlet. The injection volume (1-5 μL), the dispensing speed (4-28 μL s-1) and the flow rate (30-240 μL/min) were systematically optimized using 5 mmol L-1 Fe(CN)6 4-/Fe(CN)63- as redox probe, previously prepared in 0.5 mol L-1 KCl. The proposed device exhibited great analytical performance under the optimized conditions (volume = 1 μL; dispensing speed = 4 μL s-1; flow rate = 60 μL/min). The analytical frequency and relative standard deviation for injection-to-injection repeatability (n = 20) were 250 inj/h and 7.3%, respectively. Considering the reported preliminary data, the proposed device offers great potentiality for studies in bioanalytical, forensic, clinical and environmental applications. Furthermore, the microfabrication in polyester films makes possible the integration of other analytical tools including analytical separation towards the development of a fully integrated microfluidic device with sample-in-answer-out capability in this low-cost platform.
Cyro Chagas– PhD Student, Universidade Federal de Goiás, Anapolis, Goias, Brazil
Universidade Federal de Goiás
Anapolis, Goias, Brazil
Cyro L. S. Chagas is graduated in Industrial Chemistry from the State University of Goiás, Brazil (2009) and received his M.Sc. from the same university in 2013. Currently, he is a forth-year PhD student in Chemistry at the Federal University of Goiás. His current interests are microfabrication, electrophoresis and microfluidic devices for bioanalytical and environmental analyzes.