Dispositivos sob demanda: desenvolvimento de sistemas microfluídicos e sensores eletroquímicos por impressão 3D

Abstract

3D printing technology has been widely explored as an alternative method of manufacturing analytical microdevices. This technology has been solving many limitations of conventional microfabrication techniques due to its ability to build microstructures with different materials and geometries in a simple, fast and low-cost way. In this sense, this thesis describes the use of 3D printing to manufacture analytical platforms for applications involving counting E. coli cells embedded in droplets based on contactless conductometric detection (C4D), online monitoring of chemical reactions by mass spectrometry (MS) and estradiol detection in electrochemical analysis. For C4D measurements, microfluidic devices were printed containing Tjunction microchannels and two electrodes integrated in the antiparallel arrangement. The droplets with incorporated cells were monitored in real time using the C4D system. The proposed approach demonstrated the ability to detect E. coli cells in the concentration range between 86.5 and 8650 CFU droplet-1 with a detection limit of 63.66 CFU droplet-1. For the development of the miniaturized reactor used in the monitoring of chemical reactions by MS, a microfluidic device was built containing a channel in the shape of a 3D serpentine and another one containing a channel in the Y-shaped. Both devices were evaluated for monitoring the Katritzky reaction, injecting simultaneously 2,4,6-triphenylpriryllium (TPP) and amino acid (glycine or alanine) solutions and the reaction product were monitored online by MS at different flow rates. The acquired spectra demonstrated that the relative abundances of the products obtained with the device containing the 3D serpentine channel had an order of magnitude up to three times greater than those obtained with the Y-shaped device. The device performance in 3D serpentine was also evaluated comparing with the traditional ESI(+)-MS technique. The 3D serpentine printed reactor promoted the reaction quickly and with a higher rate of product formation compared to the ESI(+)- MS technique. The electrochemical cell containing integrated electrodes was entirely manufactured by 3D printing. The electrochemical device was manufactured in a single step with a manufacturing time of 12 min and a cost of US$ 0.08. Preliminary tests for the detection of 17β - estradiol by DPV reached an LOD of 0.1 μmol L-1 and an analytical curve with a linear range of 0.19 to 25 μmol L-1. These results demonstrate the excellent versatility of 3D printing technology being applied in different areas of bioanalytical chemistry. The counting method of counting bacteria, the device for online monitoring of chemical reactions, as well as the electrochemical cell for detection of hormones offer instrumental simplicity, low cost, high sensitivity, allowing the opening of new application possibilities in different areas of chemistry.