Fabrication and testing of interdigitated microelectrode arrays whose structure includes non-cytotoxic hydrogenated amorphous silicon-carbon alloy (a-Si x C 1-x :H) as the surface to be biofunctionalized for capturing enteropathogenic Escherichia coli (E. coli, EPEC) are presented. a-Si x C 1-x :H films were obtained by enhanced chemical vapor deposition (PECVD). The extract method was used to assess the cytotoxicity of the films. The design of the PIMAs includes two layers of a-Si x C 1-x :H, one intrinsic layer deposited onto silicon dioxide (SiO 2 ) before evaporating titanium (Ti), and one doped layer deposited onto the Ti-microelectrodes. Electrical impedance spectroscopy (EIS) was used to know the effects of the biofunctionalization layer, conductivity of the medium and any capture of bacteria by antibodies on the microelectrodes. According to the results, the high hydrogen dilution contributes to low incorporation of CH n groups improving the non cytotoxicity of the films, and the capture of bacteria on the microelectrodes improves the sensitivity. It manifests itself as a shift of the low cutoff frequency (F low ) of the impedance spectrum to the right, allowing the device to sense at frequencies lower than F low . A percentage change in impedance of 1600% at 100 Hz was obtained after 5 minutes in contact with medium with EPEC concentration of 8.5 × 10 8 CFU/mL.

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Abstract-A biofunctionalization process of a-SiC:H surfaces has been applied to an interdigitated microelectrode array (IMA) whose microelectrodes are covered by this material. The biofunctionalization process has been monitored stage by stage using Fourier transform infrared spectroscopy (FTIR), while its effects on the electrical behavior of the IMA were recorded in electrical impedance spectra. The process involves hydroxylation, silanization, generation of aldehyde groups, binding via protein A, immobilization of anti-Escherichia coli polyclonal antibodies, entrapping and detection of enterotoxigenic Escherichia coli (ETEC) in Luria-Bertani medium. The FTIR spectra confirm the success of the process. Regarding the performance of the IMA, although the detection of ETEC is successful and its percentage change in impedance reaches a value of 133.37% to 10 7 CFU/mL, some considerations may be taken into account to improve the sensitivity of the IMA by mean of the optimization of both the IMA design and the biofunctionalization process.Keywords-Hydrogenated amorphous silicon carbide, biofunctionalization process, enterotoxigenic Escherichia coli, Fourier transform infrared spectroscopy, electrical impedance spectroscopy.