Staff member

Laura González Claramonte

PhD Student
+34 934 039 163
Staff member publications

Botaya, Luis, Otero, Jorge, González, Laura, Coromina, Xavier, Gomila, Gabriel, Puig-Vidal, Manel, (2015). Quartz tuning fork-based conductive atomic force microscope with glue-free solid metallic tips Sensors and Actuators A: Physical 232, 259-266

Abstract Here, we devise a conductive Atomic Force Microscope (C-AFM) based on quartz tuning forks (QTFs) and metallic tips capable of simultaneously imaging the topography and conductance of a sample with nanoscale spatial resolution. The system is based on a header design which allows the metallic tip to be placed in tight and stable mechanical contact with the QTF without the need to use any glue. This allows electrical measurements to be taken with an electrically excited QTF with the two prongs free. The amplitude oscillation of the QTF is used to control the tip-sample distance and to acquire the topographic images. Meanwhile, the metallic tip is connected to a current–voltage amplifier circuit to measure the tip-sample field emission/tunneling current and to produce the conductive images. This method allows decoupled electrical measurement of the topography and electrical properties of the sample. The results we obtain from calibration samples demonstrate the feasibility of this measurement method and the adequacy of the performance of the system.

Keywords: AFM, Conductive AFM, Quartz tuning fork

González, L., Otero, J., Agusil, J. P., Samitier, J., Adan, J., Mitjans, F., Puig-Vidal, M., (2014). Micropattern of antibodies imaged by shear force microscopy: Comparison between classical and jumping modes Ultramicroscopy 136, 176-184

Quartz tuning fork devices are increasingly being used as nanosensors in Scanning Probe Microscopy. They offer some benefits with respect to standard microfabricated cantilevers in certain experimental setups including the study of biomolecules under physiological conditions. In this work, we compare three different working modes for imaging micropatterned antibodies with quartz tuning fork sensors: apart from the classical amplitude and frequency modulation strategies, for first time the jumping mode is implemented using tuning forks. Our results show that the molecules suffer less degradation when working in the jumping mode, due to the reduction of the interaction forces.

Otero, J., Baños, R., González, L., Torrents, E., Juárez, A., Puig-Vidal, M., (2013). Quartz tuning fork studies on the surface properties of Pseudomonas aeruginosa during early stages of biofilm formation Colloids and Surfaces B: Biointerfaces 102, 117-123

Scanning probe microscopy techniques are powerful tools for studying the nanoscale surface properties of biofilms, such as their morphology and mechanical behavior. Typically, these studies are conducted using atomic force microscopy probes, which are force nanosensors based on microfabricated cantilevers. In recent years, quartz tuning fork (QTF) probes have been used in morphological studies due to their better performance in certain experiments with respect to standard AFM probes. In the present work QTF probes were used to measure not only the morphology but also the nanomechanical properties of Pseudomonas aeruginosa during early stages of biofilm formation. Changes in bacterium size and the membrane spring constant were determined in biofilms grown for 20, 24 and 28. h on gold with and without glucose in the culture media. The results obtained using the standard AFM and QTF probes were compared. Both probes showed that the bacteria forming the biofilm increased in size over time, but that there was no dependence on the presence of glucose in the culture media. On the other hand, the spring constant increased over time and there was a clear difference between biofilms grown with and without glucose. This is the first time that QTF probes have been used to measure the nanomechanical properties of microbial cell surfaces and the results obtained highlight their potential for studying biological samples beyond topographic measurements.

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