by Keyword: scanning dielectric microscopy

Checa, Marti, Jin, Xin, Millan-Solsona, Ruben, Neumayer, Sabine M., Susner, Michael A., McGuire, Michael A., OHara, Andrew, Gomila, Gabriel, Maksymovych, Petro, Pantelides, Sokrates T., Collins, Liam, (2022). Revealing Fast Cu-Ion Transport and Enhanced Conductivity at the CuInP2S6?In4/3P2S6 Heterointerface Acs Nano 16, 15347-15357

Checa M, Millan-Solsona R, Mares AG, Pujals S, Gomila G, (2021). Fast Label-Free Nanoscale Composition Mapping of Eukaryotic Cells Via Scanning Dielectric Force Volume Microscopy and Machine Learning Small Methods 5,

Mapping the biochemical composition of eukaryotic cells without the use of exogenous labels is a long-sought objective in cell biology. Recently, it has been shown that composition maps on dry single bacterial cells with nanoscale spatial resolution can be inferred from quantitative nanoscale dielectric constant maps obtained with the scanning dielectric microscope. Here, it is shown that this approach can also be applied to the much more challenging case of fixed and dry eukaryotic cells, which are highly heterogeneous and show micrometric topographic variations. More importantly, it is demonstrated that the main bottleneck of the technique (the long computation times required to extract the nanoscale dielectric constant maps) can be shortcut by using supervised neural networks, decreasing them from weeks to seconds in a wokstation computer. This easy-to-use data-driven approach opens the door for in situ and on-the-fly label free nanoscale composition mapping of eukaryotic cells with scanning dielectric microscopy. © 2021 The Authors. Small Methods published by Wiley-VCH GmbH

JTD Keywords: label-free mapping, machine learning, nanoscale, scanning dielectric microscopy, Biochemical composition, Cells, Constant, Cytology, Data-driven approach, Dielectric forces, Dielectric materials, Eukaryotic cells, Label-free mapping, Machine learning, Mapping, Nanoscale, Nanoscale composition, Nanoscale spatial resolution, Nanotechnology, Scanning, Scanning dielectric microscopy, Supervised neural networks

Balakrishnan H, Millan-Solsona R, Checa M, Fabregas R, Fumagalli L, Gomila G, (2021). Depth mapping of metallic nanowire polymer nanocomposites by scanning dielectric microscopy Nanoscale 13, 10116-10126

Polymer nanocomposite materials based on metallic nanowires are widely investigated as transparent and flexible electrodes or as stretchable conductors and dielectrics for biosensing. Here we show that Scanning Dielectric Microscopy (SDM) can map the depth distribution of metallic nanowires within the nanocomposites in a non-destructive way. This is achieved by a quantitative analysis of sub-surface electrostatic force microscopy measurements with finite-element numerical calculations. As an application we determined the three-dimensional spatial distribution of ?50 nm diameter silver nanowires in ?100 nm-250 nm thick gelatin films. The characterization is done both under dry ambient conditions, where gelatin shows a relatively low dielectric constant, ?r ? 5, and under humid ambient conditions, where its dielectric constant increases up to ?r ? 14. The present results show that SDM can be a valuable non-destructive subsurface characterization technique for nanowire-based nanocomposite materials, which can contribute to the optimization of these materials for applications in fields such as wearable electronics, solar cell technologies or printable electronics. © The Royal Society of Chemistry.

JTD Keywords: composite, constant, electrodes, mode, nanostructures, objects, progress, subsurface, tomography, Composite materials, Dielectric materials, Electric force microscopy, Electrostatic force, Force microscopy, Low dielectric constants, Nanocomposites, Numerical calculation, Polymer nanocomposite, Printable electronics, Scanning dielectric microscopy, Silver nanowires, Solar cell technology, Stretchable conductors, Subsurface characterizations, Transparent electrodes, Wearable technology

Di Muzio M, Millan-Solsona R, Dols-Perez A, Borrell JH, Fumagalli L, Gomila G, (2021). Dielectric properties and lamellarity of single liposomes measured by in-liquid scanning dielectric microscopy Journal Of Nanobiotechnology 19,

Liposomes are widely used as drug delivery carriers and as cell model systems. Here, we measure the dielectric properties of individual liposomes adsorbed on a metal electrode by in-liquid scanning dielectric microscopy in force detection mode. From the measurements the lamellarity of the liposomes, the separation between the lamellae and the specific capacitance of the lipid bilayer can be obtained. As application we considered the case of non-extruded DOPC liposomes with radii in the range ~ 100–800 nm. Uni-, bi- and tri-lamellar liposomes have been identified, with the largest population corresponding to bi-lamellar liposomes. The interlamellar separation in the bi-lamellar liposomes is found to be below ~ 10 nm in most instances. The specific capacitance of the DOPC lipid bilayer is found to be ~ 0.75 µF/cm2 in excellent agreement with the value determined on solid supported planar lipid bilayers. The lamellarity of the DOPC liposomes shows the usual correlation with the liposome's size. No correlation is found, instead, with the shape of the adsorbed liposomes. The proposed approach offers a powerful label-free and non-invasive method to determine the lamellarity and dielectric properties of single liposomes. [Figure not available: see fulltext.].

JTD Keywords: constant, force, lamellarity, liposomes, membrane capacitance, model, nanoscale, scanning dielectric microscopy, Lamellarity, Liposomes, Membrane capacitance, Nanoscale, Polarization properties, Scanning dielectric microscopy

Checa M, Millan‐solsona R, Mares AG, Pujals S, Gomila G, (2021). Dielectric imaging of fixed hela cells by in‐liquid scanning dielectric force volume microscopy Nanomaterials 11,

Mapping the dielectric properties of cells with nanoscale spatial resolution can be an im-portant tool in nanomedicine and nanotoxicity analysis, which can complement structural and mechanical nanoscale measurements. Recently we have shown that dielectric constant maps can be obtained on dried fixed cells in air environment by means of scanning dielectric force volume mi-croscopy. Here, we demonstrate that such measurements can also be performed in the much more challenging case of fixed cells in liquid environment. Performing the measurements in liquid media contributes to preserve better the structure of the fixed cells, while also enabling accessing the local dielectric properties under fully hydrated conditions. The results shown in this work pave the way to address the nanoscale dielectric imaging of living cells, for which still further developments are required, as discussed here.

JTD Keywords: atomic force microscopy (afm), capacitance, constant, dielectric properties, electrostatic force microscopy (efm), functional microscopy, nanoscale, scanning dielectric microscopy (sdm), Atomic force microscopy (afm), Dielectric properties, Dielectrophoretic separation, Electrostatic force microscopy (efm), Functional micros-copy, Scanning dielectric microscopy (sdm), Scanning probe microscopy (spm)

Kyndiah A, Checa M, Leonardi F, Millan-Solsona R, Di Muzio M, Tanwar S, Fumagalli L, Mas-Torrent M, Gomila G, (2021). Nanoscale Mapping of the Conductivity and Interfacial Capacitance of an Electrolyte-Gated Organic Field-Effect Transistor under Operation Advanced Functional Materials 31,

© 2020 Wiley-VCH GmbH Probing nanoscale electrical properties of organic semiconducting materials at the interface with an electrolyte solution under externally applied voltages is key in the field of organic bioelectronics. It is demonstrated that the conductivity and interfacial capacitance of the active channel of an electrolyte-gated organic field-effect transistor (EGOFET) under operation can be probed at the nanoscale using scanning dielectric microscopy in force detection mode in liquid environment. Local electrostatic force versus gate voltage transfer characteristics are obtained on the device and correlated with the global current–voltage transfer characteristics of the EGOFET. Nanoscale maps of the conductivity of the semiconducting channel show the dependence of the channel conductivity on the gate voltage and its variation along the channel due to the space charge limited conduction. The maps reveal very small electrical heterogeneities, which correspond to local interfacial capacitance variations due to an ultrathin non-uniform insulating layer resulting from a phase separation in the organic semiconducting blend. Present results offer insights into the transduction mechanism at the organic semiconductor/electrolyte interfaces at scales down to ≈100 nm, which can bring substantial optimization of organic electronic devices for bioelectronic applications such as electrical recording on excitable cells or label-free biosensing.

JTD Keywords: Atomic force microscopy, Bioelectronic devices, Electrolyte gated organic field effect transistors, In-liquid scanning dielectric microscopy, Organic semiconducting blend