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Gupta P, Ruzicka E, Benicewicz BC, Sundararaman R, Schadler LS. Dielectric Properties of Polymer Nanocomposite Interphases Using Electrostatic Force Microscopy and Machine Learning. ACS APPLIED ELECTRONIC MATERIALS 2023; 5:794-802. [PMID: 36873258 PMCID: PMC9979787 DOI: 10.1021/acsaelm.2c01331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 12/27/2022] [Indexed: 06/18/2023]
Abstract
Knowing the dielectric properties of the interfacial region in polymer nanocomposites is critical to predicting and controlling dielectric properties. They are, however, difficult to characterize due to their nanoscale dimensions. Electrostatic force microscopy (EFM) provides a pathway to local dielectric property measurements, but extracting local dielectric permittivity in complex interphase geometries from EFM measurements remains a challenge. This paper demonstrates a combined EFM and machine learning (ML) approach to measuring interfacial permittivity in 50 nm silica particles in a PMMA matrix. We show that ML models trained to finite-element simulations of the electric field profile between the EFM tip and nanocomposite surface can accurately determine the interface permittivity of functionalized nanoparticles. It was found that for the particles with a polyaniline brush layer, the interfacial region was detectable (extrinsic interface). For bare silica particles, the intrinsic interface was detectable only in terms of having a slightly higher or lower permittivity. This approach fully accounts for the complex interplay of filler, matrix, and interface permittivity on the force gradients measured in EFM that are missed by previous semianalytic approaches, providing a pathway to quantify and design nanoscale interface dielectric properties in nanodielectric materials.
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Affiliation(s)
- Praveen Gupta
- College
of Engineering and Mathematical Sciences, University of Vermont, Burlington, Vermont05405, United States
- Department
of Materials Science and Engineering, Rensselaer
Polytechnic Institute, Troy, New York12180, United States
| | - Eric Ruzicka
- College
of Arts and Sciences, University of South
Carolina, Columbia, South Carolina29208, United States
| | - Brian C. Benicewicz
- College
of Arts and Sciences, University of South
Carolina, Columbia, South Carolina29208, United States
| | - Ravishankar Sundararaman
- Department
of Materials Science and Engineering, Rensselaer
Polytechnic Institute, Troy, New York12180, United States
| | - Linda S. Schadler
- College
of Engineering and Mathematical Sciences, University of Vermont, Burlington, Vermont05405, United States
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2
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Lozano H, Millan-Solsona R, Blanco-Cabra N, Fabregas R, Torrents E, Gomila G. Electrical properties of outer membrane extensions from Shewanella oneidensis MR-1. NANOSCALE 2021; 13:18754-18762. [PMID: 34747424 DOI: 10.1039/d1nr04689f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Shewanella oneidensis MR-1 is a metal-reducing bacterium that is able to exchange electrons with solid-phase minerals outside the cell. These bacterial cells can produce outer membrane extensions (OMEs) that are tens of nanometers wide and several microns long. The capability of these OMEs to transport electrons is currently under investigation. Tubular chemically fixed OMEs from S. oneidensis have shown good dc conducting properties when measured in an air environment. However, no direct demonstration of the conductivity of the more common bubble-like OMEs has been provided yet, due to the inherent difficulties in measuring it. In the present work, we measured the electrical properties of bubble-like OMEs in a dry air environment by Scanning Dielectric Microscopy (SDM) in force detection mode. We found that at the frequency of the measurements (∼2 kHz), OMEs show an insulating behavior, with an equivalent homogeneous dielectric constant εOME = 3.7 ± 0.7 and no dephasing between the applied ac voltage and the measured ac electric force. The dielectric constant measured for the OMEs is comparable to that obtained for insulating supramolecular protein structures (εprotein = 3-4), pointing towards a rich protein composition of the OMEs, probably coming from the periplasm. Based on the detection sensitivity of the measuring instrument, the upper limit for the ac longitudinal conductivity of bubble-like OMEs in a dry air environment has been set to σOME,ac < 10-5 S m-1, a value several orders of magnitude smaller than the dc conductivity measured in tubular chemically fixed OMEs. The lack of conductivity of bubble-like OMEs can be attributed to the relatively large separation between cytochromes in these larger OMEs and to the suppression of cytochrome mobility due to the dry environmental conditions.
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Affiliation(s)
- Helena Lozano
- Nanoscale bioelectric characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain.
| | - Ruben Millan-Solsona
- Nanoscale bioelectric characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain.
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franqués 1, 08028, Barcelona, Spain
| | - Nuria Blanco-Cabra
- Bacterial infections and antimicrobial therapies, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain
| | - Rene Fabregas
- Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
| | - Eduard Torrents
- Bacterial infections and antimicrobial therapies, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain
| | - Gabriel Gomila
- Nanoscale bioelectric characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain.
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franqués 1, 08028, Barcelona, Spain
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Wang S, Luo Z, Liang J, Peng S, Hu J, He J, Li Q. Nanoscale mapping of electric polarizability in a heterogeneous dielectric material with surface irregularities. NANOTECHNOLOGY 2021; 32:505711. [PMID: 34525468 DOI: 10.1088/1361-6528/ac26ff] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 09/15/2021] [Indexed: 06/13/2023]
Abstract
Nanoscale mapping of electric polarizability in a heterogeneous dielectric material with surface irregularities is of scientific and technical significance, but remains challenging. Here, we present an approach based on intermodulation electrostatic force microscopy (EFM) in conjunction with finite element computation for precise and high-resolution mapping of polarizability in dielectric materials. Instead of using electrostatic force in conventional quantitative EFM approaches, the force gradient is acquired to achieve an unprecedented spatial resolution. In the meantime, the finite element model is applied to eliminate the interference from the heterogeneity and surface irregularity of the sample. This approach directly reveals the high polarization ability of the amorphous region in a ferroelectric, semi-crystalline polymer with significant surface roughness, i.e. poly (vinylidene fluoride-co-chlorotrifluoroethylene), in which the result is consistent with the predicted data in the latest research. This work presenting a quantitative approach to nanoscale mapping of electric polarizability with unprecedented spatial resolution may help to reveal the complex property-structure correlation in heterogeneous dielectric materials.
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Affiliation(s)
- Shaojie Wang
- State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing, People's Republic of China
| | - Zhen Luo
- State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing, People's Republic of China
| | - Jiajie Liang
- State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing, People's Republic of China
| | - Simin Peng
- State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing, People's Republic of China
| | - Jun Hu
- State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing, People's Republic of China
| | - Jingliang He
- State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing, People's Republic of China
| | - Qi Li
- State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing, People's Republic of China
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Checa M, Millan-Solsona R, Mares AG, Pujals S, Gomila G. Fast Label-Free Nanoscale Composition Mapping of Eukaryotic Cells Via Scanning Dielectric Force Volume Microscopy and Machine Learning. SMALL METHODS 2021; 5:e2100279. [PMID: 34928004 DOI: 10.1002/smtd.202100279] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/28/2021] [Indexed: 06/14/2023]
Abstract
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.
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Affiliation(s)
- Martí Checa
- Nanoscale Bioelectrical Characterization Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer Baldiri i Reixac 11-15, Barcelona, 08028, Spain
| | - Ruben Millan-Solsona
- Nanoscale Bioelectrical Characterization Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer Baldiri i Reixac 11-15, Barcelona, 08028, Spain
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, Carrer Martí i Franquès 1, Barcelona, 08028, Spain
| | - Adrianna Glinkowska Mares
- Nanoscopy for Nanomedicine Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer Baldiri i Reixac 11-15, Barcelona, 08028, Spain
| | - Silvia Pujals
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, Carrer Martí i Franquès 1, Barcelona, 08028, Spain
- Nanoscopy for Nanomedicine Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer Baldiri i Reixac 11-15, Barcelona, 08028, Spain
| | - Gabriel Gomila
- Nanoscale Bioelectrical Characterization Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer Baldiri i Reixac 11-15, Barcelona, 08028, Spain
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, Carrer Martí i Franquès 1, Barcelona, 08028, Spain
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Balakrishnan H, Millan-Solsona R, Checa M, Fabregas R, Fumagalli L, Gomila G. Depth mapping of metallic nanowire polymer nanocomposites by scanning dielectric microscopy. NANOSCALE 2021; 13:10116-10126. [PMID: 34060583 DOI: 10.1039/d1nr01058a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
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, εr∼ 5, and under humid ambient conditions, where its dielectric constant increases up to εr∼ 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.
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Affiliation(s)
- Harishankar Balakrishnan
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain.
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Lee H, Shin K, Moon W. Capacitive Measurements of SiO 2 Films of Different Thicknesses Using a MOSFET-Based SPM Probe. SENSORS 2021; 21:s21124073. [PMID: 34199213 PMCID: PMC8231994 DOI: 10.3390/s21124073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/09/2021] [Accepted: 06/09/2021] [Indexed: 11/18/2022]
Abstract
We utilized scanning probe microscopy (SPM) based on a metal-oxide-silicon field-effect transistor (MOSFET) to image interdigitated electrodes covered with oxide films that were several hundred nanometers in thickness. The signal varied depending on the thickness of the silicon dioxide film covering the electrodes. We deposited a 400- or 500-nm-thick silicon dioxide film on each sample electrode. Thick oxide films are difficult to analyze using conventional probes because of their low capacitance. In addition, we evaluated linearity and performed frequency response measurements; the measured frequency response reflected the electrical characteristics of the system, including the MOSFET, conductive tip, and local sample area. Our technique facilitated analysis of the passivation layers of integrated circuits, especially those of the back-end-of-line (BEOL) process, and can be used for subsurface imaging of various dielectric layers.
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Affiliation(s)
- Hoontaek Lee
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang-si 37673, Gyeongsangbuk-do, Korea;
| | - Kumjae Shin
- Safety System R&D Group, Korea Institute of Industrial Technology (KITECH), 15 Jisiksaneop-ro, Hayang-eup, Gyeongsan-si 38408, Gyeongsangbuk-do, Korea;
| | - Wonkyu Moon
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang-si 37673, Gyeongsangbuk-do, Korea;
- Correspondence: ; Tel.: +82-54-279-2184; Fax: +82-54-279-0489
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7
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Checa M, Millan-Solsona R, Glinkowska Mares A, Pujals S, Gomila G. Dielectric Imaging of Fixed HeLa Cells by In-Liquid Scanning Dielectric Force Volume Microscopy. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:1402. [PMID: 34070690 PMCID: PMC8226567 DOI: 10.3390/nano11061402] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 05/21/2021] [Accepted: 05/23/2021] [Indexed: 01/16/2023]
Abstract
Mapping the dielectric properties of cells with nanoscale spatial resolution can be an important 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 microscopy. 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.
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Affiliation(s)
- Martí Checa
- Nanoscale Bioelectric Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
| | - Ruben Millan-Solsona
- Nanoscale Bioelectric Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
- Departament d’Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain;
| | - Adrianna Glinkowska Mares
- Nanoscopy for Nanomedicine, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
| | - Silvia Pujals
- Departament d’Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain;
- Nanoscopy for Nanomedicine, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
| | - Gabriel Gomila
- Nanoscale Bioelectric Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
- Departament d’Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain;
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8
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Millan-Solsona R, Checa M, Fumagalli L, Gomila G. Mapping the capacitance of self-assembled monolayers at metal/electrolyte interfaces at the nanoscale by in-liquid scanning dielectric microscopy. NANOSCALE 2020; 12:20658-20668. [PMID: 33043923 DOI: 10.1039/d0nr05723a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Organic self-assembled monolayers (SAMs) at metal/electrolyte interfaces have been thoroughly investigated both from fundamental and applied points of view. A relevant figure of merit of metal/SAM/electrolyte interfaces is the specific capacitance, which determines the charge that can be accumulated at the metal electrode. Here, we show that the specific capacitance of non-uniform alkanethiol SAMs at gold/electrolyte interfaces can be quantitatively measured and mapped at the nanoscale by in-liquid scanning dielectric microscopy in force detection mode. We show that sub-100 nm spatial resolution in ultrathin (<1 nm) SAMs can be achieved, largely improving the performance of current sensing characterization techniques. The present results provide access to study the dielectric properties of metal/SAM/electrolyte interfaces at scales that have remained unexplored until now.
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Affiliation(s)
- Ruben Millan-Solsona
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, C/Martí i Franquès 1, 08028, Barcelona, Spain
| | - Martí Checa
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain.
| | - Laura Fumagalli
- Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK and National Graphene Institute, University of Manchester, Manchester M13 9PL, UK
| | - Gabriel Gomila
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, C/Martí i Franquès 1, 08028, Barcelona, Spain
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9
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Labardi M, Bertolla A, Sollogoub C, Casalini R, Capaccioli S. Lateral resolution of electrostatic force microscopy for mapping of dielectric interfaces in ambient conditions. NANOTECHNOLOGY 2020; 31:335710. [PMID: 32353839 DOI: 10.1088/1361-6528/ab8ede] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The attainable lateral resolution of electrostatic force microscopy (EFM) in an ambient air environment on dielectric materials was characterized on a reference sample comprised of two distinct, immiscible glassy polymers cut in a cross-section by ultramicrotomy. Such a sample can be modeled as two semi-infinite dielectrics with a sharp interface, presenting a quasi-ideal, sharp dielectric contrast. Electric polarizability line profiles across the interface were obtained, in both lift-mode and feedback-regulated dynamic mode EFM, as a function of probe/surface separation, for different cases of oscillation amplitudes. We find that the results do not match predictions for dielectric samples, but comply well or are even better than predicted for conductive interfaces. A resolution down to 3 nm can be obtained by operating in feedback-regulated EFM realized by adopting constant-excitation frequency-modulation mode. This suggests resolution is ruled by the closest approach distance rather than by average separation, even with probe oscillation amplitudes as high as 10 nm. For better comparison with theoretical predictions, effective probe radii and cone aperture angles were derived from approach curves, by also taking into account the finite oscillation amplitude of the probe, by exploiting a data reduction procedure previously devised for the derivation of interatomic potentials.
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Affiliation(s)
- M Labardi
- CNR-IPCF, Sede Secondaria di Pisa, Largo Pontecorvo 3, 56127, Pisa, Italy
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Albonetti C, Chiodini S, Annibale P, Stoliar P, Martinez RV, Garcia R, Biscarini F. Quantitative phase-mode electrostatic force microscopy on silicon oxide nanostructures. J Microsc 2020; 280:252-269. [PMID: 32538463 DOI: 10.1111/jmi.12938] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/05/2020] [Accepted: 06/12/2020] [Indexed: 02/02/2023]
Abstract
Phase-mode electrostatic force microscopy (EFM-Phase) is a viable technique to image surface electrostatic potential of silicon oxide stripes fabricated by oxidation scanning probe lithography, exhibiting an inhomogeneous distribution of localized charges trapped within the stripes during the electrochemical reaction. We show here that these nanopatterns are useful benchmark samples for assessing the spatial/voltage resolution of EFM-phase. To quantitatively extract the relevant observables, we developed and applied an analytical model of the electrostatic interactions in which the tip and the surface are modelled in a prolate spheroidal coordinates system, fitting accurately experimental data. A lateral resolution of ∼60 nm, which is comparable to the lateral resolution of EFM experiments reported in the literature, and a charge resolution of ∼20 electrons are achieved. This electrostatic analysis evidences the presence of a bimodal population of trapped charges in the nanopatterned stripes.
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Affiliation(s)
- C Albonetti
- Consiglio Nazionale delle Ricerche - Istituto per lo Studio dei Materiali Nanostrutturati (CNR-ISMN), Bologna, Italy
| | - S Chiodini
- Consiglio Nazionale delle Ricerche - Istituto per lo Studio dei Materiali Nanostrutturati (CNR-ISMN), Bologna, Italy.,Instituto de Nanociencia de Aragon (INA), Universidad de Zaragoza, Zaragoza, Spain
| | - P Annibale
- Consiglio Nazionale delle Ricerche - Istituto per lo Studio dei Materiali Nanostrutturati (CNR-ISMN), Bologna, Italy.,Present address: Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - P Stoliar
- Consiglio Nazionale delle Ricerche - Istituto per lo Studio dei Materiali Nanostrutturati (CNR-ISMN), Bologna, Italy.,National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan
| | - R V Martinez
- Materials Science Factory, Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC, Madrid, Spain.,Present address: School of Industrial Engineering, Purdue University, West Lafayette, Indiana, U.S.A
| | - R Garcia
- Materials Science Factory, Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC, Madrid, Spain
| | - F Biscarini
- Consiglio Nazionale delle Ricerche - Istituto per lo Studio dei Materiali Nanostrutturati (CNR-ISMN), Bologna, Italy.,Department of Life Sciences, Università di Modena e Reggio Emilia, Modena, Italy.,Center for Translational Neurophysiology-Istituto Italiano di Tecnologia, Ferrara, Italy
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Checa M, Millan-Solsona R, Blanco N, Torrents E, Fabregas R, Gomila G. Mapping the dielectric constant of a single bacterial cell at the nanoscale with scanning dielectric force volume microscopy. NANOSCALE 2019; 11:20809-20819. [PMID: 31657419 DOI: 10.1039/c9nr07659j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Mapping the dielectric constant at the nanoscale of samples showing a complex topography, such as non-planar nanocomposite materials or single cells, poses formidable challenges to existing nanoscale dielectric microscopy techniques. Here we overcome these limitations by introducing Scanning Dielectric Force Volume Microscopy. This scanning probe microscopy technique is based on the acquisition of electrostatic force approach curves at every point of a sample and its post-processing and quantification by using a computational model that incorporates the actual measured sample topography. The technique provides quantitative nanoscale images of the local dielectric constant of the sample with unparalleled accuracy, spatial resolution and statistical significance, irrespectively of the complexity of its topography. We illustrate the potential of the technique by presenting a nanoscale dielectric constant map of a single bacterial cell, including its small-scale appendages. The bacterial cell shows three characteristic equivalent dielectric constant values, namely, εr,bac1 = 2.6 ± 0.2, εr,bac2 = 3.6 ± 0.4 and εr,bac3 = 4.9 ± 0.5, which enable identifying different dielectric properties of the cell wall and of the cytoplasmatic region, as well as, the existence of variations in the dielectric constant along the bacterial cell wall itself. Scanning Dielectric Force Volume Microscopy is expected to have an important impact in Materials and Life Sciences where the mapping of the dielectric properties of samples showing complex nanoscale topographies is often needed.
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Affiliation(s)
- Martí Checa
- Nanoscale Bioelectrical Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028, Barcelona, Spain
| | - Ruben Millan-Solsona
- Nanoscale Bioelectrical Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028, Barcelona, Spain
| | - Nuria Blanco
- Bacterial Infections: Antimicrobial Therapies, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona
| | - Eduard Torrents
- Bacterial Infections: Antimicrobial Therapies, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona
| | - Rene Fabregas
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028, Barcelona, Spain
| | - Gabriel Gomila
- Nanoscale Bioelectrical Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028, Barcelona, Spain
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Cheong LZ, Zhao W, Song S, Shen C. Lab on a tip: Applications of functional atomic force microscopy for the study of electrical properties in biology. Acta Biomater 2019; 99:33-52. [PMID: 31425893 DOI: 10.1016/j.actbio.2019.08.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 07/17/2019] [Accepted: 08/13/2019] [Indexed: 12/11/2022]
Abstract
Electrical properties, such as charge propagation, dielectrics, surface potentials, conductivity, and piezoelectricity, play crucial roles in biomolecules, biomembranes, cells, tissues, and other biological samples. However, characterizing these electrical properties in delicate biosamples is challenging. Atomic Force Microscopy (AFM), the so called "Lab on a Tip" is a powerful and multifunctional approach to quantitatively study the electrical properties of biological samples at the nanometer level. Herein, the principles, theories, and achievements of various modes of AFM in this area have been reviewed and summarized. STATEMENT OF SIGNIFICANCE: Electrical properties such as dielectric and piezoelectric forces, charge propagation behaviors play important structural and functional roles in biosystems from the single molecule level, to cells and tissues. Atomic force microscopy (AFM) has emerged as an ideal toolkit to study electrical property of biology. Herein, the basic principles of AFM are described. We then discuss the multiple modes of AFM to study the electrical properties of biological samples, including Electrostatic Force Microscopy (EFM), Kelvin Probe Force Microscopy (KPFM), Conductive Atomic Force Microscopy (CAFM), Piezoresponse Force Microscopy (PFM) and Scanning ElectroChemical Microscopy (SECM). Finally, the outlook, prospects, and challenges of the various AFM modes when studying the electrical behaviour of the samples are discussed.
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Gramse G, Schönhals A, Kienberger F. Nanoscale dipole dynamics of protein membranes studied by broadband dielectric microscopy. NANOSCALE 2019; 11:4303-4309. [PMID: 30778459 PMCID: PMC6457197 DOI: 10.1039/c8nr05880f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 02/02/2019] [Indexed: 06/09/2023]
Abstract
We investigate the nearfield dipole mobility of protein membranes in a wide frequency range from 3 kHz to 10 GHz. The results of our nanoscale dielectric images and spectra of bacteriorhodopsin (bR) reveal Debye relaxations with time constants of τ ∼ 2 ns and τ ∼ 100 ns being characteristic of the dipole moments of the bR retinal and α-helices, respectively. However, the dipole mobility and therefore the protein biophysical function depend critically on the amount of surface water surrounding the protein, and the characteristic mobility in the secondary structure is only observed for humidity levels <30%. Our results have been achieved by adding the frequency as a second fundamental dimension to quantitative dielectric microscopy. The key elements for the success of this advanced technique are the employed heterodyne detection scheme, the broadband electrical signal source, a high frequency optimized cabling, development of calibration procedures and precise finite element modelling. Our study demonstrates the exciting possibilities of broadband dielectric microscopy for the investigation of dynamic processes in cell bioelectricity at the individual molecular level. Furthermore, the technique may shed light on local dynamic processes in related materials science applications like semiconductor research or nano-electronics.
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Affiliation(s)
- Georg Gramse
- Johannes Kepler University, Biophysics Institute, Gruberstr. 40, 4020 Linz, Austria.
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Sacha GM, Verdaguer A, Salmeron M. A Model for the Characterization of the Polarizability of Thin Films Independently of the Thickness of the Film. J Phys Chem B 2018; 122:904-909. [PMID: 29087709 DOI: 10.1021/acs.jpcb.7b06975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The dielectric properties of thin films can be modified relative to the bulk material because the interaction between film and substrate influences the mobility of the atoms or molecules in the first layers. Here we show that a strong scale effect occurs in nanometer size octadecylammine thin films. This effect is attributed to the different distribution of molecules depending on the size of the film. To accurately describe this effect, we have developed a model which is a reinterpretation of the linearized Thomas-Fermi approximation. Within this model, we have been able to characterize the polarizability of thin films independently of the thickness of the film.
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Affiliation(s)
- G M Sacha
- Universidad Autónoma de Madrid , Campus de Cantoblanco, 28049 Madrid, Spain
| | - A Verdaguer
- Institut de Ciència de Materials de Barcelona ICMAB-CSIC , Campus de la UAB, 08193 Bellaterra, Spain
| | - M Salmeron
- Materials Science Division, Lawrence Berkeley National Laboratory , 94720 Berkeley, California, United States
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15
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El Khoury D, Fedorenko V, Castellon J, Bechelany M, Laurentie JC, Balme S, Fréchette M, Ramonda M, Arinero R. Characterization of Dielectric Nanocomposites with Electrostatic Force Microscopy. SCANNING 2017; 2017:4198519. [PMID: 29109811 PMCID: PMC5661829 DOI: 10.1155/2017/4198519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 06/22/2017] [Accepted: 08/03/2017] [Indexed: 05/12/2023]
Abstract
Nanocomposites physical properties unexplainable by general mixture laws are usually supposed to be related to interphases, highly present at the nanoscale. The intrinsic dielectric constant of the interphase and its volume need to be considered in the prediction of the effective permittivity of nanodielectrics, for example. The electrostatic force microscope (EFM) constitutes a promising technique to probe interphases locally. This work reports theoretical finite-elements simulations and experimental measurements to interpret EFM signals in front of nanocomposites with the aim of detecting and characterizing interphases. According to simulations, we designed and synthesized appropriate samples to verify experimentally the ability of EFM to characterize a nanoshell covering nanoparticles, for different shell thicknesses. This type of samples constitutes a simplified electrostatic model of a nanodielectric. Experiments were conducted using either DC or AC-EFM polarization, with force gradient detection method. A comparison between our numerical model and experimental results was performed in order to validate our predictions for general EFM-interphase interactions.
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Affiliation(s)
- D. El Khoury
- Institut d'Electronique et des Systèmes, Université de Montpellier, 34095 Montpellier Cedex 5, France
| | - V. Fedorenko
- Institut Européen des Membranes, IEM UMR-5635, Université de Montpellier, ENSCM, CNRS, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
| | - J. Castellon
- Institut d'Electronique et des Systèmes, Université de Montpellier, 34095 Montpellier Cedex 5, France
| | - M. Bechelany
- Institut Européen des Membranes, IEM UMR-5635, Université de Montpellier, ENSCM, CNRS, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
| | - J.-C. Laurentie
- Institut d'Electronique et des Systèmes, Université de Montpellier, 34095 Montpellier Cedex 5, France
| | - S. Balme
- Institut Européen des Membranes, IEM UMR-5635, Université de Montpellier, ENSCM, CNRS, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
| | - M. Fréchette
- Hydro-Québec's Research Institute, Varennes, QC, Canada J3X 1S1
| | - M. Ramonda
- Centre de Technologie de Montpellier, Université de Montpellier, 34095 Montpellier Cedex 5, France
| | - R. Arinero
- Institut d'Electronique et des Systèmes, Université de Montpellier, 34095 Montpellier Cedex 5, France
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Van Der Hofstadt M, Fabregas R, Millan-Solsona R, Juarez A, Fumagalli L, Gomila G. Internal Hydration Properties of Single Bacterial Endospores Probed by Electrostatic Force Microscopy. ACS NANO 2016; 10:11327-11336. [PMID: 28024372 DOI: 10.1021/acsnano.6b06578] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We show that the internal hydration properties of single Bacillus cereus endospores in air under different relative humidity (RH) conditions can be determined through the measurement of its electric permittivity by means of quantitative electrostatic force microscopy (EFM). We show that an increase in the RH from 0% to 80% induces a large increase in the equivalent homogeneous relative electric permittivity of the bacterial endospores, from ∼4 up to ∼17, accompanied only by a small increase in the endospore height, of just a few nanometers. These results correlate the increase of the moisture content of the endospore with the corresponding increase of environmental RH. Three-dimensional finite element numerical calculations, which include the internal structure of the endospores, indicate that the moisture is mainly accumulated in the external layers of the endospore, hence preserving the core of the endospore at low hydration levels. This mechanism is different from what we observe for vegetative bacterial cells of the same species, in which the cell wall at high humid atmospheric conditions is not able to preserve the cytoplasmic region at low hydration levels. These results show the potential of quantitative EFM under environmental humidity control to study the hygroscopic properties of small-scale biological (and nonbiological) entities and to determine its internal hydration state. A better understanding of nanohygroscopic properties can be of relevance in the study of essential biological processes and in the design of bionanotechnological applications.
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Affiliation(s)
- Marc Van Der Hofstadt
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
- Departament d'Enginyeries: Electrònica, Universitat de Barcelona , C/Martí i Franqués 1, Barcelona 08028, Spain
| | - Rene Fabregas
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
- Departament d'Enginyeries: Electrònica, Universitat de Barcelona , C/Martí i Franqués 1, Barcelona 08028, Spain
| | - Ruben Millan-Solsona
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
| | - Antonio Juarez
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
- Departament de Microbiologia, Universitat de Barcelona , Av. Diagonal 643, Barcelona 08028, Spain
| | - Laura Fumagalli
- School of Physics and Astronomy, University of Manchester , Oxford Road, Manchester M13 9PL, United Kingdom
| | - Gabriel Gomila
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
- Departament d'Enginyeries: Electrònica, Universitat de Barcelona , C/Martí i Franqués 1, Barcelona 08028, Spain
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