Sizing single nanoscale objects from polarization forces

Abstract

Sizing natural or engineered single nanoscale objects is fundamental in many areas of science and technology. To achieve it several advanced microscopic techniques have been developed, mostly based on electron and scanning probe microscopies. Still for soft and poorly adhered samples the existing techniques face important challenges. Here, we propose an alternative method to size single nanoscale objects based on the measurement of its electric polarization. The method is based on Electrostatic Force Microscopy measurements combined with a specifically designed multiparameter quantification algorithm, which gives the physical dimensions (height and width) of the nanoscale object. The proposed method is validated with ~50 nm diameter silver nanowires, and successfully applied to ~10 nm diameter bacterial polar flagella, an example of soft and poorly adhered nanoscale object. We show that an accuracy comparable to AFM topographic imaging can be achieved. The main advantage of the proposed method is that, being based on the measurement of long-range polarization forces, it can be applied without contacting the sample, what is key when considering poorly adhered and soft nanoscale objects. Potential applications of the proposed method to a wide range of nanoscale objects relevant in Material, Life Sciences and Nanomedicine is envisaged.

Quantitative phase‐mode electrostatic force microscopy on silicon oxide nanostructures

“…Equation 12is used for fitting spectroscopic curves within a range of distances z close to H. Specifically, the H value used in EFM-Phase experiments on silicon oxide structures is H = 40 nm (cp. to Section 'EFM-Phase on SiO x stripes: inhomogeneous charge distribution'), therefore, the fitting procedures are performed in the z range (Miyahara et al, 2015;Lozano et al, 2019) where η tip maintains constant within an error of ≈ 2% (cp. to Appendix).…”

“…These techniques were proven useful in studying the localization of trapped charges in thin films (Silveira & Marohn, 2004; Chen et al ., 2005a; Chen et al ., 2005b; Muller & Marohn, 2005), quantum dots (Tevaarwerk et al ., 2005) and nanotubes (Chin et al ., 2008); to measure the resistance at metal–semiconductor interfaces and grain boundaries in operating devices (Annibale et al ., 2007); to relate electrical properties, such as dielectric permittivity (Gramse et al ., 2009; El Khoury et al ., 2016; Fumagalli et al ., 2018), conductivity (Castellano‐Hernández & Sacha, 2015; Aurino et al ., 2016), piezoelectricity (Moon et al ., 2017) and percolation pathways (Barnes & Buratto, 2018), directly to the organization of the material at the mesoscopic length scales. Charge distribution in supramolecular architectures (Dabirian et al ., 2009; Borgani et al ., 2014; Garrett et al ., 2018), biomolecules (Gil et al ., 2002; Cuervo et al ., 2014; Dols‐Perez et al ., 2015; Lozano et al ., 2018; Lozano et al ., 2019), living organism (Esteban‐Ferrer et al ., 2014; Van Der Hofstadt et al ., 2016a; Van Der Hofstadt et al ., 2016b) and 2D materials (Collins et al ., 2013; Miyahara et al ., 2015; Shen et al ., 2018; Altvater et al ., 2019) was recently addressed with these techniques. The information obtained can be used as input for the design and optimization of device layouts, and ultimately for the simulation of functional devices and circuits.…”

Alpha-synuclein oligomers alter the spontaneous firing discharge of cultured midbrain neurons

“…Remarkably, as oligomeric species have sizes as small as the AFM tip radius (i.e., 5 nm), they exhibited ∼100 nm in length. As commonly observed for small objects, the length determined by AFM is of smaller accuracy and the size evaluation from the height profiles is more realistic (Lozano et al, 2019).…”

Spatial Resolution and Capacitive Coupling in the Characterization of Nanowire Nanocomposites by Scanning Dielectric Microscopy

“…The capacitance gradient, dC / dz , is obtained from the calculated electric force obtained by integration of the Maxwell stress tensor on the tip surface, as described above (Fumagalli et al, 2012). All calculations have been done by using the electrostatic module of COMSOL MULTIPHYSICS 5.4 following similar methods to the ones described in the following publications (Lozano et al, 2018, 2019; Fabregas & Gomila, 2020).

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