Scanning ion conductance microscopy (SICM) belongs to the family of scanning probe techniques. These techniques exploit the interaction between a sharp probe and a sample surface; by moving the probe along parallel lines, the local physical properties can be thus mapped. SICM main characteristics are the working environment, a bath of saline solution, and the absence of contact between probe and sample. It is mainly used to obtain high-resolution topographic images of nonconducting surfaces; however, it can be also employed to measure the stiffness of compliant samples.

Polycrystalline lead lanthanum zirconate titanate (PLZT) thin films have been prepared by a polymeric chemical route to understand the mechanisms of phase transformations and map the microstructure and elastic properties at the nanoscale in these films. X-ray diffraction, atomic force microscopy (AFM) and ultrasonic force microscopy (UFM) have been used as investigative tools. On one side, PLZT films with mixed-phase show that the pyrochlore phase crystallizes predominantly in the bottom film-electrode interface while a pure perovskite phase crystallizes in top film surface. On the contrary, pyrochlore-free PLZT films show a non-uniform microstrain and crystallite size along the film thickness with a heterogeneous complex grainy structure leading to different elastic properties at nanoscale. (C) 2014 Elsevier Ltd. All rights reserved.

Scanning ion conductance microscopy (SICM) is a scanning probe microscopy particularly suitable for the investigation of living biological specimens due to its low invasivity. Recently, this technique has been used not only to perform 3D-imaging, but also to stimulate and guide neuronal growth cones. In particular, it has been demonstrated that one can guide the cone growth for tens of micrometres by means of recurrent and non-contact SICM scanning along a defined line, with a pipette having an internal hydrostatic pressure. Accurate measurements of the mechanical forces acting on the cell membrane in these stimulation protocols are essential to explain the biological mechanisms involved. Herein a setup specifically developed for this purpose, combining together SICM, atomic force microscopy (AFM) and inverted optical microscopy is described. In this configuration, a SICM pipette can be approached to an AFM cantilever while monitoring the cantilever deflection as a function of the hydrostatic pressure applied to the pipette and the relative distance. In this way, one can directly measure mechanical forces down to 20 pN. The same apparatus is thus sufficient to calibrate a given pipette and immediately use it to study the hydrostatic pressure effects on living cells.

The variation in the glass transition temperature of thin polymeric films represents a phenomenon yet to be fully explained. To date, it is widely agreed that it is linked to the interfaces that the film forms with the air and the supporting substrate. Herein, we address one of the main issues regarding the viscoelastic behavior of the region near the free interface of thick polystyrene films where a reduction in the glass transition temperature is expected to occur. We have measured, as a function of the temperature, the elastic and viscous responses of polystyrene films with molecular weights above and below the critical value for the occurrence of molecular entanglement. The experiments have been carried out by means of scanning probe microscopy in a configuration combining the acquisition of force versus distance and indentation versus time curves. We show that the viscoelastic behavior of polystyrene films with thickness down to 30 nm can be successfully evaluated in the time scale from tenths to tens of seconds. In particular, we observe that the viscoelastic behavior of thick film surfaces has a similar dependence from the temperature as the viscoelastic behavior of the bulk, independently if the molecular weight is above or below the critical value. We estimate that the region at the free interface with a reduced glass transition temperature, if present, has a thickness below 3 nm.

The present paper reports on a novel lithographic approach at the nanoscale level, which is based on scanning probe microscopy (SPM) and nanoimprint lithography (NIL). The experimental set-up consists of an atomic force microscope (AFM) operated via software specifically developed for the purpose. In particular, this software allows one to apply a predefined external load for a given lapse of time while monitoring in real-time the relative distance between the tip and the sample as well as the normal and lateral force during the embossing process. Additionally, we have employed AFM tips sculptured by means of focused ion beam in order to create indenting tools of the desired shape. Anti-sticking layers can also be used to functionalize the tips if one needs to investigate the effects of different treatments on the indentation and de-molding processes. The lithographic capabilities of this set-up are demonstrated on a polystyrene NIL-patterned sample, where imprinted features have been obtained upon using different normal load values for increasing time intervals, and on a thermoplastic polymer film, where the imprint process has been monitored in real-time.

We present a fibre-top probe fabricated by carving a tipped cantilever on an optical fibre, with the tip machined in correspondence of the fibre core. When approached to an optical prism illuminated under total internal reflection conditions, the tip of the cantilever detects the optical tunnelling signal, while the light coupled from the opposite end of the fibre measures the deflection of the cantilever. Our results suggest that fibre-top technology can be used for the development of a new generation of hybrid probes that can combine atomic force microscopy with scanning near field optical microscopy.

The fabrication of novel atomic force microscopy (AFM) probes for nanoindentation and nanoimprint lithography (NIL) is presented. Nanomachining induced by focused ion beam (FIB) were employed in order to modify the original tip shape of commercial silicon AFM probes. The FIB-modified probes are used both to perform experiments as to image the corresponding tip-induced surface modifications. With this approach, a relationship between the hardness of a material and the shape of the indenter has been found in the nanoindentation application, and we have obtained information related to the force acting on the mold during its detaching from the polymer film in the AFM-NIL application.

The fabrication and performances of cantilevered probes with reduced parasitic capacitance starting from a commercial Si3N4 cantilever chip is presented. Nanomachining and metal deposition induced by focused ion beam techniques were employed in order to modify the original insulating pyramidal tip and insert a conducting metallic tip. Two parallel metallic electrodes deposited on the original cantilever arms are employed for tip biasing and as ground plane in order to minimize the electrostatic force due to the capacitive interaction between cantilever and sample surface. Excitation spectra and force-to-distance characterization are shown with different electrode configurations. Applications of this scheme in electrostatic force microscopy, Kelvin probe microscopy and local anodic oxidation is discussed.

The effectiveness and adequacy of a home-built scanning force microscope (SFM) able to cover a volume of approximately 1.2 x 1.2 x 0.13 mm(3) (X x Y x Z) were tested on calibrating objects, as well as on cytological and histological samples. The instrument was designed for matching the magnification range of an optical microscope (approximately 20-1200x) but its dynamics were one or two orders of magnitude higher, thanks to a lateral resolution of about 10 nm. Images ranging in size from 1.2 x 1.2 mm(2) to 1 x 1 microm(2) showed a quality comparable to that given by other SFMs on similar materials. The 'Milliscope' is a curious but effective imaging tool whose operating range overlaps at one extreme with a goldsmith's eyepiece, and at the other with an electron microscope. The intrinsic limits of scanning probe techniques and of the available SFM cantilevers prevented us taking complete advantage of the wide height range of our scanner. However, our results show that an instrument having a very wide scan area, obtained through simple, inexpensive and intrinsically linear techniques, can give a good performance even at small scan sizes. This encourages us to develop wide scan instruments, which could further increase the already extensive use of scanning force microscopy in biology.

In the present study we test a compact disk pickup as the cantilever position sensor in an atomic force microscope (AFM). The pickup is placed on top of the optical microscope used for the visual inspection and alignment of the specimen. The AFM is also equipped with its own cantilever movement sensor system. Both the built-in and the new detection devices are simultaneously active for comparison purposes. Two different measurements are performed in sequence on the same sample each using one sensor at a time as the error signal source for the AFM feedback loop. The pickup has demonstrated good sensitivity as well as excellent performance in terms of compactness, reliability, and cost.

Theory and practice of the magnetic resonance microscopy by mechanical detection methods are revisited. Sensitivity and future developments are discussed.

The development of a spectrometer for simultaneous mechanical and electromagnetic detection of electron paramagnetic resonance working at 23 GHz and under vacuum is described. Experiments realized on different samples show the performances of the apparatus. Possible perspectives are presented.

The peculiar advantages of simultaneous observation by electromagnetic and micromechanical methods in EPR spectroscopy are discussed. The development of a novel apparatus with the capability of this simultaneous detection is described. Experiments at 23 GHz show the performance of the apparatus. The problems related to the sensitivity and to the spatial resolution are analyzed. Future prospects are presented. Copyright 1999 Academic Press.

Solvent-cast stearic acid samples have been studied by using atomic force microscopy to inspect surface topography and measure tip-sample interactions. Differences between the topography in air and in water suggest that such films are likely to rearrange when dipped in water in order to expose the carboxylic group to water. Force-distance curves performed in aqueous solutions at different pH values show repulsive forces arising at high pH values, when both the silicon nitride tip and the carboxylic groups become negatively charged. When the tip is withdrawn, after sample indentation, an adhesive force with attractive surges and detachments appears. We make the hypothesis that such detachments are due to stearic acid molecules adhering strongly to the tip and forming bridges between tip and film surface. These molecules detach from the tip at different forces and distances. The adhesive force depends on the liquid environment. Its dependence on the scanning rate indicates a viscoelastic behavior of the bridges. Also the film shows viscoelastic properties when compressed at different rates.

An hybrid atomic force-scanning near-field optical microscope (AFM-SNOM) has been realized starting from a home-built AFM. The instrument uses a tetrahedral SiN tip for force and near field detection and is designed to provide, besides simple imaging, a full three-dimensional (3-D) mapping of force, friction and light intensity on the sample. High-resolution optical images of dielectric samples are presented together with curves describing the behavior of the collected optical intensity as a function of tip-object distance. AFM images and force-distance curves are reported as well and are compared with those obtained from the optical channel. Subwavelength features of the samples can be easily appreciated in both kinds of images, and the refractive index of the object can be computed from the attenuation constant of the tunneling light detected by the tip, with the AFM curve providing a convenient way of detecting the contact point. The spatial resolution of this kind of measurement is far better than that obtainable with any other index-measuring device. Homogeneous glass samples as well as monomode channel waveguides were analyzed in our experiments. The refractive index of several different prisms, made either of BK7 (n=1.519 at /spl lambda/=532 nm) or of SF58 (n=1.932) glass, could be measured with our near-field technique. As for the channel waveguides, the accuracy of our measurements lets us detect their presence and lateral extension in the substrate but is not yet sufficient to allow the reconstruction of their index profile.

Hybrid superconductor–semiconductor (S–Sm) nanostructures were fabricated by integrating standard ultraviolet photolithography and direct patterning of photoresist with an atomic force microscope (AFM). This novel technology was used to fabricate Nb–InAs–Nb weak links comparable in length to the coherence length. These structures exhibit high critical currents up to 10 μA/μm in planar geometry at 0.3 K. The fabrication protocol is based on the modification of photolithographically defined patterns by AFM static ploughing of the photoresist. Wet chemical etching is subsequently used for the definition of nanoscale S–Sm–S bridges. Additionally Lift-off procedures allowed the fabrication of submicron superconducting bridges. Successful fabrication of the nanostructures was verified by electrical characterization and by AFM and scanning electron microscope structural characterization.

A new scanning method, 'touch and lift', aimed to improve the simultaneous acquisition of topography and force-distance curves on each point of the scanned surface, is presented. This method does not damage the sample or the cantilever and enables us to collect a lot of data in a relatively short time. Its most important feature is that data are directly organized in 'force-slices', i.e. images giving immediate qualitative information on the physico-chemical structure of the sample. We present and discuss such images for two samples: a fluorescein isothyocyanate grating on silicon in air and a peroxidase grating on silicon in water, measuring the spatial variation of stiffness, attractive forces and adhesion in both cases.