Showing papers by "Pietro Ferraro published in 2018"
TL;DR: A broad discussion about the noise issue in DH is provided, with the aim of covering the best-performing noise reduction approaches that have been proposed so far and quantitative comparisons among these approaches will be presented.
Abstract: Digital holography (DH) has emerged as one of the most effective coherent imaging technologies. The technological developments of digital sensors and optical elements have made DH the primary approach in several research fields, from quantitative phase imaging to optical metrology and 3D display technologies, to name a few. Like many other digital imaging techniques, DH must cope with the issue of speckle artifacts, due to the coherent nature of the required light sources. Despite the complexity of the recently proposed de-speckling methods, many have not yet attained the required level of effectiveness. That is, a universal denoising strategy for completely suppressing holographic noise has not yet been established. Thus the removal of speckle noise from holographic images represents a bottleneck for the entire optics and photonics scientific community. This review article provides a broad discussion about the noise issue in DH, with the aim of covering the best-performing noise reduction approaches that have been proposed so far. Quantitative comparisons among these approaches will be presented.
176 citations
TL;DR: This work reports a reliable full-angle tomographic phase microscopy method for flowing quasi-spherical cells along microfluidic channels and demonstrates significant progress with respect to the state of the art of in-flow TPM by showing a general extension to cells having almost spherical shapes while they are flowing in suspension.
Abstract: We report a reliable full-angle tomographic phase microscopy (FA-TPM) method for flowing quasi-spherical cells along microfluidic channels. This method lies in a completely passive optical system, i.e. mechanical scanning or multi-direction probing of the sample is avoided. It exploits the engineered rolling of cells while they are flowing along a microfluidic channel. Here we demonstrate significant progress with respect to the state of the art of in-flow TPM by showing a general extension to cells having almost spherical shapes while they are flowing in suspension. In fact, the adopted strategy allows the accurate retrieval of rotation angles through a theoretical model of the cells' rotation in a dynamic microfluidic flow by matching it with phase-contrast images resulting from holographic reconstructions. So far, the proposed method is the first and the only one that permits to get in-flow TPM by probing the cells with full-angle, achieving accurate 3D refractive index mapping and the simplest optical setup, simultaneously. Proof of concept experiments were performed successfully on human breast adenocarcinoma MCF-7 cells, opening the way for the full characterization of circulating tumor cells (CTCs) in the new paradigm of liquid biopsy.
79 citations
TL;DR: This work introduces a label-free optical marker (LOM) to detect red-blood-cell (RBC) phenotypes, demonstrating that a single set of all-optical parameters can clearly identify a signature directly related to an erythrocyte disease through modeling each RBC as a biological lens.
Abstract: The gold-standard methods for anemia diagnosis are complete blood counts and peripheral-smear observations. However, these do not allow for a complete differential diagnosis as that requires biochemical assays, which are label-dependent techniques. On the other hand, recent studies focus on label-free quantitative phase imaging (QPI) of blood samples to investigate blood diseases by using video-based morphological methods. However, when sick cells are very similar to healthy ones in terms of morphometric features, identification of a blood disease becomes challenging even with QPI. Here, we introduce a label-free optical marker (LOM) to detect red-blood-cell (RBC) phenotypes, demonstrating that a single set of all-optical parameters can clearly identify a signature directly related to an erythrocyte disease through modeling each RBC as a biological lens. We tested this novel biophotonic analysis by proving that several inherited anemias, such as iron-deficiency anemia, thalassemia, hereditary spherocytosi...
48 citations
TL;DR: In this article, the authors presented a novel electro-drawing set up and strategy to parallelize the process and to avoid the pedestal at the microneedle basis, based on titanium micro-heaters integrated onto the pyroelectric substrate.
Abstract: Biodegradable polymer microneedles are recognized as a valuable route for transdermal drug delivery as well as for cutaneous treatments. According to the industrial needs, the present trend is to fabricate microneedles through stamp-less techniques. Electro-drawing has been recently proposed as an alternative fast and mild temperature strategy to the stamp based techniques for the fabrication of biodegradable polymer microneedles. However, previously presented electro-drawn microneedles were fabricated by a point-like thermal stimulation, thus, they could not be electro-drawn in parallel and displayed a pedestal at their basis. Here, we present a novel electro-drawing set up and strategy to parallelize the process and to avoid the pedestal at the microneedle basis. The new set-up is based on titanium micro-heaters integrated onto the pyroelectric substrate which is the electric field generator enabling the electro-drawing. The micro-heaters configuration has been chosen starting from numerical simulations to guarantee uniform heating on large areas, in contrast to the local heating by hot tip, allowing the generation of a uniform electric field which is a basic condition for an in parallel fabrication of microneedles. Additionally, thanks to the stronger electric field, it was possible to apply a double step electro-drawing, where the second step is carried out at higher distance in order to avoid microneedle shrinkage while avoiding further growing of the microneedles.
34 citations
TL;DR: By exploiting random rolling of cells while they are flowing along a microfluidic channel, it is possible to obtain phase-contrast tomography thus obtaining complete retrieval of both 3D-position and orientation of rotating cells.
30 citations
TL;DR: The results show that the label‐free character of the technique would allow biologists to perform systematic and reliable studies on cell death process induced by cadmium and it is believed that more in general this can be easily extended to others heavy metals, thus avoiding the time‐consuming, expensive and invasive label‐based procedures used nowadays in the field.
Abstract: Among all environmental pollutants, the toxic heavy metal cadmium is considered as a human carcinogen. Cadmium may induce cell death by apoptosis in various cell types, although the underlying mechanisms are still unclear. In this paper we show how a label-free digital holography (DH)-based technique is able to quantify the evolution of key biophysical parameters of cells during the exposure to cadmium for the first time. Murine embryonic fibroblasts NIH 3T3 are chosen here as cellular model for studying the cadmium effects. The results demonstrate that DH is able to retrieve the temporal evolution of different key parameters such as cell volume, projected area, cell thickness and dry mass, thus providing a full quantitative characterization of the cell physical behaviour during cadmium exposure. Our results show that the label-free character of the technique would allow biologists to perform systematic and reliable studies on cell death process induced by cadmium and we believe that more in general this can be easily extended to others heavy metals, thus avoiding the time-consuming, expensive and invasive label-based procedures used nowadays in the field. In fact, pollution by heavy metals is severe issue that needs rapid and reliable methods to be settled.
26 citations
TL;DR: In this article, an inspection optical technique based on ESPI can be adopted successfully for assessing fully integrity of stainless steel keg, in particular two kegs, the first pre-finished and the second with a known leak, are compared in order to test the possibility to employ ESPI as a non-destructive testing tool to quickly revealing the presence and to partially locate a leak in automatic way.
23 citations
TL;DR: The possibility of printing ordered microdots of high viscous inks such as poly(lactic-co-glycolic acid) (PLGA) by exploiting the spontaneous breakup of a thin fiber generated through nozzle-free pyro-electrospinning is shown.
Abstract: Electrohydrodynamic jetting is emerging as a successful technique for printing inks with resolutions well beyond those offered by conventional inkjet printers. However, the variety of printable inks is still limited to those with relatively low viscosities (typically <20 mPa s) due to nozzle clogging problems. Here, we show the possibility of printing ordered microdots of high viscous inks such as poly(lactic-co-glycolic acid) (PLGA) by exploiting the spontaneous breakup of a thin fiber generated through nozzle-free pyro-electrospinning. The PLGA fiber is deposited onto a partially wetting surface, and the breakup is achieved simply by applying an appropriate thermal stimulation, which is able to induce polymer melting and hence a mechanism of surface area minimization due to the Plateau–Rayleigh instability. The results show that this technique is a good candidate for extending the printability at the microscale to high viscous inks, thus extending their applicability to additional applications, such as ...
22 citations
TL;DR: A completely label-free biophysical (morphometric and optical) property characterization of living monocytes in flow is implemented, confirming the possibility to differentiate monocytes from other cell classes in flow, thus avoiding chemical cell staining or labeling, which are nowadays used.
Abstract: We implemented a completely label-free biophysical (morphometric and optical) property characterization of living monocytes in flow, using measurements obtained from two coherent imaging techniques: a pure light scattering approach to obtain an optical signature (OS) of cells, and a digital holography (DH) approach to achieve optical cell reconstructions in flow. A precise 3D cell alignment platform, taking advantage of viscoelastic fluid properties and microfluidic channel geometry, was used to investigate the OS of cells to achieve their refractive index, ratio of the nucleus over cytoplasm, and overall cell dimension. Further quantitative phase-contrast reconstructions by DH were employed to calculate surface area, dry mass, and biovolume of monocytes by using the OS outcomes as input parameters. The results show significantly different biophysical cell properties, confirming the possibility to differentiate monocytes from other cell classes in flow, thus avoiding chemical cell staining or labeling, which are nowadays used.
18 citations
TL;DR: A label-free holographic total internal reflection microscopy technique is shown; the technique is able to evaluate quantitatively the contact area of live fibroblast cells adhering onto the surface of a ferroelectric lithium niobate crystal, and results show values of contact area significantly different between cells adhered to the positive or negative face of the crystal.
Abstract: The surface of a c- cut ferroelectric crystal at room temperature is characterized by the so-called screening surface charges, able to compensate the charge due to the spontaneous polarization. Recently, these charges inspired the investigation of the interaction affinity of live cells with lithium niobate and lithium tantalate crystals. However, different knowledge gaps still remain that prevent a reasonable application of these materials for biological applications. Here, a label-free holographic total internal reflection microscopy is shown; the technique is able to evaluate quantitatively the contact area of live fibroblast cells adhering onto the surface of a ferroelectric lithium niobate crystal. The results show values of contact area significantly different between cells adhering onto the positive or negative face of the crystal. This reinforces the reasons for using the polarization charge of these materials to study and/or control cellular processes and, thus, to develop an innovative platform based on polar dielectric functional substrates.
16 citations
TL;DR: This work presents what it calls biofilm electrostatic test (BET) as a simple, rapid, and highly reproducible tool for evaluating in vitro the ability of bacteria to form biofilms through electrostatic interaction with a pyroelectrified carrier.
Abstract: Biofilms are detrimental to human life and industrial processes due to potential infections, contaminations, and deterioration. Therefore, the evaluation of microbial capability to form biofilms is of fundamental importance for assessing how different environmental factors may affect their vitality. Nowadays, the approaches used for biofilm evaluation are still poor in reliability and rapidity and often provide contradictory results. Here, we present what we call biofilm electrostatic test (BET) as a simple, rapid, and highly reproducible tool for evaluating in vitro the ability of bacteria to form biofilms through electrostatic interaction with a pyroelectrified carrier. The results show how the BET is able to produce viable biofilms with a density 6-fold higher than that on the control, after just 2 h incubation. The BET could pave the way to a rapid standardization of the evaluation of bacterial resistance among biofilm-producing microorganisms. In fact, due to its simplicity and cost-effectiveness, it is well suited for a rapid and easy implementation in a microbiology laboratory.
TL;DR: A full and accurate characterization of the movement of particles subjected to acoustophoresis in a microfluidic environment by holographic imaging is reported, allowing the retrieval of the acoustic energy densities and pressure amplitudes through full holographic analysis.
Abstract: The development of techniques able to characterize and map the pressure field is crucial for the widespread use of acoustofluidic devices in biotechnology and lab-on-a-chip platforms. In fact, acoustofluidic devices are powerful tools for driving precise manipulation of microparticles and cells in microfluidics in non-contact modality. Here, we report a full and accurate characterization of the movement of particles subjected to acoustophoresis in a microfluidic environment by holographic imaging. The particle displacement along the direction of the ultrasound wave propagation, coinciding with the optical axis, is observed and investigated. Two resonance frequencies are explored, varying for each the amplitude of the applied signal. The trajectories of individual tracers, accomplished by holographic measurements, are fitted with the theoretical model thus allowing the retrieval of the acoustic energy densities and pressure amplitudes through full holographic analysis. The absence of prior calibration, being independent of the object shape and the possibility of implementing automatic analysis make the use of holography very appealing for applications in devices for biotechnologies.
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TL;DR: In this article, a holographic technique that combines quantitative phase imaging with a custom setup designed to form and manipulate bubbles is proposed to provide an unparalleled insight into bubble dynamics through the combination of full-field thickness estimation, 3D imaging, and fast acquisition time.
Abstract: The dynamics and stability of thin liquid films have fascinated scientists over many decades Thin film flows are central to numerous areas of engineering, geophysics, and biophysics and occur over a wide range of length, velocity, and liquid properties scales In spite of many significant developments in this area, we still lack appropriate quantitative experimental tools with the spatial and temporal resolution necessary for a comprehensive study of film evolution We propose tackling this problem with a holographic technique that combines quantitative phase imaging with a custom setup designed to form and manipulate bubbles The results, gathered on a model aqueous polymeric solution, provide an unparalleled insight into bubble dynamics through the combination of full-field thickness estimation, three-dimensional imaging, and fast acquisition time The unprecedented level of detail offered by the proposed methodology will promote a deeper understanding of the underlying physics of thin film dynamics
TL;DR: This work shows that STDH is able to improve the spatial resolution as well and introduces a new oblique STDH modality to record and process hybrid ST representations, paving the way to the use of STDH for super-resolution imaging onboard microfluidic devices.
Abstract: Space–time digital holography (STDH) exploits the object motion to record the hologram in a hybrid ST domain This representation adds new capabilities to conventional DH, eg, unlimited field of view and variable phase shifting This is the best candidate for imaging biological samples flowing in microfluidic channels Here, we show that STDH is able to improve the spatial resolution as well Different from other super-resolution approaches, stitching between holograms or their spectra is no longer required Moreover, we introduce a new oblique STDH modality to record and process hybrid ST representations This allows improving resolution in 2D with one single object scan, paving the way to the use of STDH for super-resolution imaging onboard microfluidic devices
TL;DR: The investigation furnishes an interesting result that the complex behavior of the NPs can be fully comprehended and explained by considering the superposition of both EP and DEP forces.
Abstract: Electrophoresis (EP) and dielectrophoresis (DEP) are the two well-established methodologies to manipulate nanoparticles (NPs). Recently, DEP by a virtual electrode platform was demonstrated on ferroelectric substrates, where the driving force is due to the strong electric field generated by the pyroelectric effect, thus opening new scenarios for manipulating the matter. Such an innovative approach named pyroelectric-DEP has several advantages over traditional EP and DEP. However, a detailed study on this novel approach is required for understanding the complex pathways traced by NPs under the action of the pyroelectric-driven forces and thus for explaining the final patterns. Here, we investigate experimentally the dynamic behavior of CdSe NPs through time-lapse fluorescence microscopy imaging. Complete visualization and measurement of the directed-assembling process of NPs immersed in polydimethylsiloxane fluid is reported, which shows some unpredicted results with respect to the previous works, thus opening the route for designing in principle a reversible and switchable device allowing two different and reversible final NP-patterned states. The observed phenomena are fully analyzed by experimental and simulated analysis, and the movements of NPs is performed to elucidate in depth the involved processes. The investigation furnishes an interesting result that the complex behavior of the NPs can be fully comprehended and explained by considering the superposition of both EP and DEP forces.
TL;DR: In this article, single fibres of polymer nanocomposite PVDF-HFP containing MWCNT were formed by Pyro-EHD electrospinning, and the improvement of electrical conductivity is of one order of magnitude and the electrical percolation threshold is reduced from 2.5 to 0.3
07 Sep 2018
TL;DR: The non-invasive investigation of circulating human breast adenocarcinoma cells in microfluidic environment is demonstrated by implementing the full-angle tomographic phase microscopy (TPM) in a completely passive optical system.
Abstract: We demonstrate the non-invasive investigation of circulating human breast adenocarcinoma cells in microfluidic environment by implementing the full-angle tomographic phase microscopy (TPM). The proposed approach lies in a completely passive optical system, i.e. avoiding mechanical scanning or multi-direction probing of the sample and exploiting the engineered rolling of cells while they are flowing along a microfluidic channel.
01 Aug 2018
TL;DR: In this paper, the authors compared the performance and the extent of damage suffered by polypropylene composites reinforced with natural fiber fabrics and subjected to flexural loads, in particular, laminates including jute, flax and basalt woven fibers.
Abstract: Recently, low environmental impact and potential use in a wide range of applications have been the main driving reasons supporting the rapid growth of the research interest toward the investigation and development of items based on natural fiber composites. This paper compares the performance and the extent of damage suffered by polypropylene (PP) composites reinforced with natural fiber fabrics and subjected to flexural loads. In particular, laminates including jute, flax and basalt woven fibers have been prepared by typical film stacking and compression molding techniques. A premodified matrix (PPC) including 2 wt% of a coupling agent was also considered. Measurements were carried out on at least 5 determinations for each kind of samples. All flexural parameters appeared to be significantly increased for specimens based on PPC with respect to the ones based on neat PP with effects particularly pronounced in presence of basalt fibers. Despite the use of the same content of coupling agent, this finding can be attributed the achievement of a different extent of interfacial adhesion, in turn, due to the different nature of reinforcing fibers. The influence of both the matrix modification and the nature of reinforcing fibers on the extent of induced flexural damage were assessed in non-destructive way by Electronic Speckle Pattern Interferometry and by Scanning Electron Microscopy observations of cryofractured surfaces.
TL;DR: In this article, the pyroelectrohydrodynamic effect is exploited for patterning polymer fibers with high resolution in order to solve the problem of high-resolution polymer fiber fabrication.
Abstract: Nanomicropatterning of polymers and direct printing methods are becoming prominent nanofabrication tools in multiple fields of application from medicine to aerospace technology. All the available processes are very expensive, requiring complex equipment and highly trained staff. Often the desired pattern cannot be realized easily and the method used for the fabrication would be a direct consequence of the material of interest, with a significant limitation in case of highly viscous polymers. We propose a very simple, low cost method that exploits the pyroelectrohydrodynamic effect for patterning polymer fibers with high resolution. In particular, we focus on the fabrication of nanocomposite polymer fiber with good mechanical and electrical properties. We start from studying the instability phase of patterning for low concentrated polymeric solutions and discuss the condition of continuous printing. Moreover, the same technique is applied for the patterning of footpath as master for the realization of microfluidic chips. The simplicity of the method proposed, associated with the high-resolution patterning achievable at nanoscale, suggest innovative and widespread uses of general purpose for in situ and noninvasive instruments in different fields of research and business cases.
01 Jan 2018
TL;DR: The novel concept proposed, based on the activation of the pyroelectrodynamic effect, offers the ability of working on fluidic multiphase materials for processing biomaterials (biocompatible and biodegradable) in order to fabricate scaffold for tissue engineering application and high-viscous polymers for the fabrication of 3D microobjects, avoiding the typical chaotic spiraling effect usually occurring in conventional electrospinning systems.
Abstract: The possibility of shaping the soft matter into complex patterned structures is becoming very important in the realm of nanotechnology. Microelectronic components, flexible electronic circuits, optical waveguides, microlenses, 3D scaffolds for tissue engineering, biomaterials, and biosensors are just a few examples of possible applications of high-resolution patterns. Many different approaches have been developed and tested for materials manipulation and microfabrication purposes. Very recently, the ink-jet printing approach has opened new frontiers for noncontact printing and high-resolution dispensing. The advantages of the ink-jet printing approach also have been expanded by the invention of 3D printers actually used to synthesize a three-dimensional object through the new concept of additive manufacturing process. The work and the experiments reported in this chapter are related to the description of an unconventional approach developed for the manipulation of liquid and polymeric materials. The novel concept proposed, based on the activation of the pyroelectrodynamic effect, offers the ability of working on fluidic multiphase materials for processing biomaterials (biocompatible and biodegradable) in order to fabricate scaffold for tissue engineering application and high-viscous polymers for the fabrication of 3D microobjects, avoiding the typical chaotic spiraling effect usually occurring in conventional electrospinning systems.
TL;DR: In this paper, the authors demonstrate that ultrasound field calibration and imaging are achievable in a vertical resonator using digital holography, showing that it is a flexible tool to assist the diffusion of acoustophoresis microfluidic devices.
Abstract: We demonstrate that ultrasound field calibration and imaging are achievable in a vertical resonator using digital holography, showing that it is a flexible tool to assist the diffusion of acoustophoresis microfluidic devices.
07 Sep 2018
TL;DR: It is shown that the joint action of ML and BM3D overcomes their respective limitations and achieves quasi noise free DH reconstructions.
Abstract: Digital holograms can be severely degraded by a mixture of speckle and incoherent additive noise. The problem is more severe in the case of IRDH, due to the large speckle grain. In order to suppress the speckles, here we present the MLDH-BM3D, a method specifically suited to filter DH images that combines Multiple DH captures, named Looks, to the BM3D, a numerical filter conceived in order to take advantage from a very sparse representation of the object features. We show that the joint action of ML and BM3D overcomes their respective limitations and achieves quasi noise free DH reconstructions.
25 Jun 2018
TL;DR: In this article, trajectories of three particles inside a bubble film are revealed by holographic 3D tracking during the bubble growth, and the authors studied the thin-film drainage process by a digital holographic recording system.
Abstract: Thin-film drainage process has been studied by a digital holographic recording system. In this study, trajectories of three particles inside a bubble film are revealed by holographic 3D tracking during the bubble growth.
07 Sep 2018
TL;DR: This work built up an optofluidic platform based on DHM able to perform analysis in microfluidic environment and takes advantage of this technique to identify, sort and reconstruct the morphology of different classes of microplastics dispersed in water and to provide an effective assessment of their abundance.
Abstract: Digital holographic microscopy (DHM) has proved to be a powerful imaging tool for identifying, analysing and reconstructing the 3D shape of cells and small organisms in their natural environment. In fact, DHM has the advantage, compared to other imaging techniques, to be a non-intrusive, non-destructive and label-free method for in situ measurements. This makes holography the most suitable tool for underwater imaging, where many of the species under investigation are very fragile and can be damaged. In particular, we built up an optofluidic platform based on DHM able to perform such analysis in microfluidic environment, i.e. in dynamic conditions and also in case of a turbid medium. In this work, we take advantage of this technique to identify, sort and reconstruct the morphology of different classes of microplastics (e.g. PVC, PET, PP, etc.) dispersed in water, which are among the major pollutants in the ocean, and to provide an effective assessment of their abundance. By adopting special algorithms for numerical processing of the acquired images, we try to separate the plastics from other materials, such as organic debris (shell fragments, animals parts, diatoms, etc.) and other items (metal paint coatings, tar, glass, etc.).
16 Sep 2018
TL;DR: In this paper, a repeatable and accurate method to pattern fluorescent particles into polymer microlens array and flexible elastomeric membranes is presented, which uses intense electric field generated by a Periodically Poled Lithium Niobate (PPLN) in order to direct the self-assembly electrophoretic and dielectrophoric forces.
Abstract: We present a repeatable and accurate method to pattern fluorescent particles into polymer microlens array and flexible elastomeric membranes. This method uses intense electric field generated by a Periodically Poled Lithium Niobate (PPLN) in order to direct the self-assembly electrophoretic and dielectrophoretic forces.
01 Jan 2018
07 Sep 2018
TL;DR: In this article, the authors exploited the possibility to use Electronic Speckle Pattern Interferometry (ESPI) for the characterization of different racing tyres with particular attention to the tyres shoulder section.
Abstract: In this work is exploited the possibility to use Electronic Speckle Pattern Interferometry (ESPI) for the characterization of different tyres with particular attention to the tyres shoulder section. Tyres characterization is of fundamental importance for vehicle dynamics modelling, since they are the main responsible of vehicles dynamical behaviour and thanks to their ability to deform, they allow to drive a vehicle generating the appropriate interaction forces at the interface with the road. Their behaviour is a consequence to their very complex structure. Two different racing tyres, one for car and other for motorcycle, have been considered. The investigation has been focused at the aim to evaluate and measure the section’s components in order to get accurate information about the different layers along through the tyres shoulder section. Here we demonstrate that the different layers (rubber, nylon, steel) can be easily highlighted and identified by mean of the ESPI that, thanks to its high sensitivity, is capable to estimate the different out of plane displacement of the different layers that respond in a different way (i.e. with a different deformation) to a thermal stimulus highlighting the layers themselves. Moreover, we introduce a de-noising step in the reconstruction process: in particular we enhance the wrapped phase information by using a suitable algorithm called SPADEDH. It is important to note that the assessment about the different layers along the section is a very difficult task to obtain by visual inspection or classical microscopy. In fact, the condition of the cutted surface, or rather the strong inhomogeneity and the roughness make impossible to obtain good images especially in the shoulder area.
01 Jul 2018
TL;DR: In this paper, a holographic system for the evaluation of the 3D topography and thickness of evolving thin liquid films is proposed, which is of great interest to industrial processes and life science.
Abstract: The thickness of thin liquid films is of great interest to industrial processes and life science. Here we propose a holographic system for the evaluation of the 3D topography and thickness of evolving thin liquid film.
01 Jan 2018