Showing papers by "Pietro Ferraro published in 2014"
TL;DR: This work proves the new procedure for healthy red blood cells (RBCs) (i.e., discocytes) having a concave surface in their central region and shows that the method can be also useful to classify, in terms of morphology, different varieties of RBCs.
Abstract: Three dimensional (3D) morphometric analysis of flowing and not-adherent cells is an important aspect for diagnostic purposes. However, diagnostics tools need to be quantitative, label-free and, as much as possible, accurate. Recently, a simple holographic approach, based on shape from silhouette algorithm, has been demonstrated for accurate calculation of cells biovolume and displaying their 3D shapes. Such approach has been adopted in combination with holographic optical tweezers and successfully applied to cells with convex shape. Nevertheless, unfortunately, the method fails in case of specimen with concave surfaces. Here, we propose an effective approach to achieve correct 3D shape measurement that can be extended in case of cells having concave surfaces, thus overcoming the limit of the previous technique. We prove the new procedure for healthy red blood cells (RBCs) (i.e., discocytes) having a concave surface in their central region. Comparative analysis of experimental results with a theoretical 3D geometrical model of RBC is discussed in order to evaluate accuracy of the proposed approach. Finally, we show that the method can be also useful to classify, in terms of morphology, different varieties of RBCs.
124 citations
TL;DR: It is shown that, by using the sparsity measure coefficient regarded as a refocusing criterion in the holographic reconstruction, it is possible to recover the focus plane and establish the degree of sparsity of digital holograms, when samples of the diffraction Fresnel propagation integral are used as a sparse signal representation.
Abstract: Several automatic approaches have been proposed in the past to compute the refocus distance in digital holography (DH). However most of them are based on a maximization or minimization of a suitable amplitude image contrast measure, regarded as a function of the reconstruction distance parameter. Here we show that, by using the sparsity measure coefficient regarded as a refocusing criterion in the holographic reconstruction, it is possible to recover the focus plane and, at the same time, establish the degree of sparsity of digital holograms, when samples of the diffraction Fresnel propagation integral are used as a sparse signal representation. We employ a sparsity measurement coefficient known as Gini's index thus showing for the first time, to the best of our knowledge, its application in DH, as an effective refocusing criterion. Demonstration is provided for different holographic configurations (i.e., lens and lensless apparatus) and for completely different objects (i.e., a thin pure phase microscopic object as an in vitro cell, and macroscopic puppets) preparation.
103 citations
TL;DR: In this paper, a pyroelectric cartridge is used to inject hydrophobic and hydrophilic bioactive agents into a hypodermic needle in order to deliver drugs.
Abstract: Hypodermic needle injection is still the most common method of drug delivery despite its numerous limitations and drawbacks, such as pain, oneshot administration, and risk of infection. Seeking a viable, safe, and pain-free alternative to the over 16 billion injections per year has therefore become a top priority for our modern technological society. Here, a system that uses a pyroelectric cartridge in lieu of the syringe piston as a potential solution is discussed. Upon stimulation, the cartridge electro-draws, at room temperature, an array of drug-encapsulated, biodegradable polymer microneedles, able to deliver into hypodermic tissue both hydrophobic and hydrophilic bioactive agents, according to a predefi ned chrono-programme. This mould-free and contact-free method permits the fabrication of biodegradable polymer microneedles into a ready-to-use confi guration. In fact, they are formed on a fl exible substrate/holder by drawing them directly from drop reservoirs, using a controlled electro-hydrodynamic force. Tests of insertion are performed and discussed in order to demonstrate the possibility to prepare microneedles with suitable geometric and mechanical properties using this method.
81 citations
TL;DR: A new effective method for encoding in a single complex wavefront the contribution of multiple incoherent reconstructions is proposed, thus allowing to obtain a single synthetic digital hologram that show significant speckle-reduction when optically projected by a Spatial Light Modulator (SLM).
Abstract: In digital holography (DH) a mixture of speckle and incoherent additive noise, which appears in numerical as well as in optical reconstruction, typically degrades the information of the object wavefront. Several methods have been proposed in order to suppress the noise contributions during recording or even during the reconstruction steps. Many of them are based on the incoherent combination of multiple holographic reconstructions achieving remarkable improvement, but only in the numerical reconstruction i.e. visualization on a pc monitor. So far, it has not been shown the direct synthesis of a digital hologram which provides the denoised optical reconstruction. Here, we propose a new effective method for encoding in a single complex wavefront the contribution of multiple incoherent reconstructions, thus allowing to obtain a single synthetic digital hologram that show significant speckle-reduction when optically projected by a Spatial Light Modulator (SLM).
71 citations
TL;DR: This paper investigates the use of a digital holographic microscope, with partial spatial coherent illumination, for the automated detection and tracking of spermatozoa and characterized cell motility on clinical samples of seminal fluid.
Abstract: In this paper we investigate the use of a digital holographic microscope, with partial spatial coherent illumination, for the automated detection and tracking of spermatozoa. This in vitro technique for the analysis of quantitative parameters is useful for assessment of semen quality. In fact, thanks to the capabilities of digital holography, the developed algorithm allows us to resolve in-focus amplitude and phase maps of the cells under study, independently of focal plane of the sample image. We have characterized cell motility on clinical samples of seminal fluid. In particular, anomalous sperm cells were characterized and the quantitative motility parameters were compared to those of normal sperm.
69 citations
TL;DR: In this article, the most significant achievements reached in 2013 on holographic imaging are described and discussed in detail, and the authors describe shortly what appeared to them to be the most important achievements reached.
Abstract: Although holography is topic that goes back to the 1950s, the research in this field continues to be very active worldwide. A continuous growth is confirmed by the publication of more than 2000 papers each year in archival journal on different holographic issues. Here we describe shortly what appeared to us to be the most significant achievements reached in 2013 on holographic imaging.
66 citations
TL;DR: The 3D tracking of micro-objects, based on digital holography, is proposed through the analysis of the complex wavefront of the light scattered by the micro-samples through a direct wavefront analysis at the focal plane overcoming the limitation of the conventional back focal plane interferometry.
Abstract: The 3D tracking of micro-objects, based on digital holography, is proposed through the analysis of the complex wavefront of the light scattered by the micro-samples. Exploiting the advantages of the off-axis full-field holographic interferometry, the tracking of multiple objects is achieved by a direct wavefront analysis at the focal plane overcoming the limitation of the conventional back focal plane interferometry in which only one object at a time can be tracked. Furthermore, the method proposed and demonstrated here is a step forward with respect to other holographic tracking tools. The approach is tested in two experiments, the first investigates the Brownian motion of particles trapped by holographic optical tweezers, while the second relates to the cell motility in a 3D collagen matrix, thus showing its usefulness for lab-on-chip systems in typical bioassay testing.
59 citations
TL;DR: It is demonstrated that ML-DH benefits from the presence of the RBCs, providing enhancement in terms of numerical resolution and noise suppression thus obtaining images whose quality is higher than the quality achievable in the case of a liquid without occlusive objects.
Abstract: Imaging through turbid media is a challenging topic. A liquid is considered turbid when dispersed particles provoke strong light scattering, thus destroying the image formation by any standard optical system. Generally, colloidal solutions belong to the class of turbid media since dispersed particles have dimensions ranging between 0.2 μm and 2 μm. However, in microfluidics, another relevant issue has to be considered in the case of flowing liquid made of a multitude of occluding objects, e.g. red blood cells (RBCs) flowing in veins. In such a case instead of severe scattering processes unpredictable phase delays occur resulting in a wavefront distortion, thus disturbing or even hindering the image formation of objects behind such obstructing layer. In fact RBCs can be considered to be thin transparent phase objects. Here we show that sharp amplitude imaging and phase-contrast mapping of cells hidden behind biological occluding objects, namely RBCs, is possible in harsh noise conditions and with a large field-of view by Multi-Look Digital Holography microscopy (ML-DH). Noteworthy, we demonstrate that ML-DH benefits from the presence of the RBCs, providing enhancement in terms of numerical resolution and noise suppression thus obtaining images whose quality is higher than the quality achievable in the case of a liquid without occlusive objects.
58 citations
TL;DR: In this article, a novel scheme for solar energy harvesting based on the pyroelectric effect has been demonstrated, which is based on an optical system focusing solar radiation onto a ferroelectric crystal (i.e., lithium niobate).
50 citations
TL;DR: In this paper, the main draw-backs are the nozzle-clogging and single-jet spinneret,respectively, which is a real limitation in terms of usable polymers and for patterning active organics.
Abstract: lthough electrospinning (ES) allows the production ofunsurpassed nanoscale polymer fibers, the major draw-backs are the nozzle-clogging and single-jet spinneret,respectively. This is a real limitation in terms of usablepolymers and for patterning active organics. Nowadays themicro-engineering of smart materials could represent a newroute for many fields of technology ranging from theproduction of electronic and photonic devices
50 citations
TL;DR: A pyro-concentrator able to accumulate biomolecules directly onto a conventional binding surface to open the way to a mass-based technology for sensing molecules at very low concentrations, in environmental as well as in diagnostics applications.
Abstract: Biomolecule detection is important in many fields, but obviously becomes increasingly difficult as concentrations decrease. Here, the authors demonstrate a method to dispense and concentrate biomolecules onto a target slide, greatly improving the detection limits.
TL;DR: In this paper, the authors show that, in cases where the blood flows along a microfluidic channel at sufficient speed, the hologram acts as a selective filter, discarding the unwanted scattering.
Abstract: Achieving a clear vision through turbid fluids is a highly desirable goal in microfluidics. In particular, observing particles dipped inside blood shows fascinating perspectives in all fields of bio-medical research. White-light microscopy cannot provide clear imaging due to the strong scattering of light by red blood cells. Here we solve the problem by Digital Holography microscopy. We show that, in cases where the blood flows along a microfluidic channel at sufficient speed, the hologram acts as a selective filter. This occurs due to the Doppler frequency shift experienced by the photons hitting the red blood cells, discarding the unwanted scattering. In cases where the blood flow is not quick enough to take advantage of the Doppler shift, multiple holograms can be processed to produce a clear image of the object. We show that the correlation coefficients between multiple acquisitions at different fluid speeds can be adopted to study the visibility of the fringes due to the moving colloidal particles in the medium. Hence, we estimate the threshold velocity required to completely discard all the scattered photons. In this way the object is seen as dipped in a transparent liquid thus completely eliminating the negative effect of turbidity on the imaging.
TL;DR: In this article, an optical method based on Raman spectroscopy was used to separate X-and Y-chromosome-bearing sperm cells, overcoming many of the limitations associated with current sex-sorting protocols.
Abstract: X- and Y-chromosome-bearing sperm cell sorting is of great interest, especially for animal production management systems and genetic improvement programs. Here, we demonstrate an optical method based on Raman spectroscopy to separate X- and Y-chromosome-bearing sperm cells, overcoming many of the limitations associated with current sex-sorting protocols. A priori Raman imaging of bull spermatozoa was utilized to select the sampling points (head-neck region), which were then used to discriminate cells based on a spectral classification model. Main variations of Raman peaks associated with the DNA content were observed together with a variation due to the sex membrane proteins. Next, we used principal component analysis to determine the efficiency of our device as a cell sorting method. The results (>90% accuracy) demonstrated that Raman spectroscopy is a powerful candidate for the development of a highly efficient, non-invasive, and non-destructive tool for sperm sexing.
TL;DR: This paper reports the theoretical formulation of the synthetizing recording process, experimental evidence of various cases demonstrating quantitative phase retrieval by adopting this intrinsic phase-shifting procedure, and the proposed method, which could be particularly suited in all cases where the object shift is an intrinsic feature of the investigated system.
Abstract: We investigate the spatio-temporal scanning of a single-pixel row for building up synthetic interferograms or digital holograms, shifted each other of a desired phase step. This unusual recording modality exploits the object movement to synthesize interferograms with extended Field of View and improved noise contrast. We report the theoretical formulation of the synthetizing recording process and experimental evidence of various cases demonstrating quantitative phase retrieval by adopting this intrinsic phase-shifting procedure. The proposed method could be particularly suited in all cases where the object shift is an intrinsic feature of the investigated system, as e.g. in microfluidics imaging.
TL;DR: Two macro categories are divided: methods used to reconstruct three-dimensional generic objects and methods for objects recorded on a tilted plane with respect to hologram one, and different applications for each are proposed.
Abstract: The microscope is one of the most useful tools for exploring and measuring the microscopic world. However, it has some restrictions in its applications because the microscope’s depth of field (DOF) is not sufficient for obtaining a single image with the necessary magnification in which the whole longitudinal object volume is in focus. Currently, the answer to this issue is the extended focused image. Techniques proposed over the years to overcome the limited DOF constraint of the holographic systems and to obtain a completely in-focus image are discussed. We divide them in two macro categories: the first one involves methods used to reconstruct three-dimensional generic objects (including techniques inherited from traditional microscopy, such as the sectioning and merging approach, or multiplane imaging), while the second area involves methods for objects recorded on a tilted plane with respect to hologram one (including not only the use of reconstruction techniques and rotation matrices, but also the introduction of a numerical cubic phase plate or hologram deformations). The aim is to compare these methods and to show how they work under the same conditions, proposing different applications for each.
TL;DR: In this paper, a hybrid microfluidic chip made by assembling a polar-dielectric crystal with polymeric microfluideic channels is presented. But the chip does not have the capability of self-assembly and manipulation of CNTs.
Abstract: Carbon nanoparticles are becoming ubiquitous in many fields of science and technology. However, a grand challenge remains in assembling, patterning, and positioning or even simple manipulation of CNTs for complex functional assemblies. CNTs have in fact enormous perspectives for application in biotechnologies as bactericide agents or as prominent tools for investigating cell mechanisms, or more in general as functionalized nanoparticle-vectors, but their exploitation requires viable technology at the lab-on-a-chip scale. Many approaches have been attempted in developing technologies for manipulating CNTs. One elective approach is based on electric fields driven mechanisms such as DEP forces. A variety of chips have been designed and realized with this aim. Here we report on a novel hybrid microfluidic chip made by assembling a polar-dielectric crystal with polymeric microfluidic channels. One challenging feature of such a hybrid device approach, based on an electrode-free dielectrophoretic (DEP) approach, is that it makes use of surface charge templates for self-assembling and manipulation of CNTs in liquid media directly into a microfluidic channel. Here various examples of self-assembly in microfluidic channels as well as separation and collection of two classes of nano/microparticles are reported. The method can open the way to novel fabrication protocols for the realisation of future flexible devices with new and more complex functionalities, highly desirable in electronics as well as in biotechnology at the lab-on-a-chip scale.
TL;DR: An improved TIRDHM system is developed, taking advantage of a refractive index mismatch between the prism and the sample substrate, to allow phase-shifting DH with just a single-beam interferometric configuration.
Abstract: Total Internal Reflection Digital Holographic Microscopy (TIRDHM) is recognized to be a powerful tool for retrieving quantitative phase images of cell-substrate interfaces, adhesions, and tissue structures close to the prism surface. In this Letter, we develop an improved TIRDHM system, taking advantage of a refractive index mismatch between the prism and the sample substrate, to allow phase-shifting DH with just a single-beam interferometric configuration. Instead of the traditional off-axis method, phase-shift method is used to retrieve amplitude and phase images in coherent light and TIR modality. Essentially, the substrate-prism interface acts like a beam splitter generating a reference beam, where the phase-shift dependence on the incident angle is exploited in this common-path configuration. With the aim to demonstrate the technique's validity, some experiments are performed to establish the advantage of this compact and simple configuration, in which the reference arm in the setup is avoided.
TL;DR: A new three-dimensional holographic tracking method capable to track, simultaneously and in a single step, all the spatial coordinates of micro-objects using the enhanced correlation coefficient (ECC) maximization method applied directly on the holographic reconstructed complex wave fields.
Abstract: We propose here a new three-dimensional (3D) holographic tracking method capable to track, simultaneously and in a single step, all the spatial coordinates of micro-objects. The approach is based on the enhanced correlation coefficient (ECC) maximization method but applied, for the first time to the best of our knowledge, directly on the holographic reconstructed complex wave fields. The key novelty of the proposed strategy is its ability to calculate simultaneously the 3D coordinates of cells, without decoupling the contribution of amplitude and phase. The proposed strategy is tested on living cells (i.e., NIH 3T3 mouse fibroblast) flowing into a microfluidic channel and compared with classical holographic tracking approach. Theoretical description and experimental validation of the proposed strategy are reported.
TL;DR: In this paper, a new automatic technique for speckle reduction in the context of digital holographic images is presented, in which bidi-mensional empirical mode decomposition is used to decompose the image signal and then filtered through the Frost filter.
Abstract: The paper presents a new automatic technique for speckle reduction in the context of digital holog- raphy. Speckle noise is a superposition of unwanted spots over objects of interest, due to the behavior of a coherence source of radiation with the object surface characteristics. In the proposed denoising method, bidi- mensional empirical mode decomposition is used to decompose the image signal, which is then filtered through the Frost filter. The proposed technique was preliminarily tested on the "Lena" image for quality assessment in terms of peak signal-to-noise ratio. Then, its denoising capability was assessed on different holographic images on which also the comparison (using both blind metrics and visual inspection) with the leading strategies in the state of the art was favorably performed. © 2014 Society of Photo-Optical Instrumentation Engineers (SPIE) (DOI: 10.1117/1.OE.53.11 .XXXXXX)
29 May 2014
TL;DR: In this article, the application of Electronic Speckle Pattern Interferometry (ESPI) is employed for inspecting composite materials subject to thermal load, and the evaluation of the effective delaminated area of damaged polymer/Carbon Nanotubes fiber reinforced composites after flexural tests is presented.
Abstract: In this work, the application of Electronic Speckle Pattern Interferometry (ESPI) is employed for inspecting composite materials subject to thermal load. The composite samples are of interest in the aerospace industry. Through realtime surface illumination by visible laser (i.e. 532 nm), the ESPI technique allows the non-contact, non-destructive, full frame and real time detection of micro-deformations, micro-cracks, residual stress and delamination. The evaluation of the effective delaminated area of damaged polymer/Carbon Nanotubes fiber reinforced composites after flexural tests is presented.
TL;DR: It is shown, for the first time, that in some specific configurations exact solutions of the Gerchberg–Saxton algorithm can be achieved so as to produce a limited number of light intensity spots in a clean array.
TL;DR: It is shown that DHM generates useful information on the dimensions and structure of human sperm, not revealed by conventional phase-contrast microscopy, in particular the volume of vacuoles, and suggested its use as an additional prognostic tool in assisted reproduction technology.
Abstract: The morphology of the sperm head has often been correlated with the outcome of in vitro fertilization, and has been shown to be the sole parameter in semen of value in predicting the success of intracytoplasmic sperm injection and intracytoplasmic morphologically selected sperm injection. In this paper, we have studied whether digital holographic microscopy (DHM) may be useful to obtain quantitative data on human sperm head structure and compared this technique with high-power digitally enhanced Nomarski optics. The main advantage of digital holography is that high-resolution three-dimensional quantitative sample imaging may be automatically produced by numerical refocusing of a two-dimensional image at different object planes without any mechanical scanning. We show that DHM generates useful information on the dimensions and structure of human sperm, not revealed by conventional phase-contrast microscopy, in particular the volume of vacuoles, and suggest its use as an additional prognostic tool in assisted reproduction technology.
TL;DR: This work demonstrates a similar and more compact holographic system based on an external cavity quantum cascade laser emitting at 8 μm, which allows the acquisition of speckle holograms of scattering objects, which can be processed in real time.
Abstract: Mid-infrared digital holography based on CO2 lasers has proven to be a powerful coherent imaging technique due to reduced sensitivity to mechanical vibrations, increased field of view, high optical power, and possible vision through scattering media, e.g., smoke. Here we demonstrate a similar and more compact holographic system based on an external cavity quantum cascade laser emitting at 8 μm. Such a setup, which includes a highly sensitive microbolometric camera, allows the acquisition of speckle holograms of scattering objects, which can be processed in real time. In addition, by exploiting the broad laser tunability, we can acquire holograms at different wavelengths, from which we extract phase images not subjected to phase wrapping, at synthetic wavelengths ranging from hundreds of micrometers to several millimeters.
TL;DR: In this paper, a simple large scale biological sample phase detection device called gravity driven high throughput phase detecting cytometer based on quantitative interferometric microscopy to obtain flowing red blood cells phase.
TL;DR: In this paper, a single step approach for fabricating free-standing polymer membranes reinforced with arrayed self-assembled carbon nanotubes (CNTs) is described, which self-assembles spontaneously by electrode-free DC dielectrophoresis based on surface charge templates.
Abstract: Here, we report on a single step approach for fabricating free-standing polymer membranes reinforced with arrayed self-assembled carbon nanotubes (CNTs). The CNTs are self-assembled spontaneously by electrode-free DC dielectrophoresis based on surface charge templates. The electrical charge template is generated through the pyroelectric effect onto periodically poled lithium niobate ferroelectric crystals. A thermal stimulus enables simultaneously the self-assembly of the CNTs and the cross-linking of the host polymer. Examples of thin polydimethylsiloxane membranes reinforced with CNT patterns are shown.
TL;DR: In this paper, an alternative method to off-axis configuration to record and analyse the microscopical phase object information in total internal reflection dispensing with the use of reference arm is presented.
Abstract: TIRDHM is a technique that allows to analyse the phase change of microscopical sections produced on the prism surface due to material attached on the top Therefore, due to the evanescence waves properties we can analyse quantitatively the properties and specific morphology located to few nanometers on the top of surface contact In this work, we study and present an alternative method to off-axis configuration to record and analyse the microscopical phase object information in Total Internal Reflection dispensing with the use of reference arm
ENEA1
TL;DR: In this paper, the pyroelectric effect activated onto a Lithium Niobate crystal is exploited for the fabrication on demand of microlens array using high viscous polymer materials.
Abstract: In this work we present a direct printing of microlenses using high viscous polymer materials. In particular the pyro-electric effect activated onto a Lithium Niobate crystal is exploited for the fabrication on demand of microlens array.
01 Jan 2014
TL;DR: In this article, nonlinear crystals are used to build coherent light sources in spectral regions where laser sources are limited, or do not exist, and optical parametric oscillators as well as harmonic and difference frequency generators are finding increasing application in high sensitivity spectroscopy.
Abstract: Nonlinear crystals are, nowadays, key devices to build coherent sources emitting radiation from the UV to the IR spectral range. Applications of nonlinear optics are primarily based on frequency conversion, through harmonic generation or sum and difference frequency mixing. These nonlinear frequency conversion techniques make possible coherent light sources in spectral regions where laser sources are limited, or do not exist. Light sources based on nonlinear crystals, like optical parametric oscillators as well as harmonic and difference frequency generators, are finding increasing application in high sensitivity spectroscopy.
TL;DR: In this paper, the authors investigate the ability of new tools in giving information about internal damage on composites and compare the delamination extensions with the measurements from literature on impacted autoclave cured laminates.
Posted Content•
TL;DR: The review is intended both for summarizing the state-of-art on the semen analysis and recent achievement obtained by means of digital holography and for exploring new possible applications of digital HoloHolography in this field.
Abstract: Male reproductive health in both humans and animals is an important research field in biological study. In order to characterize the morphology, the motility and the concentration of the sperm cells, which are the most important parameters to feature them, digital holography demonstrated to be an attractive technique. Indeed, it is a labelfree, non-invasive and high-resolution method that enables the characterization of live specimen. The review is intended both for summarize the state-of-art on the semen analysis and recent achievement obtained by means of digital holography and for exploring new possible applications of digital holography in this field.