Showing papers by "Pietro Ferraro published in 2020"

Microplastic Identification via Holographic Imaging and Machine Learning

Abstract: Microplastics (MPs) are a major environmental concern due to their possible impact on water pollution, wildlife, and the food chain. Reliable, rapid, and high‐throughput screening of MPs from other components of a water sample after sieving and/or digestion is still a highly desirable goal to avoid cumbersome visual analysis by expert users under the optical microscope. Here, a new approach is presented that combines 3D coherent imaging with machine learning (ML) to achieve accurate and automatic detection of MPs in filtered water samples in a wide range at microscale. The water pretreatment process eliminates sediments and aggregates that fall out of the analyzed range. However, it is still necessary to clearly distinguish MPs from marine microalgae. Here, it is shown that, by defining a novel set of distinctive “holographic features,” it is possible to accurately identify MPs within the defined analysis range. The process is specifically tailored for characterizing the MPs' “holographic signatures,” thus boosting the classification performance and reaching accuracy higher than 99% in classifying thousands of items. The ML approach in conjunction with holographic coherent imaging is able to identify MPs independently from their morphology, size, and different types of plastic materials.

Perspectives on liquid biopsy for label‐free detection of “circulating tumor cells” through intelligent lab‐on‐chips

Abstract: Circulating tumor cells (CTCs) are rare tumor cells released from primary, metastatic, or recurrent tumors in the peripheral blood of cancer patients. CTCs isolation from peripheral blood and their molecular characterization represent a new marker in cancer screening, a diagnostic tool called “liquid biopsy” (LB). Compared to traditional tissue biopsy that is invasive and does not reveal tumor heterogeneity, LB is noninvasive and reflects in “real‐time” tumor dynamism and drug sensitivity. In the frame of LB, a new paradigm based on single‐cell and label‐free analysis based on morphological analysis is emerging. Here, we review the latest research developments in this emerging vision of LB. In particular, we survey and discuss recent improvements in microfluidics, imaging label‐free diagnosis and cell classification by artificial intelligence and how to combine them to realize an intelligent platform based on lab‐on‐chip technology. This prospect appears to open up promising and intriguing new scenarios for cancer management through single‐cell analysis that will revolutionize the future of early cancer diagnosis and therapeutic choice with disruptive impact on the society.

Compact off-axis holographic slide microscope: design guidelines.

Abstract: Holographic microscopes are emerging as suitable tools for in situ diagnostics and environmental monitoring, providing high-throughput, label-free, quantitative imaging capabilities through small and compact devices. In-line holographic microscopes can be realized at contained costs, trading off complexity in the phase retrieval process and being limited to sparse samples. Here we present a 3D printed, cost effective and field portable off-axis holographic microscope based on the concept of holographic microfluidic slide. Our scheme removes complexity from the reconstruction process, as phase retrieval is non iterative and obtainable by hologram demodulation. The configuration we introduce ensures flexibility in the definition of the optical scheme, exploitable to realize modular devices with different features. We discuss trade-offs and design rules of thumb to follow for developing DH microscopes based on the proposed solution. Using our prototype, we image flowing marine microalgae, polystyrene beads, E.coli bacteria and microplastics. We detail the effect on the performance and costs of each parameter, design, and hardware choice, guiding readers toward the realization of optimized devices that can be employed out of the lab by non-expert users for point of care testing.

Gold Nanorods and Nanoprisms Mediate Different Photothermal Cell Death Mechanisms In Vitro and In Vivo.

Abstract: Photothermal therapy (PTT) is an efficient method of inducing localized hyperthermia and can be achieved using gold nanoparticles as photothermal agents. However, there are many hurdles to get over before this therapy can safely reach the clinics, including nanoparticles' optimal shape and the accurate prediction of cellular responses. Here, we describe the synthesis of gold nanorods and nanoprisms with similar surface plasmon resonances in the near-infrared (NIR) and comparable photothermal conversion efficiencies and characterize the response to NIR irradiation in two biological systems, melanoma cells and the small invertebrate Hydra vulgaris. By integrating animal, cellular, and molecular biology approaches, we show a diverse outcome of nanorods and nanoprisms on the two systems, sustained by the elicitation of different pathways, from necrosis to programmed cell death mechanisms (apoptosis and necroptosis). The comparative multilevel analysis shows great accuracy of in vivo invertebrate models to predict overall responses to photothermal challenging and superior photothermal performance of nanoprisms. Understanding the molecular pathways of these responses may help develop optimized nanoheaters that, safe by design, may improve PTT efficacy for clinical purposes.

Comparison between different non-destructive techniques methods to detect and characterize impact damage on composite laminates

Abstract: This paper aims to investigate the ability of ultrasonic and electronic speckle pattern interferometry to analyse the low-velocity impact internal damage mechanisms on basalt composite laminates an...

Learning Diatoms Classification from a Dry Test Slide by Holographic Microscopy.

Abstract: Diatoms are among the dominant phytoplankters in marine and freshwater habitats, and important biomarkers of water quality, making their identification and classification one of the current challenges for environmental monitoring. To date, taxonomy of the species populating a water column is still conducted by marine biologists on the basis of their own experience. On the other hand, deep learning is recognized as the elective technique for solving image classification problems. However, a large amount of training data is usually needed, thus requiring the synthetic enlargement of the dataset through data augmentation. In the case of microalgae, the large variety of species that populate the marine environments makes it arduous to perform an exhaustive training that considers all the possible classes. However, commercial test slides containing one diatom element per class fixed in between two glasses are available on the market. These are usually prepared by expert diatomists for taxonomy purposes, thus constituting libraries of the populations that can be found in oceans. Here we show that such test slides are very useful for training accurate deep Convolutional Neural Networks (CNNs). We demonstrate the successful classification of diatoms based on a proper CNNs ensemble and a fully augmented dataset, i.e., creation starting from one single image per class available from a commercial glass slide containing 50 fixed species in a dry setting. This approach avoids the time-consuming steps of water sampling and labeling by skilled marine biologists. To accomplish this goal, we exploit the holographic imaging modality, which permits the accessing of a quantitative phase-contrast maps and a posteriori flexible refocusing due to its intrinsic 3D imaging capability. The network model is then validated by using holographic recordings of live diatoms imaged in water samples i.e., in their natural wet environmental condition.

Layered 3D Printing by Tethered Pyro-Electrospinning

Abstract: Nowadays it is easy to imagine that the exploitation of different additive manufacturing approaches could find use in regenerative medicine and frontiers nanotechnology with a strong interest in the development of in vivo bio-incubators that better replicate the tissue environment. Various electrospinning technologies have been exploited for the fabrication of composite polymeric architectures, where fibers have been used for the construction layer by layer of micro-architectures. Unfortunately, in case of processing biomaterials, the intrinsic factors of the materials could become obstacles when considering such advanced engineering methods. Here, for the first time, we use the pyro-EHD process for the fabrication of layered three-dimensional architectures made using a biodegradable and biocompatible polymer. The proposed approach for layered 3D printing works at mild temperature allowing deposition at high resolution and great flexibility in manufacturing, avoiding high voltage generators, and nozzles. The layered 3D printing, activated by the pyro-electric effect, is discussed and characterized in terms of geometrical features and processing parameters. Different geometries and micro-architecture (wall, square, triangle, and hybrid structures) have been demonstrated and over printing of composite polymer, obtained by mixing multiwall carbon nanotubes and fluorochrome, has been discussed, focusing on the use of a biodegradable and biocompatible polymer.

Cellular Uptake of Mildly Oxidized Nanographene for Drug-Delivery Applications

Abstract: Graphene family materials (GFMs) have large perspectives for drug-delivery applications, but their internalization in live cells is under investigation in a wide variety of studies in order to asse...

Characterization of ‘green’ composite laminates after flexural tests by speckle interferometry

Abstract: For many years, the use of advanced composite materials in aeronautics, automotive, and sports applications has been well established. The characteristics of composite materials in terms of weight reduction, fatigue, and corrosion resistance make them competitive in many cases with respect to conventional ones (i.e., metal alloys). On the other hand, the fabrication process of the most employed composites reinforced by carbon or glass fibers requires complex steps that are not always environmentally friendly. In fact, such composite materials are not themselves “green.” For these reasons, in the last decades, the use of natural reinforcing fibers has gained increasing attention, allowing the development of new materials sharing the same advantages with conventional composite systems while respecting the environment. Due to their structural complexity, these materials are not always compatible with the use of standard nondestructive evaluation methods, e.g., ultrasounds testing. The effective use of speckle holographic techniques as nondestructive evaluation methods in full field and noncontact modality is proved on “green” composite materials. In particular, electronic speckle pattern interferometry is tested on different kinds of specimens preliminarily subjected to flexural tests. Results show that, in most cases, the damage appears more severe on the back side of specimens, opposite to the loaded one, with the sole exception of basalt laminates.

Biped Walking of Magnetic Microrobot in Oscillating Field for Indirect Manipulation of Non-Magnetic Objects

Abstract: Magnetic microrobots have been developed for various biomedical applications, such as microswimmers for indirect manipulation and assembly of objects. When non-magnetic targets fall or adhere to the substrate by gravity, the indirect manipulation is required to move objects on substrate surface. Inspired by human walking, a novel magnetic microrobot with two pseudopods was designed. Driven by a periodic magnetic field, the structure can subtly lift and move two feet alternately to walk forward. The amplitude and frequency of oscillation were optimized and the controllability of the system was evaluated through performing the motion along planned paths with a velocity of 3.5 mm/s. Finally, microbeads and cell aggregates were pushed and arranged together by the microrobot, which shows potential application in flexible microassembly on substrate surface.

Detecting Collagen Molecules at Picogram Level through Electric Field-Induced Accumulation.

Abstract: The demand for sensors capable of measuring low-abundant collagen in human fluids has highly increased in recent years Indeed, collagen is expected to be a biomarker for chronic diseases and could monitor their progression Here we show detection of highly diluted samples of collagen at picogram level thanks to an innovative pyro-electrohydrodynamic jet (p-jet) system Through the intense electric fields generated by the pyroelectric effect in a ferroelectric crystal, the collagen solution was concentrated on a small area of a slide that was appropriately functionalized to bind proteins The collagen molecules were labeled by an appropriate fluorophore to show how the number of tiny droplets influences the limit of detection of the technique The results show that the p-jet is extremely promising for overcoming the current detection limits of collagen-based products in human fluids, performing 10 times better than the enzyme-linked immunosorbent assay (ELISA) and thus paving the way for the early diagnosis of related chronic diseases

Stitching sub-aperture in digital holography based on machine learning.

Abstract: Sub-aperture stitching in digital holography (DH) is a very important issue both for the spatial resolution improvement as well as for measuring larger aperture through synthetic enlargement of numerical aperture. In fact, sub-apertures stitching permits to greatly expand the capabilities of optical metrology thus allowing to accurately measure complex optical surfaces such as large spherical and aspheric. Stitching operations can be difficult and cumbersome depending on geometric parameters of specific objects under test. However, here we show that machine learning can definitively aid this process. In fact, here we propose for the first time, to the best of our knowledge, a novel sub-aperture stitching approach based on machine learning applied to an array of different phase-maps sub-apertures recorded by an off-axis digital holographic systems. Essentially, we construct a network according to computation model of sub-aperture stitching and remove the alignment errors and system aberration of sub-aperture maps by training the network. Correct measurement of the surface topography of hemisphere surface is demonstrated thus validating the proposed learning approach. Reported results demonstrate that machine learning can be a useful tool for simplifying the process and for making it a reliable and accurate tool in optical metrology.

Pyroelectric Tweezers for Handling Liquid Unit Volumes

Abstract: Liquids are the primary environments in which chemical, physical, and biological processes occur. Considering a liquid bridge as liquid unit volume (LUV) element, it is highly desirable to develop reliable tools for handling such volumes. Herein, a sort of intelligent microfluidic platform based on the pyroelectric‐electrohydrodynamics (EHD) is shown for manipulating liquid bridges and thus performing multiple functions in a flexible and simple way. Several basic operations with liquid bridges using an EHD‐pin matrix based on the pyroelectric effect engineered in ferroelectric crystals are demonstrated. By activating pyro‐EHD effect in predetermined positions (pins of the array), the locomotion and handling of single or multiple LUVs simultaneously are controlled. In particular, multiple operations such as lift, displacement, mixing, stretching, and carrying vector for microparticles, are shown. These tweezers based on a pyro‐EHD matrix can open the route for a multipurpose platform driven by physical intelligence and can be used for driving locomotion and operate manifolds functionalities in many areas of science and technology at microscale as well as nanoscale with advantages to be activated by the sole thermal stimulus, controlled remotely, and in noncontact mode.

Optobiology: live cells in optics and photonics

Abstract: A new intriguing paradigm recently emerged in BioPhotonics in which a single biological element like a simple cell can be used as optical or photonic component having well-defined features. Based on this novel concept, interaction between light and biological matter can be exploited in many circumstances as a useful tool in various fields of science and technology. In fact, it is surprising as well as exciting that the optical behavior of living cells permits to use them as micro-lenses for imaging, photonic micro-resonators or optical waveguide. Moreover, it has been demonstrated that biological cells behave as advanced probes for optical tweezing able to manipulate the matter at nanoscale and also as sub-wavelength probes of localized fluorescence. Here, we present an overview of these fascinating applications of biological lenses. The aim of the present Topical Review is introducing a completely new scenario to the community of scientists working in optics and photonics. A developing research field is presented in which live cells can be employed and exploited as optical components for unbelievable applications spanning from simple imaging to manipulation of soft matter to biomedical diagnosis. Several and most significant studies and discoveries will be illustrated and discussed.

Automatic removal of phase aberration in holographic microscopy for drug sensitivity detection of ovarian cancer cells

Abstract: Real-time and long-term monitoring of the morphological changes of cells in biomedical science is highly desired Quantitative phase imaging (QPI) obtained by various interferometric methods is the ideal tool for monitoring such processes as it allows to get quantitative information and thus assessing the right response on cell behaviors Among QPI, digital holography (DH) in microscope configuration is a powerful tool as it is tolerant versus defocusing and for this reason is able to compensate for eventual defocusing effect during long time-lapse recording Moreover, DH dynamic phase imaging for biological specimens has several advantages, namely non-invasive, label-free, and high-resolution However, in DH, one of the main limitations is due to the need compensate aberrations due to the optical components in the object beam In fact, the image of the object is inevitably embedded in aberrations due to the microscope objective (MO) and other optical components in the optical setup Here, we propose an automatic and robust phase aberration compensation method based on a synthetic difference (SD) image process The method is able to detect automatically object-free regions From such regions, hologram’s aberrations can be accurately evaluated and cleaned up in the final QPI maps Thanks to our method, temporal evolutions of cell morphological parameters were quantitatively analyzed, hence helping in studying the drug sensitivity of ovarian cancer cells The experimental results demonstrated that the proposed method could robustly separate the object-free region from the distorted phase image and automatically compensate the total aberrations without any manual interventions, extra components, prior knowledge of the object, and optical setup

Exploiting a holographic polarization microscope for rapid autofocusing and 3D tracking.

Abstract: We report a fast autofocusing and accurate 3D tracking scheme for a digital hologram (DH) that intrinsically exploits a polarization microscope setup with two off-axis illumination beams having different polarization. This configuration forms twin-object images that are recorded in a digital hologram by angular and polarization multiplexing technique. We show that the separation of the two images on the recording plane follows a linear relationship with the defocus distance and indicates the defocus direction. Thus, in the entire field of view (FOV), the best focus distance of each object can be directly retrieved by identifying the respective separation distance with a cross-correlation algorithm, at the same time, 3D tracking can be performed by calculating the transverse coordinates of the two images. Moreover, we estimate this linear relationship by utilizing the numerical propagation calculation based on a single hologram, in which the focus distance of one of the objects in the FOV is known. We proved the proposed approach in accurate 3D tracking through multiple completely different experimental cases, i.e., recovering the swimming path of a marine alga (tetraselmis) in water and fast refocusing of ovarian cancer cells under micro-vibration stimulation. The reported experimental results validate the proposed strategy’s effectiveness in dynamic measurement and 3D tracking without multiple diffraction calculations and any precise knowledge about the setup. We claim that it is the first time that a holographic polarization multiplexing setup is exploited intrinsically for 3D tracking and/or fast and accurate refocusing. This means that almost any polarization DH setup, thanks to our results, can guarantee accurate focusing along the optical axis in addition to polarization analysis of the sample, thus overcoming the limitation of the poor axial resolution.

Lock-in Thermography as a tool for the Detection of Damages in “Eco” Composite Materials

Abstract: Thanks to their advanced properties, composite materials have found applications in important industrial sectors. In particular, in the last decades, the use of natural reinforcing fibers has gained an increasing attention allowing the development of new materials with the same advantages of conventional composite systems but respecting the environment, too. In this frame, the development and identification of fast and low cost non-destructive tools for their quality control is of fundamental importance. In this work, the Lock-in thermography was tested for the analysis of samples belonging to six different "eco" composite materials on which delamination damage was induced. The results obtained are promising and show how the active thermography technique used is well suited for the detection of this kind of defects allowing also a quantitative characterization of their extension.

Optical characterizations of airless radial tire

Abstract: In this work is analyzed the possibility to use optical techniques for the characterization of airless radial tire. Electronic Speckle Pattern Interferometry (ESPI), laser scanner based on principle of triangulation and Digital Image Correlation (DIC) have been used to acquire and study this kind of tire. A MICHELIN® X® TWEEL® UTV has been considered as case study. The acquisitions have been used for the measurement of the shape for testing junction areas and to evaluate the structure behavior under a vertical load.

Holographic imaging boosts machine learning for accurate micro-plastics recognition in seawater sample

Abstract: An effective strategy, that combines Digital Holography with machine learning, for achieving accurate and automatic identification of microplastics in filtered water sample, is proposed, reaching over 99% in classification performance among microplastics and diatoms.

Highly sensitive detection of low abundant molecules by pyro-electrohydro-dynamic jetting

Abstract: The effective detection of low-concentrated molecules in small volumes represents a significant challenge in many sectors such as biomedicine, safety, and pollution. Here, we show an easy way to dispense liquid droplets from few μl volume (0.2-0.5 μl) of a mother drop, used as reservoir, by using a pyro-electrohydro-dynamic jetting (p-jet) dispenser. This system is proposed for multi-purpose applications such as printing viscous fluids and as a biosensor system. The p-jet system is based on the pyroelectric effect of polar dielectric crystals such as lithium niobate (LN). The electric field generated by the pyroelectric effect acts electro-hydrodynamically on the sample of liquid, allowing the deposition of small volumes. The p-jet approach allows to obtain the dispensing of drops of very small volumes (up to tenths of a picoliter) avoiding the use of syringes and nozzles generally used in standard technologies. The reliability of the technique as a biosensor is demonstrated both in the case of oligonucleotides and in a sample of clinical interest, namely gliadin. The results show the possibility of detecting these biomolecules even when they are low abundant, i.e. down to attomolar. The results show a marked improvement in the detection limit (LOD) when compared with the conventional technique (ELISA). Moreover, it has been presented the possibility of using the p-jet as a useful tool in the detection of biomarkers, present in the blood but currently not detectable with conventional techniques and related to neurodegenerative diseases such as Alzheimer.

Conical microstructures made of biopolymers for guiding and delivering light

Abstract: Optical microstructures are of very high interest for delivering and or guiding optical radiation. Beyond the replacement of conventional hypodermic syringes, the use of microneedles opened the route towards portable lab on chip devices where the same microneedle could be used for drug delivery and photodynamic therapy, focusing the light thorough the needle tips. Here we propose for the first time an innovative approach for the fabrication of polymeric conical structures and the optical characterization of the light guided through a pyro-electrodrawn micro needle. A point-like thermal stimulation of a ferroelectric crystal enabled the electro-drawing of single or parallelized needles. The results reported show the possibility of tuning the geometry and the dimension of the structures produced and their use for controlling and guiding external light. The structures have been realized using a biocompatible and biodegradable polymer thus such conical structures in principle could be implantable. The conical structures have been characterized in terms of geometry, shape and emitted light profile. We report experimental results and discuss results and perspectives for exploiting them.

Damage evaluation on 3Dimensional Carbon Fibre laminates by speckle interferometry

Abstract: In this work, the evaluation of damaged areas due to low velocity impact tests at different impact energy values on Carbon Fibre (CF) laminates with 3D fabric, made by infusion technology and reinforced with epoxy resin, were investigated by NDI (Non-destructive Investigation) technique based on speckle interferometry. Composites are characterized by several interacting failure modes such as matrix breakage, fibre failure and delaminations, which can be simultaneously induced by low velocity impacts. It can be very difficult to detect by visual inspections of the structures such phenomena. The aim of this study is to evaluate the damaged area due to an impact event. CF composite laminates were impact damaged with four energy levels (5, 10, 20, 30J) at room temperature, by drop weight impact machine. The results showed that ESPI technique was able to identify barely visible low-velocity impact damages.

Holographic phase imaging to observe intracellular dynamics of plant cells during dehydration

Abstract: We show that dehydrating process can be effective for improving the phase-contrast in bioimaging, thus permitting a better observation of plant cells with the scope of learning more about cellular dynamics.