Paolo Bisegna | University of Rome Tor Vergata (original) (raw)

Papers by Paolo Bisegna

Springer eBooks, Jul 15, 2006

This paper deals with single-mode passive damping of piezoactuated structures. The problem of shu... more This paper deals with single-mode passive damping of piezoactuated structures. The problem of shunting in the best way a piezoelectric actuator is discussed, and a new passive shunt circuit, given by the parallel of an inductance and a capacitance in series to a resistance, is here proposed. For a sufficiently high piezoelectric coupling coefficient, it is analytically shown to be more performant than the classical resistive-inductive shunt circuit, in the sense that it guarantees an higher exponential time decay rate of the free vibrations.

Civil-comp proceedings, Jul 2, 2009

A layer-wise first-order shear deformation theory is adopted to construct a model of three-layer ... more A layer-wise first-order shear deformation theory is adopted to construct a model of three-layer piezoelectric sandwich plates. A finite-element formulation of this model, based on a bilinear quadrangular four-node finite element with thirteen degrees of freedom per node, is developed, and any locking phenomenon is avoided by using a reduced-integration technique. This formulation is adopted in the analysis of the vibration suppression problem of a cantilever steel plate, equipped with two piezoelectric patches placed near its clamped edge.

Proceedings of SPIE, Apr 27, 2000

Medical Engineering & Physics, Oct 1, 2017

The performance of a novel microfluidic impedance cytometer (MIC) with coplanar configuration is ... more The performance of a novel microfluidic impedance cytometer (MIC) with coplanar configuration is investigated in-silico. The main feature of the device is the ability to provide accurate particle-sizing despite the well-known measurement sensitivity to particle trajectory. The working principle of the device is presented and validated by means of an original virtual laboratory providing close-to-experimental synthetic data streams. It is shown that a metric correlating with particle trajectory can be extracted from the signal traces and used to compensate the trajectory-induced error in the estimated particle size, thus reaching high-accuracy. An analysis of relevant parameters of the experimental setup is also presented.

Analytical and Bioanalytical Chemistry, Mar 18, 2020

Microfluidic applications such as active particle sorting or selective enrichment require particl... more Microfluidic applications such as active particle sorting or selective enrichment require particle classification techniques that are capable of working in real-time. In this paper, we explore the use of neural networks for fast label-free particle characterization during microfluidic impedance cytometry. A recurrent neural network is designed to process data from a novel impedance chip layout for enabling real-time multi-parametric analysis of the measured impedance data streams. As demonstrated with both synthetic and experimental datasets, the trained network is able to characterize with good accuracy size, velocity and cross-sectional position of beads, red blood cells and yeasts, with a unitary prediction time of 0.4 ms. The proposed approach can be extended to other device designs and cell types for electrical-parameter extraction. This combination of microfluidic impedance cytometry and machine learning can serve as a stepping stone to real time single-cell analysis and sorting.

bioRxiv (Cold Spring Harbor Laboratory), Nov 5, 2022

Antimicrobial peptides (AMPs) represent a promising class of compounds to fight antibiotic-resist... more Antimicrobial peptides (AMPs) represent a promising class of compounds to fight antibiotic-resistant infections. In most cases, they kill bacteria by making their membrane permeable and therefore exhibit low propensity to induce bacterial resistance. In addition, they are often selective, killing bacteria at concentrations lower than those at which they are toxic to the host. However, clinical applications of AMPs are hindered by a limited understanding of their interactions with bacteria and human cells. Standard susceptibility testing methods are based on the analysis of the growth of a bacterial population and therefore require several hours. Moreover, different assays are required to assess the toxicity to host cells. In this work, we propose the use of microfluidic impedance cytometry to explore the action of AMPs on both bacteria and host cells, in a rapid manner and with single-cell resolution. We show that the electrical signatures of Bacillus megaterium (B. megaterium) cells and human red blood cells (RBCs) reflect the action of a representative antimicrobial peptide, DNS-PMAP23. In particular, the impedance phase at high frequency (e.g., 11 or 20 MHz) is a reliable label-free metric for monitoring DNS-PMAP23 bactericidal activity and toxicity to RBCs. The impedance-based characterization is validated by comparison with standard antibacterial activity assays and absorbance-based hemolytic activity assays. Furthermore, we demonstrate the applicability of the technique to a mixed sample of B. megaterium cells and RBCs, which paves the way to study AMP selectivity for bacterial versus eukaryotic cells in presence of both cell types.

International Journal of Rotating Machinery, 2012

Ideal bladed rotors are rotationally symmetric, as a consequence they exhibit couples of degenera... more Ideal bladed rotors are rotationally symmetric, as a consequence they exhibit couples of degenerate eigenmodes at coinciding frequencies. When even small imperfections are present destroying the periodicity of the structure (disorder or mistuning), each couple of degenerate eigenfrequencies splits into two distinct values (frequency split) and the corresponding modal shapes exhibit vibration amplitude peaks concentrated around few blades (localization phenomenon). In this paper a continuous model describing the in-plane vibrations of a mistuned bladed rotor is derived via the homogenization theory. Imperfections are accounted for as deviations of the mass and/or stiffness of some blades from the design value; a perturbation approach is adopted in order to investigate the frequency split and localization phenomena arising in the imperfect structure. Numerical simulations show the effectiveness of the proposed model, requiring much lower computational effort than classical finite element schemes.

Lab on a Chip, 2016

Please note that technical editing may introduce minor changes to the text and/or graphics, which... more Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal's standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains.

Journal of Sound and Vibration, May 1, 2011

This paper put forth a new approach, based on the mathematical theory of homogenization, to study... more This paper put forth a new approach, based on the mathematical theory of homogenization, to study the vibration localization phenomenon in disordered rotationally periodic structures. In order to illustrate the method, a case-study structure is considered, composed of pendula ...

Journal of microelectromechanical systems, Oct 1, 2010

AbstractA new microfluidic cytometer for single-cell dielectric spectroscopy is proposed in this... more AbstractA new microfluidic cytometer for single-cell dielectric spectroscopy is proposed in this paper and analyzed in silico by means of a finite-element model. The device, inspired by electrical impedance tomography, includes two circumferential arrays of electrodes instead of just ...

Sensors and Actuators B-chemical, Mar 1, 2018

While there is a great interest in microfluidic impedance cytometry as a label-free approach for ... more While there is a great interest in microfluidic impedance cytometry as a label-free approach for singleparticle analysis, the accuracy of the technique is challenged by the positional dependence issue, i.e. identical particles flowing in the microchannel along different trajectories provide different signals. We solve this issue without resorting to particle focusing, by means of a straightforward modification of the conventional wiring scheme for the standard impedance chip comprising two pairs of facing electrodes. Instead of applying the AC voltage to electrodes on the same side of the channel and collecting the differential current flowing through the electrodes on the other side, we apply the AC voltage to diagonally opposite electrodes and collect the differential current flowing through the remaining ones. Therefore, the bipolar signal recorded upon the passage of a particle shows opposite pulses with different amplitude. The relative difference of the latter is a new metric enabling a simple compensation procedure of the signal impedance for off-center particles. Impedance data for 5.2, 6, and 7 m particles are collected, and coefficients of variation in (electrical) diameter of particles respectively of 2.8%, 1%, and 1.2%, similar to the manufacturers' quoted values, are obtained. The novel operation mode is successfully implemented also in a coplanar electrode configuration, exploiting two pairs of liquid electrodes.

Sensors and Actuators B-chemical, Aug 1, 2017

Microfluidic impedance-based devices with coplanar electrode layout represent an attractive tool ... more Microfluidic impedance-based devices with coplanar electrode layout represent an attractive tool for low-cost, label-free, single-cell analysis. However, their usefulness has long been limited by the positional dependence of the measured signals, i.e., identical particles traveling along different paths provide different traces. In this paper we show that it is possible to significantly reduce this unwanted effect via straightforward signal processing, by exploiting the richness of the information contained in the recorded traces.

Biophysical Journal, Sep 1, 2003

A model describing the role of transversal and longitudinal diffusion of cGMP and Ca 21 in signal... more A model describing the role of transversal and longitudinal diffusion of cGMP and Ca 21 in signaling in the rod outer segment of vertebrates is developed. Utilizing a novel notion of surface-volume reaction and the mathematical theories of homogenization and concentrated capacity, the diffusion of cGMP and Ca 21 in the interdiscal spaces is shown to be reducible to a one-parameter family of diffusion processes taking place on a single rod cross section; whereas the diffusion in the outer shell is shown to be reducible to a diffusion on a cylindrical surface. Moreover, the exterior flux of the former serves as a source term for the latter, alleviating the assumption of a well-stirred cytosol. A previous model of visual transduction that assumes a well-stirred rod outer segment cytosol (and thus contains no spatial information) can be recovered from this model by imposing a ''bulk'' assumption. The model shows that upon activation of a single rhodopsin, cGMP changes are local, and exhibit both a longitudinal and a transversal component. Consequently, membrane current is also highly localized. The spatial spread of the single photon response along the longitudinal axis of the outer segment is predicted to be 3-5 mm, consistent with experimental data. This approach represents a tool to analyze pointwise signaling dynamics without requiring averaging over the entire cell by global Michaelis-Menten kinetics.

Journal of Intelligent Material Systems and Structures, 2000

New finite-element formulations are developed for the analysis of a plate having thin piezoelectr... more New finite-element formulations are developed for the analysis of a plate having thin piezoelectric actuators bonded on its upper and/or lower surfaces. The proposed finite elements are two-dimensional, quadrangular, four-node, Mindlin-type, locking-free, and have five degrees of freedom per node. These are the deflection of the middle plane of the plate, the rotations of the fibers normal to the middle plane and the actuation electric potentials of the piezoelectric actuators. The effectiveness of the proposed finite-element formulations is shown by studying some case problems, whose analytical solutions are available.

Nanotechnology, Jul 11, 2018

The accurate determination of the geometrical features of quasi one-dimensional nanostructures is... more The accurate determination of the geometrical features of quasi one-dimensional nanostructures is mandatory for reducing errors and improving repeatability in the estimation of a number of geometry-dependent properties in nanotechnology. In this paper a method for the reconstruction of length and spatial orientation of single nanowires (NWs) is presented. Those quantities are calculated from a sequence of scanning electron microscope (SEM) images taken at different tilt angles using a simple 3D geometric model. The proposed method is evaluated on a collection of SEM images of single GaAs NWs. It is validated through the reconstruction of known geometric features of a standard reference calibration pattern. An overall uncertainty of about 1% in the estimated length of the NWs is achieved.

Frontiers in Molecular Neuroscience, Jan 13, 2023

Incontri di studio, Oct 5, 2018

meccanica cellulare, disciplina ponte fra biologia cellulare e meccanica, può grandemente giovars... more meccanica cellulare, disciplina ponte fra biologia cellulare e meccanica, può grandemente giovarsi delle recenti tecnologie di microscala, che, grazie alla loro efficacia in termini di capacità di processo, costi e facilità di fabbricazione, rendono possibili nuove direzioni di ricerca. In questo lavoro sono discussi due esempi di tali tecnologie: la citometria microfluidica ad impedenza e l'elettrodeformazione degli eritrociti. La primà e una tecnologia lab-on-chip che offre una soluzione semplice e non invasiva per identificare e monitorare le caratteristiche biofisiche e meccaniche a livello di singola cella, senza richiedere alcuna marcatura. La seconda, complementare alla prima, rende possibile la deformazione cellulare tramite un campo elettrico applicato. * * * A. − Cell mechanics is a discipline that bridges cell biology with mechanics. Emerging microscale technologies are opening new venues in the field, due to their costeffectiveness, relatively easy fabrication, and high throughput. Two examples of those technologies are discussed here: microfluidic impedance cytometry and erythrocyte electrodeformation. The former is a lab-on-chip technology offering a simple, non-invasive, label-free method for counting, identifying and monitoring cellular biophysical and mechanical function at the single-cell level. The latter is a useful complement to the former, enabling cell deformation under the influence of an applied electric field.. I Robert Hooke discovered the law of elasticity which bears his name in. He first described this discovery in the anagram "ceiiinosssttuv",

Computer Methods in Applied Mechanics and Engineering, Aug 1, 2018

An isogeometric analysis formulation for simulating red blood cell (RBC) electro-deformation is p... more An isogeometric analysis formulation for simulating red blood cell (RBC) electro-deformation is presented. Electrically-induced cell deformation experiments are receiving increasing attention as an attractive strategy for single-cell mechanical phenotyping. As the RBC structure consists in a very thin biological membrane enclosing a nearly-incompressible fluid, (i) a surface shell kinematic model and (ii) the imposition of the shell enclosed-volume conservation constraint are proposed within the isogeometric analysis framework. With regard to the electro-deformation, an accurate evaluation of the electric-field induced forces is achieved by the Maxwell stress tensor approach. A staggered fixed-point iteration scheme is then proposed for performing the electro-mechanical coupling, in order to use reliable mechanical and electrical problem solvers sequentially. Supported by the comparison with experimental results and reference solutions, numerical simulations concerning the large deformation of a RBC by optical tweezers and an in silico electro-deformation experiment prove the accuracy and the effectiveness of the proposed formulation.

Meccanica, Apr 6, 2016

Due to its crucial role in pathophysiology, erythrocyte deformability represents a subject of int... more Due to its crucial role in pathophysiology, erythrocyte deformability represents a subject of intense experimental and modeling research. Here a computational approach to electro-deformation for erythrocyte mechanical characterization is presented. Strong points of the proposed strategy are: i) an accurate computation of the mechanical actions induced on the cell by the electric field, ii) a microstructurally-based continuum model of the erythrocyte mechanical behavior, iii) an original rotation-free shell finite element, especially suited to the application in hand. As proved by the numerical results, the developed tool is effective and sound, and can foster the role of electro-deformation in single-cell mechanical phenotyping.