Publications
264 results found
Rizou ME, Prodromakis T, 2016, A planar micro-magnetic platform for stimulation of neural cells in vitro, 12th IEEE Biomedical Circuits and Systems Conference (BioCAS), Publisher: IEEE, Pages: 34-37, ISSN: 2163-4025
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- Citations: 4
Biolek D, Corinto F, Prodromakis T, et al., 2016, EU COST Action IC1401-Pushing the Frontiers of Memristive Devices to Systems, 18th Mediterranean Electrotechnical Conference (MELECON), Publisher: IEEE, ISSN: 2158-8481
Cortese S, Trapatseli M, Khiat A, et al., 2016, A TiO<sub>2</sub>-based Volatile Threshold Switching Selector Device with 107 non linearity and sub 100 pA Off Current., International Symposium on VLSI Technology, Systems and Application (VLSI-TSA), Publisher: IEEE, ISSN: 1930-8868
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- Citations: 6
Papadimitriou KI, Zeimpekis I, Moschou D, et al., 2015, Towards a high-precision, embedded system for versatile sensitive biosensing measurements
This paper demonstrates a versatile, high-Accuracy, data-Acquisition electronic platform for biosensing measurements, capable of collecting minute current and voltage input signals, stemming from various types of amperometric and potentiometric biosensors. The instrument is able to process the incoming analog signals in a digital manner and export them back to the user either as an amplified analog signal or in digital format through a USB 2.0 interface. The proposed system comprises off-The-shelf IC components and a commercially available FPGA-based DSP unit. The performance of the instrumentation platform has been tested initially by means of very small ideal current and voltage signals generated by precise electronic equipments and subsequently has been validated via proof-of-concept experiments with amperometric and potentiometric sensors. The results shown in this paper exhibit potential for integrating specific sections of the proposed instrumentation board with appropriate biosensors, towards developing affordable, yet reliable Point-Of-Care (POC) diagnostic tools for sensitive biochemical measurements.
Serb A, Khiat A, Prodromakis T, 2015, An RRAM Biasing Parameter Optimizer, IEEE TRANSACTIONS ON ELECTRON DEVICES, Vol: 62, Pages: 3685-3691, ISSN: 0018-9383
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- Citations: 23
Mostafa H, Khiat A, Serb A, et al., 2015, Implementation of a spike-based perceptron learning rule using TiO<sub>2-<i>x</i></sub> memristors, FRONTIERS IN NEUROSCIENCE, Vol: 9, ISSN: 1662-453X
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- Citations: 28
Marei I, Chester A, Carubelli I, et al., 2015, Assessment of Parylene C Thin Films for Heart Valve Tissue Engineering, TISSUE ENGINEERING PART A, Vol: 21, Pages: 2504-2514, ISSN: 1937-3341
Background: Scaffolds are a key component of tissue-engineered heart valves (TEHVs). Several approaches had been adopted in the design of scaffolds using both natural and synthetic resources. We have investigated the suitability of parylene C (PC), a vapor deposited polymeric material, for the use as a scaffold in TEHV.Aims: To evaluate the adsorption of extracellular matrix components onto plasma-activated PC and study the biocompatibility of PC by measuring cellular adhesion, viability, apoptosis, and phenotypic expression of valve endothelial and interstitial cells. Finally, the mechanical properties of PC were compared with those of native aortic valve cusp tissue.Methods: PC slides were plasma activated and then coated with gelatin, type I collagen, or fibronectin. Porcine pulmonary valve endothelial and interstitial cells were then grown on plasma oxidized PC with different types of coatings and their adhesion was observed after 20 h of incubation. Cell viability was tested using the MTS assay, and apoptosis was estimated using TUNEL staining. The mechanical properties of PC and valve tissue were measured using a Bose Mechanical Tester. Finally, cell-seeded PC films were exposed to pulsatile pressure and aortic shear stress, respectively, to test their durability in a dynamic environment.Results: Our findings show that collagen and fibronectin could bind to plasma oxidized PC. Both valve endothelial and interstitial cells adhered to protein-coated ECM. PC had a profile of mechanical stiffness and ultimate tensile strength that were comparable with or in excess of those seen in porcine aortic valve cusps. Cells were still attached to PC films after 3 days of exposure to up to 50 mmHg pulsatile pressure or aortic levels of shear stress.Conclusion: PC is a promising candidate for use as a scaffold in tissue engineering heart valves. Additional studies are required to determine both the durability and long-term performance of cell-seeded PC when in a
Moschou D, Trantidou T, Regoutz A, et al., 2015, Surface and Electrical Characterization of Ag/AgCl Pseudo-Reference Electrodes Manufactured with Commercially Available PCB Technologies, SENSORS, Vol: 15, Pages: 18102-18113, ISSN: 1424-8220
Lab-on-Chip is a technology that could potentially revolutionize medical Point-of-Care diagnostics. Considerable research effort is focused towards innovating production technologies that will make commercial upscaling financially viable. Printed circuit board manufacturing techniques offer several prospects in this field. Here, we present a novel approach to manufacturing Printed Circuit Board (PCB)-based Ag/AgCl reference electrodes, an essential component of biosensors. Our prototypes were characterized both structurally and electrically. Scanning Electron Microscopy (SEM) and X-Ray Photoelectron Spectroscopy (XPS) were employed to evaluate the electrode surface characteristics. Electrical characterization was performed to determine stability and pH dependency. Finally, we demonstrate utilization along with PCB pH sensors, as a step towards a fully integrated PCB platform, comparing performance with discrete commercial reference electrodes.
Berdan R, Serb A, Khiat A, et al., 2015, A mu-controller-based system for interfacing selectorless RRAM crossbar arrays, IEEE Transactions on Electron Devices, Vol: 62, Pages: 2190-2196, ISSN: 0018-9383
Selectorless crossbar arrays of resistive randomaccess memory (RRAM), also known as memristors, conduct large sneak currents during operation, which can significantly corrupt the accuracy of cross-point analog resistance (M t ) measurements. In order to mitigate this issue, we have designed, built, and tested a memristor characterization and testing (mCAT) instrument that forces redistribution of sneak currents within the crossbar array, dramatically increasing M t measurement accuracy. We calibrated the mCAT using a custom-made 32 × 32 discrete resistive crossbar array, and subsequently demonstrated its functionality on solid-state TiO 2-x RRAM arrays, on wafer and packaged, of the same size. Our platform can measure standalone M t in the range of 1 kΩ to 1 MΩ with <;1% error. For our custom resistive crossbar, 90% of devices of the same resistance range were measured with <;10% error. The platform's limitations have been quantified using large-scale nonideal crossbar simulations.
Gupta I, Serb A, Berdan R, et al., 2015, A Cell Classifier for RRAM Process Development, IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS, Vol: 62, Pages: 676-680, ISSN: 1549-7747
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- Citations: 16
Trantidou T, Terracciano CM, Kontziampasis D, et al., 2015, Biorealistic cardiac cell culture platforms with integrated monitoring of extracellular action potentials, Scientific Reports, Vol: 5, ISSN: 2045-2322
Current platforms for in vitro drug development utilize confluent, unorganized monolayers of heart cells to study the effect on action potential propagation. However, standard cell cultures are of limited use in cardiac research, as they do not preserve important structural and functional properties of the myocardium. Here we present a method to integrate a scaffolding technology with multi-electrode arrays and deliver a compact, off-the-shelf monitoring platform for growing biomimetic cardiac tissue. Our approach produces anisotropic cultures with conduction velocity (CV) profiles that closer resemble native heart tissue; the fastest impulse propagation is along the long axis of the aligned cardiomyocytes (CVL) and the slowest propagation is perpendicular (CVT), in contrast to standard cultures where action potential propagates isotropically (CVL ≈ CVT). The corresponding anisotropy velocity ratios (CVL/CVT = 1.38 – 2.22) are comparable with values for healthy adult rat ventricles (1.98 – 3.63). The main advantages of this approach are that (i) it provides ultimate pattern control, (ii) it is compatible with automated manufacturing steps and (iii) it is utilized through standard cell culturing protocols. Our platform is compatible with existing read-out equipment and comprises a prompt method for more reliable CV studies.
Prodromakis T, Lu W, Yang J, et al., 2015, Solid-state Memristive Devices and Systems, IEEE JOURNAL ON EMERGING AND SELECTED TOPICS IN CIRCUITS AND SYSTEMS, Vol: 5, Pages: 121-122, ISSN: 2156-3357
Trapatseli M, Carta D, Regoutz A, et al., 2015, Conductive Atomic Force Microscopy Investigation of Switching Thresholds in Titanium Dioxide Thin Films, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 119, Pages: 11958-11964, ISSN: 1932-7447
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- Citations: 30
Li Q, Serb A, Prodromakis T, et al., 2015, A Memristor SPICE Model Accounting for Synaptic Activity Dependence, PLOS ONE, Vol: 10, ISSN: 1932-6203
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- Citations: 23
Carta D, Mountjoy G, Regoutz A, et al., 2015, X-ray Absorption Spectroscopy Study of TiO<sub>2-<i>x</i></sub> Thin Films for Memory Applications, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 119, Pages: 4362-4370, ISSN: 1932-7447
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- Citations: 29
Li Q, Xu H, Khiat A, et al., 2015, Impact of Active Areas on Electrical Characteristics of TiO<sub>2</sub> based Solid-State Memristors, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 185-188, ISSN: 0271-4302
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- Citations: 5
Serb A, Redman-White W, Papavassiliou C, et al., 2015, Limitations and precision requirements for read-out of passive, linear, selectorless RRAM arrays, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 189-192, ISSN: 0271-4302
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- Citations: 4
Brivio S, Covi E, Serb A, et al., 2015, Gradual set dynamics in HfO<sub>2</sub>-based memristor driven by sub-threshold voltage pulses, International Conference on Memristive Systems (MEMRISYS), Publisher: IEEE
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- Citations: 18
Salaoru I, Li Q, Khiat A, et al., 2014, Coexistence of memory resistance and memory capacitance in TiO<sub>2</sub> solid-state devices, NANOSCALE RESEARCH LETTERS, Vol: 9, ISSN: 1931-7573
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- Citations: 19
Li Q, Yoon WJ, Ju H, 2014, Optimization of an organic photovoltaic device via modulation of thickness of photoactive and optical spacer layers, NANOSCALE RESEARCH LETTERS, Vol: 9, ISSN: 1931-7573
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- Citations: 17
Humphrey E, Trantidou T, Kane C, et al., 2014, Improved calcium cycling is associated with microtubule reorganisation in anisotropic cardiomyocyte cultures, CARDIOVASCULAR RESEARCH, Vol: 103, ISSN: 0008-6363
Trantidou T, Tariq M, Terracciano CM, et al., 2014, Parylene C-Based Flexible Electronics for pH Monitoring Applications, Sensors, Vol: 14, Pages: 11629-11639, ISSN: 1424-8239
Emerging materials in the field of implantable sensors should meet the needs for biocompatibility; transparency; flexibility and integrability. In this work; we present an integrated approach for implementing flexible bio-sensors based on thin Parylene C films that serve both as flexible support substrates and as active H+ sensing membranes within the same platform. Using standard micro-fabrication techniques; a miniaturized 40-electrode array was implemented on a 5 μm-thick Parylene C film. A thin capping film (1 μm) of Parylene on top of the array was plasma oxidized and served as the pH sensing membrane. The sensor was evaluated with the use of extended gate discrete MOSFETs to separate the chemistry from the electronics and prolong the lifetime of the sensor. The chemical sensing array spatially maps the local pH levels; providing a reliable and rapid-response (<5 s) system with a sensitivity of 23 mV/pH. Moreover; it preserves excellent encapsulation integrity and low chemical drifts (0.26–0.38 mV/min). The proposed approach is able to deliver hybrid flexible sensing platforms that will facilitate concurrent electrical and chemical recordings; with application in real-time physiological recordings of organs and tissues.
Li Q, Khiat A, Salaoru I, et al., 2014, Stochastic switching of TiO<sub>2</sub>-based memristive devices with identical initial memory states, NANOSCALE RESEARCH LETTERS, Vol: 9, ISSN: 1931-7573
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- Citations: 9
Trantidou T, Rao C, Barrett H, et al., 2014, Selective hydrophilic modification of Parylene C films: a new approach to cell micro-patterning for synthetic biology applications, Biofabrication, Vol: 6, ISSN: 1758-5090
We demonstrate a simple, accurate and versatile method to manipulate Parylene C, a material widely known for its high biocompatibility, and transform it to a substrate that can effectively control the cellular microenvironment and consequently affect the morphology and function of the cells in vitro. The Parylene C scaffolds are fabricated by selectively increasing the material's surface water affinity through lithography and oxygen plasma treatment, providing free bonds for attachment of hydrophilic biomolecules. The micro-engineered constructs were tested as culture scaffolds for rat ventricular fibroblasts and neonatal myocytes (NRVM), toward modeling the unique anisotropic architecture of native cardiac tissue. The scaffolds induced the patterning of extracellular matrix compounds and therefore of the cells, which demonstrated substantial alignment compared to typical unstructured cultures. Ca2+ cycling properties of the NRVM measured at rates of stimulation 0.5–2 Hz were significantly modified with a shorter time to peak and time to 90% decay, and a larger fluorescence amplitude (p < 0.001). The proposed technique is compatible with standard cell culturing protocols and exhibits long-term pattern durability. Moreover, it allows the integration of monitoring modalities into the micro-engineered substrates for a comprehensive interrogation of physiological parameters.
Khiat A, Salaoru I, Prodromakis T, 2014, Resistive switching characteristics of indium-tin-oxide thin film devices, PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE, Vol: 211, Pages: 1194-1199, ISSN: 1862-6300
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- Citations: 3
Salaoru I, Khiat A, Li Q, et al., 2014, Origin of the OFF state variability in ReRAM cells, JOURNAL OF PHYSICS D-APPLIED PHYSICS, Vol: 47, ISSN: 0022-3727
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- Citations: 21
Rao C, Barratt H, Prodromakis T, et al., 2014, Tissue Engineering Techniques in Cardiac Repair and Disease Modelling, CURRENT PHARMACEUTICAL DESIGN, Vol: 20, Pages: 2048-2056, ISSN: 1381-6128
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- Citations: 3
Li Q, Khiat A, Salaoru I, et al., 2014, Memory Impedance in TiO<sub>2</sub> based Metal-Insulator-Metal Devices, SCIENTIFIC REPORTS, Vol: 4, ISSN: 2045-2322
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- Citations: 84
Berdan R, Lim C, Khiat A, et al., 2014, A Memristor SPICE Model Accounting for Volatile Characteristics of Practical ReRAM, IEEE ELECTRON DEVICE LETTERS, Vol: 35, Pages: 135-137, ISSN: 0741-3106
Li Q, Khiat A, Salaoru I, et al., 2014, Origin of Stochastic Resistive Switching in Devices with Phenomenologically Identical Initial States, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 1428-1431, ISSN: 0271-4302
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- Citations: 2
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