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    ZnO-PEDOT core-shell nanowires: An ultrafast, high contrast and transparent electrochromic display

    , Article Solar Energy Materials and Solar Cells ; Volume 145 , 2016 , Pages 200-205 ; 09270248 (ISSN) Kateb, M ; Safarian, S ; Kolahdouz, M ; Fathipour, M ; Ahamdi, V ; Sharif University of Technology
    We report fabrication of ultrafast and high contrast transparent electrochromic device desired for display application using nanostructured electrode. To this end, poly (3,4-ethylenedioxythiophene) (PEDOT) nanotubes were synthesized by simple electrochemical polymerization method on hydrothermally grown ZnO nanowires array as electrode. The PEDOT nanotubes of 20 nm average wall thickness characterized by SEM, TEM and EDS. The manufactured cell was subjected to electrochemical test and spectrophotometery that showed high contrast of 54% during ultrafast switching time of <2.2 ms. In addition, high coloration efficiency of 234 cm2/C, ultrahigh diffusion coefficient of 2.01×10-4 cm2/s and... 

    Smart chip for visual detection of bacteria using the electrochromic properties of polyaniline

    , Article Analytical Chemistry ; Volume 91, Issue 23 , 2019 , Pages 14960-14966 ; 00032700 (ISSN) Ranjbar, S ; Farahmand Nejad, M. A ; Parolo, C ; Shahrokhian, S ; Merkoci, A ; Sharif University of Technology
    American Chemical Society  2019
    Finding fast and reliable ways to detect pathogenic bacteria is crucial for addressing serious public health issues in clinical, environmental, and food settings. Here, we present a novel assay based on the conversion of an electrochemical signal into a more convenient optical readout for the visual detection of Escherichia coli. Electropolymerizing polyaniline (PANI) on an indium tin oxide screen-printed electrode (ITO SPE), we achieved not only the desired electrochromic behavior but also a convenient way to modify the electrode surface with antibodies (taking advantage of the many amine groups of PANI). Applying a constant potential to the PANI-modified ITO SPE induces a change in their... 

    Electrochromism: An emerging and promising approach in (bio)sensing technology

    , Article Materials Today ; Volume 50 , 2021 , Pages 476-498 ; 13697021 (ISSN) Farahmand Nejad, M. A ; Ranjbar, S ; Parolo, C ; Nguyen, E. P ; Álvarez Diduk, R ; Hormozi Nezhad, M. R ; Merkoçi, A ; Sharif University of Technology
    Elsevier B.V  2021
    Electrochromism (EC) is a unique property of certain materials that undergo an electrochemical-induced change in colouration. During the last decades, electrochromic materials (ECMs) have been applied in a variety of technologies ranging from smart windows to information displays and energy storage devices. More recently, ECMs have attracted the attention of the (bio)sensing community thanks to their ability to combine the sensitivity of electrochemical methods with the intuitive readout of optical sensors. Although still a nascent technology, EC-based sensors are on the rise with several targets (e.g. cancer biomarkers, bacteria, metabolites and pesticides), which have already been detected... 

    Pulsed laser deposition of W-V-O composite films: preparation, characterization and gasochromic studies

    , Article Solar Energy Materials and Solar Cells ; Volume 92, Issue 8 , 2008 , Pages 878-883 ; 09270248 (ISSN) Ranjbar, M ; Mahdavi, S. M ; Iraji zad, A ; Sharif University of Technology
    Modified tungsten oxide films by vanadium oxide provide neutrally coloring electrochromic electrodes for smart windows technology. In this study W-V-O mixed oxide films were fabricated by Nd:YAG pulsed laser deposition (PLD), λ=1064 nm, from mixed pressed powders of (WO3)1-x(V2O5)x, x=0, 0.09, 0.17, 0.23, 0.29 and 0.33, at 13.3 Pa oxygen partial pressure and 200 °C temperature on glass substrates. X-ray photoelectron spectroscopy (XPS) revealed V5+, V4+, W6+ and W5+ surface oxide states, where the ratio of W5+/W6+ enhances by the amount of vanadium in the films. Surface morphology was studied by scanning electron microscope (SEM) and optical properties by transmission-reflection spectra.... 

    An investigation on electrochromic properties of (WO3)1-x-(Fe2O3)x thin films

    , Article Thin Solid Films ; Volume 515, Issue 2 SPEC. ISS , 2006 , Pages 644-647 ; 00406090 (ISSN) Azimirad, R ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
    Elsevier  2006
    In this research, the effect of Fe2O3 content on the electrochromic properties of WO3 in thermally evaporated (WO3)1-x-(Fe2O3)x thin films (0 ≤ x ≤ 0.4) has been studied. The atomic composition of the deposited metal oxides was determined by X-ray photoelectron spectroscopy analysis. The surface morphology of the thin films has been examined by atomic force microscopy. The surface roughness of all the films was measured about 1.3 nm with an average lateral grain size of 30 nm showing a smooth and nanostructured surface. The electrochromic properties of (WO3)1-x-(Fe2O3)x thin films deposited on ITO/glass substrate were studied in a LiClO4 + PC electrolyte by using ultraviolet-visible... 

    Predicting atrial fibrillation termination using ECG features, a comparison

    , Article 2008 1st International Symposium on Applied Sciences in Biomedical and Communication Technologies, ISABEL 2008, Aalborg, 25 October 2008 through 28 October 2008 ; 2008 ; 9781424426478 (ISBN) Saberi, S ; Esmaeili, V ; Towhidkhah, F ; Moradi, M. H ; Sharif University of Technology
    In this study, surface ECG recordings have been used to accomplish a non-invasive method which can predict spontaneous termination of Atrial Fibrillation (AF) and discriminate terminating (T) and non-terminating (N) AF episodes. The data set was provided by Physionet including holter recordings of 50 patients (20 training and 30 test sets). Concerning that most relevant information about the AF exists in the atrial fibrillatory wave, Several spectral and time-frequency parameters were extracted from the ECG signal after canceling the QRST complex. Also a temporal feature, RR interval variation, representing the ventricular activity was calculated. These parameters were evaluated using a... 

    Synthesis and Investigation of Electrochromic Component Stimuli- Esponsive Based on Aniline Pentamer

    , M.Sc. Thesis Sharif University of Technology Rezaei Zangeneh, Moein (Author) ; Pourjavdi, Ali (Supervisor)
    The use of polyaniline as an electrochromic conductive polymer was highly regarded. However, due to problems such as poor solubility, the researchers decided to use aniline oligomer as an alternative. Meanwhile, aniline pentamer received more attention due to its good solubility in organic solvents and acceptable conductivity. On the other hand, it is possible to increase the conductivity and also to respond more to stimuli to groups that have certain characteristics. In this study, aniline pentamer and carbazole-derived were used. First, nitro and bromoethanol groups are added to carbazole. Due to its fluorescence properties, carbazole can, in addition to increasing the conductivity, which... 

    ECG denoising and compression by sparse 2D separable transform with overcomplete mixed dictionaries

    , Article Machine Learning for Signal Processing XIX - Proceedings of the 2009 IEEE Signal Processing Society Workshop, MLSP 2009, 2 September 2009 through 4 September 2009, Grenoble ; 2009 ; 9781424449484 (ISBN) Ghaffari, A ; Palangi, H ; Babaie Zadeh, M ; Jutten, C ; IEEE Signal Processing Society ; Sharif University of Technology
    In this paper, an algorithm for ECG denoising and compression based on a sparse separable 2-dimensional transform for both complete and overcomplete dictionaries is studied. For overcomplete dictionary we have used the combination of two complete dictionaries. The experimental results obtained by the algorithm for both complete and overcomplete transforms are compared to soft thresholding (for denoising) and wavelet db9/7 (for compression). It is experimentally shown that the algorithm outperforms soft thresholding for about 4dB or more and also outperforms Extended Kalman Smoother filtering for about 2dB in higher input SNRs. The idea of the algorithm is also studied for ECG compression,... 

    Synthesis and electrochromic study of sol-gel cuprous oxide nanoparticles accumulated on silica thin film

    , Article Thin Solid Films ; Volume 517, Issue 24 , 2009 , Pages 6700-6706 ; 00406090 (ISSN) Akhavan, O ; Tohidi, H ; Moshfegh, A. R ; Sharif University of Technology
    In this study, electrochromic properties of cuprous oxide nanoparticles, self-accumulated on the surface of a sol-gel silica thin film, have been investigated by using UV-visible spectrophotometry in a lithium-based electrolyte cell. The cuprous oxide nanoparticles showed a reversible electrochromic process with a thin film transmission reduction of about 50% in a narrow wavelength range of 400-500 nm, as compared to the bleached state of the film. Using optical transmission measurement, we have found that the band gap energy of the films reduced from 2.7 eV for Cu2O to 1.3 eV for CuO by increasing the annealing temperature from 220 to 300 °C in an N2 environment for 1 h. Study of the band... 

    Design, Construction and Application of Nanostructured Electrochemical Biosensor Based on Aptamers for Diagnosis Some of the Pathogenic Bacteria

    , Ph.D. Dissertation Sharif University of Technology Ranjbar, Saba (Author) ; Shahrokhian, Saeed (Supervisor)
    Since that pathogenic bacteria have a predominant role in different aspects of human life such as clinical analysis and spread of contagious disease, food quality control and monitoring of environmental microbial infections, the aim of these studies is design and construction of electrochemical and electro-optical biosensors based on nanomaterials employing specific aptamer and antibody for detection of different bacteria in various real samples. An impedimetric biosensor based on nanoporous gold (NPG) was presented in the first part of the thesis for detection of Salmonella typhimurium as one of the main food- borne pathogenic bacterium. Three-dimensional structure of NPG was synthesized... 

    Improved electrochromical properties of sol-gel WO3 thin films by doping gold nanocrystals

    , Article Thin Solid Films ; Volume 518, Issue 8 , 2010 , Pages 2250-2257 ; 00406090 (ISSN) Naseri, N ; Azimirad, R ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
    In this investigation, the effect of gold nanocrystals on the electrochromical properties of sol-gel Au doped WO3 thin films has been studied. The Au-WO3 thin films were dip-coated on both glass and indium tin oxide coated conducting glass substrates with various gold concentrations of 0, 3.2 and 6.4 mol%. Optical properties of the samples were studied by UV-visible spectrophotometry in a range of 300-1100 nm. The optical density spectra of the films showed the formation of gold nanoparticles in the films. The optical bandgap energy of Au-WO3 films decreased with increasing the Au concentration. Crystalline structure of the doped films was investigated by X-ray diffractometry, which... 

    Detection of characteristic points of ecg using quadratic spline wavelet transfrom

    , Article 3rd International Conference on Signals, Circuits and Systems, SCS 2009, 6 November 2009 through 8 November 2009, Medenine ; 2009 ; 9781424443987 (ISBN) Niknazar, M ; Vahdat, B. V ; Mousavi, S. R ; Sharif University of Technology
    This paper presents a method for ECG characteristic points detection based on Wavelet Transform (WT). Wavelet Transform leads to more accurate results in analyzing nonstationary signals such as ECG. The selected wavelet is quadratic spline wavelet. Using quadratic spline mother wavelet, a method for detection of QRS complex and T and P waves is presented and evaluated with the help of MIT-BIH Arrhythmia database. Experimental results show excellent performance of the proposed method. © 2009 IEEE  

    Fetal R-wave detection from multichannel abdominal ECG recordings in low SNR

    , Article Proceedings of the 31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society: Engineering the Future of Biomedicine, EMBC 2009, 2 September 2009 through 6 September 2009, Minneapolis, MN ; 2009 , Pages 344-347 ; 9781424432967 (ISBN) Kharabian, S ; Shamsollahi, M. B ; Sameni, R ; Sharif University of Technology
    Abdominal recordings of fetal ECG (fECG) have lower signal-to-noise ratio (SNR) as compared with invasive procedures. In this paper we have combined two previously proposed methods, one for extracting fECG, called πCA and the other, a transformation based on Hilbert transform to enhance the R-peaks. The combination of these methods seems to work well in situations of noisy data and fetal repositioning. Also a comparison is done by using ICA in order to extract the fetal signals. Performance of both methods is studied separately. Results show that applying the transformation on the components extracted with the use of πCA (after maternal ECG cancellation), had a very good performance. Also,... 

    Multi-channel electrocardiogram denoising using a Bayesian filtering framework

    , Article 2006 Computers in Cardiology, CIC, Valencia, 17 September 2006 through 20 September 2006 ; Volume 33 , 2006 , Pages 185-188 ; 02766574 (ISSN); 1424425328 (ISBN); 9781424425327 (ISBN) Sameni, R ; Shamsollahi, M. B ; Jutten, C ; Sharif University of Technology
    In some recent works, model-based filtering approaches have been proved as effective methods for extracting ECG signals from single channel noisy recordings. The previously developed methods, use a highly realistic nonlinear ECG model for the construction of Bayesian filters. In this work, a multi-channel extension of the previous approach is developed, by using a three dimensional model of the cardiac dipole vector. The results have considerable improvement compared with the single channel approach. The method is hence believed to be applicable to low SNR multi-channel recordings  

    A combined dynamical sequential network for generating coupled cardiovascular signals with different beat types

    , Article ; 2010 3rd International Symposium on Applied Sciences in Biomedical and Communication Technologies, ISABEL 2010, 7 November 2010 through 10 November 2010 , 2010 ; 9781424481323 (ISBN) Sayadi, O ; Shamsollahi, M. B ; Sharif University of Technology
    We present generalizations of the previously published artificial models for generating abnormal cardiac rhythms to provide simulations of coupled cardiovascular (CV) signals with different beat morphologies. Using a joint dynamical formulation, we generate the normal morphologies of the cardiac cycle using a sum of Gaussian kernels, fitted to real CV recordings. The joint inter-dependencies of CV signals are introduced by assuming the same angular frequency and a phase coupling. Abnormal beats are then specified as new dynamical trajectories. An ergadic first-order Markov chain is also used for switching between normal and abnormal beat types. Probability transitions can be learned from... 

    ECG denoising using modulus maxima of wavelet transform

    , Article Proceedings of the 31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society: Engineering the Future of Biomedicine, EMBC 2009, 2 September 2009 through 6 September 2009, Minneapolis, MN ; 2009 , Pages 416-419 ; 9781424432967 (ISBN) Ayat, M ; Shamsollahi, M. B ; Mozaffari, B ; Kharabian, S ; Sharif University of Technology
    ECG denoising has always been an important issue in medical engineering. The purposes of denoising are reducing noise level and improving signal to noise ratio (SNR) without distorting the signal. This paper proposes a method for removing white Gaussian noise from ECG signals. The concepts of singularity and local maxima of the wavelet transform modulus were used for analyzing singularity and reconstructing the ECG signal. Adaptive thresholding was used to remove white Gaussian noise modulus maximum of wavelet transform and then reconstruct the signal. ©2009 IEEE  

    Multichannel electrocardiogram decomposition using periodic component analysis

    , Article IEEE Transactions on Biomedical Engineering ; Volume 55, Issue 8 , August , 2008 , Pages 1935-1940 ; 00189294 (ISSN) Sameni, R ; Jutten, C ; Shamsollahi, M. B ; Sharif University of Technology
    In this letter, we propose the application of the generalized eigenvalue decomposition for the decomposition of multichannel electrocardiogram (ECG) recordings. The proposed method uses a modified version of a previously presented measure of periodicity and a phase-wrapping of the RR-interval, for extracting the "most periodic" linear mixtures of a recorded dataset. It is shown that the method is an improved extension of conventional source separation techniques, specifically customized for ECG signals. The method is therefore of special interest for the decomposition and compression of multichannel ECG, and for the removal of maternal ECG artifacts from fetal ECG recordings. © 2006 IEEE  

    Model-based ECG fiducial points extraction using a modified extended Kalman filter structure

    , Article 2008 1st International Symposium on Applied Sciences in Biomedical and Communication Technologies, ISABEL 2008, Aalborg, 25 October 2008 through 28 October 2008 ; December , 2008 ; 9781424426478 (ISBN) Sayadi, O ; Shamsollahi, M. B ; Sharif University of Technology
    This paper presents an efficient algorithm based on a nonlinear dynamical model for the precise extraction of the characteristic points of electrocardiogram (ECG), which facilitates the HRV analysis. Determining the precise position of the waveforms of an ECG signal is complicated due to the varying amplitudes of its waveforms, the ambiguous and changing form of the complex and morphological variations with unknown sources of drift. A model-based approach handles these complications; therefore a method based on the usage of this concept in an extended Kalman filter structure has been developed. The fiducial points are detected using both the parameters of Gaussian-functions of the model, and... 

    Wavelet-based 2-D ECG data compression method using SPIHT and VQ coding

    , Article EUROCON 2007 - The International Conference on Computer as a Tool, Warsaw, 9 September 2007 through 12 September 2007 ; December , 2007 , Pages 133-137 ; 142440813X (ISBN); 9781424408139 (ISBN) Sahraeian, S. M. E ; Fatemizadeh, E ; Sharif University of Technology
    An improved wavelet-based 2-D ECG data compression method is presented which employs a double stage compression. In the first stage the set partitioning in hierarchical trees (SPIHT) algorithm is used to compress the 2-D data array formed by cutting and beat-aligning the heartbeat data sequence. In the second stage vector quantization is applied to the residual image obtained from the previous stage. The 2-D approach utilizes both inter-beat and inter-sample redundancies in the ECG signal The proposed algorithm is applied to several records in the MIT-BIH arrhythmia database. Results show lower Percent Root mean square Difference (PRD) than 1-D methods and several 2-D methods for the same... 

    Efficient compression of ECG signals based on two dimensional wavelet transform and SPIHT coding algorithm

    , Article 2005 International Conference on Mathematics and Engineering Techniques in Medicine and Biological Sciences, METMBS'05, Las Vegas, NV, 20 June 2005 through 23 June 2005 ; 2005 , Pages 82-86 ; 9781932415834 (ISBN) Moazami Goudarzi, M ; Rabiee, H. R ; Ghanbari, M ; Sharif University of Technology
    Signal compression is an important element encountered in data storage applications. Over the years various techniques for data reductions have been proposed. In this paper we introduce an effective method for compressing semi-periodic signals. Although the approach is applicable to any semi-periodic signal, our attention is focused on the compression of electrocardiogram (ECG) signals. An ECG signal is composed of many similar beats which makes it to behave semi-periodic This paper deals with beat variation periods and exploits the correlation between cycles (inter-beat) and correlation within each cycle (intra-beat) for compression. For efficient compression a 2-dimensional array is...