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    Study and Fabrication of Flexible and Stretchable Electronic Circuits

    , M.Sc. Thesis Sharif University of Technology Valinejad, Amir Ali (Author) ; Sarvari, Reza (Supervisor) ; Kolahdouz Esfahani, Mohammad Reza (Supervisor)
    In recent years, flexible electronics have started to attract a tremendeos amount of attention, partly on its remarkable growth in new technologies like IoT, wearable electronics, personal and health care devices. This emerging field offers many advantages compared to its traditional rigid counterparts, such as bendability, stretchablity, recyclability and biocompatibility. Inkjet printing is one of the most promising method for realizing flexible electronics due to its low-investment cost, fully additive nature, low material westage, relatively low temperature process and non-contact patterning.A printed circuit board (PCB), is undoubtedly a vital part of any electronics systems. So,... 

    Amplified electrochemical DNA sensor based on polyaniline film and gold nanoparticles

    , Article Electroanalysis ; Volume 25, Issue 6 , 2013 , Pages 1373-1380 ; 10400397 (ISSN) Saberi, R. S ; Shahrokhian, S ; Marrazza, G ; Sharif University of Technology
    In this work, an electrochemical DNA biosensor, based on a dual signal amplified strategy by employing a polyaniline film and gold nanoparticles as a sensor platform and enzyme-linked as a label, for sensitive detection is presented. Firstly, polyaniline film and gold nanoparticles were progressively grown on graphite screen-printed electrode surface via electropolymerization and electrochemical deposition, respectively. The sensor was characterized by scanning electron microscopy (SEM), cyclic voltammetry and impedance measurements. The polyaniline-gold nanocomposite modified electrodes were firstly modified with a mixed monolayer of a 17-mer thiol-tethered DNA probe and a spacer thiol,... 

    Rapid sol gel synthesis of BaFe12O19 nanoparticles: An excellent catalytic application in the electrochemical detection of tramadol in the presence of acetaminophen

    , Article Microchemical Journal ; Volume 156 , 2020 Bagherinasab, Z ; Beitollahi, H ; Yousefi, M ; Bagherzadeh, M ; Hekmati, M ; Sharif University of Technology
    Elsevier Inc  2020
    The present study reports synthesis of BaFe12O19 nanoparticles by sol gel technique followed by its characterization using Energy dispersive X-ray spectroscopy (EDS), X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM) analysis, and Fourier-transform infrared spectroscopy (FTIR). The BaFe12O19 nanoparticles have been applied to construct a modified graphite screen-printed electrode (GSPE). BaFe12O19/GSPE has been applied as a working electrode in the analysis of tramadol and acetaminophen by voltammetric techniques. The BaFe12O19/GSPE showed a good selectiveness for analysis of tramadol in the presence of acetaminophen with the... 

    Design of a low-cost broadband loaded dipole antenna for VHF/UHF frequency range

    , Article IET Microwaves, Antennas and Propagation ; Volume 13, Issue 12 , 2019 , Pages 1983-1988 ; 17518725 (ISSN) Bod, M ; Ahmadi Boroujeni, M ; Mohammadpour Aghdam, K ; Sharif University of Technology
    Institution of Engineering and Technology  2019
    This study describes the concept and design of a low-cost super broadband dipole antenna with a passive matching network. The proposed dipole antenna is designed in three steps. First, a simple planar dipole antenna with six different loads and a balanced to unbalanced (Balun) transformer is designed by the genetic algorithm optimisation. The position and value of the loads are optimised to achieve an acceptable radiation pattern and voltage standing wave ratio (VSWR) over the desired frequency bandwidth. In the next step, the shape of the printed strip dipole antenna is optimised to improve the frequency response of the designed antenna. Finally, an LC network is added to the antenna feed... 

    Fabrication of porosity-graded biocompatible structures by 3D printing of Co-Cr-Mo alloy

    , Article European Powder Metallurgy Congress and Exhibition, Euro PM 2007, Toulouse, 15 October 2007 through 17 October 2007 ; Volume 3 , 2007 , Pages 255-260 ; 9781899072293 (ISBN) Dourandish, M ; Simchi, A ; Godlinski, D ; Sharif University of Technology
    European Powder Metallurgy Association (EPMA)  2007
    Manufacturing of complex-shaped bimetals utilizing two-color powder injection molding (2C-PIM) and three-dimensional printing (3DP) processes, which basically involve sintering of a powder/binder mixture, has been attracted a great interest. This article addresses sintering of biocompatible Co-Cr-Mo alloy for manufacturing stepwise porosity-graded composite structures. Such composite structures provide strength at the core and a porous layer for the tissue growth. To evaluate the process, two grades of gas atomized Co-Cr-Mo powder with an average particle size of 19 and 63 μm were used. Isothermal and nonisothermal sintering behavior of the loose powders under hydrogen and argon atmospheres... 

    A new ROI extraction method for FKP images using global intensity

    , Article 2012 6th International Symposium on Telecommunications, IST 2012 ; 2012 , Pages 1147-1150 ; 9781467320733 (ISBN) Ehteshami, N. S. M ; Tabandeh, M ; Fatemizadeh, E ; Sharif University of Technology
    Finger-Knuckle-Print (FKP) is one of the newest biometrics. In this paper, a novel approach has been proposed to segment the Region of Interest (ROI) of a FKP image using the global intensity. This method upgrades the speed and accuracy of segmentation stage, as well as the pace of other steps of the procedure. This has been achieved by employing the area with maximum intensity in ROI extraction, instead of using the creases of the knuckle image. To confirm this improvement, lots of experiments have been performed and the method has been compared with the only existing schemes for ROI extraction suggested by Zhang and Kekre. At the end, the captured ROI images obtained by three methods have... 

    One-dimensional adiabatic circuits with inherent charge recycling

    , Article Electronics Letters ; Volume 51, Issue 14 , July , 2015 , Pages 1056-1058 ; 00135194 (ISSN) Khorami, A ; Sharifkhani, M ; Sharif University of Technology
    Institution of Engineering and Technology  2015
    A new switching method for the stabilisation of a one-dimensional capacitor array tank for the stepwise charging of a load capacitor is presented. In this method, the tank capacitor configuration is rearranged in a circular manner once the charging process of a load capacitor finishes and before the charging process of a new load capacitor begins. Unlike previously reported methods, this method does not require backward switching for the stabilisation of tank capacitor voltages. Hence, the proposed method reduces the number of charging process steps by a factor of up to 2 compared with the conventional method. Moreover, since the tank recycles its charge inherently, the capacitive load can... 

    The maximum disjoint routing problem

    , Article 22nd International Conference on Computing and Combinatorics, COCOON 2016, 2 August 2016 through 4 August 2016 ; Volume 9797 , 2016 , Pages 319-329 ; 03029743 (ISSN); 9783319426334 (ISBN) Shahmohammadi, F ; Sharif Zadeh, A. S ; Zarrabi Zadeh, H ; Sharif University of Technology
    Springer Verlag  2016
    Motivated by the bus escape routing problem in printed circuit boards, we revisit the following problem: given a set of n axis-parallel rectangles inside a rectangular region R, find the maximum number of rectangles that can be extended toward the boundary of R, without overlapping each other. We provide an efficient algorithm for solving this problem in O(n2 log3 n log log n) time, improving over the current best O(n3)-time algorithm available for the problem  

    An algorithm for modeling print and scan operations used for watermarking

    , Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 10 November 2008 through 12 November 2008 ; Volume 5450 LNCS , 2009 , Pages 254-265 ; 03029743 (ISSN) ; 3642044379 (ISBN); 9783642044373 (ISBN) Amiri, S.H ; Jamzad, M ; Sharif University of Technology
    Watermarking is a suitable approach for digital image authentication. Robustness regarding attacks that aim to remove the watermark is one of the most important challenges in watermarking, in general. Several different attacks are reported that aim to make it difficult or impossible for the real owner of the digital watermarked image to extract the watermark. Some of such common attacks are noise addition, compression, scaling, rotation, clipping, cropping, etc. In this paper we address the issue of print and scan attack by introducing a method to model the scanner and printer. Then we will simulate the print and scan attack on the digital images to evaluate its robustness. In addition, we... 

    Finding maximum disjoint set of boundary rectangles with application to PCB routing

    , Article IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems ; Volume 36, Issue 3 , 2017 , Pages 412-420 ; 02780070 (ISSN) Ahmadinejad, A ; Zarrabi Zadeh, H ; Sharif University of Technology
    Motivated by the bus escape routing problem in printed circuit boards (PCBs), we study the following optimization problem: given a set of rectangles attached to the boundary of a rectangular region, find a subset of nonoverlapping rectangles with maximum total weight. We present an efficient algorithm that solves this problem optimally in O(n4) time, where n is the number of rectangles in the input instance. This improves over the best previous O(n6) -time algorithm available for the problem. We also present two efficient approximation algorithms for the problem that find near-optimal solutions with guaranteed approximation factors. The first algorithm finds a 2-approximate solution in O(n2)... 

    3D-Printed Sugar-Based Stents Facilitating Vascular Anastomosis

    , Article Advanced Healthcare Materials ; 2018 ; 21922640 (ISSN) Farzin, A ; Miri, A. K ; Sharifi, F ; Faramarzi, N ; Jaberi, A ; Mostafavi, A ; Solorzano, R ; Zhang, Y. S ; Annabi, N ; Khademhosseini, A ; Tamayol, A ; Sharif University of Technology
    Wiley-VCH Verlag  2018
    Microvascular anastomosis is a common part of many reconstructive and transplant surgical procedures. While venous anastomosis can be achieved using microvascular anastomotic coupling devices, surgical suturing is the main method for arterial anastomosis. Suture-based microanastomosis is time-consuming and challenging. Here, dissolvable sugar-based stents are fabricated as an assistive tool for facilitating surgical anastomosis. The nonbrittle sugar-based stent holds the vessels together during the procedure and are dissolved upon the restoration of the blood flow. The incorporation of sodium citrate minimizes the chance of thrombosis. The dissolution rate and the mechanical properties of... 

    Design, fabrication, and accuracy of a novel noncovering lock-mechanism bilateral patient-specific drill guide template for nondeformed and deformed thoracic spines

    , Article HSS Journal ; Volume 17, Issue 2 , 2021 , Pages 213-222 ; 15563316 (ISSN) Ashouri Sanjani, M ; Mohammadi Moghadam, S ; Azimi, P ; Arjmand, N ; Sharif University of Technology
    SAGE Publications Inc  2021
    Background: Pedicle screw (PS) placement has been widely used in fusion surgeries on the thoracic spine. Achieving cost-effective yet accurate placements through nonradiation techniques remains challenging. Questions/Purposes: Novel noncovering lock-mechanism bilateral vertebra-specific drill guides for PS placement were designed/fabricated, and their accuracy for both nondeformed and deformed thoracic spines was tested. Methods: One nondeformed and 1 severe scoliosis human thoracic spine underwent computed tomographic (CT) scanning, and 2 identical proportions of each were 3-dimensional (3D) printed. Pedicle-specific optimal (no perforation) drilling trajectories were determined on the CT... 

    Scaffold Fabrication for Corneal Regeneration

    , Ph.D. Dissertation Sharif University of Technology Mahdavi Salimi, Sharareh (Author) ; Abdekhodaie, Mohammad Jafar (Supervisor) ; Mashayekhan, Shohreh (Supervisor) ; Baradaran Rafiei, Alireza (Co-Supervisor)
    3D bioprinting technology is a promising approach for corneal stromal tissue regeneration. At first, two different concentrations of GelMA macromer (7.5% and 12.5%) were tested for corneal stroma bioprinting. Due to high macromer concentrations, 12.5% GelMA was stiffer than 7.5% GelMA, which made it easier to handle. In terms of water content and optical transmittance of the bioprinted scaffolds, we observed that scaffold with 12.5% GelMA concentration was closer to the native corneal stroma tissue. Subsequently, cell proliferation, gene and protein expression of human corneal stromal cells encapsulated in the bioprinted scaffolds were investigated. Cytocompatibility in 12.5% GelMA scaffolds... 

    A novel screen-printed TiO2 photoelectrochemical sensor for direct determination and reduction of hexavalent chromium

    , Article Electrochemistry Communications ; Volume 61 , 2015 , Pages 110-113 ; 13882481 (ISSN) Siavash Moakhar, R ; Goh, G. K. L ; Dolati, A ; Ghorbani, M ; Sharif University of Technology
    Elsevier Inc  2015
    A novel and simple photoelectrochemical (PEC) sensor to detect Cr(VI) based on screen-printed TiO2 modified with gold nanoparticles is presented. The proposed PEC sensor showed a very low detection limit (S/N = 3) of 0.004 μM, over a wide linear concentration range from 0.01 μM to 100 μM with a high sensitivity of 11.88 μA.μM-1 Cr(VI). Results also indicated good anti-interference and superb recovery in natural media application for Cr(VI) sensing  

    Photovoltaic performance improvement in vacuum-assisted meniscus printed triple-cation mixed-halide perovskite films by surfactant engineering

    , Article ACS Applied Energy Materials ; Volume 2, Issue 9 , 2019 , Pages 6209-6217 ; 25740962 (ISSN) Parvazian, E ; Abdollah Zadeh, A ; Dehghani, M ; Taghavinia, N ; Sharif University of Technology
    American Chemical Society  2019
    Scalable coating methods have recently emerged as practical alternative deposition techniques to the conventional spin-coating despite their lower yielding power conversion efficiencies (PCEs). The most important barrier acting against the use of scalable deposition methods to get a highly absorbing (>95%) film with controlled morphology in the high crystallinity of perovskite particles is the impossibility of antisolvent dripping during the deposition. Here, we demonstrate the positive role of both the surfactant-engineering and the vacuum-annealing (<100 Pa) process in improving the device performance to overcome this limit. A detailed optimization of the vacuum-assisted meniscus printing... 

    Evaluation of aspergillus niger and penicillium simplicissimum for their ability to leach Zn–Ni–Cu from waste mobile phone printed circuit boards

    , Article Journal of Material Cycles and Waste Management ; 2021 ; 14384957 (ISSN) Arshadi, M ; Esmaeili, A. R ; Yaghmaei, S ; Arab, B ; Sharif University of Technology
    Springer Japan  2021
    In this research, Zn, Ni, and Cu recovery from mobile phone printed circuit boards was investigated. The initial pH and pulp density using Aspergillus niger or Penicillium simplicissimum fungi were optimized to improve the recovery of Zn, Ni, and Cu using a central composite design. Fungi were able to recover 97% of Cu. Often for Ni recovery, A. niger was more effective, but in low pulp densities and low pH, P. simplicissimum was preferred. For recovery of Zn, A. niger is more appropriate at pH lower than 6, but P. simplicissimum outperforms at pH higher than 6. Under the optimum conditions (pulp density of 4 gL−1 and initial pH 10), the respective recovery of Cu, Ni, and Zn was determined... 

    Fabrication and Investigation of Printing Mechanism in order to Deposit Semiconductor thin Films for Photovoltaic Devices

    , M.Sc. Thesis Sharif University of Technology Akbari, Hamid Reza (Author) ; Taghavinia, Nima (Supervisor)
    Finding a reliable and reproducible method to deposit thin films of semiconductors is a huge leap forward in order to fabricate nano-structured solar cells. As the third and forth generation of solar cells are based on semiconductors which are soluble in solvents and can be deposited with solution-based methods, finding a proper printing mechanics can lead to cheap solar panels. In this thesis we have designed and fabricated an apparatus to deposit lead iodide films. These thin films can be used to fabricate perovskite solar cells which are based on methylammonium lead iodide perovskite. We have also investigated different inks consisting of different additives and solvents best suited for... 

    On the rectangle escape problem

    , Article Theoretical Computer Science ; Volume 689 , 2017 , Pages 126-136 ; 03043975 (ISSN) Ahmadinejad, A ; Assadi, S ; Emamjomeh Zadeh, E ; Yazdanbod, S ; Zarrabi Zadeh, H ; Sharif University of Technology
    Motivated by the bus escape routing problem in printed circuit boards, we study the following rectangle escape problem: given a set S of n axis-aligned rectangles inside an axis-aligned rectangular region R, extend each rectangle in S toward one of the four borders of R so that the maximum density over the region R is minimized. The density of each point p∈R is defined as the number of extended rectangles containing p. We show that the problem is hard to approximate to within a factor better than 3/2 in general. When the optimal density is sufficiently large, we provide a randomized algorithm that achieves an approximation factor of 1+ε with high probability improving over the current best... 

    Fabrication of hierarchically porous silk fibroin-bioactive glass composite scaffold via indirect 3D printing: Effect of particle size on physico-mechanical properties and in vitro cellular behavior

    , Article Materials Science and Engineering C ; Volume 103 , 2019 ; 09284931 (ISSN) Razaghzadeh Bidgoli, M ; Alemzadeh, I ; Tamjid, E ; Khafaji, M ; Vossoughi, M ; Sharif University of Technology
    Elsevier Ltd  2019
    In order to regenerate bone defects, bioactive hierarchically scaffolds play a key role due to their multilevel porous structure, high surface area, enhanced nutrient transport and diffusion. In this study, novel hierarchically porous silk fibroin (SF) and silk fibroin-bioactive glass (SF-BG) composite were fabricated with controlled architecture and interconnected structure, by combining indirect three-dimensional (3D) inkjet printing and freeze-drying methods. Further, the effect of 45S5 Bioactive glass particles of different sizes (<100 nm and 6 μm) on mechanical strength and cell behavior was investigated. The results demonstrated that the hierarchical structure in this scaffold was... 

    The effect of Li on the tensile properties of cast Al-Mg2Si metal matrix composite

    , Article Materials Science and Engineering A ; Volume 490, Issue 1-2 , 2008 , Pages 250-257 ; 09215093 (ISSN) Hadian, R ; Emamy, M ; Varahram, N ; Nemati, N ; Sharif University of Technology
    The effects of both Li modification and cooling rate on the microstructure and tensile properties of an in situ prepared Al-15%Mg2Si composite were investigated. It was found that the addition of 0.3%Li reduces the average size of Mg2Si primary particles from ∼30 to ∼6 μm. The effect of cooling rate was investigated by the use of a mold with different section test bars. The results showed an increase in both UTS and elongation values with reduction in section thicknesses corresponding to increasing cooling rates. Adding Li also raised the tensile strength and elongation values and reduced the number of decohered particles observed in fracture surfaces thereby increasing the alloy's...