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  • Smartphone-Based Multiplexed Biosensing Tools for Health Monitoring

    Beduk, Tutku; Beduk, Duygu; Hasan, Mohd Rahil; Guler Celik, Emine; Kosel, Jurgen; Narang, Jagriti; Salama, Khaled N.; Timur, Suna (Biosensors, MDPI AG, 2022-07-29) [Article]
    Many emerging technologies have the potential to improve health care by providing more personalized approaches or early diagnostic methods. In this review, we cover smartphone-based multiplexed sensors as affordable and portable sensing platforms for point-of-care devices. Multiplexing has been gaining attention recently for clinical diagnosis considering certain diseases require analysis of complex biological networks instead of single-marker analysis. Smartphones offer tremendous possibilities for on-site detection analysis due to their portability, high accessibility, fast sample processing, and robust imaging capabilities. Straightforward digital analysis and convenient user interfaces support networked health care systems and individualized health monitoring. Detailed biomarker profiling provides fast and accurate analysis for disease diagnosis for limited sample volume collection. Here, multiplexed smartphone-based assays with optical and electrochemical components are covered. Possible wireless or wired communication actuators and portable and wearable sensing integration for various sensing applications are discussed. The crucial features and the weaknesses of these devices are critically evaluated.
  • Minimally-invasive, real-time, non-destructive, species-independent phytohormone biosensor for precision farming

    Bu Khamsin, Abdullah; Ait Lahcen, Abdellatif; Filho, Jose De Oliveira; Shetty, Saptami; Blilou, Ikram; Kosel, Jürgen; Salama, Khaled N. (Biosensors and Bioelectronics, Elsevier BV, 2022-07-06) [Article]
    To keep up with population growth, precision farming technologies must be implemented to sustainably increase agricultural output. The impact of such technologies can be expanded by monitoring phytohormones, such as salicylic acid. In this study, we present a plant-wearable electrochemical sensor for in situ detection of salicylic acid. The sensor utilizes microneedle-based electrodes that are functionalized with a layer of salicylic acid selective magnetic molecularly imprinted polymers. The sensor's capability to detect the phytohormone is demonstrated both in vitro and in vivo with a limit of detection of 2.74 μM and a range of detection that can reach as high as 150 μM. Furthermore, the selectivity of the sensor is verified by testing the sensor on commonly occurring phytohormones. Finally, we demonstrate the capability of the sensor to detect the onset of fungal infestation in Tobacco 5 min post-inoculation. This work shows that the sensor could serve as a promising platform for continuous and non-destructive monitoring in the field and as a fundamental research tool when coupled with a portable potentiostat.
  • 3D Concentric Electrodes-Based Alternating Current Electrohydrodynamics: Design, Simulation, Fabrication, and Potential Applications for Bioassays

    Silva, Raphaela; Rauf, Sakandar; Dong, Ming; Chen, Liang; Bagci, Hakan; Salama, Khaled N. (Biosensors, MDPI AG, 2022-04-06) [Article]
    Two-dimensional concentric asymmetric microelectrodes play a crucial role in developing sensitive and specific biological assays using fluid micromixing generated by alternating current electrohydrodynamics (ac-EHD). This paper reports the design, simulation, fabrication, and characterization of fluid motion generated by 3D concentric microelectrodes for the first time. Electric field simulations are used to compare electric field distribution at the electrodes and to analyze its effects on microfluidic micromixing in 2D and 3D electrodes. Three-dimensional devices show higher electric field peak values, resulting in better fluid micromixing than 2D devices. As a proof of concept, we design a simple biological assay comprising specific attachment of streptavidin beads onto the biotin-modified electrodes (2D and 3D), which shows ~40% higher efficiency of capturing specific beads in the case of 3D ac-EHD device compared to the 2D device. Our results show a significant contribution toward developing 3D ac-EHD devices that can be used to create more efficient biological assays in the future.
  • Experimental identification of the second-order non-Hermitian skin effect with physics-graph-informed machine learning

    Shang, Ce; Liu, Shuo; Shao, Ruiwen; Han, Peng; Zang, Xiaoning; Zhang, Xiangliang; Salama, Khaled N.; Gao, Wenlong; Lee, Ching Hua; Thomale, Ronny; Manchon, Aurelien; Zhang, Shuang; Cui, Tie Jun; Schwingenschlögl, Udo (arXiv, 2022-03-01) [Preprint]
    Topological phases of matter are conventionally characterized by the bulk-boundary correspondence in Hermitian systems: The topological invariant of the bulk in d dimensions corresponds to the number of (d − 1)-dimensional boundary states. By extension, higherorder topological insulators reveal a bulk-edge-corner correspondence, such that n-th order topological phases feature (d − n)-dimensional boundary states. The advent of nonHermitian topological systems sheds new light on the emergence of the non-Hermitian skin effect (NHSE) with an extensive number of boundary modes under open boundary conditions. Still, the higher-order NHSE remains largely unexplored, particularly in the experiment. We introduce an unsupervised approach – physics-graph-informed machine learning (PGIML) – to enhance the data mining ability of machine learning with limited domain knowledge. Through PGIML, we experimentally demonstrate the second-order NHSE in a two-dimensional non-Hermitian topolectrical circuit. The admittance spectra of the circuit exhibit an extensive number of corner skin modes and extreme sensitivity of the spectral flow to the boundary conditions. The violation of the conventional bulk-boundary correspondence in the second-order NHSE implies that modification of the topological band theory is inevitable in higher dimensional non-Hermitian systems.
  • A Portable Molecularly Imprinted Sensor for On-Site and Wireless Environmental Bisphenol A Monitoring

    Beduk, Tutku; Gomes, Matilde; De Oliveira Filho, Jose; Shetty, Saptami Suresh; Khushaim, Walaa; Garcia-Ramirez, Ricardo; Durmus, Ceren; Ait Lahcen, Abdellatif; Salama, Khaled N. (Frontiers in Chemistry, Frontiers Media SA, 2022-02-16) [Article]
    The detection of pollutant traces in the public and environmental waters is essential for safety of the population. Bisphenol A (BPA) is a toxic chemical widely used for the production of food storage containers by plastic industries to increase the storage ability. However, the insertion of BPA in water medium leads to serious health risks. Therefore, the development of low-cost, practical, sensitive, and selective devices to monitor BPA levels on-site in the environment is highly needed. Herein, for the first time, we present a homemade portable potentiostat device integrated to a laser-scribed graphene (LSG) sensor for BPA detection as a practical environmental pollutant monitoring tool. Recently, there has been an increasing need regarding the development of graphene-based electrochemical transducers (e.g., electrodes) to obtain efficient biosensing platforms. LSG platform is combined with molecularly imprinted polymer (MIP) matrix. LSG electrodes were modified with gold nanostructures and PEDOT polymer electrodeposition to create a specific MIP biomimetic receptor for ultrasensitive BPA detection. The sensing device has a Bluetooth connection, wirelessly connected to a smartphone providing high sensitivity and sensitivity (LOD: 3.97 nM in a linear range of .01–10 µM) toward BPA. Two commercial bottled water samples, tap water, commercial milk, and baby formula samples have been used to validate the reliability of the portable sensor device.
  • Inherent Surface Activation of Laser-Scribed Graphene Decorated with Au and Ag Nanoparticles: Simultaneous Electrochemical Behavior toward Uric Acid and Dopamine

    Beduk, Tutku; De Oliveira Filho, José Ilton; Ait Lahcen, Abdellatif; Mani, Veerappan; Salama, Khaled N. (Langmuir, American Chemical Society (ACS), 2021-11-17) [Article]
    Laser-scribed graphene electrodes (LSGEs) have attracted great attention for the development of electrochemical (bio)sensors due to their excellent electronic properties, large surface area, and high porosity, which enhances the electrons’ transfer rate. An increasing active surface area and defect sites are the quickest way to amplify the electrochemical sensing attributes of the electrodes. Here, we have found that the activation procedure coupled to the electrodeposition of metal nanoparticles resulted in a significant amplification of the active area and the analytical performance. This preliminary study is supported by the demonstration of the simultaneous electrochemical sensing of dopamine (DA) and uric acid (UA) by the electrochemically activated LSGEs (LSGE*s). Furthermore, the electrodeposition of two different metal nanoparticles, gold (Au) and silver (Ag), was performed in multiple combinations on working and reference electrodes to investigate the enhancement in the electrochemical response of LSGE*s. Current enhancements of 32, 27, and 35% were observed from LSGE* with WE:Au/RE:LSG/CE:LSGE, WE:Au/RE:Au/CE:LSGE, and WE:Au/RE:Ag/CE:LSGE, compared to the same combinations of LSGEs without any surface activation. A homemade and practical potentiostat, KAUSTat, was used in these electrochemical depositions in this study. Among all of the combinations, the surface area was increased 1.6-, 2.0-, and 1.2-fold for WE:Au/RE:LSG/CE:LSGE, WE:Au/RE:Au/CE:LSGE, and WE:Au/RE:Ag/CE:LSGE prepared from LSGE*s, respectively. To evaluate the analytical performance, DA and UA were detected simultaneously in the presence of ascorbic acid. The LODs of DA and UA are calculated to be ∼0.8 and ∼0.6 μM, respectively. Hence, this study has the potential to open new insights into new surface activation strategies with a combination of one-step nanostructured metal depositions by a custom-made potentiostat. This novel strategy could be an excellent and straightforward method to enhance the electrochemical transducer sensitivity for various electrochemical sensing applications.
  • A Hardware/Software Co-design Methodology for In-memory Processors

    Yantir, Hasan Erdem; Eltawil, Ahmed; Salama, Khaled N. (Journal of Parallel and Distributed Computing, Elsevier BV, 2021-11) [Article]
    The bottleneck between the processor and memory is the most significant barrier to the ongoing development of efficient processing systems. Therefore, a research effort begun to shift from processor-centric architectures to memory-centric architectures. Various in-memory processor architectures have been proposed to break this barrier to pave the way for ever-demanding memory-bound applications. Associative in-memory processing is a successful candidate for truly in-memory computing, in which processor and memory are combined in the same location to eliminate the expensive data access costs. The architecture exhibits an unmatched advantage for data-intensive applications due to its memory-centric design principles. On the other hand, this advantage can be revealed fully by an efficient design methodology. This study puts further progressive effort by proposing a hardware/software design methodology for associative in-memory processors. The methodology aims to decrease energy consumption and area requirement of the processor architecture specifically programmed to perform a given task. According to the evaluation of nine different benchmarks, such as fast Fourier transform and multiply-accumulate, the proposed design flow accomplishes an average 7% reduction in memory area and 18% savings in total energy consumption.
  • Resistive Neural Hardware Accelerators

    Smagulova, Kamilya; Fouda, Mohammed E.; Kurdahi, Fadi; Salama, Khaled N.; Eltawil, Ahmed (arXiv, 2021-09-08) [Preprint]
    Deep Neural Networks (DNNs), as a subset of Machine Learning (ML) techniques, entail that real-world data can be learned and that decisions can be made in real-time. However, their wide adoption is hindered by a number of software and hardware limitations. The existing general-purpose hardware platforms used to accelerate DNNs are facing new challenges associated with the growing amount of data and are exponentially increasing the complexity of computations. An emerging non-volatile memory (NVM) devices and processing-in-memory (PIM) paradigm is creating a new hardware architecture generation with increased computing and storage capabilities. In particular, the shift towards ReRAM-based in-memory computing has great potential in the implementation of area and power efficient inference and in training large-scale neural network architectures. These can accelerate the process of the IoT-enabled AI technologies entering our daily life. In this survey, we review the state-of-the-art ReRAM-based DNN many-core accelerators, and their superiority compared to CMOS counterparts was shown. The review covers different aspects of hardware and software realization of DNN accelerators, their present limitations, and future prospectives. In particular, comparison of the accelerators shows the need for the introduction of new performance metrics and benchmarking standards. In addition, the major concerns regarding the efficient design of accelerators include a lack of accuracy in simulation tools for software and hardware co-design.
  • Laser-scribed graphene sensor based on gold nanostructures and molecularly imprinted polymers: Application for Her-2 cancer biomarker detection

    Lahcen, Abdellatif Ait; Rauf, Sakandar; Aljedaibi, Abdulrahman; De Oliveira Filho, José Ilton; Beduk, Tutku; Mani, Veerappan; Alsharee, Husam N.; Salama, Khaled N. (Sensors and Actuators B: Chemical, Elsevier BV, 2021-08-09) [Article]
    Laser scribed graphene (LSG) has shown great potential as a sensing platform due to its high sensitivity, simplicity, porosity, and flexibility. In this context, we report a novel biosensing platform that utilizes LSG electrodes modified with nanostructured gold and molecularly imprinted polymer (MIP) to enhance its sensitivity and selectivity. This biomimetic sensing platform is used to detect the human epidermal growth factor receptor 2 (Her-2) protein, a significant breast cancer biomarker. Hence, a simple and accurate biomimetic sensor is developed in this study. To the best of our knowledge, this is the first report on nanostructured gold modified MIP-based LSG sensor for Her-2. LSG electrodes are fabricated by irradiation of a polyimide sheet using a CO2 laser. Nanostructured gold is electrodeposited onto the LSG to enhance its sensitivity and facilitate better Her-2 immobilization on the sensor surface. For MIP preparation, 3, 4-ethylenedioxythiophene (EDOT) was electropolymerized after pre-adsorption of Her-2 on the electrode surface for 20 min. The MIP deposition, removal, and adsorption parameters were investigated and optimized. The developed sensing strategy showed an excellent ability to detect Her-2 in the concentration range from 1 to 200 ng/mL with a LOD of 0.43 ng/mL. The biomimetic sensor showed high selectivity towards the detection of Her-2 in the presence of other interfering molecules and appreciable recovery values of Her-2 in the spiked undiluted human serum samples. Finally, to show the potential application of the developed LSG-AuNS-MIP sensor as a point-of-care device, the sensor is integrated with a homemade open-source electrochemical analyzer KAUSTat to detect Her-2.
  • Tris(Keto-Hydrazone): A Fully Integrated Highly Stable and Exceptionally Sensitive H 2 S Capacitive Sensor

    Yuvaraja, Saravanan; Bhyranalyar, Veerabhadraswamy Nagarajappa; Bhat, Sachin A.; Vijjapu, Mani Teja; Surya, Sandeep Goud; Yelamaggad, Channabasaveshwar Veerappa; Salama, Khaled N. (Advanced Electronic Materials, Wiley, 2021-06-23) [Article]
    Here a novel tris(keto-hydrazone) monomer having secondary amines and alkoxy groups to detect toxic hydrogen sulfide (H2S) gas is reported. The as-synthesized tris(keto-hydrazone) monomer is successfully integrated on a micro-fabricated device to realize an organic capacitive sensor. The organic sensor's quantitative detection capability toward H2S gas and its specificity against the other toxic gases and volatile organic compounds are investigated. The capacitance sensor achieves an excellent sensitivity (80% parts per million–1) toward H2S gas with an experimental limit of detection of around 25 parts per billion. Besides, the fabricated capacitive sensor displays minimal response to humidity (0.005% RH–1), and high ambient stability (≈8 months) without compromising sensing performance. Furthermore, the energy-dispersive X-ray spectroscopy spectrum analysis confirms the adsorption of sulfur atoms over the surface of the monomer after the exposure to H2S gas. After that, a short purge of N2 gas would suffice to revive the whole device and can work with negligible losses.
  • Robust, Long-Term, and Exceptionally Sensitive Microneedle-Based Bioimpedance Sensor for Precision Farming

    Bu Khamsin, Abdullah; Moussi, Khalil; Tao, Ran; Lubineau, Gilles; Blilou, Ikram; Salama, Khaled N.; Kosel, Jürgen (Advanced Science, Wiley, 2021-06-17) [Article]
    Precision farming has the potential to increase global food production capacity whilst minimizing traditional inputs. However, the adoption and impact of precision farming are contingent on the availability of sensors that can discern the state of crops, while not interfering with their growth. Electrical impedance spectroscopy offers an avenue for nondestructive monitoring of crops. To that end, it is reported on the deployment of impedimetric sensors utilizing microneedles (MNs) that can be used to pierce the waxy exterior of plants to obtain sensitive impedance spectra in open-air settings with an average relative noise value of 3.83%. The sensors are fabricated using a novel micromolding and release method that is compatible with UV photocurable and thermosetting polymers. Assessments of the quality of the MNs under scanning electron microscopy show that the replication process is high in fidelity to the original design of the master mold and that it can be used for upward of 20 replication cycles. The sensor's performance is validated against conventional planar sensors for obtaining the impedance values of Arabidopsis thaliana. As a change is detected in impedance due to lighting and hydration, this raises the possibility for their widespread use in precision farming.
  • IoT Enabled, Leaf Wetness Sensor on the Flexible Substrates for In-situ Plant Disease Management

    Patle, Kamlesh S.; Saini, Riya; Kumar, Ahlad; Surya, Sandeep Goud; Palaparthy, Vinay S; Salama, Khaled N. (IEEE Sensors Journal, IEEE, 2021-06-16) [Article]
    Early plant disease detection and providing the control measures have become highly desirable to improve crop yield. Leaf wetness duration (LWD) is one of the essential parameters related to the development of fungal disease on the leaf canopy. To measured LWD, the leaf wetness sensor (LWS) is widely used. Commercially available LWS are made on printed circuit board (PCB) technology, which has an operational issue during field deployment such as weight of the sensor, contact resistance between the sensor and the leaves, form factor and most importantly, affordability. To mitigate the issues associated with the commercially available LWS, in this work, we have fabricated the in-house IoT-enabled and affordable electronic leaf wetness sensor on the flexible substrates, which is used for integrated plant disease management. Fabricated LWS comprises the interdigitated electrodes (IDEs) on the polyimide flexible substrate. The lab measurement results indicate that fabricated LWS on the flexible substrates offers a response of about 36000% when LWS is exposed to water w.r.t air. The observed response time of the fabricated LWS is about 10 seconds and hysteresis of about ± 4 %. Further, sensor capacitance changes only by 6% over a temperature range from 20 °C to 65 °C. Furthermore, three fabricated sensors LWS and in-house developed internet of things (IoT) enabled systems are deployed on the Ocimum tenuiflorum (Tulsi) medical plant. Field measurement indicates that measured LWD using the fabricated flexible LWS and commercially available LWS (Phytos 31:LWS-L12), METER Group, Inc. USA) shows the absolute difference of 30 minutes.
  • Rapid Point-of-Care COVID-19 Diagnosis with a Gold-Nanoarchitecture-Assisted Laser-Scribed Graphene Biosensor

    Beduk, Tutku; Beduk, Duygu; De Oliveira Filho, Jose; Zihnioglu, Figen; Cicek, Candan; Sertoz, Ruchan; Arda, Bilgin; Goksel, Tuncay; Turhan, Kutsal; Salama, Khaled N.; Timur, Suna (Analytical Chemistry, American Chemical Society (ACS), 2021-06-03) [Article]
    The global pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus has revealed the urgent need for accurate, rapid, and affordable diagnostic tests for epidemic understanding and management by monitoring the population worldwide. Though current diagnostic methods including real-time polymerase chain reaction (RT-PCR) provide sensitive detection of SARS-CoV-2, they require relatively long processing time, equipped laboratory facilities, and highly skilled personnel. Laser-scribed graphene (LSG)-based biosensing platforms have gained enormous attention as miniaturized electrochemical systems, holding an enormous potential as point-of-care (POC) diagnostic tools. We describe here a miniaturized LSG-based electrochemical sensing scheme for coronavirus disease 2019 (COVID-19) diagnosis combined with three-dimensional (3D) gold nanostructures. This electrode was modified with the SARS-CoV-2 spike protein antibody following the proper surface modifications proved by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) characterizations as well as electrochemical techniques. The system was integrated into a handheld POC detection system operated using a custom smartphone application, providing a user-friendly diagnostic platform due to its ease of operation, accessibility, and systematic data management. The analytical features of the electrochemical immunoassay were evaluated using the standard solution of S-protein in the range of 5.0-500 ng/mL with a detection limit of 2.9 ng/mL. A clinical study was carried out on 23 patient blood serum samples with successful COVID-19 diagnosis, compared to the commercial RT-PCR, antibody blood test, and enzyme-linked immunosorbent assay (ELISA) IgG and IgA test results. Our test provides faster results compared to commercial diagnostic tools and offers a promising alternative solution for next-generation POC applications.
  • Reply to “Comment on ‘Scattering Cancellation-Based Cloaking for the Maxwell-Cattaneo Heat Waves’”

    Farhat, Mohamed; Guenneau, Sebastien; Chen, P.-Y.; Alù, A.; Salama, Khaled N. (Physical Review Applied, American Physical Society (APS), 2021-05-28) [Article]
    Comment [1] points out possible inconsistencies in the notations of our paper [2] and, based on these remarks, it questions the validity of our conclusions. In this Reply, we demonstrate the general validity of all conclusions in Ref. [2], and we take the opportunity to clarify our notation and our results and to discuss their domain of validity.
  • Breath as the Mirror of Our body, is the Answer Really Blowing in the Wind? Recent Technologies in Exhaled Breath Analysis Systems as Non-invasive Sensing Platforms

    Beduk, Tutku; Durmus, Ceren; Hanoglu, Simge Balaban; Beduk, Duygu; Salama, Khaled N.; Goksel, Tuncay; Turhan, Kutsal; Timur, Suna (TrAC Trends in Analytical Chemistry, Elsevier BV, 2021-05-14) [Article]
    Health care monitoring is an enormous field of research that has great potential to solve many problems in human life. In recent years, non-invasive health monitoring has become a prerequisite for early diagnosis of various diseases such as lung cancer, oxidative stress, diabetes, to enable the prompt treatment and screening of crucial chemicals. Although analyzing of exhaled breath has been correlated with advanced analytical techniques such as gas chromatography and infrared spectroscopy, breath analyzing biosensing systems offer a cost-effective, sensitive platform for a straightforward analysis. However, current non-invasive sensing strategies have been lacking in practicality in terms of the design and usage, on-site ability and accessibility. This review will critically discuss current commercialized breath analyzers, the recent achievements for the use of the detection towards chemical and biological substances from exhaled breath as non-invasive sensing systems including challenges/drawbacks by addressing the practical applications and concerns in the field. The different fabrication strategies, methodology of detection techniques involved in the development of the breath analyzing systems will be overviewed and discussed along with the future opportunities for possible point of care applications with smartphone integration in this review. The scientific and technological challenges in the field are discussed in the conclusion.
  • Hardware Acceleration of High Sensitivity Power-Aware Epileptic Seizure Detection System Using Dynamic Partial Reconfiguration

    Elhosary, Heba; Zakhari, Michael H.; Elgammal, Mohamed A.; Kelany, Khaled A. Helal; Ghany, Mohamed A. Abd El; Salama, Khaled N.; Mostafa, Hassan (IEEE Access, IEEE, 2021-05-11) [Article]
    In this paper, a high-sensitivity low-cost power-aware Support Vector Machine (SVM) training and classification based system, is hardware implemented for a neural seizure detection application. The training accelerator algorithm, adopted in this work, is the sequential minimal optimization (SMO). System blocks are implemented to achieve the best trade-off between sensitivity and the consumption of area and power. The proposed seizure detection system achieves 98.38% sensitivity when tested with the implemented linear kernel classifier. The system is implemented on different platforms: such as Field Programmable Gate Array (FPGA) Xilinx Virtex-7 board and Application Specific Integrated Circuit (ASIC) using hardware-calibrated UMC 65nm CMOS technology. A power consumption evaluation is performed on both the ASIC and FPGA platforms showing that the ASIC power consumption is lower by at least 65% when compared with the FPGA counterpart. A power-aware system is implemented with FPGAs by the adoption of the Dynamic Partial Reconfiguration (DPR) technique that allows the dynamic operation of the system based on power level available to the system at the expense of degradation of the system accuracy. The proposed system exploits the advantages of DPR technology in FPGAs to switch between two proposed designs providing a decrease of 64% in power consumption.
  • Binary transition metal oxide modified laser-scribed graphene electrochemical aptasensor for the accurate and sensitive screening of acute myocardial infarction

    Rauf, Sakandar; Mani, Veerappan; Ait Lahcen, Abdellatif; Yuvaraja, Saravanan; Beduk, Tutku; Salama, Khaled N. (Electrochimica Acta, Elsevier BV, 2021-05-01) [Article]
    Laser-scribed graphene (LSG) electrodes have gained significant interest due to the ease in fabrication, surface modification, and potential to develop various types of electrochemical sensors and biosensors. In these studies, a new type of zinc ferrite nanoparticles (ZnFe2O4 NPs) modified LSG electrochemical sensing system comprising LSG-ZnFe2O4 working electrode, LSG reference, and LSG counter electrode on a single polyimide substrate is presented. LSG-ZnFe2O4 electrodes are fabricated by drop-casting a solution of ZnFe2O4 NPs onto the LSG electrode, which gave a 31% enhancement of sensitivity and electrocatalytic activity compared to the bare LSG electrode. LSG-ZnFe2O4 electrochemical aptasensor for acute myocardial infarction (AMI) screening is developed by detecting the cardiac Troponin-I (cTn-I) biomarker. The results show that the developed aptasensor could detect a broad concentration range of cTn-I with a limit of detection of 0.001 ng/mL and a sensitivity of 19.32 (±0.25) µA/(ng/mL). In addition to this, LSG-ZnFe2O4-aptasensor shows higher selectivity towards the detection of cTn-I and negligible cross-reactivity with other interfering biomolecules. Finally, it is demonstrated that LSG-ZnFe2O4-aptasensor can easily detect different concentrations of cTn-I spiked in human serum samples. These results show that the LSG-ZnFe2O4-aptasensor is a promising diagnostic tool to monitor cTn-I and could be a potential candidate to develop point-of-care devices for cTn-I biomarker detection and various other disease biomarkers in the future.
  • A 0.002-mm2 8-bit 1-MS/s low-power time-based DAC (T-DAC)

    Hassan, Ali H.; Mostafa, Hassan; Refky, Mohamed; Salama, Khaled N.; Soliman, Ahmed M. (IET Circuits, Devices & Systems, Institution of Engineering and Technology (IET), 2021-04-08) [Article]
    Digital-to-analogue converters (DACs) are essential blocks for interfacing the digital environment with the real world. A novel architecture, using a digital-to-time converter (DTC) and a time-to-voltage converter (TVC), is employed to form a low-power time-based DAC (T-DAC) that fits low-power low-speed applications. This novel conversion mixes the digital input code into a digital pulse width modulated (D-PWM) signal through the DTC circuit, then converts this D-PWM signal into an analogue voltage through the TVC circuit. This new T-DAC is not only an energy-efficient design but also an area-efficient implementation. Power optimization is achieved by controlling the supply voltage of the TVC circuit with a discontinuous waveform using a low bias current. Moreover, the implementation area is optimized by proposing a new DAC architecture with a coarse-fine DTC circuit. Post-layout simulations of the proposed T-DAC is conducted using industrial hardware-calibrated 0.13 μm. Complementary metal oxide semiconductor technology with a 1 V supply voltage, 1 MS/s conversion rate, and 0.9 μW power dissipation.
  • Enhanced acoustic pressure sensors based on coherent perfect absorber-laser effect

    Farhat, Mohamed; Ahmed, Waqas Waseem; Khelif, Abdelkrim; Salama, Khaled N.; Wu, Ying (Journal of Applied Physics, AIP Publishing, 2021-03-14) [Article]
    Lasing is a well-established field in optics with several applications. Yet, having lasing or huge amplification in other wave systems remains an elusive goal. Here, we utilize the concept of coherent perfect absorber-laser to realize an acoustic analog of laser with a proven amplification of more than 10 4 in terms of the scattered acoustic signal at a frequency of a few kHz. The obtained acoustic laser (or the coherent perfect absorber-laser) is shown to possess extremely high sensitivity and figure of merit with regard to ultra-small variations of the pressure (density and compressibility) and suggests its evident potential to build future acoustic pressure devices such as precise sensors.
  • On Coding and Decoding Reconfigurable Radiation Pattern Modulation Symbols

    Celis Sierra, Sebastian; Farhat, Mohamed; Zhang, Li; Bagci, Hakan; Eltawil, Ahmed; Salama, Khaled N. (Electronics, MDPI AG, 2021-03-06) [Article]
    In this paper, we propose the theoretical framework for a reconfigurable radiation pattern modulation (RRPM) scheme, which is reminiscent of the index modulation technique. In the proposed scheme, information is encoded using far-field radiation patterns generated by a set of programmable radiating elements. A considerable effort has been invested to allow for high transmission of the reconfigurable radiation pattern symbols; yet, the receiving system has received little attention and has always been considered ideal. Depending on the number of receivers and their respective positions, two variables are considered here for data transmission: the sampling resolution and the fraction of the covered space by the receiving antennas. Hence, we quantitatively investigate their effect on the bit-error-rate (BER) by making use of a limited number of measurements that approximate the behavior of the system under real-field conditions.

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