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Tertiary education is at the forefront of future-proof education providing a theoretical foundation to advance knowledge and drive innovation. Exploring preservice teachers’ perspective of what it takes to remain relevant amidst this increasingly complex, uncertain, volatile, ambiguous world is proactively necessary as emerging configurations challenge the role of teachers and the dynamics of the educative process. These preservice general science teachers (n=113) describe their point of view on ensuring the relevance of science education in the future through drawing and narrative description. Qualitative data were analyzed using thematic analysis, and four main themes emerged. Their perception of how Science education can be future-proofed centered on (1) highly advanced technology use, (2) personalized and adaptive learning (3) curated and open accessible learning resources, and (4) sustainability, social responsibility, and ethics-centered. These conceptions enable these future teachers who are also future leaders to prepare for the challenges and opportunities of a future world. These findings offer valuable insights into the need for teacher training institutions to recalibrate for the future skills in education that their graduates must possess and the curriculum development to promote innovative and inclusive teaching practices. more...

Abstract Ionic fluidic devices are gaining interest due to their role in enabling self-powered neuromorphic computing systems. In this study, we present an approach that integrates an iontronic fluidic memristive (IFM) device with low input impedance and a triboelectric nanogenerator (TENG) based on ferrofluid (FF), which has high input impedance. By incorporating contact separation electromagnetic (EMG) signals with low input impedance into our FF TENG device, we enhance the FF TENG’s performance by increasing energy harvesting, thereby enabling the autonomous powering of IFM devices for self-powered computing. Further, replicating neuronal activities using artificial iontronic fluidic systems is key to advancing neuromorphic computing. These fluidic devices, composed of soft-matter materials, dynamically adjust their conductance by altering the solution interface. We developed voltage-controlled memristor and memcapacitor memory in polydimethylsiloxane (PDMS) structures, utilising a fluidic interface of FF and polyacrylic acid partial sodium salt (PAA Na+). The confined ion interactions in this system induce hysteresis in ion transport across various frequencies, resulting in significant ion memory effects. Our IFM successfully replicates diverse electric pulse patterns, making it highly suitable for neuromorphic computing. Furthermore, our system demonstrates synapse-like learning functions, storing and retrieving short-term (STM) and long-term memory (LTM). The fluidic memristor exhibits dynamic synapse-like features, making it a promising candidate for the hardware implementation of neural networks. FF TENG/EMG device adaptability and seamless integration with biological systems enable the development of advanced neuromorphic devices using iontronic fluidic materials, further enhanced by intricate chemical designs for self-powered electronics. more...

Abstract The electroelastomer cylindrical actuators, a typical representation of soft actuators, have recently aroused increasing interest owing to their advantages in flexibility, deformability, and spatial utilization rate. Proprioception is crucial for controlling and monitoring the shape and position of these actuators. However, most existing flexible sensors have a modulus mismatch with the actuation unit, hindering the free movement of these actuators. Herein, a low-modulus strain sensor based on laser-induced cellular graphitic flakes (CGF) onto the surface of hollow TPU fibers (HTF) is present. Through the electrostatic self-assembly technology, the flexible sensor features a unique hybrid sensing unit including soft HTF as substrate and rigid CGF as conductive path. As a result, the sensor simultaneously possesses desirable modulus (~0.155 MPa), a gauge factor of 220.3 (25% more...

Abstract In recent years, the utilization of 3D printing technology in micro and nano device manufacturing has garnered significant attention. Advancements in 3D printing have enabled achieving sub-micron level precision. Unlike conventional micro-machining techniques, 3D printing offers versatility in material selection, such as polymers. 3D printing technology has been gradually applied to the general field of microelectronic devices such as sensors, actuators and flexible electronics due to its adaptability and efficacy in microgeometric design and manufacturing processes. Furthermore, 3D printing technology has also been instrumental in the fabrication of microfluidic devices, both through direct and indirect processes. This paper provides an overview of the evolving landscape of 3D printing technology, delineating the essential materials and processes involved in fabricating microelectronic and microfluidic devices in recent times. Additionally, it synthesizes the diverse applications of these technologies across different domains. more...

Abstract To understand the complex dynamics of neural activity in the brain across various temporal and spatial scales, it is crucial to record intracortical multimodal neural activity by combining electrophysiological recording and calcium imaging techniques. This poses significant constraints on the geometrical, mechanical, and optical properties of the electrodes. Here, transparent flexible graphene–ITO-based neural microelectrodes with small feature sizes are developed and validated for simultaneous electrophysiology recording and calcium imaging in the hippocampus of freely moving mice. A micro-etching technique and an oxygen plasma pre-treating method are introduced to facilitate large-area graphene transfer and establish stable low-impedance contacts between graphene and metals, leading to the batch production of high-quality microelectrodes with interconnect widths of 10 μm and recording sites diameters of 20 μm. These electrodes exhibit appropriate impedance and sufficient transparency in the field of view, enabling simultaneous recording of intracortical local field potentials and even action potentials along with calcium imaging in freely moving mice. Both types of electrophysiological signals are found to correlate with calcium activity. This proof-of-concept work demonstrates that transparent flexible graphene–ITO-based neural microelectrodes are promising tools for multimodal neuroscience research. more...

Abstract The quantification of immune cell subpopulations in blood is important for the diagnosis, prognosis and management of various diseases and medical conditions. Flow cytometry is currently the gold standard technique for cell quantification; however, it is laborious, time-consuming and relies on bulky/expensive instrumentation, limiting its use to laboratories in high-resource settings. Microfluidic cytometers offering enhanced portability have been developed that are capable of rapid cell quantification; however, these platforms involve tedious sample preparation and processing protocols and/or require the use of specialized/expensive instrumentation for flow control and cell detection. Here, we report an artificial intelligence-enabled microfluidic cytometer for rapid CD4+ T cell quantification in whole blood requiring minimal sample preparation and instrumentation. CD4+ T cells in blood are labeled with anti-CD4 antibody-coated microbeads, which are driven through a microfluidic chip via gravity-driven slug flow, enabling pump-free operation. A video of the sample flowing in the chip is recorded using a microscope camera, which is analyzed using a convolutional neural network-based model that is trained to detect bead-labeled cells in the blood flow. The functionality of this platform was evaluated by analyzing fingerprick blood samples obtained from healthy donors, which revealed its ability to quantify CD4+ T cells with similar accuracy as flow cytometry ( more...

Abstract Due to the limited thermoelectric (TE) performance of polymer materials and the inherent rigidity of inorganic materials, developing low-cost, highly flexible, and high-performance materials for flexible thermocouple sensors (FTCSs) remains challenging. Additionally, dual-mode (contact/non-contact) temperature monitoring in FTCSs is underexplored. This study addresses these issues by using p-type (PEDOT:PSS/CNTs, 2:1) and n-type (MXene/Bi2Se3, 2:1) TE materials applied via screen printing and compression onto a PPSN substrate (paper/PDMS/Si3N₄). The resulting FTCSs exhibit excellent TE properties: electrical conductivities of 61,197.88 S/m (n-type) and 55,697.77 S/m (p-type), Seebeck coefficients of 39.88 μV/K and -29.45 μV/K, and power factors (PFs) of 97.66 μW/mK² and 55.64 μW/mK², respectively. In contact mode, the sensor shows high-temperature sensitivity (S T = 379.5 μV/°C), a broad detection range (20-200 °C), high resolution (~0.3 °C), and fast response (~12.6 ms). In non-contact mode, it maintains good sensitivity (S Tmax = 52.67 μV/°C), a broad detection range, high resolution (~0.8 °C), and even faster response (~9.8 ms). The sensor also demonstrates strong mechanical durability, maintaining stable performance after 1000 bending cycles. When applied to dual-mode temperature monitoring in wearable devices and lithium batteries, the FTCS shows high accuracy and reliability compared to commercial K-type thermocouples, indicating significant potential for advanced medical monitoring systems and smart home technologies. more...

Abstract In recent years, microfluidic systems have evolved to incorporate increasingly complex multi-layer and multi-material structures. While conventional 2-dimensional microfluidic systems are typically fabricated with lithographic techniques, the increase in system complexity necessitates a more versatile set of fabrication techniques. Similarly, although 3D printing can easily produce intricate microfluidic geometries, integrating multiple membranes and electrode components remains challenging. This study proposes a toolkit for fabricating free-standing 3-dimensional microfluidic systems for biomedical devices, incorporating flow channels, electrodes, and membranes. The fabrication techniques include molding separation using 3D printed molds, laser-based processing, and component assembly, each achieving micron resolution. Here, we introduce a novel approach to integrate membranes into microfluidics by directly curing elastomer-based microfluidics with the membrane through replica molding, while preserving membrane functionality by effectively removing elastomer residues through reactive ion etching. The resulting membrane-elastomer microfluidic component significantly simplifies the assembly of intricate microfluidic systems, reducing the device size to millimeter dimensions, suitable for implantable applications. The toolkit’s versatility is demonstrated by a redox flow iontophoretic drug delivery prototype at the millimeter scale, featuring two electrodes, four membranes, and four microfluidic channels. more...

Students must grasp creative thinking as a crucial 21st-century talent to enhance learning achievement. Empirical research indicates that pupils' creative thinking skills and learning successes require enhancement and attention. This study examines the impact of a project based learning framework with STEAM methodology and self-efficacy levels on creative thinking abilities and learning achievement in primary computer education, focusing on computer architecture. A quasi-experimental pretest-posttest non-equivalent control group design was utilized to develop the research design. One hundred students were enrolled, of which 50 were divided into the experimental and control groups. Research data was collected using questionnaires and test devices. Student self-efficacy was assessed using a 44-item questionnaire, creative thinking skills were evaluated with a 10-question essay test, and student learning achievement was measured using a multiple-choice test. Data analysis entails the application of descriptive and inferential statistics, specifically using MANCOVA. Research indicates that implementing the project based learning framework with STEAM methodology is effective in enhancing students' creative thinking abilities and academic performance. Research shows that self-efficacy affects creative thinking skills and learning achievement differently. A p-value of less than 0.05 denotes this. The project based learning framework with STEAM methodology has been proven to help enhance creative thinking abilities and learn accomplishment through simultaneous and partial testing. This strategy is indicated for enhancing creative thinking skills and improving learning achievement. more...

Abstract Thermal-actuation and piezoresistive-detection effects have been employed to pump the effective quality factor of MEMS resonators, targeting simple self-oscillation and better sensing performance in the air. However, the ratio of the pumped effective quality factor to the inherent mechanical quality factor, crucial for characterizing the amplification, is hard to obtain. The main difficulty stems from hidden Lorentz peaks caused by feedthrough effects and the pump effect once the current is applied. In this paper, we demonstrated the presence of high-order harmonic components in the output of thermal-piezoresistive resonators when the oscillation amplitude is sufficiently large. By utilizing second-order harmonics, we achieved the improvement in signal-to-bias ratio of, 20.85 dB compared to that without feedthrough cancellation and 9.67 dB compared to that using a de-embedded method when the bias current is 6.20 mA. Furthermore, the inherent mechanical quality factor is extracted at a low current of 1.8 mA with a value of 5800 using the second-order harmonics, and a nearly two orders of magnitude enhancement in Q factor can be obtained before entering the self-oscillation regime. An amplitude bias instability as good as 55 ppm and a frequency bias instability as good as 10 ppb are realized in the nonlinear operation regime with a pumped effective quality factor of 576k. The paper contributes to the fundamental understanding of the Q pump effect together with harmonic analysis of the thermal-piezoresistive resonators and also pushes forward the development of low-power consumption self-oscillation resonant sensors. more...

Abstract Traditional gyrocompasses, while capable of providing autonomous directional guidance and path correction, face limitations in widespread applications due to their large size, making them unsuitable for compact devices. Microelectromechanical system (MEMS) gyrocompasses offer a promising alternative for miniaturization. However, current MEMS gyrocompasses require the integration of motor rotation modulation technology to achieve high-precision north-finding, whereas conventional motors in previous research introduce large volume and residual magnetism, thus undermining their size advantage. Here, we innovatively propose a miniature MEMS gyrocompass based on a MEMS traveling-wave micromotor, featuring the first integration of a chip-scale rotational actuator and combined with a precise multi-position braking control system, enabling high accuracy and fast north-finding. The proposed gyrocompass made significant advancements, reducing its size to 50 × 42.5 × 24.5 mm³ and achieving an azimuth accuracy of 0.199° within 2 min, which is half the volume of the smallest existing similar devices while offering twice the performance. These improvements indicate that the proposed gyrocompass is suitable for applications in indoor industrial robotics, autonomous driving, and other related fields requiring precise directional guidance. more...

Abstract The microinjection of Zebrafish embryos is significant to life science and biomedical research. In this article, a novel automated system is developed for cell microinjection. A sophisticated microfluidic chip is designed to transport, hold, and inject cells continuously. For the first time, a microinjector with microforce perception is proposed and integrated within the enclosed microfluidic chip to judge whether cells have been successfully punctured. The deep learning model is employed to detect the yolk center of zebrafish embryos and locate the position of the injection needle within the yolk, which enables enhancing the precision of cell injection. A prototype is fabricated to achieve automatic batch microinjection. Experimental results demonstrated that the injection efficiency is about 20 seconds per cell. Cell puncture success rate and cell survival rate are 100% and 84%, respectively. Compared to manual operation, this proposed system improves cell operation efficiency and cell survival rate. The proposed microinjection system has the potential to greatly reduce the workload of the experimenters and shorten the relevant study period. more...

Abstract Nanomechanical photothermal sensing has significantly advanced single-molecule/particle microscopy and spectroscopy, and infrared detection. In this approach, the nanomechanical resonator detects shifts in resonant frequency due to photothermal heating. However, the relationship between photothermal sensitivity, response time, and resonator design has not been fully explored. This paper compares three resonator types - strings, drumheads, and trampolines - to explore this relationship. Through theoretical modeling, experimental validation, and finite element method simulations, we find that strings offer the highest sensitivity (with a noise equivalent power of 280 fW/Hz1/2 for strings made of silicon nitride), while drumheads exhibit the fastest thermal response. The study reveals that photothermal sensitivity correlates with the average temperature rise and not the peak temperature. Finally, the impact of photothermal back-action is discussed, which can be a major source of frequency instability. This work clarifies the performance differences and limits among resonator designs and guides the development of advanced nanomechanical photothermal sensors, benefiting a wide range of applications. more...

The technological training of Early Childhood Education students is essential for the development of their Digital Teaching Competences (DTC), and are crucial for their future work as teachers. The aim of the present study is to assess the level of digital competence of students and to analyze the differences between two universities that provide this training at different moments during the degree (1st and 4th years), considering variables such as sex, age, teaching experience, and the use of technology. The methodology used was quasi-experimental, with a pretest and posttest design, using the DigCompEdu questionnaire to measure self-perception of DTC. The results showed that after the training, the students perceived themselves as having a lower level of digital competence as compared to their estimated level before the training. Likewise, it was found that the first-year students had a greater self-perception of their digital competence as compared to the fourth-year students. In addition, the previous teaching experience and the frequent use of technologies significantly influenced the perception of the students in their last year of the degree. In conclusion, the study highlights the importance of having didactic maturity, as well as training that includes both pedagogic and technological knowledge, so that future Early Childhood Education teachers fully develop their digital competences. This underlines the need for educational programs that into account the level of maturity of the students, and that promote technical and pedagogic skills that will result in the creation of enriching and meaningful learning environments. more...

This study aims to investigate the impact of using the flipped classroom strategy on motivation and academic achievement in learning science among 9th-grade students Proved as an innovative technique, flipped learning improves academic performance, enhances students’ motivation, supports independent learning, triggers higher thinking skills, and establishes lifelong learning. In disadvantaged places at war like Palestine, there are no studies exploring students' engagement with flipped learning in sciences using empirical evidence including a large population of 2489 females and 2366 males with a representative sample of 333 students Pre and post-test assessment, observation, and two semi-structured interviews with teachers and students are utilized in addition to providing multimedia resources related to the Floral Plant unit in the 9th-grade curriculum has been tailored to the content and needs of teachers and students and distributed through social media platforms. A significant difference in the achievement scores, motivation, and overall positive shift in attitudes regarding homework, students' and teachers' roles, and time management between the experimental group and the control group indicates the positive impact of the flipped classroom method on teachers and students both female and male students. more...

Abstract The technology of through-silicon via (TSV) is extensively employed for achieving dense 3D integration. TSV facilitates the electrical interconnection of various layers of integrated circuits in a vertical orientation, thereby allowing for the creation of sophisticated and space-efficient systems that incorporate diverse functionalities. This work reports TSV fabrication with dual annealing-CMP processes to explore the influence of annealing and CMP processes on the evolution of TSV-Cu microstructures and protrusions. The results show that the dual CMP process can effectively reduce protrusion at high temperatures. The Cu protrusion height increased as both the annealing temperature and duration increased, which was consistent with the high-temperature annealing results, whereas a random phenomenon occurred under 250 °C annealing. A phase field model related to the TSV grain size was established to quantitatively explore the grain morphology distribution and thermal-mechanical behavior. The results show that the strain in copper is nonuniform and that the degree of plastic deformation for each grain is closely related to its distribution. The quantity of grains within the TSV is the most important factor for protrusion. As the average grain size increases, the prominence of copper grain protrusions within TSV intensifies, and the anisotropy of the Cu grains becomes more pronounced. The thermal-mechanical behavior strongly depends on the grain orientation near the top of the TSV, which can cause TSV protrusion irregularities. This work may provide more opportunities to design high-performance TSV preparation methods from the viewpoint of the dual CMP process. more...

Abstract Microelectronic magnetic sensors are essential in diverse applications, including automotive, industrial, and consumer electronics. Hall-effect devices hold the largest share of the magnetic sensor market, and they are particularly valued for their reliability, low cost and CMOS compatibility. This paper introduces a novel 3-axis Hall-effect sensor element based on an inverted pyramid structure, realized by leveraging MEMS micromachining and CMOS processing. The devices are manufactured by etching the pyramid openings with TMAH and implanting the sloped walls with n-dopants to define the active area. Through the use of various bias-sense detection modes, the device is able to detect both in-plane and out-of-plane magnetic fields within a single compact structure. In addition, the offset can be significantly reduced by one to three orders of magnitude by employing the current-spinning method. The device presented in this work demonstrated high in-plane and out-of-plane current- and voltage-related sensitivities ranging between 64.1 to 198 V A−1 T− 1 and 14.8 to 21.4 mV V−1 T−1, with crosstalk below 4.7%. The sensor exhibits a thermal noise floor which corresponds to approximately $$0.5\,\mu \text{T}/\sqrt{\text{Hz}}$$ 0.5 μ T / Hz at 1.31 V supply. This novel Hall-effect sensor represents a promising and simpler alternative to existing state-of-the-art 3-axis magnetic sensors, offering a viable solution for precise and reliable magnetic field sensing in various applications such as position feedback and power monitoring. more...

ICT can be a powerful tool for learning, but it is crucial that teachers know how to use it effectively. Digital competence enables teachers to tailor learning to the individual needs of students, making it more engaging and motivating, while creating more meaningful learning experiences. The objectives of this study were: (1) to assess the self-perceived digital competencies of future teachers, considering gender and educational stage, (2) to compare the self-perceived digital competencies of future teachers based on their educational stage and gender, and the interaction between these two factors, and (3) to explore how students' academic performance influences their digital competencies. This study is a non-experimental, ex post facto analysis with a sample of 897 students from both Infant and Primary School levels. The findings reveal no significant differences in digital competencies between future teachers based on gender, nor in the intersection of gender and educational stage. However, significant differences were found according to educational stage, both in the individual dimensions of the instrument and in overall competence. Primary education students reported higher levels of self-perceived digital competence compared to prospective EFL teachers. more...

Nowadays, physics learning in the classroom should no longer only focus on achieving academics. It must prepare students to face challenges in the future. One of the abilities that are important for learners is problem solving, and the problem-solving ability that is becoming increasingly important in today's digital era is computational thinking skills. Although computational thinking skills can be developed through worksheets, their integration into learning practices remains suboptimal. This study examines the effects of the ExPRession-based E-Worksheet (EBEW) on enhancing students' computational thinking skills in physics education. A quantitative approach with a pre-test and post-test quasi-experimental design was employed, involving 59 students divided into two groups. The control group participated in a simple laboratory practicum using discovery learning-based worksheets, while the experiment group engaged in a practicum facilitated by EBEW. Both groups completed a pre-test prior to the learning sessions. Results suggest that students using EBEW showed significantly deeper CT skills as compared to those using discovery learning-based worksheets. EBEW’s structured learning phases, involving deep problem understanding, root cause analysis, predictive solution modeling, investigative procedures, and conclusion synthesis, effectively aided students in enhancing CT and problem-solving skills. These findings then suggest that EBEW not only enhances student learning on direct current circuit topics but also provides a readily extensible scaffold for broader STEM activities. This study underlines that EBEW has the potential to revolutionize physics learning with computational thinking by systemic processes of problem-solving. The present research was specifically directed toward DC circuits topic. However, the principles of EBEW are potentially applicable to other areas in physics for extended training in skills related to CT and to the reform of STEM education. more...

Abstract Existing gastrointestinal (GI) diagnostic tools are unable to non-invasively monitor mucosal tight junction integrity in vivo beyond the esophagus. In the GI tract, local inflammatory processes induce alterations in tight junction proteins, enhancing paracellular ion permeability. Although transepithelial electrical resistance (TEER) may be used in the laboratory to assess mucosal barrier integrity, there are no existing methodologies for characterizing tight junction dilation in vivo. Addressing this technology gap, intraluminal bioimpedance sensing may be employed as a localized, non-invasive surrogate to TEER electrodes used in cell cultures. Thus far, bioimpedance has only been implemented in esophagogastroduodenoscopy (EGD) due to the need for external electronics connections. In this work, we develop a novel, noise-resilient Bluetooth-enabled ingestible device for the continuous, non-invasive measurement of intestinal mucosal “leakiness.” As a proof-of-concept, we validate wireless impedance readout on excised porcine tissues in motion. Through an animal study, we demonstrate how the device exhibits altered impedance response to tight junction dilation induced on mice colonic tissue through calcium-chelator exposure. Device measurements are validated using standard benchtop methods for assessing mucosal permeability. more...

Low-temperature cracking (LTC) is a critical form of pavement distress in cold regions. The fracture toughness in the semicircular bending (SCB) test serves as an indicator of LTC growth. Firstly, this study evaluated the effect of adding nano Al2O3 on the improvement of hot mix asphalt (HMA) fracture toughness. Another goal of the paper was to investigate the influence of different parameters, such as temperature (-5, -15, and -25 °C), loading mode (I, II, and I/II), crack geometry (vertical and angular cracks), and nano-modification, on the fracture toughness of HMA by using machine learning technique. An artificial neural network (ANN) was employed to quantify the impact of these parameters. The findings of this research clearly show that although asphalt mixtures in cold region are prone to thermal cracks, the addition of nano Al2O3 improves their resistance by 12% in comparison with control mixtures. The ANN analysis identified loading mode is the most significant factor affecting fracture toughness (48% contribution). Temperature followed with a 28% contribution, while crack geometry and nano Al2O3 modification each contributed 12%. more...

The accurate approximation is a benefit of the modern machine learning technique, which also disappeared the problems of traditional empirical methods, such as human and technical errors plus environmental pollution. Although there are many good samples on the state-of-the-art regarding the machine learning prediction of strength properties of steel fiber reinforced concrete, fewer articles are dedicated to proposing empirical formulations. This paper brings some novel empirical formulations to identify the strength properties of macro steel fiber-reinforced concrete. A 2650 multi-national data records are used to perform the regression, which is an exclusive dataset. This archive is the largest available dataset used in the state-of-the-art steel fiber-reinforced concrete prediction process, which is beneficial for supervised learning. Since the user must be careful regarding overtraining with such a vast resource, a successful strategy provided by the authors in previous research is utilized in which various machine learning techniques are compared to forecast the considered properties. So the Ridge, Lasso, and linear methods are used as regressors to predict the strength properties and the constants. Symbolic regression, a powerful tool for producing empirical formulations, is used for creating mathematical expressions regarding the strength properties. The performance is also evaluated based on well-known error analysis metrics. The formulations are presented for flat, waved, and hooked end fibers, the most common fibers used in construction engineering. The machine learning-driven formulations are exclusive due to the utilized strategy and the resources, and the precision of the relations are denoted, which presents the superiority to traditional methods. more...

The safety evaluation of retaining structures, especially in cases of potential instability or disaster, frequently depends on empirical methods that apply overall safety factors. In this article, an innovative approach employing probabilistic methods to assess the reliability of gravity retaining walls, considering uncertainties in parameters and their inherent variability, has been introduced. This study applies First Order Reliability Method (FORM) to assess the influence of construction defects and soil-structure friction on gravity wall reliability. his approach represents notable progress over traditional empirical methods, which rely on total safety factors and frequently manage uncertainties arbitrarily. The paper is indeed novel as it integrates probabilistic methods into the analysis of gravity retaining wall stability, offering a more nuanced understanding of the reliability of these structures. This contribution seeks to enhance safety assessments and rehabilitation strategies in civil engineering practices, with a focus on addressing uncertainties in geotechnical parameters and construction defects. more...

The published researches on the mechanical behaviour of granular soils reinforced with crushed glass particles from recycled glass waste is notably limited compared to studies involving glass powder. The disposal of waste glass presents significant environmental challenges, highlighting the need for innovative recycling solutions. This study investigates the use of crushed waste glass as a reinforcement material for sand to enhance its mechanical properties, offering a sustainable solution in geotechnical engineering. To achieve this goal, a series of direct shear experiments were conducted on three categories of river sand, each with a different mean particle size (D50 = 2.00 mm, 1.00 mm, and 0.63 mm). These sands were mixed with varying amounts of crushed waste glass (CWG = 0, 10, 20, and 30%) and subjected to three various normal stresses: 50, 200, and 400 kPa. The obtained data demonstrated clearly the combined impact of crushed waste glass and mean particle size on the angle of repose, internal friction angle, peak and residual friction angles, as well as the excess and maximum dilatancy angles for the sand-CWG mixtures. The results showed that as the crushed waste glass content (CWG) and mean particle size (D50) increased, the sand-CWG mixtures exhibited higher values of repose and internal friction angles. The study concludes that crushed waste glass can effectively reinforce sand, benefiting both waste recycling and construction material performance. These findings support sustainable civil engineering practices by reducing the environmental impact of waste glass and improving sandy soil performance. Future research should investigate the long-term durability and environmental impacts of using crushed glass in various geotechnical applications. more...

Engineered cementitious composites (ECC) provide enhanced ductile behavior thanks to multiple-cracking arising from the synergistic optimization of fiber-matrix interface adhesion behavior. According to the micromechanics based design theory of ECC, there are two critical conditions that should be satisfied to guarantee the strain-hardening. According to the first condition fiber bridging strength should be greater than the cracking strength for any crack plane. Secondly, complementary energy of fiber bridging should be greater than the crack tip toughness. Both criteria are directly related with the fiber/matrix interface bonding parameters and critical for the success of ECC design. These interfacial bonding parameters are well documented for poly-vinyl alcohol (PVA) fiber reinforced ECC and poly-ethylene (PE) fiber reinforced ECC. However, interfacial bonding parameters need to be determined for the relatively new type of ECC known as high-tenacity polypropylene fiber reinforced ECC (HTPP-ECC). This study focuses on the effect of different curing conditions on HTPP fiber/matrix bonding parameters (frictional bond strength, slip hardening coefficient and chemical debond-related energy). These parameters have been experimentally determined by using a special single fiber pull-out test setup. Results showed that water curing or partial water curing at the initial periods of hydration has a positive influence on fiber/matrix frictional bond strength. The chemical debond-related energy and slip hardening coefficient values of HTPP-ECC interfaces were found excessively low and did not significantly affected from the curing conditions, which is reasonable for most of the hydrophobic fibers. more...

Concentric bracing systems are a popular solution for strengthening moment frames due to their high lateral stiffness, ease of installation, and low cost. However, buckling in compression members can result in sudden loss of strength and less deformability. Researchers have suggested using steel slit dampers to increase deformability and energy dissipation in this system by directing damage away from bracing members. In this study, 265 finite element models were analyzed in ABAQUS software based on previous experimental investigations and the installation configuration of the combined elliptical slit elements with Chevron bracing system in a moment frame. The effects of varying each geometric parameter of the element, including thickness, width, height, and number of slits, as well as the minor diameter of the elliptical slit, on the behavioral characteristics have been investigated in a three-dimensional parametric space. These characteristics are such as elastic stiffness, ductility, force capacity, and cyclic energy dissipation. Finally, and based on conducted numerical analysis, suitable ranges for each geometric parameter have been proposed to facilitate optimal design of the element. more...

Nowadays, concrete is one of the most commonly used building and pavement materials. The type of concrete that has been used more than the other types is the concrete reinforced with steel. Due to the disadvantages of reinforcing concrete with steel such as corrosion, heavy weight, high cost and high-energy production, Glass Fiber Geogrid Mesh (GFGM) is chosen in this study for investigating the flexural reinforcement in the concrete beams. Fifty concrete beams in dimensions of 65 cm × 15 cm × 15 cm with different layers of GFGM, placements, curing times (28 and 90 days) and various concrete mixing designs (25 and 30 MPa) were reinforced in order to be compared with the unreinforced concrete beams (control beams). Then, the beams were tested under three-point bending test using displacement control mechanism. The results showed that the peak load capacity increased at most to 48.6 % in comparison with the Control Beams. Furthermore, a complete bonding between the GFGM and the concrete was indicated. It was also observed that the deflection at the midspan of the specimens reinforced with different Geogrid placements did not follow a specific pattern. more...

Masonry buildings remain popular worldwide due to their readily available materials, high compressive strength, ease of construction, and affordability. Therefore, understanding the impact of mortar on the compressive strength of masonry is essential. This study aimed to determine the compressive strength and failure patterns of masonry, focusing particularly on mortar. An experimental program was conducted, involving a total of 54 specimens: 27 cubes, 27 cylinders, and 9 masonry prisms. The cement-to-sand ratio (c/s) varied at ratios of 1:3, 1:4, and 1:5, while the water-to-cement ratio (w/c) remained fixed at 0.45. Each prism consisted of 5 bricks separated by a 10 mm mortar layer. Compressive strength data for cubes and cylinders were collected at 3, 7, and 28 days, while data for prisms were collected only at 28 days. The best results have been obtained at a c/s ratio of 1:3, with compressive strengths of 3555.5 psi for cubes, 3282.98 psi for cylinders, and a compressive force value of 129.33 kN for prisms at 28 days. The compressive strength of cubes and cylinders increases by approximately 68.19% and 64.61%, respectively, and the compressive force of masonry prisms increases by approximately 76.48% at 28 days when the cement-to-sand ratio is changed from 1:5 to 1:3. Stresses, graphs, and failure patterns have been analyzed and compared with the Bangladesh National Building Code (BNBC) 2020 and available literature, revealing a strong correlation. more...

Utilization of landfills for possible construction projects requires investigation and improvement of geomaterials in these areas. In this research, the effects of lime on improving the behavior of soil materials in Isfahan landfill were investigated through a series of laboratory experiments. Unstabilized and stabilized samples with 3 %, 6 % and 9 % lime were tested. Direct shear tests under different overburden and falling head permeability tests were conducted. X-ray diffraction tests were also performed to check the structure of the samples. Also, the scanning electron microscope images of the tested samples were prepared and compared. The results indicate that the lime-stabilization improves the stress-strain behavior of the treated samples. At the strains greater than 1 %, the positive effect of lime-stabilization of treated soil samples is obvious. Tests results indicate that the optimal amount of lime for Isfahan landfill’s soil stabilization is 6 %. Stabilization of samples with 6% lime under vertical overburden stresses of 0.5, 1 and 2 kg/cm2 increases the maximum shear strength of the samples by 113.95 %, 30.95 % and 9.88 %, respectively. The results show that the permeability coefficient of stabilized samples decreases with the increase of lime content. Stabilization using 3 %, 6 % and 9 % lime has resulted in a decrease of 14.66 %, 84.83 % and 93.62 % of the permeability coefficient of the landfill soil samples compared to the unstabilized samples, respectively. The results also show that the decreasing rate of permeability coefficient is increasing up to 6 % of lime and beyond that has decreased. more...

This study evaluates the intake tower's effect on the buttress dam responses, considering the access bridge and reservoir under seismic loading in ANSYS using the finite element model. Wimbleball dam in England is assigned as a case study to assess the effects of different characteristics of the system components on seismic responses. Some parameters were applied, such as the presence of the intake tower and access bridge, reservoir water level, intake tower height, and internal water level. Nine cases with and without intake towers and access bridges have been studied by raising the reservoir water level, intake tower height, and internal water level, resulting in three-dimensional seismic analyses. Circular frequencies, crest displacements, and heel stresses of the dam have been presented for current cases. The interaction between the reservoir, dam, and intake tower can alter the case's stiffness and consequently change its frequencies. The modal analysis responses presented that the case's frequencies were reduced by raising the reservoir water level by up to 40% and increasing the intake tower height by up to 19%. The seismic results show that the heel stresses of the middle buttress increase by raising the reservoir water level by up to 39%. For constant water levels in the reservoir and tower, displacements and stresses of the middle buttress increased by increasing the intake tower height by up to 3% and 43%, respectively. more...

Recent seismic incidents in Turkey have raised concerns among engineers about the potential performance of existing buildings in earthquakes. Due to its location in a somewhat active seismic region, Bangladesh is susceptible to experiencing catastrophic damage if a heavy to moderate earthquake hits. Therefore, the assessment of the seismic capacity of existing buildings is essential to investigate potential risks. Before this, Bangladesh did not have a seismic assessment or retrofitting guideline. However, the Public Works Department (PWD) of Bangladesh has now adopted the seismic assessment procedure from the Japan Building Disaster Prevention Association Manual (JBDPA, 2001) and published it as CNCRP (2015). On top of that, the building design code of Bangladesh (BNBC) has been updated, and the calculation of seismic demand has also changed. This study aims to assess an existing RC building located in Bangladesh for local seismic loads and retrofit it if found vulnerable. A six-storeyed RC building was assessed in detail. The building's seismic capacity was calculated using the suggestions of the CNCRP seismic assessment manual (2015), which depends on the strength and ductility capacity of structural members. The storey collapse mechanism was considered; therefore, the capacity of each storey was computed by considering the lateral capacities (both strength and ductility) of all columns in that storey. The columns were classified according to tributary area, and their failure mechanism was identified. The seismic index was computed utilizing the strength and ductility correlations. After evaluation, some floors were found vulnerable, and the necessary reinforcement specifications were computed following the CNCRP retrofit manual (2015). The retrofit design was established, and a comprehensive re-examination was conducted. Ultimately, the building was found safe according to the CNCRP seismic assessment manual (2015) after the retrofit. more...

Incineration is the most commonly employed alternate disposal strategy of biomedical waste across the globe, which produces Biomedical Waste Incinerated Fly Ash (BMWIFA). BMWIFA is often disposed of in landfills to prevent environmental contamination. Due to limited space and the high cost of land disposal, recycling methods and ash reuse in various systems have been developed. Therefore, the present study evaluates the performance of BMWIFA and Ordinary Portland Cement (OPC) blends as stabilizing agents for the base layers of low-volume roads (LVRs). Different trial mixes of crushed aggregate (CA), BMWIFA, and OPC were tested to find the optimum mix. The stabilizer content was considered to be 3.0%, 5.0%, and 7.0% of the total dry weight of the mix, in which the BMWIFA (a)/OPC (c) ratio is taken as 100/0, 80/20, 60/40, 40/60, 20/80, and 0/100 in each percentage of stabilizer. Optimum values of compaction characteristics were used for strength evaluations of mixes in terms of unconfined compressive strength (UCS) and indirect tensile strength (ITS) at 7, 14, and 28 days of air curing. The mix proportions 97% CA, 95% CA, and 93% CA stabilized with 3% (a/c = 20/80), 5% (a/c = 40/60), 7% (a/c = 60/40) binders respectively, satisfied the 7-day UCS requirements (3MPa) according to the Ministry of Rural Development (MoRD) for LVR cement-treated bases and were found durable. Furthermore, the Toxicity Characteristics Leaching Procedure (TCLP) analysis for various heavy metals reveals that the CA, BMWIFA, and OPC compositions were non-hazardous materials. Finally, this study's findings recommend the use of BMWIFA and OPC blends as stabilizers in low-volume road construction. more...

Online learning, especially in higher education, has grown in recent years and the study of its didactic implications has also increased. Online experiences have been found to be as successful as face-to-face ones, but there is a concern about a lack of social interaction among students. This makes it necessary for teachers to plan collaborative activities. Therefore, the aim of the present work is to analyse the main design features of collaborative activities that have been reported as successful in higher education. A total of 46 articles published between the years 2018 and 2023 were analysed in a systematic review based on the PRISMA Statement. Their main elements were grouped into three categories: contextual factors; pedagogical strategies; and ICT tools and resources that favour the development of such activities. By way of conclusion, recommendations for the design and instruction of a collaborative higher education activity in an online environment are presented. more...

This study presents a transdisciplinary techno-artistic experience conducted with students of the degree in Preschool Education from the University of Valencia. The experience seeks to promote the use of technologies with a contemporary approach through new creative forms such as sound-visual cartographies. The objective is to understand the students' perception of these transdisciplinary experiences that combine art and technology and to evaluate the contribution of new knowledge, ICT skills, and reflection in the teaching and learning process. To evaluate the practice, a validated questionnaire was applied to 120 students, using a quantitative methodology with 8 scales and a total of 48 items.The analysis dimensions are the following: developed reflective skills, levels of reflective thinking, learning process, awareness of students’ own learning, the role of the teacher, connection of theory and practice in learning and experience, and innovation and adaptation to teaching objectives and competences. The results show how the activity helps university students acquire digital skills, develop their creativity, and understand the process of autonomous technological learning and reflective self-awareness, as well as the value of collaborative group work. more...

This study aims to evaluate ChatGPT’s capabilities in certain numerical analysis problem: solving ordinary differential equations. The methodology which is developed in order to conduct this research takes into account the following mathematical abilities (defined according to National Centre for Education Statistics): Conceptual Understanding, Procedural Knowledge, Problem Solving, and Application in Real-world Contexts. The outcomes demonstrate that ChatGPT’s performed very well for the set tasks, and it also gives promising results for programming code generation, with certain limitations. The effectiveness and accuracy of the answers and solutions obtained by ChatGPT are related to the type of equation, i.e., how complex it is, and also with the instructions we give to ChatGPT. It also requires further improvement of the machine learning model and the ability to provide an explanation of how the output was obtained. more...

Abstract Surface electromyogram (sEMG) serves as a means to discern human movement intentions, achieved by applying epidermal electrodes to specific body regions. However, it is difficult to obtain high-fidelity sEMG recordings in areas with intricate curved surfaces, such as the body, because regular sEMG electrodes have stiff structures. In this study, we developed myoelectrically sensitive hydrogels via 3D printing and integrated them into a stretchable, flexible, and high-density sEMG electrodes array. This electrode array offered a series of excellent human-machine interface (HMI) features, including conformal adherence to the skin, high electron-to-ion conductivity (and thus lower contact impedance), and sustained stability over extended periods. These attributes render our electrodes more conducive than commercial electrodes for long-term wearing and high-fidelity sEMG recording at complicated skin interfaces. Systematic in vivo studies were used to investigate its efficacy to control a prosthetic hand by decoding sEMG signals from the human hand via a multiple-channel readout circuit and a sophisticated artificial intelligence algorithm. Our findings demonstrate that the 3D printed gel myoelectric sensing system enables real-time and highly precise control of a prosthetic hand. more...

Abstract An intelligent humidity sensing system has been developed for real-time monitoring of human behaviors through respiration detection. The key component of this system is a humidity sensor that integrates a thermistor and a micro-heater. This sensor employs porous nanoforests as its sensing material, achieving a sensitivity of 0.56 pF/%RH within a range of 60–90% RH, along with excellent long-term stability and superior gas selectivity. The micro-heater in the device provides a high operating temperature, enhancing sensitivity by 5.8 times. This significant improvement enables the capture of weak humidity variations in exhaled gases, while the thermistor continuously monitors the sensor’s temperature during use and provides crucial temperature information related to respiration. With the assistance of a machine learning algorithm, a behavior recognition system based on the humidity sensor has been constructed, enabling behavior states to be classified and identified with an accuracy of up to 96.2%. This simple yet intelligent method holds great potential for widespread applications in medical assistance analysis and daily health monitoring. more...

Abstract Bulk Acoustic Wave (BAW) filters find applications in radio frequency (RF) communication systems for Wi-Fi, 3G, 4G, and 5G networks. In the beyond-5G (potential 6G) era, high-frequency bands (>8 GHz) are expected to require resonators with high-quality factor (Q) and electromechanical coupling ( $${k}_{t}^{2}$$ k t 2 ) to form filters with low insertion loss and high selectivity. However, both the Q and $${k}_{t}^{2}$$ k t 2 of resonator devices formed in traditional uniform polarization piezoelectric films of aluminum nitride (AlN) and aluminum scandium nitride (AlScN) decrease when scaled beyond 8 GHz. In this work, we utilized 4-layer AlScN periodically poled piezoelectric films (P3F) to construct high-frequency (~17–18 GHz) resonators and filters. The resonator performance is studied over a range of device geometries, with the best resonator achieving a $${k}_{t}^{2}$$ k t 2 of 11.8% and a $${Q}_{{\rm {p}}}$$ Q p of 236.6 at the parallel resonance frequency ( $${f}_{{\rm {p}}}$$ f p ) of 17.9 GHz. These resulting figures-of-merit are ( $${{{\rm {FoM}}}}_{1}={{k}_{t}^{2}Q}_{{\rm {p}}}$$ FoM 1 = k t 2 Q p and $${{{\rm {FoM}}}}_{2}={f}_{{\rm {p}}}{{{\rm {FoM}}}}_{1}{\times }{10}^{-9}$$ FoM 2 = f p FoM 1 × 10 − 9 ) 27.9 and 500, respectively. These and the $${k}_{t}^{2}$$ k t 2 are significantly higher than previously reported AlN/AlScN-based resonators operating at similar frequencies. Fabricated 3-element and 6-element filters formed from these resonators demonstrated low insertion losses (IL) of 1.86 and 3.25 dB, and −3 dB bandwidths (BW) of 680 MHz (fractional BW of 3.9%) and 590 MHz (fractional BW of 3.3%) at a ~17.4 GHz center frequency. The 3-element and 6-element filters achieved excellent linearity with in-band input third-order intercept point (IIP3) values of +36 and +40 dBm, respectively, which are significantly higher than previously reported acoustic filters operating at similar frequencies. more...

Abstract Flexible electromagnetic metamaterials are a potential candidate for the ideal material for electromagnetic control due to their unique physical properties and structure. Flexible electromagnetic metamaterials can be designed to exhibit specific responses to electromagnetic waves within a particular frequency range. Research shows that flexible electromagnetic metamaterials exhibit significant electromagnetic control characteristics in microwave, terahertz, infrared and other frequency bands. It has a wide range of applications in the fields of electromagnetic wave absorption and stealth, antennas and microwave devices, communication information and other fields. In this review, the currently popular fabrication methods of flexible electromagnetic metamaterials are first summarized, highlighting the electromagnetic modulation capability in different frequency bands. Then, the applications of flexible electromagnetic metamaterials in four aspects, namely electromagnetic stealth, temperature modulation, electromagnetic shielding, and wearable sensors, are elaborated and summarized in detail. In addition, this review also discusses the shortcomings and limitations of flexible electromagnetic metamaterials for electromagnetic control. Finally, the conclusion and perspective of the electromagnetic properties of flexible electromagnetic metamaterials are presented. more...

Abstract Nanoelectromechanical systems (NEMS) based on atomically-thin tungsten diselenide (WSe2), benefiting from the excellent material properties and the mechanical degree of freedom, offer an ideal platform for studying and exploiting dynamic strain engineering and cross-scale vibration coupling in two-dimensional (2D) crystals. However, such opportunity has remained largely unexplored for WSe2 NEMS, impeding exploration of exquisite physical processes and realization of novel device functions. Here, we demonstrate dynamic coupling between atomic lattice vibration and nanomechanical resonances in few-layer WSe2 NEMS. Using a custom-built setup capable of simultaneously detecting Raman and motional signals, we accomplish cross-scale mode coupling between the THz crystal phonon and MHz structural vibration, achieving GHz frequency tuning in the atomic lattice modes with a dynamic gauge factor of 61.9, the best among all 2D crystals reported to date. Our findings show that such 2D NEMS offer great promises for exploring cross-scale physics in atomically-thin semiconductors. more...

Abstract Precise and long-term electroanalysis at the single-cell level is crucial for the accurate diagnosis and monitoring of brain diseases. The reliable protection in areas outside the signal acquisition points at sharp ultramicroelectrode (UME) tips has a significant impact on the sensitivity, fidelity, and stability of intracellular neural signal recording. However, it is difficult for existing UMEs to achieve controllable exposure of the tip functional structure, which affects their ability to resist environmental interference and shield noise, resulting in unsatisfactory signal-to-noise ratio and signal fidelity of intracellular recordings. To address this issue, we chose a dense and electrochemically stable diamond-like carbon (DLC) film as the UME protection coating and developed a method to precisely control the exposed degree of the functional structure by directly fixed-point processing of the UME tip by the strong site-selectivity and good controllability of the atmospheric microplasma jet. By analyzing the interaction between the microplasma jet and the UME tip, as well as the changes in the removal length and microstructure of UME tips with processing time, the exposed tip length was precisely controlled down to the submicron scale. Biocompatibility experiments, electrochemical aging tests and real-time intracellular pH recording experiments have demonstrated that the DLC-UME with effective tip protection processed by microplasma jet has the potential to enable long-term detection of intracellular high-fidelity signals. more...

Abstract Nonlinear dynamic simulations of mechanical resonators have been facilitated by the advent of computational techniques that generate nonlinear reduced order models (ROMs) using the finite element (FE) method. However, designing devices with specific nonlinear characteristics remains inefficient since it requires manual adjustment of the design parameters and can result in suboptimal designs. Here, we integrate an FE-based nonlinear ROM technique with a derivative-free optimization algorithm to enable the design of nonlinear mechanical resonators. The resulting methodology is used to optimize the support design of high-stress nanomechanical Si3N4 string resonators, in the presence of conflicting objectives such as simultaneous enhancement of Q-factor and nonlinear Duffing constant. To that end, we generate Pareto frontiers that highlight the trade-offs between optimization objectives and validate the results both numerically and experimentally. To further demonstrate the capability of multi-objective optimization for practical design challenges, we simultaneously optimize the design of nanoresonators for three key figure-of-merits in resonant sensing: power consumption, sensitivity and response time. The presented methodology can facilitate and accelerate designing (nano) mechanical resonators with optimized performance for a wide variety of applications. more...

Abstract We present a system-level model with an on-chip temperature compensation technique for a CMOS-MEMS monolithic calorimetric flow sensing SoC. The model encompasses mechanical, thermal, and electrical domains to facilitate the co-design of a MEMS sensor and CMOS interface circuits on the EDA platform. The compensation strategy is implemented on-chip with a variable temperature difference heating circuit. Results show that the linear programming for the low-temperature drift in the SoC output is characterized by a compensation resistor R c with a resistance value of 748.21 Ω and a temperature coefficient of resistance of 3.037 × 10−3 °C−1 at 25 °C. Experimental validation demonstrates that within an ambient temperature range of 0–50 °C and a flow range of 0–10 m/s, the temperature drift of the sensor is reduced to ±1.6%, as compared to ±8.9% observed in a counterpart with the constant temperature difference circuit. Therefore, this on-chip temperature-compensated CMOS-MEMS flow sensing SoC is promising for low-cost sensing applications such as respiratory monitoring and smart energy-efficient buildings. more...

Abstract In this article, a CMOS-compatible Pirani vacuum gauge was proposed featuring enhanced sensitivity, lower detection limit, and high-temperature stability, achieved through the implementation of a surface micromachining method coupled with a temperature compensation strategy. To improve performance, a T-type device with a 1 µm gap was fabricated resulting in an average sensitivity of 1.10 V/lgPa, which was 2.89 times larger than that (0.38 V/lgPa) of a L-type device with a 100 µm gap. Additionally, FEA simulations were conducted, analyzing the influence of heater temperature on sensitivity and the attenuation of sensitivity across varying ambient temperatures. A semi-empirical theoretical mode was derived for performance prediction, demonstrating strong alignment with experimental results, underscoring its effectiveness in compensating for sensitivity attenuation. Building on the foundation, the device’s performance under different ambient temperatures was characterized and effectively compensated in two distinct operational modes: constant temperature mode and constant temperature difference mode (the whole range temperature compensation error can be controlled within 2.5%). Finally, the short-time stability (variation level is approximately 1 mV), noise floor (Vrms=384 μV) and detection limit (0.07 Pa @1 Hz) of the device were characterized, confirming its suitability for practical implementation. more...

Accurate dense reconstruction of unknown spatial environments is crucial for applications such as underground exploration and planetary missions. Existing methods face challenges like observing blind spots and the difficulty of edge feature extraction in point clouds with non-repetitive scanning LiDARs. This paper first uses a novel odometry and mapping system integrating two solid-state LiDARs and an IMU to obtain distortion-compensated point clouds and corresponding poses, which are utilized to generate submaps. Our approach then leverages these accumulated submaps to efficiently extract edge features. Experimental results demonstrate that our submap-based method effectively identifies edge features within point clouds, which can be used for association with panoramas for joint optimization in the future. more...

Abstract Recently, the biologically inspired intelligent artificial visual neural system has aroused enormous interest. However, there are still significant obstacles in pursuing large-scale parallel and efficient visual memory and recognition. In this study, we demonstrate a 28 × 28 synaptic devices array for the artificial visual neuromorphic system, within the size of 0.7 × 0.7 cm2, which integrates sensing, memory, and processing functions. The highly uniform floating-gate synaptic transistors array were constructed by the wafer-scale grown monolayer molybdenum disulfide with Au nanoparticles (NPs) acting as the electrons capture layers. Various synaptic plasticity behaviors have been achieved owing to the switchable electronic storage performance. The excellent optical/electrical coordination capabilities were implemented by paralleled processing both the optical and electrical signals the synaptic array of 784 devices, enabling to realize the badges and letters writing and erasing process. Finally, the established artificial visual convolutional neural network (CNN) through optical/electrical signal modulation can reach the high digit recognition accuracy of 96.5%. Therefore, our results provide a feasible route for future large-scale integrated artificial visual neuromorphic system. more...

Abstract Droplet microfluidics enable high-throughput screening, sequencing, and formulation of biological and chemical systems at the microscale. Such devices are generally fabricated in a soft polymer such as polydimethylsiloxane (PDMS). However, developing design masks for PDMS devices can be a slow and expensive process, requiring an internal cleanroom facility or using an external vendor. Here, we present the first complete droplet-based component library using low-cost rapid prototyping and electrode integration. This fabrication method for droplet microfluidic devices costs less than $12 per device and a full design-build-test cycle can be completed within a day. Discrete microfluidic components for droplet generation, re-injection, picoinjection, anchoring, fluorescence sensing, and sorting were built and characterized. These devices are biocompatible, low-cost, and high-throughput. To show its ability to perform multistep workflows, these components were used to assemble droplet “pixel" arrays, where droplets were generated, sensed, sorted, and anchored onto a grid to produce images. more...

Abstract This paper presents a novel technique for low-power generation of frequency combs (FC) over a wide frequency range. It leverages modal interactions between electrical and mechanical resonators in electrostatic NEMS operating in air to provide a simple architecture for FC generators. A biased voltage signal drives the electrical resonator at resonance which is set to match an integer submultiple of twice the mechanical resonator’s resonance. Experimental results demonstrate that the NEMS displacement exhibit more than 150 equidistant peaks in the case of a 2:1 modal interaction and more than 60 equidistant peaks in the case of a 1:1 modal interaction. In both cases, the Free Spectral Range (FSR) was equal to the mechanical resonance frequency. Comparison between the FCs generated by the 2:1 and 1:1 modal interactions demonstrate the superiority of the former in terms of bandwidth and stability. The superior phase coherence of the FC generated via the 2:1 modal interaction was demonstrated via time-domain analysis. Our technique has the flexibility to generate multiple frequency combs and to fine-tune their FSR depending on the number of mechanical modes accessible to and the order of the activated modal interaction. It can be integrated into portable devices and is well aligned with modern miniaturization technology. more...

Abstract The alarming prevalence and mortality rates associated with cardiovascular diseases have emphasized the urgency for innovative detection solutions. Traditional methods, often costly, bulky, and prone to subjectivity, fall short of meeting the need for daily monitoring. Digital and portable wearable monitoring devices have emerged as a promising research frontier. This study introduces a wearable system that integrates electrocardiogram (ECG) and phonocardiogram (PCG) detection. By ingeniously pairing a contact-type PZT heart sound sensing structure with ECG electrodes, the system achieves the acquisition of high-quality ECG and PCG signals. Notably, the signal-to-noise ratios (SNR) for ECG and PCG signals were measured at 44.13 dB and 30.04 dB, respectively, demonstrating the system’s remarkable stability across varying conditions. These collected signals were subsequently utilized to derive crucial feature values, including electromechanical delay (EMD), left ventricular ejection time (LVET), and pre-ejection period (PEP). Furthermore, we collected a dataset comprising 40 cases of ECG and PCG signals, enabling a comparative analysis of these three feature parameters between healthy individuals and coronary heart disease patients. This research endeavor presents a significant step forward in the realm of early, non-invasive, and intelligent monitoring of cardiovascular diseases, offering hope for earlier detection and more effective management of these life-threatening conditions. more...

Abstract The use of bulk piezoelectric transducer arrays in medical imaging is a well-established technology that operates based on thickness mode piezoelectric vibration. Meanwhile, advancements in fabrication techniques have led to the emergence of micromachined alternatives, namely, piezoelectric micromachined ultrasound transducer (PMUT) and capacitive micromachined ultrasound transducer (CMUT). These devices operate in flexural mode using piezoelectric thin films and electrostatic forces, respectively. In addition, the development of flexible ultrasound transducers based on these principles has opened up new possibilities for biomedical applications, including biomedical imaging, sensing, and stimulation. This review provides a detailed discussion of the need for flexible micromachined ultrasound transducers (MUTs) and potential applications, their specifications, materials, fabrication, and electronics integration. Specifically, the review covers fabrication approaches and compares the performance specifications of flexible PMUTs and CMUTs, including resonance frequency, sensitivity, flexibility, and other relevant factors. Finally, the review concludes with an outlook on the challenges and opportunities associated with the realization of efficient MUTs with high performance and flexibility. more...