Micro and Nano Systems Letters最新文献

We have synthesized carbon nanoparticles using mandarin juice via green synthesis rout. We have doped carbon nanoparticles in liquid crystal media and studied the surface effect on self-assembly of carbon nanoclusters on ITO coated glass surface and on graphene sheet. The purpose of this study is to construct uniform nano-micro droplets for novel applications and to understand and explore the underlying science behind molecular scale reorganization in the presence of functional surfaces like graphene. We have used density functional theory approach to confirm that the carbon nanoparticles in globular structures are dispersed in presence of graphene sheet due to chemical interaction of carbon rings (or say carbon nanoparticles) with graphene carbon atoms. In order to minimize the free energy, the carbon nanoparticles leave the carbon globular structures and are dispersed to form rectangular structures in presence of LC media at graphene surface. The carbon nanoparticles are dispersed to increase contact area with graphene surface. The results are useful in construction of desired nano-micro structures for possible novel purposes in medical field since carbon nanoparticles are biocompatible. Optical microscopy, FESEM, NMR and UV spectra verifies the droplet formation and its effect on the surface and electronic properties of carbon nanoparticles.

A novel electrochemical sensor was developed for the detection of Epinephrine (EP) utilizing Azure A (AzA), a phenothiazine dye, and citrate-capped silver nanoparticles. The interaction between Azure A and silver nanoparticles facilitated the formation of AzA/silver nanoclusters through a self-assembled approach. The morphological analysis of AzA/silver nanoclusters was conducted using field-emission scanning electron microscopy (FESEM). The nanoclusters were then immobilized on a graphite electrode via a simple drop-casting method, resulting in a modified electrode. The electrochemical properties of the modified electrode were investigated using cyclic voltammetry and linear sweep voltammetry techniques. The modified electrode exhibited enhanced electrocatalytic oxidation of EP at a lower oxidation potential of 0.27 V. The electrochemical analysis demonstrated that the modified electrode functioned as an amperometric sensor, enabling the detection of EP within a concentration range of 4.6 × 10^–7 to 3.6 × 10^–3 M, with a correlation coefficient of 0.9950 and a detection limit of 2.2 × 10^–7 M (S/N = 3). The modified electrode exhibited excellent selectivity, sensitivity, and a remarkably low detection limit, making it highly suitable for EP determination. Its ease of preparation further adds to the practicality and potential applications of this electrode.

Thrombosis is a double-edged sword. Normal thrombus formation within injured blood vessel is an important natural defensive mechanism to prevent excessive bleeding, whereas abnormal thrombus formation leads to critical disease such as stroke or myocardial infarction. One of keys in the pathophysiology mechanism involved in the thrombus formation is acute hemodynamic changes within the vessel lumen, which has been investigated mostly in pre-clinical and clinical studies. However, studies involving animal or human subjects are frequently limited by technical difficulties and requirement of substantial blood volume. Microfluidic systems have emerged as a valuable tool owing to their inherent advantages including minimal sample requirements and rapid analysis capabilities. In this mini review, we present a summary of microfluidic systems designed for thrombosis analysis, encompassing fabrication processes, design, and analysis methods. We also discuss both the potentials and limitations of microfluidic platform for the analysis of thrombus mechanisms.

Silicon nanoparticles have emerged as pivotal components in nanoscience and nanoengineering due to their inherent characteristics such as high energy capacity and outstanding optical properties. Numerous fabrication and characterization techniques have been researched so far, while a range of applications utilizing them have been developed. In this review, we aim to provide a brief overview of the distinct and representative fabrication methods of silicon nanoparticles, including top-down, bottom-up, and reduction approaches. Then, we look into various characterization techniques essential for assessing and ensuring quality and performance of fabricated silicon nanoparticles. In addition, we provide insights for silicon nanoparticle technology towards further advancements.

The demand for advanced packaging is driven by the need for low-profile, densely-integrated, large-die Si devices in substrate-based or wafer-level packaging. Die strength is a critical parameter for ultrathin dies, making die singulation a vital aspect of advanced packaging technology. In this work, we present a dicing before grinding (DBG) process to compare and analyze die strengths using a mechanical blade, stealth laser, and plasma dicing. The three DBG processes were applied to a 200 mm silicon (Si) wafer process with a die size of 10 × 10 mm² and thicknesses of 100, 200, and 300 μm, respectively. Optical and electron microscopes were employed to investigate chipping quality, sidewall damage, and surface contamination. The bare Si die’s strength was assessed using a three-point bending test. Plasma dicing before grinding (PDBG) resulted in less contamination, chipping, and cracking compared to other DBG processes. Furthermore, PDBG exhibited the highest die strength of 1052 Pa.

Silicon-on-insulator (SOI) wafers offer significant advantages for both Integrated circuits (ICs) and microelectromechanical systems (MEMS) devices with their buried oxide layer improving electrical isolation and etch stop function. For past a few decades, various approaches have been investigated to make SOI wafers and they tend to exhibit strength and weakness. In this review, we aim to overview different manufacturing routes for SOI wafers with specific focus on advantages and inherent challenges. Then, we look into how SOI wafers are characterized for quality assessment and control. We also provide insights towards potential future directions of SOI technology to further accelerate ever-growing IC and MEMS industries.

The main goal of this research is to compare the rheological behavior of hybrid nano lubricants (HNLs) with different composition ratios in a base oil. The purpose of the comparison is to determine the HNL with the best lubrication performance at the start of the vehicle. Theoretical methods have confirmed the non-Newtonian behavior in different laboratory conditions. HNLs with the composition ratio of 30:70 and 25:75 had the highest percentage of increase and decrease in viscosity, respectively 34.97% and − 1.85% at T = 55 °C, shear rate SR = 6665 s⁻¹ and solid volume fraction SVF = 1% and T = 5 °C, SR = 3999 s⁻¹ and SVF = 0.05%. To predict the viscosity of the desired HNL, in the RSM, a special model with an accuracy of R² = 0.9997 has been used. The margin of deviation (MOD) is determined in the range of − 3.43% < MOD < 4.75%. Viscosity sensitivity analysis shows that the greatest sensitivity will result from SVF changes at high SVFs. The experimental results of this study will introduce the optimal nano polishing to the craftsmen, and the theoretical part of this study will save the researchers from spending time and excessive economic costs.

Capacitive pressure sensors are essential for advanced applications like wearable medical devices, electronic skins, and biological signal detection systems. Enhancing sensitivity in these sensors is achieved by incorporating porous microstructures into the dielectric layer. The present research focuses on designing a capacitive pressure sensor comprising a porous micro-pyramidal dielectric layer featuring diagonally arranged pyramids. The effects of geometric parameters and material properties such as dielectric constant, porosity, base length, tip width, height, and the distance between the pyramidal microstructures were examined using the three-dimensional finite element simulations. A comparative analysis was conducted to evaluate the accuracy of the numerical solution. The simulation results were compared to experimental measurements, and the findings revealed a high level of agreement. The optimal quantity of data for this analysis was determined using the design of the experiment method, specifically the response surface model. The results show that arranging microstructures diagonally or laterally can impact sensitivity and initial capacitance. Specifically, employing a diagonal arrangement enhanced sensor sensitivity by up to 1.65 times while maintaining the initial capacitance relatively unaffected. Ultimately, this study derived mathematical equations from the collected data to estimate the initial capacitance and sensitivity of the sensor. The model predictions were compared to simulation results, and it was found that the models performed effectively.

Nanofluids for enhanced oil recovery offer a breakthrough solution towards tertiary recovery and consequently higher oil production. Their ability to reduce interfacial tension, alteration of formation’s wettability, higher adsorption capacity, and acceleration of disjoining pressure makes them excellent candidates for enhanced oil recovery. The main objective of this paper is to investigate the effect of polymers on zinc oxide (ZnO) nanofluids for enhanced oil recovery (EOR) and the role played by chemical modification using polymer stabilizers on nanoparticle stability in nanofluids. Nanoparticles with an average particle size of 34 nm were synthesized and used to prepare nanofluids of different concentrations and their stability was evaluated using sedimentation and UV–vis spectrophotometry tests. ZnO-synthesized nanofluids were used solely and in addition to Polyvinylpyrrolidone (PVP) and Polyvinyl alcohol (PVA) as stabilizing agents. It was noted that ZnO nanofluids with PVA stabilizer recorded the highest oil recovery of 82%. In contrast, the ZnO nanofluids without stabilizing agents registered the lowest recovery rate during the flooding experiment. The results revealed that a higher injection rate increases the oil recovery and reduces the viscous fingering effect with a better displacement front. Furthermore, nanofluids containing polymeric stabilizing agents achieved better recovery factors compared to ZnO nanofluids without stabilizing agents. This phenomenon was also observed in the interfacial tension test where nanofluids with PVA and PVP stabilizers reduced the IFT by 59% and 61% respectively.

Deterministic lateral displacement (DLD) is a passive, label-free, continuous-flow method for particle separation. Since its discovery in 2004, it has been widely used in medical tests to separate blood cells, bacteria, extracellular vesicles, DNA, and more. Despite the very simple idea of the DLD method, many details of its mechanism are not yet fully understood and studied. Known analytical equations for the critical diameter of separated particles include only the gap between the columns in the DLD array and the fraction of the column shift. The dependence of the critical diameter on the post diameter, channel height, and a number of other geometric parameters remains unexplored. The problems also include the effect of flow rate and particle concentration on the critical diameter and separation efficiency. At present, DLD devices are mainly developed through numerical simulation and experimental validation. However, it is necessary to find fundamental regularities that would help to improve the separation quantitatively and qualitatively. This review discusses the principle of particle separation, the physical aspects of flow formation, and hydrodynamic forces acting on particles in DLD microchannels. Various analytical models of a viscous flow in an array of cylindrical posts are described. Prospects for further research are outlined.