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Cancer is a dangerous and sometimes life-threatening disease that can have several negative consequences for the body, is a leading cause of mortality, and is becoming increasingly difficult to detect. Each form of cancer has its own set of traits, symptoms, and therapies, and early identification and management are important for a positive prognosis. Doctors utilize a variety of approaches to detect cancer, depending on the kind and location of the tumor. Imaging tests such as X-rays, Computed Tomography scans, Magnetic Resonance Imaging scans, and Positron Emission Tomography (PET) scans, which may provide precise pictures of the body’s interior structures to spot any abnormalities, are some of the tools that doctors use to diagnose cancer. This article evaluates computational-intelligence approaches and provides a means to impact future work by focusing on the relevance of machine learning and deep learning models such as K Nearest Neighbour (KNN), Support Vector Machine (SVM), Naïve Bayes, Decision Tree, Deep Neural Network, Deep Boltzmann machine, and so on. It evaluates information from 114 studies using Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR). This article explores the advantages and disadvantages of each model and provides an outline of how they are used in cancer diagnosis. In conclusion, artificial intelligence shows significant potential to enhance cancer imaging and diagnosis, despite the fact that there are a number of clinical issues that need to be addressed.

Scientists are drawn to the new green composites because they may demonstrate qualities that are comparable to those of composites made of synthetic fibers due to concerns about environmental contamination. In this work, the potential for using the produced green composite in different buckling load-bearing structural applications is explored. The work on composite buckling characteristics is vital because one needs to know the composite’s structural stability since buckling leads to structural instability. The buckling properties of composite specimens with epoxy as the matrix and chemically treated cellulose microfibrils as reinforcements are examined numerically in this study when exposed to axial compressive stress. The numerical model is first created based on the finite element method model. Its validity is checked using ANSYS software by contrasting the critical buckling loads determined through research for three samples. The numerical findings acquired using the finite element method are then contrasted with those produced using the regression equation derived from the ANOVA. The utilization of the created green composite in different buckling load-bearing structural applications is investigated in this study. As a result of the green composite’s unaltered buckling properties compared to synthetic composites, it has the potential to replace numerous synthetic composites, improving environmental sustainability.

This review paper gives an insight into the microstructural, mechanical, biological, and corrosion resistance of spark plasma sintered magnesium (Mg) composites. Mg has a mechanical property similar to natural human bones as well as biodegradable and biocompatible properties. Furthermore, Mg is considered a potential material for structural and biomedical applications. However, its high affinity toward oxygen leads to oxidation of the material. Various researchers optimize the material composition, processing techniques, and surface modifications to overcome this issue. In this review, effort has been made to explore the role of process techniques, especially applying a typical powder metallurgy process and the sintering technique called spark plasma sintering (SPS) in the processing of Mg composites. The effect of reinforcement material on Mg composites is illustrated well. The reinforcement’s homogeneity, size, and shape affect the mechanical properties of Mg composites. The evidence shows that Mg composites exhibit better corrosion resistance, as the reinforcement act as a cathode in a Mg matrix. However, in most cases, a localized corrosion phenomenon is observed. The Mg composite’s high corrosion rate has adversely affected cell viability and promotes cytotoxicity. The reinforcement of bioactive material to the Mg matrix is a potential method to enhance the corrosion resistance and biocompatibility of the materials. However, the impact of SPS process parameters on the final quality of the Mg composite needs to be explored.

The most well-known and widely used non-traditional manufacturing method is electrical discharge machining (EDM). It is well-known for its ability to cut rigid materials and high-temperature alloys that are difficult to machine with traditional methods. The significant challenges encountered in EDM are high tool wear rate, low material removal rate, and high surface roughness caused by the continuous electric spark generated between the tool and the workpiece. Researchers have reported using a variety of approaches to overcome this challenge, such as combining the die-sinking EDM process with cryogenic treatment, cryogenic cooling, powder-mixed processing, ultrasonic assistance, and other methods. This paper examines the results of these association techniques on various performance measures, such as material removal rate (MRR), tool wear rate (TWR), surface roughness, surface integrity, and recast layer formed during machining, and identifies potential gap areas and proposes a solution. The manuscript is useful for improving performance and introducing new resolutions to the field of EDM machining.

We produced an anodic aluminum oxide (AAO) structure with periodic nanopores on the surface of flip-chip blue light-emitting diodes (FC-BLEDs). The nanopores had diameters ranging from 73 to 85 nm and were separated by distances ranging from approximately 10 to 15 nm. The light extraction efficiency enhancement of the FC-BLEDs subjected to different durations of the second pore-widening process was approximately 1.6–2.9%. The efficiency enhancement may be attributed to the following mechanism: periodic nanopores on the surface of FC-BLEDs reduce the critical angle of total reflection and effective energy transfer from a light emitter into a surface plasmon mode produced by AAO.

The effect of adding molybdenum to the heavy tungsten alloy of W-Ni-Fe on its material characteristics was examined in the current study. The elemental powders of tungsten, iron, nickel, and molybdenum, with a composition analogous to W-3Fe-7Ni-xMo (x = 0, 22.5, 45, 67.5 wt.%), were fabricated using the spark plasma sintering (SPS) technique at a sintering temperature of 1400 °C and under pressure of 50 MPa. The sintered samples were subjected to microstructural characterization and tested for mechanical strength. The smallest grain size of 9.99 microns was observed for the 45W-45Mo alloy. This alloy also gave the highest tensile and yield strengths of 1140 MPa and 763 MPa, respectively. The hardness increased with the increased addition of molybdenum. The high level of hardness was observed for 67.5Mo with a 10.8% increase in the base alloy’s hardness. The investigation resulted in the alloy of 45W-7Ni-3Fe-45Mo, observed to provide optimum mechanical properties among all the analyzed samples.

There is a massive demand for low-weight high strength materials in automotive, space aerospace, and even structural industries in this present engineering world. These industries attract composites only because of their high strength, resistance to wear, and low weight. Among these composites, metal matrix composite finds wide applications due to its elevated properties, excellent resistance property, corrosion resistance, etc. The reinforcements exist in particles, fiber, and whiskers. Among the three, particles play an important role because of their availability and wettability with the metal matrix. Additionally, among the various metal matrices such as aluminum, magnesium, copper, titanium, etc., aluminum plays a vital role among metal matrices because of its cost, availability in abundance, and castability. Stir casting is the most inexpensive and straightforward composite fabrication technique among the prevailing techniques. Even though so many factors contribute to the elevated property of composites, metal matrix, and reinforcement phase, uniform distribution and wettability are essential factors among all the other factors. This review aims to develop a composite with elevated property in a cost-effective manner. Cost includes metal matrix, reinforcement, and processing technique. Various works have been tabulated to achieve the above objective, and analysis was carried out on tensile strength concerning microstructure. This review paper explores the challenges in composite fabrication and finds a solution to overcome them.

The effect of molybdenum additions on the phases, microstructures, and mechanical properties of pre-alloyed Ti6Al4V was studied through the spark plasma sintering technique. Ti6Al4V-xMo (where x = 0, 2, 4, 6 wt.% of Mo) alloys were developed, and the sintered compacts were characterized in terms of their phase composition, microstructure, and mechanical properties. The results show that the equiaxed primary alpha and Widmänstatten (alpha + beta) microstructure in pre-alloyed Ti6Al4V is transformed into a duplex and globular model with the increasing content of Mo from 0 to 6%. The changing pattern of the microstructure of the sample strongly influences the properties of the material. The solid solution hardening element such as Mo enhances mechanical properties such as yield strength, ultimate tensile strength, ductility, and hardness compared with the pre-alloyed Ti6Al4V alloy.

This review paper provides insight into current developments in refractory high-entropy alloys (RHEAs) based on previous and currently available literature. High-temperature strength, high-temperature oxidation resistance, and corrosion resistance properties make RHEAs unique and stand out from other materials. RHEAs mainly contain refractory elements like W, Ta, Mo, Zr, Hf, V, and Nb (each in the 5–35 at% range), and some low melting elements like Al and Cr at less than 5 at%, which were already developed and in use for the past two decades. These alloys show promise in replacing Ni-based superalloys. In this paper, various manufacturing processes like casting, powder metallurgy, metal forming, thin-film, and coating, as well as the effect of different alloying elements on the microstructure, phase formation, mechanical properties and strengthening mechanism, oxidation resistance, and corrosion resistance, of RHEAs are reviewed.

The evolution of a sustainable green composite in various loadbearing structural applications tends to reduce pollution, which in turn enhances environmental sustainability. This work is an attempt to promote a sustainable green composite in buckling loadbearing structural applications. In order to use the green composite in various structural applications, the knowledge on its structural stability is a must. As the structural instability leads to the buckling of the composite structure when it is under an axial compressive load, the work on its buckling characteristics is important. In this work, the buckling characteristics of a woven flax/bio epoxy (WFBE) laminated composite plate are investigated experimentally and numerically when subjected to an axial compressive load. In order to accomplish the optimization study on the buckling characteristics of the composite plate among various structural criterions such as number of layers, the width of the plate and the ply orientation, the optimization tool “response surface methodology” (RSM) is used in this work. The validation of the developed finite element model in Analysis System (ANSYS) version 16 is carried out by comparing the critical buckling loads obtained from the experimental test and numerical simulation for three out of twenty samples. A comparison is then made between the numerical results obtained through ANSYS16 and the results generated using the regression equation. It is concluded that the buckling strength of the composite escalates with the number of layers, the change in width and the ply orientation. It is also noted that the weaving model of the fabric powers the buckling behavior of the composite. This work explores the feasibility of the use of the developed green composite in various buckling loadbearing structural applications. Due to the compromised buckling characteristics of the green composite with the synthetic composite, it has the capability of replacing many synthetic composites, which in turn enhances the sustainability of the environment.

Tungsten heavy alloys are two-phase metal matrix composites that include W–Ni–Fe and W–Ni–Cu. The significant feature of these alloys is their ability to acquire both strength and ductility. In order to improve the mechanical properties of the basic alloy and to limit or avoid the need for post-processing techniques, other elements are doped with the alloy and performance studies are carried out. This work focuses on the developments through the years in improving the performance of the classical tungsten heavy alloy of W–Ni–Fe through doping of other elements. The influence of the percentage addition of rare earth elements of yttrium, lanthanum, and their oxides and refractory metals such as rhenium, tantalum, and molybdenum on the mechanical properties of the heavy alloy is critically analyzed. Based on the microstructural and property evaluation, the effects of adding the elements at various proportions are discussed. The addition of molybdenum and rhenium to the heavy alloy gives good strength and ductility. The oxides of yttrium, when added in a small quantity, help to reduce the tungsten’s grain size and obtain good tensile and compressive strengths at high temperatures.

In the present work, nano Cu (0, 5, 10, 15, 20, 25 wt.%) was added to W, and W–Cu composites were fabricated using the spark plasma sintering (S.P.S.) technique. The densification, microstructural evolution, tensile strength, micro-hardness, and electrical conductivity of the W–Cu composite samples were evaluated. It was observed that increasing the copper content resulted in increasing the relative sintered density, with the highest being 82.26% in the W75% + Cu25% composite. The XRD phase analysis indicated that there was no evidence of intermetallic phases. The highest ultimate (tensile) strength, micro-hardness, and electrical conductivity obtained was 415 MPa, 341.44 HV0.1, and 28.2% IACS, respectively, for a sample containing 25 wt.% nano-copper. Fractography of the tensile tested samples revealed a mixed-mode of fracture. As anticipated, increasing the nano-copper content in the samples resulted in increased electrical conductivity.

The traditional solid-state reaction method was employed to synthesize bulk calcium cobaltite (Ca349/Ca3Co4O9) ceramics via ball milling the precursor mixture. The samples were compacted using conventional sintering (CS) and spark plasma sintering (SPS) at 850, 900, and 950 °C. The X-ray diffraction (XRD) pattern indicates the presence of the Ca349 phase for samples sintered at 850 and 900 °C. In addition, SPS fosters higher densification (81.18%) than conventional sintering (50.76%) at elevated sintering temperatures. The thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA) performed on the precursor mixture reported a weight loss of ~25.23% at a temperature range of 600–820 °C. This current work aims to analyze the electrical properties (Seebeck coefficient (s), electrical resistivity (ρ), and power factor) of sintered samples as a function of temperature (35–500 °C). It demonstrates that the change in sintering temperature (conventional sintering) did not evince any significant change in the Seebeck coefficient (113–142 μV/K). However, it reported a low resistivity of 153–132 μΩ-m and a better power factor (82–146.4 μW/mK2) at 900 °C. On the contrary, the SPS sintered samples recorded a higher Seebeck coefficient of 121–181 μV/K at 900 °C. Correspondingly, the samples sintered at 950 °C delineated a low resistivity of 145–158 μΩ-m and a better power factor (97–152 μW/mK2).

Due to the growing environmental awareness, the development of sustainable green composites is in high demand in composite industries, mainly in the automotive, aircraft, construction and marine applications. This work was an attempt to experimentally and numerically investigate the dynamic characteristics of Woven Flax/Bio epoxy laminated composite plates. In addition, the optimisation study on the dynamic behaviours of the Woven Flax/Bio epoxy composite plate is carried out using the response surface methodology (RSM) by consideration of the various parameters like ply orientation, boundary condition and aspect ratio. The elastic constants of the Woven Flax/Bio epoxy composite lamina needed for the numerical simulation are determined experimentally using two methods, i.e., the usual mechanical tests as well as through the impulse excitation of vibration-based approach and made a comparison between them. The numerical analysis on the free vibration characteristics of the composite was carried out using ANSYS, a finite element analysis (FEA) software. The confirmation of the FE model was accomplished by comparing the numerical results with its experimental counterpart. Finally, a comparison was made between the results obtained through the regression equation and finite element analysis.

In this paper, we developed an isolation system for A549 human lung carcinoma cells as an effective factor for the early diagnosis of lung cancer. A microfluidic immunomagnetic method was used, in which the combination of immunomagnetic separation and a microfluidic system allowed for increased isolation efficiency with uncomplicated manipulation. In the microfluidic immunomagnetic strategy, A549 cells were combined with aptamer-conjugated carboxylated magnetic beads and then collected in a specified region by applying a magnetic field. The results were recorded using a fluorescence microscope, and the captured targets were then quantified. The isolation efficiency of A549 cells is up to 77.8%. This paper developed a simple working procedure, which is less time consuming, high-throughput, and trustworthy for the isolation of A549 cells. This procedure can be a useful reference method for the development of an effective diagnosis and treatment method for lung cancer in the future.

Titanium aluminide (TiAl) is one of the most promising materials for aerospace applications. It is a suitable replacement for nickel-based superalloys predominantly used in these applications. Titanium aluminide with superior processability is the main task in carrying out this work. A less brittle TiAl alloy was fabricated using spark plasma sintering by adding the nominal composition (2.5, 5, and 7.5 wt.%) of manganese (Mn) to Ti-48Al-2Cr-2Nb. The samples were sintered at 1150 °C using spark plasma sintering (SPS), which helped produce highly dense models with fine grain sizes at the high heating rate (here, 100 °C per minute). The effects produced by Mn additions on the densification, mechanical properties (yield strength, hardness, and % elongation), and microstructure of the Ti aluminide alloys are studied. Scanning electron microscopy (SEM) has been used to explore the sintered samples’ microstructures. The alloyed materials are entirely dissolved in the gamma matrix due to the manganese approaching its melting point. XRD and SEM analysis confirmed the new intermetallic related to Mn neither with titanium nor aluminum. The enhancement of % elongation at break is evident for the little improvement in the ductility of TiAl by the addition of Mn. The samples’ tensile fracture nature is also evidence for enhancement in the alloy’s % elongation.

In this study, Al-TiB2 compacts fabricated by spark plasma sintering methods at different temperatures were characterized for densification, microstructural development, and mechanical properties. Sintering parameters used were temperatures of 500 °C and 550 °C under the pressure of 30 MPa. A very dense microstructure with uniform phase distribution and porosity was produced in the sample sintered at 550 °C with 2.5 wt% TiB2. The same sample exhibited excellent hardness value, and a high-tensile strength attributed to full metallurgical bonding, presence of sub-micron sized grains, and their uniform distribution. These results show that the TiB2 addition enhanced the composite’s hardness, sintered density, and tensile strength. In all the sintered samples, the fractographs revealed a mixed-mode fracture (ductile and brittle).

A highly sensitive photoelectrochemical (PEC) biosensor without external bias was developed in this study. The biosensor was configured with a p-Cu2O and n-ZnO heterostructure. Hexamethylenetetramine (HMTA) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) was used to improve the crystal structure of Cu2O and ZnO and reduce the defects in the Cu2O/ZnO interface. This fabrication method provided the highly crystallized Cu2O/ZnO structure with excellent electrical property and photoresponse in visible light. The structure was applied to a biosensor for detecting two different cancerous levels of esophageal cells, namely, OE21 and OE21-1, with a high gain in photocurrent (5.8 and 6.2 times, respectively) and a low detection limit (3000 cells in 50 μL). We believe that such a p-n heterojunction PEC biosensor could advance biosensor development and provide a promising candidate for biomedical applications.

The influence of silicon carbide (SiC) addition to W-Ni-Cu-based heavy alloys has been investigated in the present study. The powders of W-Ni-Cu with varying percentages of SiC were blended and sintered using conventional and Spark Plasma Sintering (SPS) techniques. The sintered samples were characterized to determine the density, microstructure, and mechanical properties. The alloy (W-7Ni-3Cu-0.5SiC) exhibits high ultimate tensile strength 430 MPa for conventional sintering and 831 MPa for spark plasma sintering, relative sintered density 71.84% and 88.25% of conventional sintered and spark plasma sintering, respectively. After the tensile test, the fracture surfaces show a mixed-mode fracture consisting of brittle W/W intergranular and ductile mode of fracture in the matrix.

This work deals with processing, characterization, and study of the mechanical property of AA6061-ZrO _2 composite by stir casting unit combined with squeeze casting setup. Morphology study of the refined composite was measured with the help of Optical Microscope and Scanning Electron Microscopy (SEM). The Energy Dispersive x-ray spectroscopy was performed to observe the desirable elements present in the processed composite. The EDX investigation endorses the presence of Aluminum, Zirconium, and Oxygen, are the elements of the desirability. The processed composite displayed increased hardness value when related to the base aluminum alloy AA6061 at test conditions. The tensile tests have been performed for the refined specimen both in cast and heat treated conditions. 20%–63% improvement in tensile strength as an outcome of the inclusion of ZrO _2 particles and heat treatment process was recorded, and the fashion was analyzed. Finally, all the three composite specimens were tested for wear resistance property for the support of pin on disc wear test kit. The wear trend due to the addition of ZrO _2 particles was discussed in a detailed manner.

This study established a microfluidic chip for the capture of A549 human lung circulating tumor cells via the aptamer-conjugated self-assembled monolayer (SAM) of gold nanoparticles (AuNPs) in the channel. AuNPs are among the most attractive nanomaterials for the signal enhancement of biosensors owing to their unique chemical, physical, and mechanical properties. The microchip was fabricated using soft photolithography and casting and molding techniques. A self-assembly method was designed to attach AuNPs, cell-specific aptamers, and target cells onto the desired area (i.e., SAM area). In this study, the gold microelectrode configuration was characterized by fluorescence microscopy and impedance measurements to confirm the important modification steps. Subsequently, several investigations with the proposed assay were conducted with different cell samples to determine the specific binding ability of the device for A549 adenocarcinoma cancer cells. This work has ensured a simple, convenient, selective, and sensitive approach for the development of biosensors for lung cancer detection during the early stages.

In recent years, multi-axis robots are indispensable in automated factories due to the rapid development of Industry 4.0. Many related processes were required to have the increasing demand for accuracy, reproducibility, and abnormal detection. The monitoring function and immediate feedback for correction is more and more important. This present study integrated a highly sensitive lithium niobate (LiNbO3) vibration sensor as a sensor node (SN) and architecture of wireless mesh network (WMN) to develop a monitoring system (MS) for the robotic arm. The advantages of the thin-film LiNbO3 piezoelectric sensor were low-cost, high-sensitivity and good electrical compatibility. The experimental results obtained from the vibration platform show that the sensitivity achieved 50 mV/g and the reaction time within 1 ms. The results of on-site testing indicated that the SN could be configured on the relevant equipment quickly and detect the abnormal vibration in specific equipment effectively. Each SN could be used more than 10 h at the 80 Hz transmission rate under WMN architecture and the loss rate of transmission was less than 0.01% within 20 m.

Improvement of methods for reliable and early diagnosis of the cellular diseases is necessary. A biological selectivity probe, such as an aptamer, is one of the candidate recognition layers that can be used to detect important biomolecules. Lung cancer is currently a typical cause of cancer-related deaths. In this work, an electrical sensing platform is built based on amine-terminated aptamer modified-gold electrodes for the specific, label-free detection of a human lung carcinoma cell line (A549). The microdevice, that includes a coplanar electrodes configuration and a simple microfluidic channel on a glass substrate, is fabricated using standard photolithography and cast molding techniques. A procedure of self-assembly onto the gold surface is proposed. Optical microscope observations and electrical impedance spectroscopy measurements confirm that the fabricated microchip can specifically and effectively identify A549 cells. In the experiments, the capacitance element that is dominant in the change of the impedance is calculated at the appropriate frequency for evaluation of the sensitivity of the biosensor. Therefore, a simple, inexpensive, biocompatible, and selective biosensor that has the potential to detect early-stage lung cancer would be developed.

Accurate analysis at the single-cell level has become a highly attractive tool for investigating cellular content. An electroosmotic-driven microfluidic chip with arrays of 30-µm-diameter microwells was developed for single-cell electric lysis in the present study. The cellular occupancy in the microwells when the applied voltage was 5 V (82.4%) was slightly higher than that at an applied voltage of 10 V (81.8%). When the applied voltage was increased to 15 V, the cellular occupancy in the microwells dropped to 64.3%. More than 50% of the occupied microwells contain individual cells. The results of electric lysis experiments at the single-cell level indicate that the cells were gradually lysed as the DC voltage of 30 V was applied; the cell was fully lysed after 25 s. Single-cell electric lysis was demonstrated in the proposed microfluidic chip, which is suitable for high-throughput cell lysis.

Many conventional biochemical assays are performed using populations of cells to determine their quantitative biomolecular profiles. However, population averages do not reflect actual physiological processes in individual cells, which occur either on short time scales or nonsynchronously. Therefore, accurate analysis at the single-cell level has become a highly attractive tool for investigating cellular content. Microfluidic chips with arrays of microwells were developed for single-cell chemical lysis in the present study. The cellular occupancy in 30-mm-diameter microwells (91.45%) was higher than that in 20-mm-diameter microwells (83.19%) at an injection flow rate of 2.8 mL/min. However, most of the occupied 20-mm-diameter microwells contained individual cells. The results of chemical lysis experiments at the single-cell level indicate that cell membranes were gradually lysed as the lysis buffer was injected; they were fully lysed after 12 s. Single-cell chemical lysis was demonstrated in the proposed microfluidic chip, which is suitable for high-throughput cell lysis.

Bio-molecular recognition is detected by the unique optical properties of self-assembled gold nanoparticles on the unclad portions of an optical fiber whose surfaces have been modified with a receptor. To enhance the performance of the sensing platform, the sensing element is integrated with a microfluidic chip to reduce sample and reagent volume, to shorten response time and analysis time, as well as to increase sensitivity. The main purpose of the present study is to design grooves on the optical fiber for the FO-LPR microfluidic chip and investigate the effect of the groove geometry on the biochemical binding kinetics through simulations. The optical fiber is designed and termed as U-type or D-type based on the shape of the grooves. The numerical results indicate that the design of the D-type fiber exhibits efficient performance on biochemical binding. The grooves designed on the optical fiber also induce chaotic advection to enhance the mixing in the microchannel. The mixing patterns indicate that D-type grooves enhance the mixing more effectively than U-type grooves. D-type fiber with six grooves is the optimum design according to the numerical results. The experimental results show that the D-type fiber could sustain larger elongation than the U-type fiber. Furthermore, this study successfully demonstrates the feasibility of fabricating the grooved optical fibers by the femtosecond laser, and making a transmission-based FO-LPR probe for chemical sensing. The sensor resolution of the sensor implementing the D-type fiber modified by gold nanoparticles was 4.1 × 10-7 RIU, which is much more sensitive than that of U-type optical fiber (1.8 × 10-3 RIU).

The preconcentration of proteins with low concentrations can be used to increase the sensitivity and accuracy of detection. A nonlinear electrokinetic flow is induced in a nanofluidic channel due to the overlap of electrical double layers, resulting in the fast accumulation of proteins, referred to as the exclusion-enrichment effect. The proposed chip for protein preconcentration was fabricated using simple standard soft lithography with a polydimethylsiloxane replica. This study extends our previous paper, in which gold nanoparticles were manually deposited onto the surface of a protein preconcentrator. In the present work, nanofractures were formed by utilizing the self-assembly of gold-nanoparticle-assisted electric breakdown. This reliable method for nanofracture formation, involving self-assembled monolayers of nanoparticles at the junction gap between microchannels, also decreases the required electric breakdown voltage. The experimental results reveal that a high concentration factor of 1.5×10(4) for a protein sample with an extremely low concentration of 1 nM was achieved in 30 min by using the proposed chip, which is faster than our previously proposed chip at the same conditions. Moreover, an immunoassay of bovine serum albumin (BSA) and anti-BSA was carried out to demonstrate the applicability of the proposed chip.

Sample preconcentration is an important step that increases the accuracy of subsequent detection, especially for samples with extremely low concentrations. Due to the overlapping of electrical double layers in the nanofluidic channel, the concentration polarization effect can be generated by applying an electric field. Therefore, a nonlinear electrokinetic flow is induced, which results in the fast accumulation of proteins in front of the induced ionic depletion zone, the so-called exclusion-enrichment effect. Nanofractures were created in this work to preconcentrate proteins via the exclusion-enrichment effect. The protein sample was driven by electroosmotic flow and accumulated at a specific location. The preconcentration chip for proteins was fabricated using simple standard soft lithography with a polydimethylsiloxane replica. Nanofractures were formed by utilizing nanoparticle-assisted electric breakdown. The proposed method for nanofracture formation that utilizes nanoparticle deposition at the junction gap between microchannels greatly decreases the required electric breakdown voltage. The experimental results indicate that a protein sample with an extremely low concentration of 1 nM was concentrated to 1.5×10(4)-fold in 60 min using the proposed chip.

This paper presents a study on the impedance spectroscopy methods applied to 2-electrode and 3-electrode biosensors. While 3-electrode electrochemical biosensors have been extensively studied and applied in various applications, the 2-electrode configuration of electrochemical biosensors still lacks comprehensive investigation for real-world applications. In particular, the miniaturization of the 3-electrode configuration for integration into microfluidic devices has been explored due to the relatively limited number of previous studies. A commercial screen-printed gold electrode was employed to develop immunosensors for bovine serum albumin (BSA) detection. The comparisons were performed on non-Faradaic and Faradic immunosensors corresponding to 2-electrode and 3-electrode configurations through impedance measurements. The results show the performance of both types of sensors in detecting BSA protein. While the 2-electrode configuration-based sensor can detect the BSA protein with a sensitivity of 12 Ω/µM, the 3-electrode configuration-based sensor shows superior results with a sensitivity of 7.2 kΩ/µM. Besides, the results also indicate that the 2-electrode configuration-based sensor can easily be miniaturized to integrate into a microfluidic channel to develop lab-on-a-chip systems. Although the 3-electrode configuration demonstrates advancements compared to the 2-electrode configuration, the 2-electrode system based on non-Faradaic processes still shows high potential for future applications. [ABSTRACT FROM AUTHOR]