Enzyme Method-Based Microfluidic Chip for the Rapid Detection of Copper Ions

Application of Micro/Nanomotors in Environmental Remediation: A Review

The advent of self-propelled micro/nanomotors represents a paradigm shift in the field of environmental remediation, offering a significant enhancement in the efficiency of conventional operations through the exploitation of the material phenomenon of active motion. Despite the considerable promise of micro/nanomotors for applications in environmental remediation, there has been a paucity of reviews that have focused on this area. This review identifies the current opportunities and challenges in utilizing micro/nanomotors to enhance contaminant degradation and removal, accelerate bacterial death, or enable dynamic environmental monitoring. It illustrates how mobile reactors or receptors can dramatically increase the speed and efficiency of environmental remediation processes. These studies exemplify the wide range of environmental applications of dynamic micro/nanomotors associated with their continuous motion, force, and function. Finally, the review discusses the challenges of transferring these exciting advances from the experimental scale to larger-scale field applications.

A remote-controlled portable workstation for highly sensitive and real-time chemiluminescent detection of cadmium

The prevention of pollution requires real-time monitoring of cadmium (Cd2+) concentration in the food, as it has a dramatic impact on poultry and can pose a threat to human health. Here, we fabricate a portable workstation integrating a microfluidic chip that facilitates real-time monitoring of Cd2+ levels in real samples by utilizing the Luminol-KMnO4 chemiluminescence (CL) system. Interestingly, Cd2+ can significantly enhance the CL signal, resulting in sensitive detection of Cd2+ in the range of 0-0.18 mg/L with the limit of detection (LOD) of 0.207 μg/L. Furthermore, a remote-controlled unit is integrated into the portable workstation to form a remote-controlled portable workstation (RCPW) performing automated point-of-care testing (POCT) of Cd2+. The as-prepared strategy allows remote control of RCPW to avoid long-distance transportation of samples to achieve real-time target monitoring. Consequently, this system furnishes RCPW for monitoring Cd2+ levels in real samples, thereby holding potential for applications in preventing food pollution.

Mixing Performance Analysis and Optimal Design of a Novel Passive Baffle Micromixer

Micromixers, as crucial components of microfluidic devices, find widespread applications in the field of biochemistry. Due to the laminar flow in microchannels, mixing is challenging, and it significantly impacts the efficiency of rapid reactions. In this study, numerical simulations of four baffle micromixer structures were carried out at different Reynolds numbers (Re = 0.1, Re = 1, Re = 10, and Re = 100) in order to investigate the flow characteristics and mixing mechanism under different structures and optimize the micromixer by varying the vertical displacement of the baffle, the rotation angle, the horizontal spacing, and the number of baffle, and by taking into account the mixing intensity and pressure drop. The results indicated that the optimal mixing efficiency was achieved when the baffle's vertical displacement was 90 μm, the baffle angle was 60°, the horizontal spacing was 130 μm, and there were 20 sets of baffles. At Re = 0.1, the mixing efficiency reached 99.4%, and, as Re increased, the mixing efficiency showed a trend of, first, decreasing and then increasing. At Re = 100, the mixing efficiency was 97.2%. Through simulation analysis of the mixing process, the structure of the baffle-type micromixer was effectively improved, contributing to enhanced fluid mixing efficiency and reaction speed.

RETRACTED: Preparation and Analysis of Structured Color Janus Droplets Based on Microfluidic 3D Droplet Printing

The microfluidic technique for the three-dimensional (3D) printing of Janus droplets offers precise control over their size, orientation, and positioning. The proposed approach investigates the impact of variables such as the volume ratio of the oil phase, droplet size, and the ratio of nonionic surfactants on the dimensions of the structured color apertures of Janus droplets. The findings reveal that structured color apertures modulate accurately. Furthermore, fabricating color patterns facilitates cat, fish, and various other specific shapes using structured color Janus droplets. The color patterns exhibit temperature-sensitive properties, enabling them to transition between display and concealed states. Herein, the adopted microfluidic technique creates Janus droplets with customizable characteristics and uniform size, solving orientation as well as space arrangement problems. This approach holds promising applications for optical devices, sensors, and biomimetic systems.

Microfluidic Wearable Devices for Sports Applications

This study aimed to systematically review the application and research progress of flexible microfluidic wearable devices in the field of sports. The research team thoroughly investigated the use of life signal-monitoring technology for flexible wearable devices in the domain of sports. In addition, the classification of applications, the current status, and the developmental trends of similar products and equipment were evaluated. Scholars expect the provision of valuable references and guidance for related research and the development of the sports industry. The use of microfluidic detection for collecting biomarkers can mitigate the impact of sweat on movements that are common in sports and can also address the issue of discomfort after prolonged use. Flexible wearable gadgets are normally utilized to monitor athletic performance, rehabilitation, and training. Nevertheless, the research and development of such devices is limited, mostly catering to professional athletes. Devices for those who are inexperienced in sports and disabled populations are lacking. Conclusions: Upgrading microfluidic chip technology can lead to accurate and safe sports monitoring. Moreover, the development of multi-functional and multi-site devices can provide technical support to athletes during their training and competitions while also fostering technological innovation in the field of sports science.

Manipulator Control System Based on Flexible Sensor Technology

The research on the remote control of manipulators based on flexible sensor technology is gradually extensive. In order to achieve stable, accurate, and efficient control of the manipulator, it is necessary to reasonably design the structure of the sensor with excellent tensile strength and flexibility. The acquisition of manual information by high-performance sensors is the basis of manipulator control. This paper starts with the manufacturing of materials of the flexible sensor for the manipulator, introduces the substrate, sensor, and flexible electrode materials, respectively, and summarizes the performance of different flexible sensors. From the perspective of manufacturing, it introduces their basic principles and compares their advantages and disadvantages. Then, according to the different ways of wearing, the two control methods of data glove control and surface EMG control are respectively introduced, the principle, control process, and detection accuracy are summarized, and the problems of material microstructure, reducing the cost, optimizing the circuit design and so on are emphasized in this field. Finally, the commercial application in this field is explained and the future research direction is proposed from two aspects: how to ensure real-time control and better receive the feedback signal from the manipulator.

Structural Optimization Design of Microfluidic Chips Based on Fast Sequence Pair Algorithm

The market for microfluidic chips is experiencing significant growth; however, their development is hindered by a complex design process and low efficiency. Enhancing microfluidic chips' design quality and efficiency has emerged as an integral approach to foster their advancement. Currently, the existing structural design schemes lack careful consideration regarding the impact of chip area, microchannel length, and the number of intersections on chip design. This inadequacy leads to redundant chip structures resulting from the separation of layout and wiring design. This study proposes a structural optimization method for microfluidic chips to address these issues utilizing a simulated annealing algorithm. The simulated annealing algorithm generates an initial solution in advance using the fast sequence pair algorithm. Subsequently, an improved simulated annealing algorithm is employed to obtain the optimal solution for the device layout. During the wiring stage, an advanced wiring method is used to designate the high wiring area, thereby increasing the success rate of microfluidic chip wiring. Furthermore, the connection between layout and routing is reinforced through an improved layout adjustment method, which reduces the length of microchannels and the number of intersections. Finally, the effectiveness of the structural optimization approach is validated through six sets of test cases, successfully achieving the objective of enhancing the design quality of microfluidic chips.

Advances in Microfluidics Techniques for Rapid Detection of Pesticide Residues in Food

Food safety is a significant issue that affects people worldwide and is tied to their lives and health. The issue of pesticide residues in food is just one of many issues related to food safety, which leave residues in crops and are transferred through the food chain to human consumption. Foods contaminated with pesticide residues pose a serious risk to human health, including carcinogenicity, neurotoxicity, and endocrine disruption. Although traditional methods, including gas chromatography, high-performance liquid chromatography, chromatography, and mass spectrometry, can be used to achieve a quantitative analysis of pesticide residues, the disadvantages of these techniques, such as being time-consuming and costly and requiring specialist staff, limit their application. Therefore, there is a need to develop rapid, effective, and sensitive equipment for the quantitative analysis of pesticide residues in food. Microfluidics is rapidly emerging in a number of fields due to its outstanding strengths. This paper summarizes the application of microfluidic techniques to pyrethroid, carbamate, organochlorine, and organophosphate pesticides, as well as to commercial products. Meanwhile, the study also outlines the development of microfluidics in combination with 3D printing technology and nanomaterials for detecting pesticide residues in food.

Research on Integrated 3D Printing of Microfluidic Chips

Microfluidic chips have the advantages of miniaturization, integration, and portability, and are widely used in the early diagnosis of major diseases, personalized medical treatment, environmental detection, health quarantine, and other fields. The existing microfluidic chip manufacturing process is difficult to operate because of complex three-dimensional channels, complicated manufacturing steps, limited printing materials, the difficulty of operating the bonding process, and the need to purchase expensive new equipment. In this paper, an integrated molding method for microfluidic chips that integrates 3D printing and polymer dissolution technology is proposed. First, the channel mold of poly(vinyl alcohol) (PVA) or high impact polystyrene (HIPS) is dissolved to complete the manufacturing of the microfluidic chip channel. The integrated 3D-forming method of microfluidic chips proposed in this paper can manufacture microchannels inside the microfluidic chip, avoid the bonding process, and eliminate the need for rapid alignment of microchannels, material modification, and other operations, thus improving the stability of the process. Finally, by comparing the microchannels made by PVA and HIPS, it is concluded that the quality of the microchannels made by HIPS is obviously better than that made by PVA. This paper provides a new idea for the fabrication of microfluidic chips and the application of HIPS.

Effect of Flow Velocity on Laminar Flow in Microfluidic Chips

Gel fibers prepared based on microfluidic laminar flow technology have important research value in constructing biomimetic scaffolds and tissue engineering. The key point of microfluidic laminar flow technology is to find the appropriate fluid flow rate in the micropipe. In order to explore the influence of flow rate on the laminar flow phenomenon of a microfluidic chip, a microfluidic chip composed of an intermediate main pipe and three surrounding outer pipes are designed, and the chip is prepared by photolithography and the composite molding method. Then, a syringe pump is used to inject different fluids into the microtubing, and the data of fluid motion are obtained through fluid dynamics simulation and finite element analysis. Finally, a series of optimal adjustments are made for different fluid composition and flow rate combinations to achieve the fluid's stable laminar flow state. It was determined that when the concentration of sodium alginate in the outer phase was 1 wt% and the concentration of CaCl₂ in the inner phase was 0.1 wt%, the gel fiber prepared was in good shape, the flow rate was the most stable, and laminar flow was the most obvious when the flow rate of both was 1 mL/h. This study represents a preliminary achievement in exploring the laminar flow rate and fabricating gel fibers, thus offering significant reference value for investigating microfluidic laminar flow technology.

Recent progress of microfluidic chips in immunoassay

Microfluidic chip technology is a technology platform that integrates basic operation units such as processing, separation, reaction and detection into microchannel chip to realize low consumption, fast and efficient analysis of samples. It has the characteristics of small volume need of samples and reagents, fast analysis, low cost, automation, portability, high throughout, and good compatibility with other techniques. In this review, the concept, preparation materials and fabrication technology of microfluidic chip are described. The applications of microfluidic chip in immunoassay, including fluorescent, chemiluminescent, surface-enhanced Raman spectroscopy (SERS), and electrochemical immunoassay are reviewed. Look into the future, the development of microfluidic chips lies in point-of-care testing and high throughput equipment, and there are still some challenges in the design and the integration of microfluidic chips, as well as the analysis of actual sample by microfluidic chips.

Detection of Tomato Ringspot Virus Based on Microfluidic Impedance Sensor

A microfluidic impedance sensor embedded with gold interdigitated array microelectrodes was utilized to rapidly detect Tomato Ringspot Virus (ToRSV) and achieve efficient and precise detection. The electrochemical impedance spectrum was obtained by immobilizing ToRSV antibody on the surface of a gold interdigital array microelectrode and mixing it with ToRSV to generate an impedance change. The electrochemical impedance spectrum was obtained. The equivalent circuit was established to analyze the mechanism of impedance change, and the quantitative linear relationship between ToRSV concentration and impedance was established. According to an equivalent circuit analysis, ToRSV increases the solution resistance Rs, the electron transfer resistance Ret on the electrode surface, and the double layer capacitance Cdl, resulting in an increase in impedance. The results reveal that the ToRSV concentration detected in the range of 0.001 to 10 μg/mL ranges from 248.8 to 687.2 kΩ at the ideal detection frequency of 10.7 Hz, with a good linear connection, R² = 0.98. When this method's detection limit is tested, the impedance value is 367.68 kΩ. 0.0032 μg/mL was the detection limit. The sensor is quick and easy to use, has high detection sensitivity, and can be used to detect other plant viruses.

Microfluidics-Based POCT for SARS-CoV-2 Diagnostics

A microfluidic chip is a tiny reactor that can confine and flow a specific amount of fluid into channels of tens to thousands of microns as needed and can precisely control fluid flow, pressure, temperature, etc. Point-of-care testing (POCT) requires small equipment, has short testing cycles, and controls the process, allowing single or multiple laboratory facilities to simultaneously analyze biological samples and diagnose infectious diseases. In general, rapid detection and stage assessment of viral epidemics are essential to overcome pandemic situations and diagnose promptly. Therefore, combining microfluidic devices with POCT improves detection efficiency and convenience for viral disease SARS-CoV-2. At the same time, the POCT of microfluidic chips increases user accessibility, improves accuracy and sensitivity, shortens detection time, etc., which are beneficial in detecting SARS-CoV-2. This review shares recent advances in POCT-based testing for COVID-19 and how it is better suited to help diagnose in response to the ongoing pandemic.