Editorial

5 pages, 201 KiB

Open AccessEditorial

Microfluidics for Biomedical Applications

by Nan Xiang and Zhonghua Ni

Biosensors 2023, 13(2), 161; https://doi.org/10.3390/bios13020161 - 20 Jan 2023

Cited by 2 | Viewed by 1928

Microfluidics refers to a technique for controlling and analyzing the fluids or micro-/nano-bioparticles in microscale channels or structures [...] Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

Research

Jump to: Editorial, Review

18 pages, 3763 KiB

Open AccessArticle

Generation of Dynamic Concentration Profile Using A Microfluidic Device Integrating Pneumatic Microvalves

by Chang Chen, Panpan Li, Tianruo Guo, Siyuan Chen, Dong Xu and Huaying Chen

Biosensors 2022, 12(10), 868; https://doi.org/10.3390/bios12100868 - 13 Oct 2022

Cited by 4 | Viewed by 2121

Abstract

Generating and maintaining the concentration dilutions of diffusible molecules in microchannels is critical for high-throughput chemical and biological analysis. Conventional serial network microfluidic technologies can generate high orders of arbitrary concentrations by a predefined microchannel network. However, a previous design requires a large [...] Read more.

Generating and maintaining the concentration dilutions of diffusible molecules in microchannels is critical for high-throughput chemical and biological analysis. Conventional serial network microfluidic technologies can generate high orders of arbitrary concentrations by a predefined microchannel network. However, a previous design requires a large occupancy area and is unable to dynamically generate different profiles in the same chip, limiting its applications. This study developed a microfluidic device enabling dynamic variations of both the concentration in the same channel and the concentration distribution in multiple channels by adjusting the flow resistance using programmable pneumatic microvalves. The key component (the pneumatic microvalve) allowed dynamic adjustment of the concentration profile but occupied a tiny space. Additionally, a Matlab program was developed to calculate the flow rates and flow resistance of various sections of the device, which provided theoretical guidance for dimension design. In silico investigations were conducted to evaluate the microvalve deformation with widths from 100 to 300 µm and membrane thicknesses of 20 and 30 µm under the activation pressures between 0 and 2000 mbar. The flow resistance of the deformed valve was studied both numerically and experimentally and an empirical model for valve flow resistance with the form of

R_{h} = a e^{b P}

was proposed. Afterward, the fluid flow in the valve region was characterized using Micro PIV to further demonstrate the adjustment mechanism of the flow resistance. Then, the herringbone structures were employed for fast mixing to allow both quick variation of concentration and minor space usage of the channel network. Finally, an empirical formula-supported computational program was developed to provide the activation pressures required for the specific concentration profile. Both linear (

C_{k}

= −0.2k + 1) and nonlinear

(C_{k}

=

{(\frac{1}{\sqrt{10}})}^{k})

concentration distribution in four channels were varied using the same device by adjusting microvalves. The device demonstrated the capability to control the concentration profile dynamically in a small space, offering superior application potentials in analytical chemistry, drug screening, and cell biology research. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

13 pages, 3245 KiB

Open AccessArticle

An Asymmetric Microfluidic/Chitosan Device for Sustained Drug Release in Guided Bone Regeneration Applications

by Xin Shi, Beibei Ma, Hongyu Chen, Wei Tan, Shiqing Ma and Guorui Zhu

Biosensors 2022, 12(10), 847; https://doi.org/10.3390/bios12100847 - 09 Oct 2022

Cited by 3 | Viewed by 1518

Abstract

One of the major challenges of guided bone regeneration (GBR) is infections caused by pathogen colonization at wound sites. In this paper, an asymmetric microfluidic/chitosan device was developed to release drugs to inhibit infections and to ensure that guided bone regeneration can be [...] Read more.

One of the major challenges of guided bone regeneration (GBR) is infections caused by pathogen colonization at wound sites. In this paper, an asymmetric microfluidic/chitosan device was developed to release drugs to inhibit infections and to ensure that guided bone regeneration can be realized. The microfluidic technique was introduced into the GBR membrane for the first time, which demonstrated more controllable drug release, more flexible clinical use and had a lower cost compared with surface treatments and embedded nanoparticles. Based on the theory of diffusion and Fick’s first law, the contact area and concentration gradient were adjusted to realize sustained drug release. The standard deviation of minocycline release over 5 days was only 12.7%, which was lower than the joint effect of porous chitosan discs and nanospheres. The in vitro experiments against E. coli and Streptococcus mutans showed the excellent antibacterial performance of the device (>95%). The in vitro experiments for fibroblasts at the microfluidic side and osteoblasts at the chitosan side showed the satisfactory biocompatibility and the ability of the device to enhance bone regeneration. Therefore, this microfluidic/chitosan device is a promising therapeutic approach to prevent infection and guide bone regeneration. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

14 pages, 3372 KiB

Open AccessArticle

Red Blood Cell Sedimentation Index Using Shear Stress of Blood Flow in Microfluidic Channel

by Yang Jun Kang

Biosensors 2022, 12(7), 547; https://doi.org/10.3390/bios12070547 - 21 Jul 2022

Cited by 3 | Viewed by 2041

Abstract

Red blood cell sedimentation has been used as a promising indicator of hematological diseases and disorders. However, to address several issues (i.e., syringe installation direction, blood on-off flow control, image-based quantification, and hemodilution) raised by the previous methods, it is necessary to devise [...] Read more.

Red blood cell sedimentation has been used as a promising indicator of hematological diseases and disorders. However, to address several issues (i.e., syringe installation direction, blood on-off flow control, image-based quantification, and hemodilution) raised by the previous methods, it is necessary to devise a new method for the effective quantification of red blood cell sedimentation under a constant blood flow. In this study, the shear stress of a blood flow is estimated by analyzing an interface in a co-flowing channel to quantify the red blood cell sedimentation in blood syringes filled with blood (hematocrit = 50%). A red blood cell sedimentation index is newly suggested by analyzing the temporal variations in the shear stress. According to the experimental investigation, the sedimentation index tends to decrease at a higher flow rate. A higher level of hematocrit has a negative influence on the sedimentation index. As a performance demonstration of the present method, the red blood cell sedimentation processes of various test bloods were quantitatively compared in terms of the shear stress, image intensity, and sedimentation velocity. It was found that the proposed index provided a more than 10-fold increase in sensitivity over the previous method (i.e., image intensity). Additionally, it provided more consistent results than another conventional sedimentation method (sedimentation velocity). In conclusion, the present index can be effectively adopted to monitor the red blood cell sedimentation in a 10-min blood delivery. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

11 pages, 1333 KiB

Open AccessArticle

Effective Enrichment of Plasmonic Hotspots for SERS by Spinning Droplets on a Slippery Concave Dome Array

by Jialin Wu, Jianpeng Cai, Yuan Fan, Ying Zhang, Hui Fang and Sheng Yan

Biosensors 2022, 12(5), 270; https://doi.org/10.3390/bios12050270 - 24 Apr 2022

Cited by 4 | Viewed by 2338

Abstract

Surface-enhanced Raman scattering (SERS) detection requires dense hotspots and a uniform distribution of analytes to obtain a stable signal with good repeatability. However, due to the coffee-ring effect on the hydrophilic substrate, and the difficulty of droplet manipulation on the superhydrophobic substrate, few [...] Read more.

Surface-enhanced Raman scattering (SERS) detection requires dense hotspots and a uniform distribution of analytes to obtain a stable signal with good repeatability. However, due to the coffee-ring effect on the hydrophilic substrate, and the difficulty of droplet manipulation on the superhydrophobic substrate, few substrates can ensure that the analytes are evenly distributed. In this work, we develop a method that can efficiently enrich plasmonic hotspots for SERS measurement on the superhydrophobic concave dome array (SCDA). The SCDA is formed by spraying hydrophobic silica nanoparticles onto a polydimethylsiloxane (PDMS) slab with a concave dome array that can physically confine the droplets and overcome the coffee-ring effect. During droplet evaporation, the SCDA is driven by a horizontal spinner, and the droplets spin on the SCDA, enabling the plasmonic nanoparticles to become closely packed to form the SERS hotspots. The limit of detection (LOD) of the dynamic-enriched SERS hotspots for crystal violet and methylene blue can reach up to 10⁻¹¹ M. Moreover, the LOD for melamine in milk can reach 5 × 10⁻⁷ M, which is lower than the safety threshold defined by the Food and Drug Administration (FDA). Based on this SERS platform, an effective, low-cost, and simple method for SERS detection in analytical chemistry and food safety is highly expected. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

11 pages, 1729 KiB

Open AccessArticle

Target-Specific Exosome Isolation through Aptamer-Based Microfluidics

by Zixuan Zhou, Yan Chen and Xiang Qian

Biosensors 2022, 12(4), 257; https://doi.org/10.3390/bios12040257 - 18 Apr 2022

Cited by 14 | Viewed by 3425

Abstract

Exosomes (30–100 nm in diameter) are a group of cell-derived membrane vesicles, packaged as valuable cargo with lipid, proteins, and genetic materials from their parent cells. With the increasing interest in exosomes for diagnostic and therapeutic applications, the rapid isolation of pure exosome [...] Read more.

Exosomes (30–100 nm in diameter) are a group of cell-derived membrane vesicles, packaged as valuable cargo with lipid, proteins, and genetic materials from their parent cells. With the increasing interest in exosomes for diagnostic and therapeutic applications, the rapid isolation of pure exosome populations has become a hot topic. In this paper, we propose modified microchannels with aptamer in a microfluidics system for rapid and efficient isolation of exosomes by targeting exosome-carrying CD63 and PTK 7. The capture efficiency in surface-modified channels reaches around 10⁷–10⁸ particles/mL in 20 min, and purified exosomes with reliable size can be achieved. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

14 pages, 13451 KiB

Open AccessArticle

A Hybrid Spiral Microfluidic Platform Coupled with Surface Acoustic Waves for Circulating Tumor Cell Sorting and Separation: A Numerical Study

by Rana Altay, Murat Kaya Yapici and Ali Koşar

Biosensors 2022, 12(3), 171; https://doi.org/10.3390/bios12030171 - 11 Mar 2022

Cited by 16 | Viewed by 4458

Abstract

The separation of circulating tumor cells (CTCs) from blood samples is crucial for the early diagnosis of cancer. During recent years, hybrid microfluidics platforms, consisting of both passive and active components, have been an emerging means for the label-free enrichment of circulating tumor [...] Read more.

The separation of circulating tumor cells (CTCs) from blood samples is crucial for the early diagnosis of cancer. During recent years, hybrid microfluidics platforms, consisting of both passive and active components, have been an emerging means for the label-free enrichment of circulating tumor cells due to their advantages such as multi-target cell processing with high efficiency and high sensitivity. In this study, spiral microchannels with different dimensions were coupled with surface acoustic waves (SAWs). Numerical simulations were conducted at different Reynolds numbers to analyze the performance of hybrid devices in the sorting and separation of CTCs from red blood cells (RBCs) and white blood cells (WBCs). Overall, in the first stage, the two-loop spiral microchannel structure allowed for the utilization of inertial forces for passive separation. In the second stage, SAWs were introduced to the device. Thus, five nodal pressure lines corresponding to the lateral position of the five outlets were generated. According to their physical properties, the cells were trapped and lined up on the corresponding nodal lines. The results showed that three different cell types (CTCs, RBCs, and WBCs) were successfully focused and collected from the different outlets of the microchannels by implementing the proposed multi-stage hybrid system. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

12 pages, 2787 KiB

Open AccessArticle

Enhanced Blood Plasma Extraction Utilising Viscoelastic Effects in a Serpentine Microchannel

by Yuchen Dai, Haotian Cha, Michael J. Simmonds, Hedieh Fallahi, Hongjie An, Hang T. Ta, Nam-Trung Nguyen, Jun Zhang and Antony P. McNamee

Biosensors 2022, 12(2), 120; https://doi.org/10.3390/bios12020120 - 14 Feb 2022

Cited by 3 | Viewed by 2786

Abstract

Plasma extraction from blood is essential for diagnosis of many diseases. The critical process of plasma extraction requires removal of blood cells from whole blood. Fluid viscoelasticity promotes cell migration towards the central axis of flow due to differences in normal stress and [...] Read more.

Plasma extraction from blood is essential for diagnosis of many diseases. The critical process of plasma extraction requires removal of blood cells from whole blood. Fluid viscoelasticity promotes cell migration towards the central axis of flow due to differences in normal stress and physical properties of cells. We investigated the effects of altering fluid viscoelasticity on blood plasma extraction in a serpentine microchannel. Poly (ethylene oxide) (PEO) was dissolved into blood to increase its viscoelasticity. The influences of PEO concentration, blood dilution, and flow rate on the performance of cell focusing were examined. We found that focusing performance can be significantly enhanced by adding PEO into blood. The optimal PEO concentration ranged from 100 to 200 ppm with respect to effective blood cell focusing. An optimal flow rate from 1 to 15 µL/min was determined, at least for our experimental setup. Given less than 1% haemolysis was detected at the outlets in all experimental combinations, the proposed microfluidic methodology appears suitable for applications sensitive to haemocompatibility. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

14 pages, 1921 KiB

Open AccessArticle

Hand-Powered Inertial Microfluidic Syringe-Tip Centrifuge

by Nan Xiang and Zhonghua Ni

Biosensors 2022, 12(1), 14; https://doi.org/10.3390/bios12010014 - 29 Dec 2021

Cited by 4 | Viewed by 2579

Abstract

Conventional sample preparation techniques require bulky and expensive instruments and are not compatible with next-generation point-of-care diagnostic testing. Here, we report a manually operated syringe-tip inertial microfluidic centrifuge (named i-centrifuge) for high-flow-rate (up to 16 mL/min) cell concentration and experimentally demonstrate its working [...] Read more.

Conventional sample preparation techniques require bulky and expensive instruments and are not compatible with next-generation point-of-care diagnostic testing. Here, we report a manually operated syringe-tip inertial microfluidic centrifuge (named i-centrifuge) for high-flow-rate (up to 16 mL/min) cell concentration and experimentally demonstrate its working mechanism and performance. Low-cost polymer films and double-sided tape were used through a rapid nonclean-room process of laser cutting and lamination bonding to construct the key components of the i-centrifuge, which consists of a syringe-tip flow stabilizer and a four-channel paralleled inertial microfluidic concentrator. The unstable liquid flow generated by the manual syringe was regulated and stabilized with the flow stabilizer to power inertial focusing in a four-channel paralleled concentrator. Finally, we successfully used our i-centrifuge for manually operated cell concentration. This i-centrifuge offers the advantages of low device cost, simple hand-powered operation, high-flow-rate processing, and portable device volume. Therefore, it holds potential as a low-cost, portable sample preparation tool for point-of-care diagnostic testing. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

22 pages, 5772 KiB

Open AccessArticle

High-Throughput, Label-Free Isolation of White Blood Cells from Whole Blood Using Parallel Spiral Microchannels with U-Shaped Cross-Section

by Amirhossein Mehran, Peyman Rostami, Mohammad Said Saidi, Bahar Firoozabadi and Navid Kashaninejad

Biosensors 2021, 11(11), 406; https://doi.org/10.3390/bios11110406 - 20 Oct 2021

Cited by 13 | Viewed by 3344

Abstract

Rapid isolation of white blood cells (WBCs) from whole blood is an essential part of any WBC examination platform. However, most conventional cell separation techniques are labor-intensive and low throughput, require large volumes of samples, need extensive cell manipulation, and have low purity. [...] Read more.

Rapid isolation of white blood cells (WBCs) from whole blood is an essential part of any WBC examination platform. However, most conventional cell separation techniques are labor-intensive and low throughput, require large volumes of samples, need extensive cell manipulation, and have low purity. To address these challenges, we report the design and fabrication of a passive, label-free microfluidic device with a unique U-shaped cross-section to separate WBCs from whole blood using hydrodynamic forces that exist in a microchannel with curvilinear geometry. It is shown that the spiral microchannel with a U-shaped cross-section concentrates larger blood cells (e.g., WBCs) in the inner cross-section of the microchannel by moving smaller blood cells (e.g., RBCs and platelets) to the outer microchannel section and preventing them from returning to the inner microchannel section. Therefore, it overcomes the major limitation of a rectangular cross-section where secondary Dean vortices constantly enforce particles throughout the entire cross-section and decrease its isolation efficiency. Under optimal settings, we managed to isolate more than 95% of WBCs from whole blood under high-throughput (6 mL/min), high-purity (88%), and high-capacity (360 mL of sample in 1 h) conditions. High efficiency, fast processing time, and non-invasive WBC isolation from large blood samples without centrifugation, RBC lysis, cell biomarkers, and chemical pre-treatments make this method an ideal choice for downstream cell study platforms. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

Review

Jump to: Editorial, Research

27 pages, 3529 KiB

Open AccessEditor’s ChoiceReview

Microfluidic Strategies for Extracellular Vesicle Isolation: Towards Clinical Applications

by Alessio Meggiolaro, Valentina Moccia, Paola Brun, Matteo Pierno, Giampaolo Mistura, Valentina Zappulli and Davide Ferraro

Biosensors 2023, 13(1), 50; https://doi.org/10.3390/bios13010050 - 29 Dec 2022

Cited by 9 | Viewed by 3020

Abstract

Extracellular vesicles (EVs) are double-layered lipid membrane vesicles released by cells. Currently, EVs are attracting a lot of attention in the biological and medical fields due to their role as natural carriers of proteins, lipids, and nucleic acids. Thus, they can transport useful [...] Read more.

Extracellular vesicles (EVs) are double-layered lipid membrane vesicles released by cells. Currently, EVs are attracting a lot of attention in the biological and medical fields due to their role as natural carriers of proteins, lipids, and nucleic acids. Thus, they can transport useful genomic information from their parental cell through body fluids, promoting cell-to-cell communication even between different organs. Due to their functionality as cargo carriers and their protein expression, they can play an important role as possible diagnostic and prognostic biomarkers in various types of diseases, e.g., cancers, neurodegenerative, and autoimmune diseases. Today, given the invaluable importance of EVs, there are some pivotal challenges to overcome in terms of their isolation. Conventional methods have some limitations: they are influenced by the starting sample, might present low throughput and low purity, and sometimes a lack of reproducibility, being operator dependent. During the past few years, several microfluidic approaches have been proposed to address these issues. In this review, we summarize the most important microfluidic-based devices for EV isolation, highlighting their advantages and disadvantages compared to existing technology, as well as the current state of the art from the perspective of the use of these devices in clinical applications. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

24 pages, 5208 KiB

Open AccessReview

Magnetoimpedance Biosensors and Real-Time Healthcare Monitors: Progress, Opportunities, and Challenges

by Valery Ortiz Jimenez, Kee Young Hwang, Dang Nguyen, Yasif Rahman, Claire Albrecht, Baylee Senator, Ongard Thiabgoh, Jagannath Devkota, Vinh Duc An Bui, Dao Son Lam, Tatiana Eggers and Manh-Huong Phan

Biosensors 2022, 12(7), 517; https://doi.org/10.3390/bios12070517 - 12 Jul 2022

Cited by 18 | Viewed by 3429

Abstract

A small DC magnetic field can induce an enormous response in the impedance of a soft magnetic conductor in various forms of wire, ribbon, and thin film. Also known as the giant magnetoimpedance (GMI) effect, this phenomenon forms the basis for the development [...] Read more.

A small DC magnetic field can induce an enormous response in the impedance of a soft magnetic conductor in various forms of wire, ribbon, and thin film. Also known as the giant magnetoimpedance (GMI) effect, this phenomenon forms the basis for the development of high-performance magnetic biosensors with magnetic field sensitivity down to the picoTesla regime at room temperature. Over the past decade, some state-of-the-art prototypes have become available for trial tests due to continuous efforts to improve the sensitivity of GMI biosensors for the ultrasensitive detection of biological entities and biomagnetic field detection of human activities through the use of magnetic nanoparticles as biomarkers. In this review, we highlight recent advances in the development of GMI biosensors and review medical devices for applications in biomedical diagnostics and healthcare monitoring, including real-time monitoring of respiratory motion in COVID-19 patients at various stages. We also discuss exciting research opportunities and existing challenges that will stimulate further study into ultrasensitive magnetic biosensors and healthcare monitors based on the GMI effect. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

24 pages, 4987 KiB

Open AccessReview

Fluorescent Biosensors for the Detection of Viruses Using Graphene and Two-Dimensional Carbon Nanomaterials

by Ahmed M. Salama, Ghulam Yasin, Mohammed Zourob and Jun Lu

Biosensors 2022, 12(7), 460; https://doi.org/10.3390/bios12070460 - 27 Jun 2022

Cited by 10 | Viewed by 3165

Abstract

Two-dimensional carbon nanomaterials have been commonly employed in the field of biosensors to improve their sensitivity/limits of detection and shorten the analysis time. These nanomaterials act as efficient transducers because of their unique characteristics, such as high surface area and optical, electrical, and [...] Read more.

Two-dimensional carbon nanomaterials have been commonly employed in the field of biosensors to improve their sensitivity/limits of detection and shorten the analysis time. These nanomaterials act as efficient transducers because of their unique characteristics, such as high surface area and optical, electrical, and magnetic properties, which in turn have been exploited to create simple, quick, and low-cost biosensing platforms. In this review, graphene and two-dimensional carbon material-based fluorescent biosensors are covered between 2010 and 2021, for the detection of different human viruses. This review specifically focuses on the new developments in graphene and two-dimensional carbon nanomaterials for fluorescent biosensing based on the Förster resonance energy transfer (FRET) mechanism. The high-efficiency quenching capability of graphene via the FRET mechanism enhances the fluorescent-based biosensors. The review provides a comprehensive reference for the different types of carbon nanomaterials employed for the detection of viruses such as Rotavirus, Ebola virus, Influenza virus H₃N₂, HIV, Hepatitis C virus (HCV), and Hepatitis B virus (HBV). This review covers the various multiplexing detection technologies as a new direction in the development of biosensing platforms for virus detection. At the end of the review, the different challenges in the use of fluorescent biosensors, as well as some insights into how to overcome them, are highlighted. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

19 pages, 2617 KiB

Open AccessReview

Droplet Manipulation under a Magnetic Field: A Review

by Gui-Ping Zhu, Qi-Yue Wang, Zhao-Kun Ma, Shi-Hua Wu and Yi-Pan Guo

Biosensors 2022, 12(3), 156; https://doi.org/10.3390/bios12030156 - 02 Mar 2022

Cited by 22 | Viewed by 4959

Abstract

The magnetic manipulation of droplets is one of the emerging magnetofluidic technologies that integrate multiple disciplines, such as electromagnetics, fluid mechanics and so on. The directly driven droplets are mainly composed of ferrofluid or liquid metal. This kind of magnetically induced droplet manipulation [...] Read more.

The magnetic manipulation of droplets is one of the emerging magnetofluidic technologies that integrate multiple disciplines, such as electromagnetics, fluid mechanics and so on. The directly driven droplets are mainly composed of ferrofluid or liquid metal. This kind of magnetically induced droplet manipulation provides a remote, wireless and programmable approach beneficial for research and engineering applications, such as drug synthesis, biochemistry, sample preparation in life sciences, biomedicine, tissue engineering, etc. Based on the significant growth in the study of magneto droplet handling achieved over the past decades, further and more profound explorations in this field gained impetus, raising concentrations on the construction of a comprehensive working mechanism and the commercialization of this technology. Current challenges faced are not limited to the design and fabrication of the magnetic field, the material, the acquisition of precise and stable droplet performance, other constraints in processing speed and so on. The rotational devices or systems could give rise to additional issues on bulky appearance, high cost, low reliability, etc. Various magnetically introduced droplet behaviors, such as deformation, displacement, rotation, levitation, splitting and fusion, are mainly introduced in this work, involving the basic theory, functions and working principles. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

29 pages, 6588 KiB

Open AccessReview

Microfluidic-Based Droplets for Advanced Regenerative Medicine: Current Challenges and Future Trends

by Hojjatollah Nazari, Asieh Heirani-Tabasi, Sadegh Ghorbani, Hossein Eyni, Sajad Razavi Bazaz, Maryam Khayati, Fatemeh Gheidari, Keyvan Moradpour, Mousa Kehtari, Seyed Mohsen Ahmadi Tafti, Seyed Hossein Ahmadi Tafti and Majid Ebrahimi Warkiani

Biosensors 2022, 12(1), 20; https://doi.org/10.3390/bios12010020 - 31 Dec 2021

Cited by 13 | Viewed by 5297

Abstract

Microfluidics is a promising approach for the facile and large-scale fabrication of monodispersed droplets for various applications in biomedicine. This technology has demonstrated great potential to address the limitations of regenerative medicine. Microfluidics provides safe, accurate, reliable, and cost-effective methods for encapsulating different [...] Read more.

Microfluidics is a promising approach for the facile and large-scale fabrication of monodispersed droplets for various applications in biomedicine. This technology has demonstrated great potential to address the limitations of regenerative medicine. Microfluidics provides safe, accurate, reliable, and cost-effective methods for encapsulating different stem cells, gametes, biomaterials, biomolecules, reagents, genes, and nanoparticles inside picoliter-sized droplets or droplet-derived microgels for different applications. Moreover, microenvironments made using such droplets can mimic niches of stem cells for cell therapy purposes, simulate native extracellular matrix (ECM) for tissue engineering applications, and remove challenges in cell encapsulation and three-dimensional (3D) culture methods. The fabrication of droplets using microfluidics also provides controllable microenvironments for manipulating gametes, fertilization, and embryo cultures for reproductive medicine. This review focuses on the relevant studies, and the latest progress in applying droplets in stem cell therapy, tissue engineering, reproductive biology, and gene therapy are separately evaluated. In the end, we discuss the challenges ahead in the field of microfluidics-based droplets for advanced regenerative medicine. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

29 pages, 8845 KiB

Open AccessReview

Recent Advances in Electrical Impedance Sensing Technology for Single-Cell Analysis

by Zhao Zhang, Xiaowen Huang, Ke Liu, Tiancong Lan, Zixin Wang and Zhen Zhu

Biosensors 2021, 11(11), 470; https://doi.org/10.3390/bios11110470 - 22 Nov 2021

Cited by 22 | Viewed by 5411

Abstract

Cellular heterogeneity is of significance in cell-based assays for life science, biomedicine and clinical diagnostics. Electrical impedance sensing technology has become a powerful tool, allowing for rapid, non-invasive, and label-free acquisition of electrical parameters of single cells. These electrical parameters, i.e., equivalent cell [...] Read more.

Cellular heterogeneity is of significance in cell-based assays for life science, biomedicine and clinical diagnostics. Electrical impedance sensing technology has become a powerful tool, allowing for rapid, non-invasive, and label-free acquisition of electrical parameters of single cells. These electrical parameters, i.e., equivalent cell resistance, membrane capacitance and cytoplasm conductivity, are closely related to cellular biophysical properties and dynamic activities, such as size, morphology, membrane intactness, growth state, and proliferation. This review summarizes basic principles, analytical models and design concepts of single-cell impedance sensing devices, including impedance flow cytometry (IFC) to detect flow-through single cells and electrical impedance spectroscopy (EIS) to monitor immobilized single cells. Then, recent advances of both electrical impedance sensing systems applied in cell recognition, cell counting, viability detection, phenotypic assay, cell screening, and other cell detection are presented. Finally, prospects of impedance sensing technology in single-cell analysis are discussed. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Microfluidics for Biomedical Applications

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (16 papers)

Editorial

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI