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1.
Microfluidics is a relatively novel interdisciplinary research area with broad applications in chemistry, physics, material science, and biology. Despite the rapid growth of the field, students'' exposure to microfluidic technologies is still limited and often insufficient to appreciate the advantages over other commonly used technologies. To this end, we designed a five-day course, “Microfluidics for microbial ecology,” in which students with very different backgrounds learn the basics of microfluidic technologies and sample a range of applications in microbial ecology. The course was created for Master and Ph.D. students interested in applying microfluidics to their research and, therefore, followed an application-oriented approach. The presentation of critical aspects of fluid flow phenomena at the microscale and an outline of the advantages and constraints of the technology provide students with the background to design and perform microfluidics-based experiments. In order to improve the effectiveness of learning in a class with diverse interests and backgrounds, two active learning exercises were implemented. The first comprised the design of an individualized microfluidics experiment in parallel with the lectures: students were guided to apply each module to their personalized application and discuss it in groups. The second was a group experimental activity, in which students jointly set up, performed, analyzed, and presented a microfluidics-based experiment. Given the multidisciplinary teaching context, the course was able to foster common conceptual ground and promote discussion among students. This application-oriented approach built upon experimental activities and in-class discussion is well suited to promote learning in a technology-related subject such as microfluidics.  相似文献   

2.
Cell movement is highly sensitive to stimuli from the extracellular matrix and media. Receptors on the plasma membrane in cells can activate signal transduction pathways that change the mechanical behavior of a cell by reorganizing motion-related organelles. Cancer cells change their migration mechanisms in response to different environments more robustly than noncancer cells. Therefore, therapeutic approaches to immobilize cancer cells via inhibition of the related signal transduction pathways rely on a better understanding of cell migration mechanisms. In recent years, engineers have been working with biologists to apply microfluidics technology to study cell migration. As opposed to conventional cultures on dishes, microfluidics deals with the manipulation of fluids that are geometrically constrained to a submillimeter scale. Such small scales offer a number of advantages including cost effectiveness, low consumption of reagents, high sensitivity, high spatiotemporal resolution, and laminar flow. Therefore, microfluidics has a potential as a new platform to study cell migration. In this review, we summarized recent progress on the application of microfluidics in cancer and other cell migration researches. These studies have enhanced our understanding of cell migration and cancer invasion as well as their responses to subtle variations in their microenvironment. We hope that this review will serve as an interdisciplinary guidance for both biologists and engineers as they further develop the microfluidic toolbox toward applications in cancer research.  相似文献   

3.
Microfluidics offers unique ways of handling and manipulating microorganisms, which has particularly benefited Caenorhabditis elegans research. Optics plays a major role in these microfluidic platforms, not only as a read-out for the biological systems of interest but also as a vehicle for applying perturbations to biological systems. Here, we describe different areas of research in C. elegans developmental biology and behavior neuroscience enabled by microfluidics combined with the optical components. In particular, we highlight the diversity of optical tools and methods in use and the strategies implemented in microfluidics to make the devices compatible with optical techniques. We also offer some thoughts on future challenges in adapting advancements in optics to microfluidic platforms.  相似文献   

4.
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5.
Herein, we demonstrate a novel method for the generation of monodisperse cell-like structures containing a biocompatible hydrogel matrix surrounded by a membrane responsive to chemical cues. Specifically, we employ droplet-based microfluidics to generate PEG-PLA polymersomes encapsulating alginate in liquid form. We investigate alginate core gelation by creating an osmotic pressure gradient across the polymeric membrane that, through expansion, allows the passage of calcium ions. The effects of calcium concentration on the core gelation are explored.  相似文献   

6.
Electro wetting-on-dielectric (EWOD) digital microfluidics (DMF) can be used to develop improved chemical screening platforms using 3-dimensional (3D) cell culture. Alginate hydrogels are one common method by which a 3D cell culture environment is created. This paper presents a study of alginate gelation on EWOD DMF and investigates designs to obtain uniform alginate hydrogels that can be repeatedly addressed by any desired liquids. A design which allows for gels to be retained in place during liquid delivery and removal without using any physical barriers or hydrophilic patterning of substrates is presented. A proof of concept screening platform is demonstrated by examining the effects of different concentrations of a test chemical on 3D cells in alginate hydrogels. In addition, the temporal effects of the various chemical concentrations on different hydrogel posts are demonstrated, thereby establishing the benefits of an EWOD DMF 3D cell culture and chemical screening platform using alginate hydrogels.  相似文献   

7.
The inaugural conference on Advances in Microfluidics and Nanofluidics was held at the Hong Kong University of Science and Technology on 5–7 January 2009 and brought together leading researchers from across a wide variety of disciplines from North America, Europe, Asia, and Oceania. This Special Topic section forms the second of the two issues dedicated to original contributions covering both fundamental physicochemical aspects of microfluidics and nanofluidics as well as their applications to the miniaturization of chemical and biological systems that were presented at the conference.In the last five years, we have observed rapid growth in the microfluidics and nanofluidics community in Asia, owing largely to the substantial strategic investments by both government and industry in the region to promote the microfabrication and nanotechnology sectors.1 The organization of a regular meeting focusing on activities in the Asia-Pacific rim region was, therefore, timely, particularly to enhance dissemination of research of the highest quality within the region and to promote collaboration between researchers in the Asian community with their counterparts from Europe and the USA.Biomicrofluidics is, therefore, proud to be closely involved with the organization of the first of such conferences, Advances in Microfluidics and Nanofluidics 2009, which was kindly hosted by the Hong Kong University of Science and Technology (HKUST). As reported in the preface to the first of the two issues dedicated to invited reviews and original contributions associated with the conference,2 the meeting, which took place over three days in the breathtaking HKUST campus overlooking Clearwater Bay in Hong Kong, was a tremendous success. Together with our colleagues, the Biomicrofluidics editors are busy putting in place arrangements for a follow-up meeting in January 2011. Given the overwhelming response and positive feedback we’ve had to date, we believe that Advances in Microfluidics and Nanofluidics will form a regular event in the calendar of the Asian microfluidics and nanofluidics community in the future.It was particularly pleasing to observe the translation of fundamental and theoretical work into advanced applied chip-based platforms for a variety of practical chemical and biological applications in the talks presented at the conference. The collection of articles in this second part, in fact, provides a gist of the flavor of the multidisciplinary research spanning the entire fundamental to applied research spectrum, which is exactly the scope which the journal intends to cover.Electrokinetics continues to be a dominant theme in this issue and within the microfluidics and nanofluidics community. The article by Ng et al.3 provides experimental evidence that might put to rest a longstanding area of debate within the electrokinetics community on the role of Faradaic charging in driving electro-osmotic flow, first proposed by Ben and Chang.4 In other electrokinetics papers, the role of interfaces is explored, for example, electrowetting on the superhydrophobic nanostructured surfaces of a lotus leaf5 and droplet manipulation in an immiscible dielectric liquid continuum under an electric field.6In addition, the characterization of the surface charge density of the nanopores etched in organic foils is reported by Xue et al.,7 which provides a deeper understanding of the mechanisms by which ions are transported in nanochannels, whereas Wei and Hsiao8 present a stochastic simulation to model the condensation of linear polyelectrolyte molecules under electric fields, in which they show the marked increase in the mobility of the polyelectrolyte chain during its unfolding in free-solution electrophoresis.Continuing along the theme of numerical simulations, particulate transport in converging-diverging microchannels was studied using a Lagrangian-Eulerian finite-element model,9 and slip arising in Couette flows over superhydrophobic surfaces was studied using a hybrid multiscale simulation that interfaces molecular dynamics simulations in the near-wall region with the continuum fluid model in the bulk.10 In other numerical studies, drop coalescence11 and nanotube transport12 were studied.Complementing these fundamental studies is the use of multiphase flows in microfluidic channels to engineer scaffolds for tissue engineering in which the bubbles trapped in liquid droplets transported in microchannels were employed to produced the pores of the scaffold.13 Other practical microfluidics applications, such as chip-based enhancement of DNA hybridization through a genetic-bead-based protocol14 and an automated ELISA chip for chemical-biological analysis with an enhancement in the detection range and time,15 also constitute papers in this Special Topic section.We hope you enjoy reading the papers in this Special Topic section and that it provides you with a feel for the broad multidisciplinary spectrum across fundamental and applied microfluidic and nanofluidic research that the conference, as well as the journal, intends to span. Do watch out for the conference announcement for the next Advances in Microfluidics and Nanofluidics meeting in 2011 on the Biomicrofluidics website (http://bmf.aip.org)—hope to see you there!  相似文献   

8.
This Special Topic section is a compilation of several original contributions covering both fundamental and practical aspects of electrokinetic microfluidic phenomena that were presented during the Electrokinetics and Microfluidics sessions held at the conference.Electrokinetics is currently the mechanism of choice for the manipulation of fluids as well as colloidal and biological particles at microscale and nanoscale dimensions.1 The popularity of electrokinetics is perhaps not so surprising as electrodes are easy to fabricate and embed into microfluidic chips, thus allowing the entire fluid and particle actuation mechanism to be completely integrated into the device. In addition, driving microfluidics with electric fields is relatively straightforward and allows for precise actuation. Nevertheless, considerable challenges remain in understanding the complex mechanisms associated with the hydrodynamics of conducting and dielectric fluids and particles under the influence of electric fields. Concomitantly, there has been an exponential increase in research and development in this field along both fundamental and applied themes in the past five years.This sustained growth in the microfluidics community of electrokinetics research has led to a sequel to the first Electrokinetic Phenomena and Microfluidics session at the 82nd ACS Colloid and Surface Science Symposium in Raleigh, NC, in 2008, and which we hope will now be a regular feature at successive ACS Colloid and Surface Science meetings. This year at the combined 2009 13th International Conference on Surface and Colloid Science (ICSCS) and the 83rd ACS Colloid and Surface Science Symposium in New York, the Electrokinetics and Microfluidics symposium proved to be extremely popular, with three keynote lectures presented by Professor Howard Stone, Professor Hsueh-Chia Chang, and Professor Thomas Healy, and 44 oral presentations. In both 2008 and 2009, Biomicrofluidics has organized a special issue to cover some of the contributions reported at these meetings.2The growing interest in using electric fields to manipulate biological entities such as cells, DNA, and even single molecules is reflected in this year’s collection of papers with dielectrophoretic (DEP) phenomena comprising the bulk of the contributions. In Ref. 3, a new theory to describe Stern layer conductance along the surface of nanocolloids is proposed, forming the basis for the derivation of a more accurate prediction of the DEP crossover frequency. This theory is then employed to determine the conformation and, hence, optimum coverage of oligonucleotides on the surface of nanocolloid functionalized molecular probes during DNA hybridization under the influence of DEP, which can be exploited for biomolecular sensing. Other fundamental DEP papers include the investigation of particle motion under DEP induced optically via a photoconductor, in which Zhu et al.4 characterized the frequency dependence of the motion through the synchronous velocity spectra of the particles, and a numerical study of particle trapping at the throat of converging-diverging microchannels under the influence of negative DEP using a transient arbitrary Lagrangian–Eulerian finite element method.5 A more practical implementation is, on the other hand, reported by Yang et al.6 in which the negative DEP is exploited to separate colorectal cancer cells from other cells in a microfluidic device as a demonstration of a portable cancer detection tool.Continuing along the separation theme, but with regard to DNA separation using pulsed-field gel electrophoresis aided by sparse but regularly ordered microfabricated arrays of nanoposts, is a Brownian dynamics simulation model reported by Ou et al.7 in which DNA channeling, which predicts that the motion of DNA is undisturbed by the presence of arrays for large spacing to DNA equilibrium size ratios and when the field lines are straight, is predicted, consistent with experimental observations. In another fundamental paper, a direct numerical simulation model is presented to predict the current-voltage relationship across conducting pores along cell membranes, which is of fundamental importance in the electroporation process.8We hope that you will enjoy reading the contributions in this special topic and that it encourages you to participate in future Electrokinetics and Microfluidics meetings at the ACS Colloid and Surface Science Symposia, which we definitely hope will continue on a regular basis.  相似文献   

9.
Microfluidics approaches have gained popularity in the field of directed cell migration, enabling control of the extracellular environment and integration with live-cell microscopy; however, technical hurdles remain. Among the challenges are the stability and predictability of the environment, which are especially critical for the observation of fibroblasts and other slow-moving cells. Such experiments require several hours and are typically plagued by the introduction of bubbles and other disturbances that naturally arise in standard microfluidics protocols. Here, we report on the development of a passive pumping strategy, driven by the high capillary pressure and evaporative capacity of paper, and its application to study fibroblast chemotaxis. The paper pumps—flowvers (flow + clover)—are inexpensive, compact, and scalable, and they allow nearly bubble-free operation, with a predictable volumetric flow rate on the order of μl/min, for several hours. To demonstrate the utility of this approach, we combined the flowver pumping strategy with a Y-junction microfluidic device to generate a chemoattractant gradient landscape that is both stable (6+ h) and predictable (by finite-element modeling calculations). Integrated with fluorescence microscopy, we were able to recapitulate previous, live-cell imaging studies of fibroblast chemotaxis to platelet derived growth factor (PDGF), with an order-of-magnitude gain in throughput. The increased throughput of single-cell analysis allowed us to more precisely define PDGF gradient conditions conducive for chemotaxis; we were also able to interpret how the orientation of signaling through the phosphoinositide 3-kinase pathway affects the cells’ sensing of and response to conducive gradients.  相似文献   

10.
Cell culture in microfluidic systems has primarily been conducted in devices comprised of polydimethylsiloxane (PDMS) or other elastomers. As polystyrene (PS) is the most characterized and commonly used substrate material for cell culture, microfluidic cell culture would ideally be conducted in PS-based microsystems that also enable tight control of perfusion and hydrodynamic conditions, which are especially important for culture of vascular cell types. Here, we report a simple method to prototype perfusable PS microfluidics for endothelial cell culture under flow that can be fabricated using standard lithography and wet laboratory equipment to enable stable perfusion at shear stresses up to 300 dyn/cm2 and pumping pressures up to 26 kPa for at least 100 h. This technique can also be extended to fabricate perfusable hybrid PS-PDMS microfluidics of which one application is for increased efficiency of viral transduction in non-adherent suspension cells by leveraging the high surface area to volume ratio of microfluidics and adhesion molecules that are optimized for PS substrates. These biologically compatible microfluidic devices can be made more accessible to biological-based laboratories through the outsourcing of lithography to various available microfluidic foundries.  相似文献   

11.
Cell migration is an essential process involved in the development and maintenance of multicellular organisms. Electric fields (EFs) are one of the many physical and chemical factors known to affect cell migration, a phenomenon termed electrotaxis or galvanotaxis. In this paper, a microfluidics chip was developed to study the migration of cells under different electrical and chemical stimuli. This chip is capable of providing four different strengths of EFs in combination with two different chemicals via one simple set of agar salt bridges and Ag/AgCl electrodes. NIH 3T3 fibroblasts were seeded inside this chip to study their migration and reactive oxygen species (ROS) production in response to different EF strengths and the presence of β-lapachone. We found that both the EF and β-lapachone level increased the cell migration rate and the production of ROS in an EF-strength-dependent manner. A strong linear correlation between the cell migration rate and the amount of intracellular ROS suggests that ROS are an intermediate product by which EF and β-lapachone enhance cell migration. Moreover, an anti-oxidant, α-tocopherol, was found to quench the production of ROS, resulting in a decrease in the migration rate.  相似文献   

12.
Paper-based microfluidics are an increasingly popular alternative to devices with conventional open channel geometries. The low cost of fabrication and the absence of external instrumentation needed to drive paper microchannels make them especially well suited for medical diagnostics in resource-limited settings. Despite the advantages of paper microfluidics, many assays performed using conventional open channel microfluidics are challenging to translate onto paper, such as bead, emulsion, and cell-based assays. To overcome this challenge, we have developed a hybrid open-channel/paper channel microfluidic device. In this design, wick-driven paper channels control the flow rates within conventional microfluidics. We fabricate these hybrid chips using laser-micromachined polymer sheets and filter paper. In contrast to previous efforts that utilized external, macroscopic paper-based pumps, we integrated micro-scale paper and open channels onto a single chip to control multiple open channels and control complex laminar flow-pattern within individual channels. We demonstrated that flow patterns within the open channels can be quantitatively controlled by modulating the geometry of the paper channels, and that these flow rates agree with Darcy''s law. The utility of these hybrid chips, for applications such as bead-, cell-, or emulsion-based assays, was demonstrated by constructing a hybrid chip that hydrodynamically focused micrometer-sized polystyrene beads stably for >10 min, as well as cells, without external instrumentation to drive fluid flow.  相似文献   

13.
Ryan D  Ren K  Wu H 《Biomicrofluidics》2011,5(2):21501
This review presents an overview of literature that describes the applications of microfluidics to assay individual cells. We quantify the content of an individual mammalian cell, so that we can understand what criteria a single-cell assay must satisfy to be successful. We put in context the justification for single-cell assays and identify the characteristics that are relevant to single-cell assays. We review the literature from the past 24 months that describe the methods that use microfabrication-conventional or otherwise-and microfluidics in particular to study individual cells, and we present our views on how an increasing emphasis on three-dimensional cell culture and the demonstration of the first chemically defined cell might impact single-cell assays.  相似文献   

14.
Inertial microfluidics has brought enormous changes in the conventional cell/particle detection process and now become the main trend of sample pretreatment with outstanding throughput, low cost, and simple control method. However, inertial microfluidics in a straight microchannel is not enough to provide high efficiency and satisfying performance for cell/particle separation. A contraction–expansion microchannel is a widely used and multifunctional channel pattern involving inertial microfluidics, secondary flow, and the vortex in the chamber. The strengthened inertial microfluidics can help us to focus particles with a shorter channel length and less processing time. Both the vortex in the chamber and the secondary flow in the main channel can trap the target particles or separate particles based on their sizes more precisely. The contraction–expansion microchannels are also capable of combining with a curved, spiral, or serpentine channel to further improve the separation performance. Some recent studies have focused on the viscoelastic fluid that utilizes both elastic forces and inertial forces to separate different size particles precisely with a relatively low flow rate for the vulnerable cells. This article comprehensively reviews various contraction–expansion microchannels with Newtonian and viscoelastic fluids for particle focusing, separation, and microfluid mixing and provides particle manipulation performance data analysis for the contraction–expansion microchannel design.  相似文献   

15.
A review is presented of the present status of the theory, the developed technology and the current applications of dielectrophoresis (DEP). Over the past 10 years around 2000 publications have addressed these three aspects, and current trends suggest that the theory and technology have matured sufficiently for most effort to now be directed towards applying DEP to unmet needs in such areas as biosensors, cell therapeutics, drug discovery, medical diagnostics, microfluidics, nanoassembly, and particle filtration. The dipole approximation to describe the DEP force acting on a particle subjected to a nonuniform electric field has evolved to include multipole contributions, the perturbing effects arising from interactions with other cells and boundary surfaces, and the influence of electrical double-layer polarizations that must be considered for nanoparticles. Theoretical modelling of the electric field gradients generated by different electrode designs has also reached an advanced state. Advances in the technology include the development of sophisticated electrode designs, along with the introduction of new materials (e.g., silicone polymers, dry film resist) and methods for fabricating the electrodes and microfluidics of DEP devices (photo and electron beam lithography, laser ablation, thin film techniques, CMOS technology). Around three-quarters of the 300 or so scientific publications now being published each year on DEP are directed towards practical applications, and this is matched with an increasing number of patent applications. A summary of the US patents granted since January 2005 is given, along with an outline of the small number of perceived industrial applications (e.g., mineral separation, micropolishing, manipulation and dispensing of fluid droplets, manipulation and assembly of micro components). The technology has also advanced sufficiently for DEP to be used as a tool to manipulate nanoparticles (e.g., carbon nanotubes, nano wires, gold and metal oxide nanoparticles) for the fabrication of devices and sensors. Most efforts are now being directed towards biomedical applications, such as the spatial manipulation and selective separation∕enrichment of target cells or bacteria, high-throughput molecular screening, biosensors, immunoassays, and the artificial engineering of three-dimensional cell constructs. DEP is able to manipulate and sort cells without the need for biochemical labels or other bioengineered tags, and without contact to any surfaces. This opens up potentially important applications of DEP as a tool to address an unmet need in stem cell research and therapy.  相似文献   

16.
Li X  Ballerini DR  Shen W 《Biomicrofluidics》2012,6(1):11301-1130113
"Paper-based microfluidics" or "lab on paper," as a burgeoning research field with its beginning in 2007, provides a novel system for fluid handling and fluid analysis for a variety of applications including health diagnostics, environmental monitoring as well as food quality testing. The reasons why paper becomes an attractive substrate for making microfluidic systems include: (1) it is a ubiquitous and extremely cheap cellulosic material; (2) it is compatible with many chemical/biochemical/medical applications; and (3) it transports liquids using capillary forces without the assistance of external forces. By building microfluidic channels on paper, liquid flow is confined within the channels, and therefore, liquid flow can be guided in a controlled manner. A variety of 2D and even 3D microfluidic channels have been created on paper, which are able to transport liquids in the predesigned pathways on paper. At the current stage of its development, paper-based microfluidic system is claimed to be low-cost, easy-to-use, disposable, and equipment-free, and therefore, is a rising technology particularly relevant to improving the healthcare and disease screening in the developing world, especially for those areas with no- or low-infrastructure and limited trained medical and health professionals. The research in paper-based microfluidics is experiencing a period of explosion; most published works have focused on: (1) inventing low-cost and simple fabrication techniques for paper-based microfluidic devices; and (2) exploring new applications of paper-based microfluidics by incorporating efficient detection methods. This paper aims to review both the fabrication techniques and applications of paper-based microfluidics reported to date. This paper also attempts to convey to the readers, from the authors' point of view the current limitations of paper-based microfluidics which require further research, and a few perspective directions this new analytical system may take in its development.  相似文献   

17.
This Special Topic section of Biomicrofluidics contains original contributions that were presented at the 82nd Colloid and Surface Science Symposium, which took place on 15–18 June 2008 at North Carolina State University. The Symposium covered a wide range of topics that are relevant to the fundamentals of fluidics and their application to biological systems.The recent interest in microfluidics and nanofluidics is constantly increasing due to the numerous applications that these techniques have to offer. They have been used for chemical and biomolecular sensing, separation of charged analytes, and single DNA molecule manipulation. These applications were facilitated by the significant increase in the range of advanced microfabrication and nanofabrication techniques. Improving and extending the range of applicability of micro- and nanofluidic techniques also requires better fundamental understanding of the physics of the transport at small length scales. The transport of fluids and solutes in microchannels and nanochannels usually occurs at very small Reynolds regime. The typical length scale and the surface forces (electrostatic, van der Waals, hydrophobic, hydration, etc.) may be comparable to the size of the channels. All these features often require the development of new experimental techniques and approaches for theoretical analysis.The importance and the substantial recent interest in micro- and nanofluidics prompted the organization of a special session on Electrokinetic Phenomena and Microfluidics as part of the program at the 82nd Colloid and Surface Science Symposium at North Carolina State University in June 2008. The collected papers in this issue of Biomicrofluidics cover some of the very important fundamental and engineering aspects of electrokinetic phenomena in micro- and nanofluidic channels. These include molecular dynamics simulation of biomolecules in confined spaces, analysis of the electric double layer effects on the fluid flow in nanochannels, hydrodynamic resistance to droplet motion in microchannels, electrophoresis in nanocomposite gels, and microfluidics for nanoparticle fabrication. The paper by Srivastava et al.1 explores the possibility of using microfluidics for fabrication of Janus nanofibers. Chang2 presented a theoretical analysis of the electro-osmosis on a salt-free microchannel by simultaneously solving the nonlinear Poisson–Boltzmann equation for the electrostatic potential distribution and the Navier–Stokes equations for the fluid flow. Trahan and Doyle3 reported theoretical analysis of DNA molecule interaction with obstacles in a microchannel. Finally, Labrot et al.4 presented studies on the droplet hydrodynamic resistance in a microfluidic channel.We hope that the reader will find the papers useful and informative.  相似文献   

18.
Detection of individual target cells among a large amount of blood cells is a major challenge in clinical diagnosis and laboratory protocols. Many researches show that two dimensional cells array technology can be incorporated into routine laboratory procedures for continuously and quantitatively measuring the dynamic behaviours of large number of living cells in parallel, while allowing other manipulations such as staining, rinsing, and even retrieval of targeted cells. In this study, we present a high-density cell self-assembly technology capable of quickly spreading over 300 000 cells to form a dense mono- to triple-layer cell arrangement in 5 min with minimal stacking of cells by the gentle incorporation of gravity and peripheral micro flow. With this self-assembled cell arrangement (SACA) chip technology, common fluorescent microscopy and immunofluorescence can be utilized for detecting and analyzing target cells after immuno-staining. Validated by experiments with real human peripheral blood samples, the SACA chip is suitable for detecting rare cells in blood samples with a ratio lower than 1/100 000. The identified cells can be isolated and further cultured in-situ on a chip for follow-on research and analysis. Furthermore, this technology does not require external mechanical devices, such as pump and valves, which simplifies operation and reduces system complexity and cost. The SACA chip offers a high-efficient, economical, yet simple scheme for identification and analysis of rare cells. Therefore, potentially SACA chip may provide a feasible and economical platform for rare cell detection in the clinic.  相似文献   

19.
Assessment of the microbial safety of water resources is among the most critical issues in global water safety. As the current detection methods have limitations such as high cost and long process time, new detection techniques have transpired among which microfluidics is the most attractive alternative. Here, we show a novel hybrid dielectrophoretic (DEP) system to separate and detect two common waterborne pathogens, Escherichia coli (E. coli), a bacterium, and Cryptosporidium parvum (C. parvum), a protozoan parasite, from water. The hybrid DEP system integrates a chemical surface coating with a microfluidic device containing inter-digitated microelectrodes to impart positive dielectrophoresis for enhanced trapping of the cells. Trimethoxy(3,3,3-trifluoropropyl) silane, (3-aminopropyl)triethoxysilane, and polydiallyl dimethyl ammonium chloride (p-DADMAC) were used as surface coatings. Static cell adhesion tests showed that among these coatings, the p-DADMAC-coated glass surface provided the most effective cell adhesion for both the pathogens. This was attributed to the positively charged p-DADMAC-coated surface interacting electrostatically with the negatively charged cells suspended in water leading to increased cell trapping efficiency. The trapping efficiency of E. coli and C. parvum increased from 29.0% and 61.3% in an uncoated DEP system to 51.9% and 82.2% in the hybrid DEP system, respectively. The hybrid system improved the cell trapping by encouraging the formation of cell pearl-chaining. The increment in trapping efficiency in the hybrid DEP system was achieved at an optimal frequency of 1 MHz and voltage of 2.5 Vpp for C. parvum and 2 Vpp for E. coli, the latter is lower than 2.5 Vpp and 7 Vpp, respectively, utilized for obtaining similar efficiency in an uncoated DEP system.  相似文献   

20.
The introduction of surface acoustic wave (SAW) technology on microfluidics has shown its powerfully controlling and actuating fluid and particle capability in a micro-nano scale, such as fluid mixing, fluid translation, microfluidic pumping, microfluidic rotational motor, microfluidic atomization, particle or cell concentration, droplet or cell sorting, reorientation of nano-objects, focusing and separation of particles, and droplet jetting. The SAW-driven droplet jetting technology enjoys the advantages of simple structure to fabricate with little hindrance, compact size to integrate with other components, high biocompatibility with biological cells or other molecule samples, large force in realizing fast fluidic actuation, and contact-free manipulation with fluid. The realization of this technology can effectively overcome some bottleneck problems in the current micro-injection technology, such as mechanical swear, complicated and bulky structure, and strict limitation of requirements on fluidic characteristics. This article reviews and reorganizes SAW-microfluidic jetting technology from decades of years, referring to the interaction mechanism theory of SAW and fluid, experimental methods of SAW-microfluidic jetting, effects of related parameters on objected pinch-off droplets, and applications of individual structures. Finally, we made a summary of the research results of the current literature and look forward and appraise where this discipline of SAW-microfluidic jetting could go in the future.  相似文献   

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