Digital microfluidics with pressure-based actuation

One of the key issues in biosensors is the time it takes for biomolecules in a solution to reach and bind to the sensor surface (particularly in low-concentration analytes). We present a novel flow scheme without microfluidic channels for label-free biosensors to decrease the delivery time of biomolecules. Through designing the biosensor in such a way that it becomes a membrane with holes, we can apply a droplet on it and push or pull it through the membrane by means of a pressure difference. Contrary to traditional microfluidics for, e.g., flow cells where the analyte flows over the sensor, the flow is now directed through the sensor. We have implemented this scheme in silicon-on-insulator biosensors and have demonstrated in a first proof-of-principle experiment, an improvement in delivery time of at least a factor of three

Optical imaging techniques in microfluidics and their applications

Microfluidic devices have undergone rapid development in recent years and provide a lab-on-a-chip solution for many biomedical and chemical applications. Optical imaging techniques are essential in microfluidics for observing and extracting information from biological or chemical samples. Traditionally, imaging in microfluidics is achieved by bench-top conventional microscopes or other bulky imaging systems. More recently, many novel compact microscopic techniques have been developed to provide a low-cost and portable solution. In this review, we provide an overview of optical imaging techniques used in microfluidics followed with their applications. We first discuss bulky imaging systems including microscopes and interferometer-based techniques, then we focus on compact imaging systems that can be better integrated with microfluidic devices, including digital in-line holography and scanning-based imaging techniques. The applications in biomedicine or chemistry are also discussed along with the specific imaging techniques

Shaping and transporting diamagnetic sessile drops

Electromagnetic fields are commonly used to control small quantities of fluids in microfluidics and digital microfluidics. Magnetic control techniques are less well studied than their electric counterparts, with only a few investigations into liquid diamagnetism. The ratio of magnetic to surface energy (magnetic Bond number B m) is an order of magnitude smaller for diamagnetic drops (B m ≈-0.3 at 1.2 T applied field) than for paramagnetic drops (B m ≈ 9.0 at 1.2 T applied field). This weaker interaction between the magnetic field and the diamagnetic drop has led to the phenomenon being overlooked in digital microfluidics. Here, we investigate shaping and transport of diamagnetic drops using magnetostatic fields. Our findings highlight how diamagnetic fluids can be used as a novel tool in the toolbox of microfluidics and digital microfluidics

Current commercialization status of electrowetting-on-dielectric (EWOD) digital microfluidics.

The emergence of electrowetting-on-dielectric (EWOD) in the early 2000s made the once-obscure electrowetting phenomenon practical and led to numerous activities over the last two decades. As an eloquent microscale liquid handling technology that gave birth to digital microfluidics, EWOD has served as the basis for many commercial products over two major application areas: optical, such as liquid lenses and reflective displays, and biomedical, such as DNA library preparation and molecular diagnostics. A number of research or start-up companies (e.g., Phillips Research, Varioptic, Liquavista, and Advanced Liquid Logic) led the early commercialization efforts and eventually attracted major companies from various industry sectors (e.g., Corning, Amazon, and Illumina). Although not all of the pioneering products became an instant success, the persistent growth of liquid lenses and the recent FDA approvals of biomedical analyzers proved that EWOD is a powerful tool that deserves a wider recognition and more aggressive exploration. This review presents the history around major EWOD products that hit the market to show their winding paths to commercialization and summarizes the current state of product development to peek into the future. In providing the readers with a big picture of commercializing EWOD and digital microfluidics technology, our goal is to inspire further research exploration and new entrepreneurial adventures

Advances in Microfluidics and Lab-on-a-Chip Technologies

Advances in molecular biology are enabling rapid and efficient analyses for effective intervention in domains such as biology research, infectious disease management, food safety, and biodefense. The emergence of microfluidics and nanotechnologies has enabled both new capabilities and instrument sizes practical for point-of-care. It has also introduced new functionality, enhanced sensitivity, and reduced the time and cost involved in conventional molecular diagnostic techniques. This chapter reviews the application of microfluidics for molecular diagnostics methods such as nucleic acid amplification, next-generation sequencing, high resolution melting analysis, cytogenetics, protein detection and analysis, and cell sorting. We also review microfluidic sample preparation platforms applied to molecular diagnostics and targeted to sample-in, answer-out capabilities

Yield Enhancement of Digital Microfluidics-Based Biochips Using Space Redundancy and Local Reconfiguration

As microfluidics-based biochips become more complex, manufacturing yield will have significant influence on production volume and product cost. We propose an interstitial redundancy approach to enhance the yield of biochips that are based on droplet-based microfluidics. In this design method, spare cells are placed in the interstitial sites within the microfluidic array, and they replace neighboring faulty cells via local reconfiguration. The proposed design method is evaluated using a set of concurrent real-life bioassays.Comment: Submitted on behalf of EDAA (http://www.edaa.com/

Testing microelectronic biofluidic systems

According to the 2005 International Technology Roadmap for Semiconductors, the integration of emerging nondigital CMOS technologies will require radically different test methods, posing a major challenge for designers and test engineers. One such technology is microelectronic fluidic (MEF) arrays, which have rapidly gained importance in many biological, pharmaceutical, and industrial applications. The advantages of these systems, such as operation speed, use of very small amounts of liquid, on-board droplet detection, signal conditioning, and vast digital signal processing, make them very promising. However, testable design of these devices in a mass-production environment is still in its infancy, hampering their low-cost introduction to the market. This article describes analog and digital MEF design and testing method

Digitális mikrofluidika = Digital Microfluidics

A projekt során létrehoztunk felül nyitott és zárt digitális mikrofluidikai eszközöket (NYÁK lapokat), melyekhez az elektromosan változtatható nedvesítés elvét, mint a folyadékcsepp mozgatásának alapelvét felhasználva, vezérlő áramkört és szoftvert illesztettünk. A fejlesztéshez szükség volt az elektródrendszer többszöri átdolgozására, valamint a felület speciális vékonyréteges kezelésére, szigetelőként PDMS elasztomer, hidrofób felületként Teflon polimer felhasználásával. A fejlesztéssel párhuzamosan új mikrofluidikai csatornákban olyan kémiai és biológiai vizsgálatokat végeztünk el, amelyek ellenőrző, illetve elővizsgálatok lehetnek egy digitális mikrofluidikai rendszerben való megvalósításhoz. A projekt elején beszerzett sztereomikroszkóp és kamera felhasználásával olyan rendszert alakítottunk ki, amellyel valós időben lehet vizsgálni a chipen végbemenő változásokat, valamint több detektálási módszert is implementáltunk. Egy gyors kameraszámítógép felhasználásával áramlási citometriás mikrofluidikai eszközt hoztunk létre, amely eredményeinket 2 konferenciakiadványban publikáltunk. A projekt keretében megvásárolt COMSOL Multiphysics szoftverrel numerikus modellszámításokkal alátámasztottuk és igazoltuk mind a digitális mikrofluidikai cseppmozgatást és dinamikákat, mind a párhuzamosan végzett elővizsgálatokhoz szükséges mikrocsatornák optimális elrendezését és működését. | During the project years we have developed open and closed digital microfluidic devices (on PCB substrates). These devices are providing fluid droplet transports using the electrowetting on dielectric phenomenon as the droplet actuation effect. This has been achieved by developing appropriate driving circuitry and software. The development included several design improvement cycles of the electrode matrix and application of different thin films to the electrodes. The final surface treatment is a thin layer of PDMS elastomer as the dielectric and another thin layer of Teflon polymer as the hydrophobic surface. New microfluidic channel systems have been designed parallel to these developments where experimental chemical and biological analyses have been conducted. These experiments were preliminary tests to their application in digital microfluidic devices. The stereomicroscope and the camera purchased at the beginning have been combined and further developed into a real-time chip monitoring system and different detection schemes were implemented. A high-fps camera computer was combined with this device to produce a novel flow cytomety device in a microfluidic environment. These results have been published in 2 conference proceedings. A numerical simulation software (COMSOL Multiphysics) have been used to confirm droplet movements and wetting dynamics, furthermore it has been utilized to characterize and optimize microfluidic channel geometry of the preliminary test devices