We present a new peristaltic micropump offering three key features: (i) a disposable pump body and a re-useable actuator unit, (ii) an intrinsic normally-closed mechanism blocking unintended liquid flows up to a pressure of 100kPa and (iii) a backpressure independent pump performance up to 40kPa. The modular concept basing on a re-usable actuator unit and a low-cost disposable microfluidic chip enables an easy and cost-efficient exchange of all contaminated parts after use, which addresses especially the needs in the health care sector. The intrinsic normally-closed feature blocks liquid flow in both directions up to a pressure difference of 100kPa when the electric power is off. The micropump is actuated in a peristaltic manner by three piezostack actuators. Up to a frequency of 15Hz the pump rate increases linearly with operation frequency leading to a pump rate of 120μL/min. This was proved for an operation voltage of 140V by pumping water. In addition the pump rate is independent on backpressure up to 40kPa and shows a linear decrease for higher pressure differences. The maximum achievable backpressure at zero flow rate was extrapolated to be 180kPa. As for all peristaltic micropumps, the pump is bidirectional, e.g. the pump direction can be changed forward to reverse mode.

This paper presents a novel Peristaltic Micro Pump with a twofold intrinsic Normally-Closed mechanism (PMP-NC2). It is based on a modular concept with a low cost disposable microfluidic chip and a re-usable actuator unit. The normally-closed mechanism prevents fluid flow without power consumption in the stand-by mode for pressures up to 150 kPa. Together with the backpressure independent pumping performance up to 80 kPa this results in a fail-safe and precise micropump. The addressed range of pump rates is up to 100 mu L/min. Due to the symmetrical setup, bi-directional pumping is possible and also air bubble tolerance is demonstrated. This results from the very low dead volume per pump chamber of only 230 nL, which leads to a complete transport of the air bubbles through the pump.

This critical review summarizes developments in microfluidic platforms that enable the miniaturization, integration, automation and parallelization of (bio-)chemical assays (see S. Haeberle and R. Zengerle, Lab Chip , 2007, 7 , 1094–1110, for an earlier review). In contrast to isolated application-specific solutions, a microfluidic platform provides a set of fluidic unit operations, which are designed for easy combination within a well-defined fabrication technology. This allows the easy, fast, and cost-efficient implementation of different application-specific (bio-)chemical processes. In our review we focus on recent developments from the last decade (2000s). We start with a brief introduction into technical advances, major market segments and promising applications. We continue with a detailed characterization of different microfluidic platforms, comprising a short definition, the functional principle, microfluidic unit operations, application examples as well as strengths and limitations of every platform. The microfluidic platforms in focus are lateral flow tests, linear actuated devices, pressure driven laminar flow, microfluidic large scale integration, segmented flow microfluidics, centrifugal microfluidics, electrokinetics, electrowetting, surface acoustic waves, and dedicated systems for massively parallel analysis. This review concludes with the attempt to provide a selection scheme for microfluidic platforms which is based on their characteristics according to key requirements of different applications and market segments. Applied selection criteria comprise portability, costs of instrument and disposability, sample throughput, number of parameters per sample, reagent consumption, precision, diversity of microfluidic unit operations and the flexibility in programming different liquid handling protocols (295 references).

This paper presents a novel Peristaltic MicroPump with a twofold intrinsic Normally-Closed mechanism (PMP-NC). It is based on a modular concept with a low cost disposable microfluidic chip and a re-usable actuator unit. The normally-closed mechanism prevents fluid flow without power consumption in the stand-by mode for pressures up to 150 kPa. Together with the backpressure independent pumping performance up to 80 kPa this results in a fail-safe and precise micropump. The addressed range of pump rates is up to 100 μL/min. Due to the symmetrical setup, bi-directional pumping is possible and also air bubble tolerance is demonstrated. This results from the very low dead volume per pump chamber of only 230 nL, which leads to a complete transport of the air bubbles through the pump.

This review summarizes recent developments in microfluidic platform approaches. In contrast to isolated application-specific solutions, a microfluidic platform provides a set of fluidic unit operations, which are designed for easy combination within a well-defined fabrication technology. This allows the implementation of different application-specific (bio-) chemical processes, automated by microfluidic process integration [1]. A brief introduction into technical advances, major market segments and promising applications is followed by a detailed characterization of different microfluidic platforms, comprising a short definition, the functional principle, microfluidic unit operations, application examples as well as strengths and limitations. The microfluidic platforms in focus are lateral flow tests, linear actuated devices, pressure driven laminar flow, microfluidic large scale integration, segmented flow microfluidics, centrifugal microfluidics, electro-kinetics, electrowetting, surface acoustic waves, and systems for massively parallel analysis. The review concludes with the attempt to provide a selection scheme for microfluidic platforms which is based on their characteristics according to key requirements of different applications and market segments. Applied selection criteria comprise portability, costs of instrument and disposable, sample throughput, number of parameters per sample, reagent consumption, precision, diversity of microfluidic unit operations and the flexibility in programming different liquid handling protocols.

This paper describes a piezostack actuated peristaltic micropump featuring a normally-closed function up to pressures of 100 kPa, when the electric power is off. The design is based on a modular setup with a re-usable actuator unit and a low-cost disposable fluidic chip that can easily be exchanged after contamination or use. Pump rates up to 40 μl/min at 28.6 Hz are demonstrated with water. The flow rates are backpressure independent up to 7 kPa, with a maximum backpressure of 45 kPa at 140 V. Also liquids with high viscosities up to 46 mPas are pumped successfully.

We present a reliable liquid waste containment for centrifugally operated lab-on-a-chip systems that works even for highly wetting reagents. It is based on the passive generation and enclosure of vacuum in a closed storage chamber that prevents all liquids from capillary reflux into the microfluidic channel network. The new waste handling presented here enabled the implementation of an integrated deoxyribonucleic acid (DNA) extraction chemistry without contamination risks based on purely passive structures. Using a 32 muL whole blood sample we achieved an extraction of 290 ng plusmn 80 ng DNA in 100 muL of eluate.

A centrifugally driven pulse-free flow has been used for generation of tripolyphosphate (TPP)-gelated chitosan beads with tunable diameters ranging from 148 to 257 μm. The production process requires a single motor as the sole actively actuated component. The 2% (w/w) chitosan solution was extruded through a polymeric nozzle with an inner diameter of 127 μm in the centrifugal field ranging from 93 to 452g and the drops were collected in an Eppendorf tube containing 10% (w/w) TPP solution at pH 4.0. The reproducibility of the bead diameters out of different nozzles was very good with overall CVs of the bead diameters down to 15% and the production rate was 45 beads per second per nozzle at 44 Hz rotor frequency. The production rate was proportional to the sixth power of the rotor frequency, which was explained by the non-Newtonian behaviour of the chitosan solution with a flow behaviour index of 0.466. An analytical model for the bead diameter and production rate has been presented and validated by the experimental data. The shrinkage of chitosan drops during gelation was estimated from the observations and the theoretical model.

We present a novel method to measure the viscosity of liquid mixtures in µLvolume plugs based on a segmented flow platform [1]. Therefore, up to three different liquids of different viscosities are injected into a common plug which is afterwards transported through an air filled channel by a 15-20 mbar vacuum below ambient pressure at the chip outlet. Rapid mixing within the plugs is enabled by internal advection and the plug velocity directly depends on the viscosity of the plug. Following this approach, the viscosities of water/PEG mixtures in the range of 1-68 mPa s could be successfully measured on-chip.

Chemie Ingenieur TechnikVolume 81, Issue 8 p. 1270-1270 VortragFree Access Mikrofluidik-Plattform zur kontinuierlichen Aufreinigung von Biomolekülen M. Karle, M. Karle marc.karle@hsg-imit.de HSG-IMIT, Wilhelm-Schickard-Straße 10, D-78052 Villingen-Schwenningen, GermanySearch for more papers by this authorJ. Miwa Dr., J. Miwa Dr. Lehrstuhl für Anwendungsentwicklung, Institut für Mikrosystemtechnik (IMTEK), Universität Freiburg, Georges-Köhler-Allee 106, D-79110 Freiburg, GermanySearch for more papers by this authorS. Haeberle Dr., S. Haeberle Dr. HSG-IMIT, Wilhelm-Schickard-Straße 10, D-78052 Villingen-Schwenningen, GermanySearch for more papers by this authorG. Roth Dr., G. Roth Dr. HSG-IMIT, Wilhelm-Schickard-Straße 10, D-78052 Villingen-Schwenningen, Germany Lehrstuhl für Anwendungsentwicklung, Institut für Mikrosystemtechnik (IMTEK), Universität Freiburg, Georges-Köhler-Allee 106, D-79110 Freiburg, GermanySearch for more papers by this authorR. Zengerle Prof. Dr., R. Zengerle Prof. Dr. HSG-IMIT, Wilhelm-Schickard-Straße 10, D-78052 Villingen-Schwenningen, Germany Lehrstuhl für Anwendungsentwicklung, Institut für Mikrosystemtechnik (IMTEK), Universität Freiburg, Georges-Köhler-Allee 106, D-79110 Freiburg, GermanySearch for more papers by this authorF. von Stetten Dr., F. von Stetten Dr. HSG-IMIT, Wilhelm-Schickard-Straße 10, D-78052 Villingen-Schwenningen, Germany Lehrstuhl für Anwendungsentwicklung, Institut für Mikrosystemtechnik (IMTEK), Universität Freiburg, Georges-Köhler-Allee 106, D-79110 Freiburg, GermanySearch for more papers by this author M. Karle, M. Karle marc.karle@hsg-imit.de HSG-IMIT, Wilhelm-Schickard-Straße 10, D-78052 Villingen-Schwenningen, GermanySearch for more papers by this authorJ. Miwa Dr., J. Miwa Dr. Lehrstuhl für Anwendungsentwicklung, Institut für Mikrosystemtechnik (IMTEK), Universität Freiburg, Georges-Köhler-Allee 106, D-79110 Freiburg, GermanySearch for more papers by this authorS. Haeberle Dr., S. Haeberle Dr. HSG-IMIT, Wilhelm-Schickard-Straße 10, D-78052 Villingen-Schwenningen, GermanySearch for more papers by this authorG. Roth Dr., G. Roth Dr. HSG-IMIT, Wilhelm-Schickard-Straße 10, D-78052 Villingen-Schwenningen, Germany Lehrstuhl für Anwendungsentwicklung, Institut für Mikrosystemtechnik (IMTEK), Universität Freiburg, Georges-Köhler-Allee 106, D-79110 Freiburg, GermanySearch for more papers by this authorR. Zengerle Prof. Dr., R. Zengerle Prof. Dr. HSG-IMIT, Wilhelm-Schickard-Straße 10, D-78052 Villingen-Schwenningen, Germany Lehrstuhl für Anwendungsentwicklung, Institut für Mikrosystemtechnik (IMTEK), Universität Freiburg, Georges-Köhler-Allee 106, D-79110 Freiburg, GermanySearch for more papers by this authorF. von Stetten Dr., F. von Stetten Dr. HSG-IMIT, Wilhelm-Schickard-Straße 10, D-78052 Villingen-Schwenningen, Germany Lehrstuhl für Anwendungsentwicklung, Institut für Mikrosystemtechnik (IMTEK), Universität Freiburg, Georges-Köhler-Allee 106, D-79110 Freiburg, GermanySearch for more papers by this author First published: 19 August 2009 https://doi.org/10.1002/cite.200950483AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume81, Issue8Special Issue: ProcessNet-Jahrestagung und 27. Jahrestagung der BiotechnologenAugust, 2009Pages 1270-1270 RelatedInformation

Two different platform concepts for microfluidic miniaturization, integration and automation of biochemical assays are presented. First, unit operations for batch-wise nucleic acid analysis on the centrifugal microfluidic platform are demonstrated, including unit operations for DNA extraction, aliquoting and real-time PCR. Second, the newly developed continuous phase transfer magnetophoresis platform is introduced. It enables continuous online process monitoring, demonstrated by implementation of unit operations for DNA extraction.

Neural drug delivery by microprobes is considered to be one of the most promising methods for treating brain related diseases since the drug liquid can be directly infused into a specific brain region. However, this requires in turn knowledge on the liquid distribution during infusion. This work evaluates the liquid distribution in agarose gel of micro-fabricated silicon probes with two different outlet styles in comparison to a conventional stainless steel capillary. The optical liquid distributions for infusion rates of 0.2, 0.5, and 1.2 μL/min are determined in a special experimental setup which allows in parallel the measurement of pressure and flow during infusion. Flexible fluidic interfacing to the silicon probes is achieved by small o-rings for easy interchangeability. Since the actual pressure and flow conditions at the outlets of the inserted microprobes cannot be directly measured, a system model of the experimental setup is derived which allows to determine these values. Information on the predominant liquid distributions for the different probe types and infusion rates is qualitatively provided. Finally, actual pressure and flow conditions as well as backflow heights are exemplary presented for an infusion rate of 0.2 μL/min.

The authors report on the concept and development of an intelligent intraoral drug delivery microsystem, that provides an alternative approach for the treatment of addiction and chronic diseases. The drug delivery system (DDS) comprises a medication replacement reservoir, a medication release mechanism, a built-in intelligence, a remote control, microsensors, and microactuators. It is thus able to release the medication in a controlled manner according to the patient needs. The emphasis of this article is on the application of sensors and microfluidic components in a real microsystem and also showing some details of two system components, namely, the osmotic pump and the flow sensor. The motivation for the microfluidic approach, the concept of the DDS, the requirements for this specific application, and the arising problems will be presented and discussed. Regarding the sensors and actuators, the problems mainly concern size and power consumption. A major challenging aspect of microfluidic component development is to avoid clogging of small channels because of particles and recrystallization of saturated fluids.

We describe a low-power micro-actuator based on electroactive polymers - also called artificial muscles - to control the aperture area of a membrane. Using this device, the flux of drug molecules out of a depot can be influenced enabling time-resolved drug delivery patterns for individual or chronotherapeutic medication, e.g. in spastic or pain therapy. The depot can therefore either be constantly pressurized and the aperture area determines the outgoing flow rate, or the depot is kept pressureless enabling diffusion based transport of the drug molecules across the membrane. Measurements describing both modes of operation are presented. Flow rates of 0 and 4 µl/min at a depot pressure of 30 mbar and diffusion rates of 2.6 µg/h and 5.9 µg/h were determined for the “closed” and “open” state of the membrane, respectively. The low power consumption of less than 10 µW for freezing a state makes this “adjustable diffusion barrier (ADB)” an interesting alternative to existing valve concepts.