Design and fabrication of a centrifugally driven microfluidic disk for fully integrated metabolic assays on whole blood

For the first time, we present a novel and fully integrated centrifugal microfluidic “ lab-on-a-disk” for rapid metabolic assays in human whole blood. All essential steps comprising blood sampling, metering, plasma extraction and the final optical detection are conducted within t = 150 s in passive structures integrated on one disposable disk. Our technology features a novel plasma extraction structure (V = 500 nL, CV < 5%) without using any hydrophobic microfluidics where the purified plasma (cRBC< 0.11%) is centrifugally separated and subsequently extracted through a capillarily primed extraction channel into the detection chamber. While this capillary extraction requires precisely defined, narrow micro-structures, the reactive mixing and detection is most efficient within larger cavities. The corresponding manufacturing technique of these macro- and micro structures in the range of 30 µ m to 1000 µ m is also presented for the first time: A novel, cost-efficient hybrid prototyping technique of a multiscale epoxy master for subsequent hot embossing of polymer disks

TIR-based dynamic liquid-level and flow-rate sensing and its application on centrifugal microfluidic platforms

For the first time we present a technique for the spatio-temporally resolved localization of liquid-gas interfaces on centrifugal microfluidic platforms based on total internal reflection (TIR) at the channel wall. The simple setup consists of a line laser and a linear image sensor array mounted in a stationary instrument. Apart from identifying the presence of (usually unwanted) gas bubbles, the here described online meniscus detection allows to measure liquid volumes with a high precision of 1.9%. Additionally, flow rates and viscosities (range: 1-10.7 mPa s) can be sensed even during rotation at frequencies up to 30 Hz with a precision of 4.7% and 4.3%, respectively

Verbindungstechnik von carbonfaserverstärkten Kunststoff-Halbzeugen in dynamischen Robotersystemen

In folgender Veröffentlichung wird eine Möglichkeit aufgezeigt, wie der zukunftsträchtige Werkstoff „Carbonfaserverstärkter Kunststoff“ (CFK) einfach und kostengünstig in hochdynamischen Robotersystemen zum Einsatz kommen kann. Hierbei ist es entscheidend, dass die aufwendige und kostenintensive Fertigung von einzelnen CFK-Bauteilen umgangen wird, ohne die herausragenden Werkstoffeigenschaften einzuschränken. Im Forschungsprojekt „Stabkinematik-Leichtbau-Roboter“ (SLR) werden dazu verschiedene Möglichkeiten erarbeitet, stattdessen auf standardmäßig angebotene Halbzeuge aus CFK zurückzugreifen. Ein zentrales Thema stellt dabei die Verbindungstechnik dar, die beim Fügen von CFK Halbzeugen (hier: Platten) erforderlich wird. Eine Vielfalt von Tests verschiedener Verbindungen zeigt, dass sich eine Fingerverzinkung für den betrachten Anwendungsfall am besten eignet. Daher werden zwei Varianten mit Fingerverzinkung genau analysiert, zum einen, eine mit Verschraubungen und, zum anderen, als Klebung. Die Ergebnisse der beiden Varianten zeigen ähnliche Festigkeitskennwerte, wobei die Klebung etwas höhere Werte aufweist. Demgegenüber ist die Schraubverbindung komfortabler zu montieren und bietet die Möglichkeit der Demontage

Optical beam guidance in monolithic polymer chips for miniaturized colorimetric assays

For the first time, we present a simple and robust optical concept to enable precise and sensitive read-out of colorimetric assays in flat lab-on-a-chip devices. The optical guidance of the probe beam through an incorporated measurement chamber to the detector is based on the total internal reflection at V-grooves in the polymer chip. This way, the optical path length through the flat measurement chamber and thus the performance of the measurements are massively enhanced compared to direct (perpendicular) beam incidence. This is demonstrated by a chip-based, colorimetric glucose-assay on serum. Outstanding features are an excellent reproducibility (CV= 1.91 %), a competitive lower limit of detection (cmin = 124 μM), and a high degree of linearity (R2 = 0.998) within a working range extending over nearly three orders of magnitude

Direct hemoglobin measurement by monolithically integrated optical beam guidance

We present a concept for optical beam guidance by total internal reflection (TIR) at V-grooves as retro reflectors which are monolithically integrated on a microfluidic "lab-on-a-disk". This way, the optical path length through a measurement chamber and thus the sensitivity of colorimetric assays is massively enhanced compared to direct (perpendicular) beam incidence. With this rugged optical concept, we determine the concentration of hemoglobin (Hb) in human whole blood. Outstanding features are a high degree of linearity (R2 = 0.993) between the optical signal and the Hb together with a reproducibility of CV= 2.9 %, and a time-to-result of 100 seconds, only

Parallelization of chip-based fluorescence immuno-assays with quantum-dot labelled beads

This paper presents an optical concept for the read-out of a parallel, bead-based fluorescence immunoassay conducted on a lab-on-a-disk platform. The reusable part of the modular setup comprises a detection unit featuring a single LED as light source, two emission-filters, and a color CCD-camera as standard components together with a spinning drive as actuation unit. The miniaturized lab-on-a-disk is devised as a disposable. In the read-out process of the parallel assay, beads are first identified by the color of incorporated quantum dots (QDs). Next, the reaction-specific fluorescence signal is quantified with FluoSpheres-labeled detection anti-bodies. To enable a fast and automated read-out, suitable algorithms have been implemented in this work. Based on this concept, we successfully demonstrated a Hepatitis-A assay on our disk-based lab-on-a-chip

Chemoselective Dual Labeling of Native and Recombinant Proteins

The attachment of two different functionalities in a site-selective fashion represents a great challenge in protein chemistry. We report site specific dual functionalizations of peptides and proteins capitalizing on reactivity differences of cysteines in their free (thiol) and protected, oxidized (disulfide) forms. The dual functionalization of interleukin 2 and EYFP proceeded with no loss of bioactivity in a stepwise fashion applying maleimide and disulfide rebridging allyl-sulfone groups. In order to ensure broader applicability of the functionalization strategy, a novel, short peptide sequence that introduces a disulfide bridge was designed and site-selective dual labeling in the presence of biogenic groups was successfully demonstrated

GEO.Cool : Kühlung mit oberflächennaher Geothermie - Möglichkeiten, Grenzen, Innovation -

Das Verbundprojekt GEO.Cool von Partnern im Landesforschungszentrum Geothermie (LFZG) hat zum Ziel, Möglichkeiten sowie Grenzen der Kühlung mit oberflächennaher Geothermie in interdisziplinärer Arbeit zu erheben und daraus Impulse für Innovationen in diesem Bereich zu gewinnen. Das Vorhaben ist in die folgenden sechs Arbeitspakete (AP) gegliedert: AP 1: Bedarfe und Systemaspekte AP 2: Systemtechnik und Planung von Anlagen zur Kühlung mit oberflächennaher Ge-othermie AP 3: Analyse von Best-Practice-Beispielen AP 4: Thermisches und hydrogeologisches Verhalten des Untergrunds AP 5: Genehmigungspraxis und Grenzwerte AP 6: Synopse, Innovationspotenzial und Transfer. Das Projekt hat eine Laufzeit vom 23.01.2017 bis zum 30.09.2019 (Förderzeitraum für alle Arbeitspakete und Projektpartner)