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Villingen-Schwenningen, Germany

Vosseler M.,HSG IMIT | Jugl M.,HSG IMIT | Zengerle R.,HSG IMIT | Zengerle R.,Albert Ludwigs University of Freiburg
Pharmaceutical Research | Year: 2011

Purpose: We present a smart intradermal interface suitable for skin-attached drug delivery devices. Our solution enables injections or infusions that are less invasive compared to subcutaneous injections and are leakage-free at the location of penetration. Methods: The intradermal interface is based on a 31-gauge cannula embedded in a slider, movable relative to a carrier plate that can easily be fixed onto the skin. By simply pushing the slider, the cannula is inserted into the dermis. Results: We performed injections and infusions with stained water and polyethylene glycol (PEG) solution in ex vivo pig skin. The sizes of coloured spots in the skin range from 3.5 mm 2 to 15.4 mm 2 for stained water depending on the infused volume. Infusing stained PEG solution resulted in stained tissue areas about one order of magnitude larger. One of three investigated leakage modes is unacceptable but can be reliably avoided by proper site selection. At low flow rates and at the beginning of an infusion an initial back pressure overshoot was identified. This effect was identified as the limiting parameter for the design of small programmable or intelligent devices based on micro actuators. Conclusions: With the proposed easy-to-use interface, intradermal injections and infusions can be performed reliably. Therefore, it is supposed to be an ideal and clinically relevant solution for self-administration of parenteral drugs in home care applications. © 2011 Springer Science+Business Media, LLC. Source


Leicht J.,Albert Ludwigs University of Freiburg | Amayreh M.,Albert Ludwigs University of Freiburg | Moranz C.,Albert Ludwigs University of Freiburg | Maurath D.,Albert Ludwigs University of Freiburg | And 2 more authors.
Digest of Technical Papers - IEEE International Solid-State Circuits Conference | Year: 2015

An electromagnetic vibration energy harvester (EMH) is an electromechanical mass-spring-damper system transducing electrical energy out of ambient vibrations. Resistive load matching [1] as well as maximum power point (MPP) AC-DC conversion [2] are highly suitable techniques for enhancing the electrical energy output of an EMH. The presented interface IC (Fig. 20.6.1) enables MPP AC-DC conversion by tracking the optimum conduction angle and by employing a hysteretic input voltage controlled inductive DC-DC boost converter. All control signals are derived from the harvester voltage itself. Thus, no additional sensor, harvester disconnection, or DC-DC converter duty-cycle control are needed. Additionally, the implemented voltage conditioning provides over-voltage protection (OVP) and application voltage regulation (VR). © 2015 IEEE. Source


Landenberger B.,Albert Ludwigs University of Freiburg | Hofemann H.,HSG IMIT | Wadle S.,Albert Ludwigs University of Freiburg | Rohrbach A.,Albert Ludwigs University of Freiburg
Lab on a Chip - Miniaturisation for Chemistry and Biology | Year: 2012

Optical gradient forces generated by fast steerable optical tweezers are highly effective for sorting small populations of cells in a lab-on-a-chip environment. The presented system can sort a broad range of different biological specimens by an automated optimisation of the tweezer path and velocity profile. The optimal grab positions for subsequent trap and cell displacements are estimated from the intensity of the bright field image, which is derived theoretically and proven experimentally. We exhibit rapid displacements of 2 μm small mitochondria, yeast cells, rod-shaped bacteria and 30 μm large protoplasts. Reliable sorting of yeast cells in a microfluidic chamber by both morphological criteria and by fluorescence emission is demonstrated. © 2012 The Royal Society of Chemistry. Source


Strohmeier O.,Albert Ludwigs University of Freiburg | Emperle A.,Albert Ludwigs University of Freiburg | Roth G.,Albert Ludwigs University of Freiburg | Mark D.,HSG IMIT | And 2 more authors.
Lab on a Chip - Miniaturisation for Chemistry and Biology | Year: 2013

Transportation of magnetic beads between different reagents plays a crucial role in many biological assays e.g. for purification of biomolecules or cells where the beads act as a mobile solid support. Therefore, usually a complex set-up either for fluidic processing or for manipulation of magnetic beads is required. To circumvent these drawbacks, we present a facile and automated method for the transportation of magnetic beads between multiple microfluidic chambers on a centrifugal microfluidic cartridge "LabDisk". The method excels by requiring only one stack of stationary permanent magnets, a specific microfluidic layout without actively controlled valves and a predefined frequency protocol for rotation of the LabDisk. Magnetic beads were transported through three fluidically separated chambers with a yield of 82.6% ± 3.6%. Bead based DNA purification from a dilution series of a Listeria innocua lysate and from a lambda phage DNA standard was demonstrated where the three chambers were used for binding, washing and elution of DNA. Recovery of L. innocua DNA was up to 68% ± 24% and for lambda phage DNA 43% ± 10% compared to manual reference purification in test tubes. Complete purification was conducted automatically within 12.5 min. Since all reagents can be preloaded onto the LabDisk prior to purification, no further hands-on steps are required during processing. Due to its modular and generic character, the presented method could also be adapted to other magnetic bead based assays e.g. to immunoassays or protein affinity purification, solely requiring the adjustment of number and volumes of the fluidic chambers. © The Royal Society of Chemistry. Source


Focke M.,Albert Ludwigs University of Freiburg | Kosse D.,HSG IMIT | Muller C.,Albert Ludwigs University of Freiburg | Reinecke H.,Albert Ludwigs University of Freiburg | And 2 more authors.
Lab on a Chip - Miniaturisation for Chemistry and Biology | Year: 2010

This critical review is motivated by an increasing interest of the microfluidics community in developing complete Lab-on-a-Chip solutions based on thin and flexible films (Lab-on-a-Foil). Those implementations benefit from a broad range of fabrication methods that are partly adopted from well-established macroscale processes or are completely new and promising. In addition, thin and flexible foils enable various features like low thermal resistance for efficient thermocycling or integration of easily deformable chambers paving the way for new means of on-chip reagent storage or fluid transport. From an economical perspective, Lab-on-a-Foil systems are characterised by low material consumption and often low-cost materials which are attractive for cost-effective high-volume fabrication of self-contained disposable chips. The first part of this review focuses on available materials, fabrication processes and approaches for integration of microfluidic functions including liquid control and transport as well as storage and release of reagents. In the second part, an analysis of the state of Lab-on-a-Foil applications is provided with a special focus on nucleic acid analysis, immunoassays, cell-based assays and home care testing. We conclude that the Lab-on-a-Foil approach is very versatile and significantly expands the toolbox for the development of Lab-on-a-Chip solutions. © The Royal Society of Chemistry 2010. Source

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