Friedrich-Wilhelm-Lübke-Koog, Germany
Friedrich-Wilhelm-Lübke-Koog, Germany

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Marx M.,Albert Ludwigs University of Freiburg | De Dorigo D.,Albert Ludwigs University of Freiburg | Nessler S.,Albert Ludwigs University of Freiburg | Rombach S.,Hahn Schickard | And 2 more authors.
Digest of Technical Papers - IEEE International Solid-State Circuits Conference | Year: 2017

MEMS gyroscopes are used in closed-loop configuration (CL) to satisfy the demand for high-performance and stable inertial sensors [1]. Due to the higher complexity and power consumption compared to open-loop solutions, these systems have usually been unsuitable for mobile battery-driven devices, e.g., for indoor navigation. Recently, the utilization of CT-ΔΣM for the readout of gyroscopes has shown to be a promising approach for reduced power consumption in a CL system [2]. In general, an accurate matching of the electrical BPF [2] to the drive and sense resonance frequencies of the sensor [3] is a prerequisite for maximizing SNR. For systems with drive frequencies fd of some tens of kHz and with a typical angular rate bandwidth of BW=50Hz, the frequency matching needs to be as precise as BW/fd<0.5%. However, the frequency variation of CT BPFs in CT-ΔΣM over PVT is large compared to DT circuits. This paper presents a fully integrated frequency tuning circuit that is based on noise observation at the input of the electrical BPF in an electromechanical CT-ΔΣM. It works in the background during normal operation, achieving a precision better than 0.25% fd and featuring a considerably lower power of 27μW and lower area of 0.06mm2 than competing approaches (see Fig. 9.4.6). © 2017 IEEE.


PubMed | Askion GmbH, ClinicaGeno Ltd, University of Zürich, Erasmus Medical Center and 5 more.
Type: | Journal: Studies in health technology and informatics | Year: 2016

Global healthcare systems are struggling with the enormous burden associated with infectious diseases, as well as the incessant rise of antimicrobial resistance. In order to adequately address these issues, there is an urgent need for rapid and accurate infectious disease diagnostics. The H2020 project DIAGORAS aims at diagnosing oral and respiratory tract infections using a fully integrated, automated and user-friendly platform for physicians offices, schools, elderly care units, community settings, etc. Oral diseases (periodontitis, dental caries) will be detected via multiplexed, quantitative analysis of salivary markers (bacterial DNA and host response proteins) for early prevention and personalised monitoring. Respiratory Tract Infections will be diagnosed by means of DNA/RNA differentiation so as to identify their bacterial or viral nature. Together with antibiotic resistance screening on the same platform, a more efficient treatment management is expected at the point-of-care. At the heart of DIAGORAS lies a centrifugal microfluidic platform (LabDisk and associated processing device) integrating all components and assays for a fully automated analysis. The project involves an interface with a clinical algorithm for the comprehensive presentation of results to end-users, thereby increasing the platforms clinical utility. DIAGORAS performance will be validated at clinical settings and compared with gold standards.


Butz N.,Albert Ludwigs University of Freiburg | Taschwer A.,Hahn Schickard | Manoli Y.,Albert Ludwigs University of Freiburg | Kuhl M.,Albert Ludwigs University of Freiburg
Digest of Technical Papers - IEEE International Solid-State Circuits Conference | Year: 2016

Functional electrical stimulation (FES) is a technique that stimulates nerves by electrical charge, but carries the risk of charge accumulation, voltage pile-up, electrode corrosion and finally tissue destruction. Using biphasic stimulus current pulses, the main transferred charge is compensated by reversing the current direction. However, due to PVT variations in integrated circuits mismatch in the biphasic waveform always occurs. Charge balancing (CB) has thus become an integral part of FES to ensure safe chronic stimulation [1]. © 2016 IEEE.


Ylli K.,Hahn Schickard | Hoffmann D.,Hahn Schickard | Willmann A.,Hahn Schickard | Folkmer B.,Hahn Schickard | And 2 more authors.
Journal of Physics: Conference Series | Year: 2015

Energy Harvesting from human motion as a means of powering body-worn devices has been in the focus of research groups for several years now. This work presents a rotational inductive energy harvester that can generate a sufficient amount of energy during normal walking to power small electronic systems. Three pendulum structures and their geometrical parameters are investigated in detail through a system model and system simulations. Based on these results a prototype device is fabricated. The masses and angles between pendulum arms can be changed for the experiments. The device is tested under real-world conditions and generates an average power of up to 23.39 mW across a resistance equal to the coil resistance of the optimal pendulum configuration. A regulated power output of the total system including power management of 3.3 mW is achieved. © Published under licence by IOP Publishing Ltd.


Schwemmer F.,Albert Ludwigs University of Freiburg | Hutzenlaub T.,Hahn Schickard | Buselmeier D.,Albert Ludwigs University of Freiburg | Paust N.,Albert Ludwigs University of Freiburg | And 4 more authors.
Lab on a Chip - Miniaturisation for Chemistry and Biology | Year: 2015

The generation of mixtures with precisely metered volumes is essential for reproducible automation of laboratory workflows. Splitting a given liquid into well-defined metered sub-volumes, the so-called aliquoting, has been frequently demonstrated on centrifugal microfluidics. However, so far no solution exists for assays that require simultaneous aliquoting of multiple, different liquids and the subsequent pairwise combination of aliquots with full fluidic separation before combination. Here, we introduce the centrifugo-pneumatic multi-liquid aliquoting designed for parallel aliquoting and pairwise combination of multiple liquids. All pumping and aliquoting steps are based on a combination of centrifugal forces and pneumatic forces. The pneumatic forces are thereby provided intrinsically by centrifugal transport of the assay liquids into dead end chambers to compress the enclosed air. As an example, we demonstrate simultaneous aliquoting of 1.) a common assay reagent into twenty 5 μl aliquots and 2.) five different sample liquids, each into four aliquots of 5 μl. Subsequently, the reagent and sample aliquots are simultaneously transported and combined into twenty collection chambers. All coefficients of variation for metered volumes were between 0.4%-1.0% for intra-run variations and 0.5%-1.2% for inter-run variations. The aliquoting structure is compatible to common assay reagents with a wide range of liquid and material properties, demonstrated here for contact angles between 20° and 60°, densities between 789 and 1855 kg m-3 and viscosities between 0.89 and 4.1 mPa s. The centrifugo-pneumatic multi-liquid aliquoting is implemented as a passive fluidic structure into a single fluidic layer. Fabrication is compatible to scalable fabrication technologies such as injection molding or thermoforming and does not require any additional fabrication steps such as hydrophilic or hydrophobic coatings or integration of active valves. © The Royal Society of Chemistry 2015.


Zhao Y.,Hahn Schickard | Schwemmer F.,Albert Ludwigs University of Freiburg | Zehnle S.,Hahn Schickard | Von Stetten F.,Hahn Schickard | And 5 more authors.
Lab on a Chip - Miniaturisation for Chemistry and Biology | Year: 2015

Microparticles are widely used as solid phase for affinity-based separation. Here, we introduce a new method for automated handling of microparticles in centrifugal microfluidics that is not restricted by the particle size and requires neither auxiliary means such as magnets nor coating of microfluidic structures. All steps are initiated and controlled by the speed of rotation only. It is based on storage and "on demand" release of pneumatic energy within tunable time frames: a slow release of the pneumatic energy triggers a first fluidic path through which the supernatant above the sedimented particles is removed. An abrupt release triggers a second path which allows for liquid routing and transport of the re-suspended particles. Re-suspension of particles is thereby achieved by quickly changing the speed of rotation. We demonstrate the exchange of the particle carrier medium with a supernatant removal efficiency of more than 99.5% and a particle loss below 4%. Re-suspension and subsequent transport of suspended particles show a particle loss below 7%. The method targets the automation of particle-based assays e.g. DNA extractions and immunoassays. It is compatible with monolithic integration and suitable for mass production technologies e.g. thermoforming or injection moulding. © The Royal Society of Chemistry.


PubMed | Hahn Schickard and Albert Ludwigs University of Freiburg
Type: Journal Article | Journal: Lab on a chip | Year: 2016

Centrifugal microfluidics shows a clear trend towards a higher degree of integration and parallelization. This trend leads to an increase in the number and density of integrated microfluidic unit operations. The fact that all unit operations are processed by the same common spin protocol turns higher integration into higher complexity. To allow for efficient development anyhow, we introduce advanced lumped models for network simulations in centrifugal microfluidics. These models consider the interplay of centrifugal and Euler pressures, viscous dissipation, capillary pressures and pneumatic pressures. The simulations are fast and simple to set up and allow for the precise prediction of flow rates as well as switching and valving events. During development, channel and chamber geometry variations due to manufacturing tolerances can be taken into account as well as pipetting errors, variations of contact angles, compliant chamber walls and temperature variations in the processing device. As an example of considering these parameters during development, we demonstrate simulation based robustness analysis for pneumatic siphon valving in centrifugal microfluidics. Subsequently, the influence of liquid properties on pumping and valving is studied for four liquids relevant for biochemical analysis, namely, water (large surface tension), blood plasma (large contact angle hysteresis), ethanol/water (highly wetting) and glycerine/water (highly viscous). In a second example, we derive a spin protocol to attain a constant flow rate under varying pressure conditions. Both examples show excellent agreement with experimental validations.


PubMed | Hahn Schickard and Albert Ludwigs University of Freiburg
Type: Journal Article | Journal: Lab on a chip | Year: 2016

We present batch-mode mixing for centrifugal microfluidics operated at fixed rotational frequency. Gas is generated by the disk integrated decomposition of hydrogen peroxide (H2O2) to liquid water (H2O) and gaseous oxygen (O2) and inserted into a mixing chamber. There, bubbles are formed that ascent through the liquid in the artificial gravity field and lead to drag flow. Additionaly, strong buoyancy causes deformation and rupture of the gas bubbles and induces strong mixing flows in the liquids. Buoyancy driven bubble mixing is quantitatively compared to shake mode mixing, mixing by reciprocation and vortex mixing. To determine mixing efficiencies in a meaningful way, the different mixers are employed for mixing of a lysis reagent and human whole blood. Subsequently, DNA is extracted from the lysate and the amount of DNA recovered is taken as a measure for mixing efficiency. Relative to standard vortex mixing, DNA extraction based on buoyancy driven bubble mixing resulted in yields of 92 8% (100 s mixing time) and 100 8% (600 s) at 130g centrifugal acceleration. Shake mode mixing yields 96 11% and is thus equal to buoyancy driven bubble mixing. An advantage of buoyancy driven bubble mixing is that it can be operated at fixed rotational frequency, however. The additional costs of implementing buoyancy driven bubble mixing are low since both the activation liquid and the catalyst are very low cost and no external means are required in the processing device. Furthermore, buoyancy driven bubble mixing can easily be integrated in a monolithic manner and is compatible to scalable manufacturing technologies such as injection moulding or thermoforming. We consider buoyancy driven bubble mixing an excellent alternative to shake mode mixing, in particular if the processing device is not capable of providing fast changes of rotational frequency or if the low average rotational frequency is challenging for the other integrated fluidic operations.


Diagnosis of infectious diseases suffers from long turnaround times for gold standard culture-based identification of bacterial pathogens, therefore impeding timely specific antimicrobial treatment based on laboratory evidence. Rapid molecular diagnostics-based technologies enable detection of microorganisms within hours however cumbersome workflows and complex equipment still prevent their widespread use in the routine clinical microbiology setting. We developed a centrifugal-microfluidic LabDisk system for rapid and highly-sensitive pathogen detection on a point-of-care analyser. The unit-use LabDisk with pre-stored reagents features fully automated and integrated DNA extraction, consensus multiplex PCR pre-amplification and geometrically-multiplexed species-specific real-time PCR. Processing merely requires loading of the sample and DNA extraction reagents with minimal hands-on time of approximately 5 min. We demonstrate detection of as few as 3 colony-forming-units (cfu) of Staphylococcus warneri, 200 cfu of Streptococcus agalactiae, 5 cfu of Escherichia coli and 2 cfu of Haemophilus influenzae in a 200 L serum sample. The turnaround time of the complete analysis from sample-to-result was 3 h and 45 min. The LabDisk consequently provides an easy-to-use molecular diagnostic platform for rapid and highly-sensitive detection of bacterial pathogens without requiring major hands-on time and complex laboratory instrumentation.

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