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1.
Lab Chip ; 14(9): 1527-37, 2014 May 07.
Article in English | MEDLINE | ID: mdl-24590165

ABSTRACT

Assay automation is the key for successful transformation of modern biotechnology into routine workflows. Yet, it requires considerable investment in processing devices and auxiliary infrastructure, which is not cost-efficient for laboratories with low or medium sample throughput or point-of-care testing. To close this gap, we present the LabTube platform, which is based on assay specific disposable cartridges for processing in laboratory centrifuges. LabTube cartridges comprise interfaces for sample loading and downstream applications and fluidic unit operations for release of prestored reagents, mixing, and solid phase extraction. Process control is achieved by a centrifugally-actuated ballpen mechanism. To demonstrate the workflow and functionality of the LabTube platform, we show two LabTube automated sample preparation assays from laboratory routines: DNA extractions from whole blood and purification of His-tagged proteins. Equal DNA and protein yields were observed compared to manual reference runs, while LabTube automation could significantly reduce the hands-on-time to one minute per extraction.


Subject(s)
Centrifugation/instrumentation , Laboratories , Microfluidic Analytical Techniques/instrumentation , Automation , Centrifugation/economics , Cost-Benefit Analysis , DNA/blood , DNA/isolation & purification , Humans , Microfluidic Analytical Techniques/economics
2.
Biomed Microdevices ; 15(1): 1-8, 2013 Feb.
Article in English | MEDLINE | ID: mdl-22833153

ABSTRACT

We present a new method for the distinct specific chemical stimulation of single cells and small cell clusters within their natural environment. By single-drop release of chemical agents with droplets in size of typical cell diameters (d <30 µm) on-demand micro gradients can be generated for the specific manipulation of single cells. A single channel and a double channel agent release cartridge with integrated fluidic structures and integrated agent reservoirs are shown, tested, and compared in this publication. The single channel setup features a fluidic structure fabricated by anisotropic etching of silicon. To allow for simultaneous release of different agents even though maintaining the same device size, the second type comprises a double channel fluidic structure, fabricated by photolithographic patterning of TMMF. Dispensed droplet volumes are V = 15 pl and V = 10 pl for the silicon and the TMMF based setups, respectively. Utilizing the agent release cartridges, the application in biological assays was demonstrated by hormone-stimulated premature bud formation in Physcomitrella patens and the individual staining of one single L 929 cell within a confluent grown cell culture.


Subject(s)
Drug Delivery Systems/instrumentation , Microfluidic Analytical Techniques/instrumentation , Single-Cell Analysis/instrumentation , Bryopsida/cytology , Bryopsida/drug effects , Cytokinins/pharmacology
3.
Biomed Microdevices ; 9(5): 675-9, 2007 Oct.
Article in English | MEDLINE | ID: mdl-17505885

ABSTRACT

In this paper, we present a novel and fully integrated centrifugal microfluidic "lab-on-a-disk" for rapid colorimetric 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, globally hydrophilized structures which obviate the need for intricate local hydrophobic surface patterning. Our technology features a plasma extraction structure (V=500 nL, CV<5%) where the purified plasma (cRBC<0.11%) is centrifugally separated, metered by an overflow and subsequently extracted by a siphon-based principle through a hydrophilic extraction channel into the detection chamber.


Subject(s)
Blood , Centrifugation/methods , Clinical Chemistry Tests/instrumentation , Microfluidic Analytical Techniques/instrumentation , Microfluidic Analytical Techniques/methods , Blood Sedimentation , Calibration , Colorimetry/instrumentation , Colorimetry/methods , Equipment Design , Ethanol/blood , Humans , Microchemistry/instrumentation , Microchemistry/methods
4.
Biomed Microdevices ; 9(6): 795-9, 2007 Dec.
Article in English | MEDLINE | ID: mdl-17534715

ABSTRACT

We present a novel concept to process human blood on a spinning polymer disk for the determination of the hematocrit level by simple visual inspection. The microfluidic disk which is spun by a macroscopic drive unit features an upstream metering structure and a downstream blind channel where the centrifugally enforced sedimentation of the blood is performed. The bubble-free priming of the blind channel is governed by centrifugally assisted capillary filling along the sloped hydrophilic side-wall and the lid as well as the special shape of the dead end of the two-layer channel. The hematocrit is indicated at the sharp phase boundary between the plasma and the segregated cellular pellet on a disk-imprinted calibrated scale. This way, we conduct the hematocrit determination of human blood within 5 min at a high degree of linearity (R(2) = 0.999) and at a high accuracy (CV = 4.7%) spanning over the physiological to pathological working range. As all processing steps including the priming, the metering to a defined volume as well as the centrifugation are executed automatically during rotation, the concept is successfully demonstrated in a conventional PC-CDROM drive while delivering the same performance (R(2) = 0.999, CV = 4.3%).


Subject(s)
Centrifugation/instrumentation , Hematocrit/instrumentation , Microfluidics/instrumentation , Centrifugation/methods , Cost-Benefit Analysis , Equipment Design , Equipment Failure Analysis , Germany , Hematocrit/methods , Microfluidics/methods , Reproducibility of Results , Sensitivity and Specificity
5.
Lab Chip ; 6(8): 1040-4, 2006 Aug.
Article in English | MEDLINE | ID: mdl-16874375

ABSTRACT

We present a novel microfluidic concept to enable a fast colorimetric alcohol assay from a single droplet of whole blood. The reduced turn-around time of 150 seconds is, on the one hand, achieved by a full process integration including metering, mixing with reagents, and sedimentation of cellular constituents. On the other hand, our novel total internal reflection (TIR) scheme allows to monitor the increase of the absorbance values in real-time. Thus, the saturation values can be predicted accurately based on an extrapolation of real-time measurements acquired during a 100 second initial period of rotation. Additionally, we present a metering structure to define nanolitre sample volumes at a coefficient of variation (CV) below 5%.


Subject(s)
Blood Chemical Analysis , Ethanol/blood , Microfluidic Analytical Techniques , Calorimetry , Humans , Microfluidics , Reproducibility of Results , Sensitivity and Specificity
6.
Biomed Microdevices ; 8(3): 209-14, 2006 Sep.
Article in English | MEDLINE | ID: mdl-16732473

ABSTRACT

In this paper, we present a novel concept for optical beam-guidance to significantly enhance the sensitivity of colorimetric assays by extending the optical path length through the detection cell which linearly impacts the resulting attenuation of a probe beam according to the law of Beer-Lambert. In our setup, the incident probe beam is deflected by 90( composite function) into the chip plane at monolithically integrated V-grooves to pass a flat detection cell at its full width (i.e., with a path length of 10 mm) instead of its usually much smaller height. Afterwards, the attenuated beam is redirected by another V-groove towards an external detector. The general beam-guidance concept is demonstrated by a glucose assay on human whole blood on a centrifugal microfluidic "lab-on-a-disk" platform made of COC. We achieve an excellent linearity with a correlation coefficient (R (2)) of 0.997 paired with a lower limit of detection (200 microM) and a good reproducibility with a coefficient of variation (CV) of 4.0% over nearly three orders of magnitude. With an accelerated sedimentation of cellular constituents by centrifugal forces, the sample of whole blood can be analyzed in a fully integrated fashion within 210 s. This time-to-result can even be improved by the numerical extrapolation of the saturation value. Additionally, the direct assay on whole blood also shows a negligible correlation with the hematocrit of the blood sample.


Subject(s)
Blood Chemical Analysis/instrumentation , Blood Glucose/analysis , Microchemistry/instrumentation , Microfluidics/instrumentation , Blood Chemical Analysis/methods , Equipment Design , Humans , Microchemistry/methods , Microfluidics/methods , Sensitivity and Specificity
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