A universal microfluidic platform as a multisensor device for cancer diagnostics, developed within the framework of the
EU project SmartHEALTH [1], will be presented. Based on a standardization concept, a microfluidic platform was
realized that contains various functional modules in order to allow in its final setup to run a complete diagnostic assay on
a chip starting with sample preparation to a final detection via a sensor array. A twofold concept was pursued for the
development and standardization: On the one hand, a standard footprint with defined areas for special functional
elements was chosen, on the other hand a toolbox-approach [2] was used whereas in a first instance different functional
fluidic modules were realized, evaluated and afterwards integrated into the microfluidic multisensor platform. One main
characteristic of the platform is that different kind of sensors can be used with the same fluidic chip. For the read-out and
fluidic control of the chip, common fluidic interfaces to the instrument were defined. This microfluidic consumable is a
hybrid system consisting of a polymer component with an integrated sensor, reagent storage on chip, integrated valves
and metering elements.
A robust optical sensor for liquid control in fluidic channels is reported. The sensor operates on light intensity
modulation resulting from alteration of total internal reflection into partial reflection. When a liquid guided in a channel
covers an integrated prism, the total internal reflection is changed into a partial reflection, resulting in an intensity
modulation of the reflected light. The set-up comprises a fibre which is built in a coupler unit with integrated LED and
photodiode as well as a prism micro-machined directly into a micro-fluidic polymeric channel by laser ablation. The
Prism is of 45-90-45° type with a dimension of 0.5 mm × 1 mm × 2 mm. In this design the radiation of the LED light
source is transmitted and collected from the prism by a 50:50 fibre coupler by means of total or partial internal reflection.
The sensor was characterised by filling alternately the channel with water and air. The influence of stray light onto the
sensor signal was tested by applying a strong uncollimated illumination of the channel. Only a small increase in the
output signal level in the presence of air but a strong increase in case of the presence of water could be detected.
A robust optical sensor for liquid control in fluidic channels is reported. The sensor operates on light intensity
modulation resulting from alteration of total internal reflection into partial reflection. When a liquid guided in a channel
covers an integrated prism, the total internal reflection is changed into a partial reflection, resulting in an intensity
modulation of the reflected light.
The set-up comprises a fibre which is built in a coupler unit with integrated LED and photodiode as well as a prism
micro-machined directly into a micro-fluidic polymeric channel by laser ablation. The Prism is of 45-90-45° type with a
dimension of 0.5 mm × 1 mm × 2 mm. In this design the radiation of the LED light source is transmitted and collected
from the prism by a 50:50 fibre coupler by means of total or partial internal reflection.
The sensor was characterised by filling alternately the channel with water and air. The signal level for the liquid in
contact with the prism was determined to be 222 mV while the signal level of the air filled channel was 336 mV. The
influence of stray light onto the sensor signal was tested by applying a strong uncollimated illumination of the channel.
Only a small increase in the output signal level in the presence of air but a strong increase in case of the presence of
water could be detected. However, the discrimination between air and liquid was still possible sufficiently (290 mV for
liquid, 340 mV for air). The sensor was also demonstrated to be operated as a micro-refractometer.
Herbert Freimuth, Frithjof von Germar, Ines Frese, Elzbieta Nahrstedt, Michael Küpper, Rainer Schenk, Björn Baser, Johannes Ott, Klaus Drese, Peter Detemple, Theodor Doll
The development of a lab-on-chip system which allows the parallel detection of a variety of different parameters of a water sample is presented. Water analysis typically comprises the determination of around 30 physical and chemical parameters. An even larger number can arise when special contaminations of organic molecules are of interest. A demonstration system has been realised to show the feasibility and performance of an integrated device for the determination of physical quantities like electrical conductivity, light absorption and turbidity. Additionally, chemical quantities like the pH-value and the content of inorganic and organic contaminations are also determined. Two chips of credit card size contain the analytical functions and will be fabricated by injection moulding. First prototypes have been manufactured by milling or precision milling for the optical components.
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