D7.2 - System Integration of Sensors for Fluorescence Based Lab on a Chip Systems

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings SENSOR 2011
D7 - Medical II
A. Witte - Fraunhofer-Institut (IPT), Aachen (Germany), R. Schmitt - RWTH Aachen Universität (Germany)
644 - 649


An important part of human medical health care is the measurement of chemical blood parameters for disease detection and rehabilitation progress monitoring. For these analysis, lab on a chip systems (LOC) have significant advantages to established laboratories, such as high portability and low testing costs.
The design process of new LOCs includes the system integration of all essential detection and fluid handling components. Within this paper the sensor integration for a lab on a chip system with time based fluorescence analysis is described. One of the main challenges for the sensor integration is a system design, which can combine a high repeat accuracy of the chip relative to the sensors with low structural complexity and costs.
The chip consists of microfluidic channels with fluorescence detection spots for the chemical blood analysis. Fibers are, beside different other approaches, a flexible way for the connection of detection instrumentation to a LOC. Thus, the excitation of the assay with light and the detection of the corresponding fluorescence signal are realized by the use of fibers. With microfluidic channel dimensions in the order of magnitude of some tens of microns, these fibers have to be aligned over the channels with a high accuracy to avoid fluorescence signal losses during the analysis process.
Repeat accuracies of less than ten microns are only achievable with ultra-precision machining and customized mounting structures for the disposable chip and the sensors. Furthermore, a bearing concept and finite element analysis are needed to reduce the displacements caused by mechanical stress and temperature.
The evaluation of the sensor integration concept shows that high repeat accuracies can be obtained using a system with low mechanical complexity. Displacements of the chip relative to the sensors do not exceed five microns with the proposed concept.