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This article presents a new integrated microfluidic/microoptic device designed for basic biochemical analysis. The microfluidic network is wet-etched in a Borofloat 33 (Pyrex) glass wafer and sealed by means of a second wafer. Unlike other similar microfluidic systems, elements of the detection system are realized with the help of microfabrication techniques and directly deposited on both sides of the microchemical chip. The detection system is composed of the combination of refractive circular or elliptical microlens arrays and chromium aperture arrays. The microfluidic channels are 60 microm wide and 25 microm deep. The elliptical microlenses have a major axis of 400 microm and a minor axis of 350 microm. The circular microlens diameters range from 280 microm to 350 microm. The apertures deposited on the outer chip surfaces are etched in a 3000-A-thick chromium layer. The overall thickness of this microchemical system is1.6 mm. A limit of detection of 3.3 nM for a Cy5 solution in phosphate buffer (pH 7.4) was demonstrated. The cross-talk signal measured between two adjacent microchannels with 1 mm pitch was1:5600, meaning thator = 1.8 x 10(-4)% of the fluorescence light power emitted from one microchannel filled with a 50 microM Cy5 solution reaches the photodetector at the adjacent microchannel. This performance compares very well with that obtainable in microchemical chips using confocal fluorescence systems, taking differences in parameters, such as excitation power into microchannels, data acquisition rates, and signal filtering into account. more...

This paper presents the fabrication of a microchemical chip for the detection of fluorescence species in microfluidics. The microfluidic network is wet-etched in a Borofloat 33 (Pyrex) glass wafer and sealed by means of a second wafer. Unlike other similar chemical systems, the detection system is realized with the help of microfabrication techniques and directly deposited on both sides of the microchemical chip. The detection system is composed of the combination of refractive microlens arrays and chromium aperture arrays. The microfluidic channels are 60 /spl mu/m wide and 25 /spl mu/m deep. The utilization of elliptical microlens arrays to reduce aberration effects and the integration of an intermediate (between the two bonded wafers) aluminum aperture array are also presented. The elliptical microlenses have a major axis of 400 /spl mu/m and a minor axis of 350 /spl mu/m. The circular microlens diameters range from 280 to 300 /spl mu/m. The apertures deposited on the outer chip surfaces are etched in a 3000-/spl Aring/-thick chromium layer, whereas the intermediate aperture layer is etched in a 1000-/spl Aring/-thick aluminum layer. The overall thickness of this microchemical system is less than 1.6 mm. The wet-etching process and new bonding procedures are discussed. Moreover, we present the successful detection of a 10-nM Cy5 solution with a signal-to-noise ratio (SNR) of 21 dB by means of this system. more...

Microfabrication technology has become a widely used approach in the development of miniaturized systems for chemical analysis in microfluidic channels. Moreover, microfabrication technology can be used to integrate microlens and aperture arrays directly onto microchemical chips. Such optical elements enable the realization of optical functions for illumination, collection and signal filtering, necessary for fluorescence detection. A new completely integrated microfluidic/micro-optic device is presented, in which refractive microlens arrays (with a diameter of a couple of hundred µm) and aluminum aperture arrays are integrated on both sides of a chemical chip. The chip is composed of two 4” thermally bonded pyrex glass wafers in which microfluidic networks are etched. The microchannels are 25 µm deep and 50 µm wide. The overall thickness of the chip with the detection system is less than 2 mm. more...

We report on our activities in the design, fabrication, characterization andsystem integration of planar micro-optical elements. Microlens arrays, gratings, dif-fusers, beam shapers and beam splitters have been fabricated, tested and integrated in chemical analysis systems (iTAS, fluorescence detection), tracking sensors for satellites, displacement sensors, optical lightpipes, LCD projector illumination, pho-tospectrometers, neural networks and multiple channel imaging systems for photo- lithography. Packaging and alignment strategies for sensors and optical microsys- tems were investigated. 1. Introduction Microfabrication technologies like photolithography, resist processing and reactive ion etching(RIE) were used to manufacture arrays of refractive and diffractive micro-optical elements. Themicro-optical elements were transfered in fused silica by RIE and replicated in polycarbonat andepoxy by embossing and casting techniques. The surface profile and the wave aberrations werecharacterized by interferometrical testing. The surface roughness was measured by atomic forcemicroscopy. more...

Micro-optical systems based on refractive microlenses are in- vestigated. These systems are integrated on a chemical chip. They focus an excitation beam into the detection volume (microliter or even submi- croliter scale) and collect the emitted light from fluorescent molecules. The fluorescence must be carefully separated by spatial and spectral filtering from the excitation. This paper presents the ray tracing simula- tion, fabrication, and measurement of three illumination systems. The measurements show that an adroit placement and combination of micro- fabricated lenses and stops can increase the separation between the excitation light and the fluorescence light. Moreover we present the suc- cessful detection of a 20 nM Cy5™ (Amersham Life Science Ltd.) solu- tion in a 100-mm-wide and 50-mm-deep microchannel (excitation volume '250 pL) using one of these illumination systems. The microchemical chip with the micro-optical system has a thickness of less than 2 mm. © 2001 Society of Photo-Optical Instrumentation Engineers. (DOI: 10.1117/1.1359522) more...