Fabrication of multilayer systems combining microfluidic and microoptical elements for fluorescence detection

• Published in: Journal of microelectromechanical systems Vol. 10; no. 4; pp. 482 - 491
• Main Authors: Roulet, J.-C., Volkel, R., Herzig, H.P., Verpoorte, E., de Rooij, N.F., Dandliker, R.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.12.2001; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aluminum; Analytical chemistry; Aperture; Apertures; Applied sciences; Arrays; Chips; Chromium; Etching; Exact sciences and technology; Fabrication; Fluorescence; General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Lenses; Mechanical engineering. Machine design; Mechanical instruments, equipment and techniques; Microfluidics; Microlenses; Micromechanical devices and systems; Microoptics; Multilayers; Nonhomogeneous media; Physics; Precision engineering, watch making; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; Signal to noise ratio; Wafers; Integrated optics; Chemical sensors; Fluorescence detector; Precision engineering; Glass; Chemical etching; Wet etching; Manufacturing processes; Refractive optics; Microlenses; Microfluid; Miniaturization; Optical sensors; Microsensors
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/84.967369

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.