Surface profiles of reflow microlenses under the influence of surface tension and gravity

Schilling, Andreas; Merz, Ruben; Ossmann, Christian; Herzig, Hans Peter

doi:10.1117/1.1304845

Cited by 84 publications

(58 citation statements)

References 8 publications

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“…We fabricated an array of microlenses in an opaque background by reflowing photoresist (with an index of refraction of 1.59) followed by electroplating of nickel around the microlenses (23)(24)(25)(26). We constructed the sample chamber from poly(dimethylsiloxane) (which is optically transparent) by using soft lithography (27,28).…”

Section: Methodsmentioning

confidence: 99%

Space- and time-resolved spectrophotometry in microsystems

Damean

Sia

Linder

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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This work describes a simple optical method for obtaining, in a single still-capture image, the continuous absorbance spectra of samples at multiple locations of microsystems. This technique uses an unmodified bright-field microscope, an array of microlenses, and a diffraction grating to disperse the light transmitted by samples of 10-to 500-m dimensions. By analyzing in a single image the first-order diffracted light, it is possible to collect the full and continuous absorbance spectra of samples at multiple locations (to a spatial resolution of Ϸ8 m) in microwells and microchannels to examine dynamic chemical events (to a time resolution of <10 ms). This article also discusses the optical basis of this method. The simultaneous resolution of wavelength, time, and space at a scale <10 m provides additional capabilities for chemical and biological analysis.poly(dimethylsiloxane) ͉ array of microlenses ͉ spectrophotometer ͉ image processing T his article describes an optical method that resolves wavelength, time, and location simultaneously for samples in microsystems. This technique, which we call micropattern spectrophotometry (PS), analyzes a continuous spectrum of wavelengths (with best performance, in the system described here, in the range of 450 to 700 nm) at multiple positions in the field of view of a microscope. This procedure provides a flexible method for analyzing the composition of samples at a number of points, or in a number of samples, simultaneously and continuously.Microsystems are now ubiquitous in chemistry and biology (1). Applications include analysis of chemical reactions (2), sorting of cells (3), and high-throughput screening (4). Because these systems often require separation (5), mixing (6, 7), and reaction (8) of components with distinct optical profiles, they would benefit from a method that allows the components to be characterized optically in space and time. Advances in miniaturization of components used in spectrophotometric systems have produced a number of useful microsystems: these systems typically work at a single wavelength at any one time (9, 10) or perform measurements at a single spatial location (11-15), and most cannot be easily interfaced with microfluidic systems (16-18). Miniaturized systems for integrating microspectrometers and microfluidics have been proposed but not demonstrated (19,20). Although fiber optic-based microspectrophotometers (21) have been described and microscope-based spectrophotometers (22) are available, they are capable of analyzing only one or only a few samples at a time, and they scan the spectrum one wavelength at a time. Also, they require alignment of a fiber optic cable to the sample region.The method described here collects spectral information at many wavelengths and for many samples simultaneously. Materials and MethodsSetup of the Micropattern Spectrophotometer. We fabricated an array of microlenses in an opaque background by reflowing photoresist (with an index of refraction of 1.59) followed by electroplating of nickel around the mi...

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Section: Methodsmentioning

confidence: 99%

Space- and time-resolved spectrophotometry in microsystems

Damean

Sia

Linder

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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“…A photoresist reflow process, resulting in a rounded channel profile, involves two procedures, 1) the melting of the patterned photoresist and the liquid resist surfaces are pulled into a shape which minimizes the energy of the system 28,29 and 2) a cooling and solidification phase follows the melting process. The shapes of the reflowed channels are well approximated by a semicylindrical surface.…”

Section: Master Mold Fabricationmentioning

confidence: 99%

Procedure for the Development of Multi-depth Circular Cross-sectional Endothelialized Microchannels-on-a-chip

Mearns

Martins‐Green

et al. 2013

JoVE

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Efforts have been focused on developing in vitro assays for the study of microvessels because in vivo animal studies are more time-consuming, expensive, and observation and quantification are very challenging. However, conventional in vitro microvessel assays have limitations when representing in vivo microvessels with respect to three-dimensional (3D) geometry and providing continuous fluid flow. Using a combination of photolithographic reflowable photoresist technique, soft lithography, and microfluidics, we have developed a multi-depth circular cross-sectional endothelialized microchannels-on-a-chip, which mimics the 3D geometry of in vivo microvessels and runs under controlled continuous perfusion flow. A positive reflowable photoresist was used to fabricate a master mold with a semicircular cross-sectional microchannel network. By the alignment and bonding of the two polydimethylsiloxane (PDMS) microchannels replicated from the master mold, a cylindrical microchannel network was created. The diameters of the microchannels can be well controlled. In addition, primary human umbilical vein endothelial cells (HUVECs) seeded inside the chip showed that the cells lined the inner surface of the microchannels under controlled perfusion lasting for a time period between 4 days to 2 weeks. Video LinkThe video component of this article can be found at

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“…For the two-dimensional calculations we use a periodic line of infinitely long cylindrical lenses [18] and we represent the lens surface as part of a perfect circle, which does not completely correspond to a real microlens fabricated by the resist melting technology, but is a good approximation for the microlenses studied. The precise form of a microlens and, hence, also its focal properties are determined by the effects of surface tension, temperature and the rate and manner of the temperature change during fabrication [19].…”

Section: Phase Singularities In the Focal Region Of Microlensesmentioning

confidence: 99%

Measuring optical phase singularities at subwavelength resolution

Dändliker

Märki

Salt

et al. 2004

J. Opt. A: Pure Appl. Opt.

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We will present experimental and theoretical studies of optical fields with subwavelength structures, in particular phase singularities and coherent detection methods with nanometric resolution. An electromagnetic field is characterized by an amplitude, a phase and a polarization state. Therefore, experimental studies require coherent detection methods, which allow one to measure the amplitude and phase of the optical field with subwavelength resolution. We will present two instruments, a heterodyne scanning probe microscope (heterodyne SNOM) and a high resolution interference microscope (HRIM). We will review some earlier work using the heterodyne SNOM, in particular the measurement of phase singularities produced by a 1 µm pitch grating with 10 nm spatial sampling. Using the HRIM we have investigated the intensity and phase distributions (with singularities) in the focal region of microlenses. The measurements are compared with the results calculated by rigorous diffraction theory.

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Surface profiles of reflow microlenses under the influence of surface tension and gravity

Cited by 84 publications

References 8 publications

Space- and time-resolved spectrophotometry in microsystems

Space- and time-resolved spectrophotometry in microsystems

Procedure for the Development of Multi-depth Circular Cross-sectional Endothelialized Microchannels-on-a-chip

Measuring optical phase singularities at subwavelength resolution

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