Fabrication Of Microfluidic Channels Research Articles

Dynamic control of extracellular environment in in vitro neural recording systems

A technique is presented for rapid fabrication of microfluidic channels on top of multichannel in vitro neural recording electrode arrays. The channels allow dynamic control of both stable and transient flow patterns over localized areas of the array, over biologically relevant timescales. A cellular model consisting of thermally sensitive dorsal root ganglion neurons was integrated into the devices. The device was used to demonstrate precise control of the extracellular microenvironment of individual cells on the array. Since the methods presented here are not specific to a particular cell type or neural recording system, the technique is amenable to a wide range of applications within the neuroscience field.

Ionscan: scanning and control software for proton beam writing

The proton beam writing technique relies on a precise beam scanning and control system that offers a simple yet flexible interface for the fabrication and design of microstructures. At the Centre for Ion Beam Applications, National University of Singapore, we have developed a suite of programs, collectively known as Ionscan, that cater for the specific needs of proton beam writing. The new version of Ionscan is developed using the Microsoft Visual C++. NET development environment in conjunction with a National Instruments analog output card and NI-DAQ drivers. With the benefit of the experience gained in proton beam writing over the years, numerous enhancements and new features have been added to the scanning software since the first version of the program that was developed using LabVIEW [A.A. Bettiol, J.A. van Khan, T.C. Sum, F. Watt, Nucl. Instr. and Meth. B 181 (2001) 49]. These include the ability to perform combined stage and magnetic (or electrostatic) scanning, which is particularly useful for the fabrication of long waveguides and microfluidic channels over lengths of up to 2.5cm. Other enhancements include the addition of the Ionutils program which gives the user the ability to design basic structures using an ASCII file format that was developed. This format contains basic information on the shape to be irradiated including the way in which it is scanned.

Automatic aligning and bonding system of PDMS layer for the fabrication of 3D microfluidic channels

This paper describes a novel system for the aligning and bonding of patterned poly(dimethylsiloxane) (PDMS) layers for the fabrication of 3D microfluidic channels. The system has the following three moving parts: (1) a rough manual back-and-forth movement for the placing of upper layer onto the lower layer, (2) a precise XYZ movement to align lower and upper layers with one another, and (3) the rotational movement for the angular matching of patterns. After the aligning, the primary curing for the bonding of aligned layers was performed on a preset heater without movement of the sample. The alignment-tests were performed for four groups (novice/manual, novice/automatic, expert/manual, expert/automatic) by using various-sized triangular patterns. The experiments demonstrate the existence of a statistically significant improvement in aligning quality in the automatic aligning group. Even to the novices who have fewer than one months’ aligning experience, the aligning accuracy is similar to the manual alignment of the expert group having more than 1 year's manual alignment experience. The system can be applied efficiently to the 3D fabrication of microfluidic channels in the laboratory.

Microfluidic channel fabrication in dry film resist for production and prototyping of hybrid chips

Microfluidic networks are patterned in a dry film resist (Ordyl SY300/550) that is sandwiched in between two substrates. The technique enables fabrication of complex biochips with active elements both in the bottom and the top substrate (hybrid chips). The resist can be double bonded at relatively low temperatures without the use of extra adhesives. A postbake transfers the resist into a rigid structure. The resist is qualified in terms of resolution, biocompatibility and fluidic sealing. Fabrication in both a fully equipped cleanroom setting as well as a minimally equipped laboratory is described. The technique is applied for dielectrophoresis-based cell separation systems and a fuel cell reaction chamber with micropillars. The dry film resist can be considered a cheap and fast alternative to SU-8.

Interface lithography: a hybrid lithographic approach for the fabrication of patternsembedded in three-dimensional structures

The aim of this study was to develop a viable technology to realize arbitrary shaped andsized patterns embedded in three-dimensional microstructures. In this paper, wepresent a new fabrication process based on a binary resist process scheme with thecombined use of electron-beam lithography and multi-tilted x-ray lithography.We demonstrate the fabrication of three-dimensional photonic crystal structureswith embedded waveguides and the fabrication of a flyover micro-fluidic channel.

Fabrication of high-aspect ratio, micro-fluidic channels and tunnels using femtosecond laser pulses and chemical etching

We present novel results obtained in the fabrication of high-aspect ratio micro-fluidic microstructures chemically etched from fused silica substrates locally exposed to femtosecond laser radiation. A volume sampling method to generate three-dimensional patterns is proposed and a systematic SEM-based analysis of the microstructure is presented. The results obtained gives new insights toward a better understanding of the femtosecond laser interaction with fused silica glass (a-SiO(2)).

Microfiber assisted fabrication of microfluidic channels using poly(dimethylsiloxane)

AIChE JournalVolume 49, Issue 11 p. 2984-2987 Bioengineering, Food and Natural Products Microfiber assisted fabrication of microfluidic channels using poly(dimethylsiloxane) Tom T. Huang, Tom T. Huang School of Chemical Engineering, and Laboratory of Renewable Resources Engineering (LORRE)Search for more papers by this authorWoo-Jin Chang, Woo-Jin Chang School of Electrical and Computer EngineeringSearch for more papers by this authorDemir Akin, Demir Akin School of Electrical and Computer EngineeringSearch for more papers by this authorRafael Gomez, Rafael Gomez School of Electrical and Computer EngineeringSearch for more papers by this authorRashid Bashir, Rashid Bashir School of Electrical and Computer Engineering, and Dept. of Biomedical EngineeringSearch for more papers by this authorNathan Mosier, Nathan Mosier Dept. of Agricultural and Biological Engineering, and Laboratory of Renewable Resources Engineering (LORRE)Search for more papers by this authorMichael R. Ladisch, Corresponding Author Michael R. Ladisch Dept. of Agricultural and Biological Engineering, Dept. of Biomedical Engineering, and Laboratory of Renewable Resources Engineering (LORRE) Purdue University, West Lafayette, IN 47907Dept. of Agricultural and Biological Engineering, Dept. of Biomedical Engineering, and Laboratory of Renewable Resources Engineering (LORRE) Purdue University, West Lafayette, IN 47907Search for more papers by this author Tom T. Huang, Tom T. Huang School of Chemical Engineering, and Laboratory of Renewable Resources Engineering (LORRE)Search for more papers by this authorWoo-Jin Chang, Woo-Jin Chang School of Electrical and Computer EngineeringSearch for more papers by this authorDemir Akin, Demir Akin School of Electrical and Computer EngineeringSearch for more papers by this authorRafael Gomez, Rafael Gomez School of Electrical and Computer EngineeringSearch for more papers by this authorRashid Bashir, Rashid Bashir School of Electrical and Computer Engineering, and Dept. of Biomedical EngineeringSearch for more papers by this authorNathan Mosier, Nathan Mosier Dept. of Agricultural and Biological Engineering, and Laboratory of Renewable Resources Engineering (LORRE)Search for more papers by this authorMichael R. Ladisch, Corresponding Author Michael R. Ladisch Dept. of Agricultural and Biological Engineering, Dept. of Biomedical Engineering, and Laboratory of Renewable Resources Engineering (LORRE) Purdue University, West Lafayette, IN 47907Dept. of Agricultural and Biological Engineering, Dept. of Biomedical Engineering, and Laboratory of Renewable Resources Engineering (LORRE) Purdue University, West Lafayette, IN 47907Search for more papers by this author First published: 16 April 2004 https://doi.org/10.1002/aic.690491129Citations: 6AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume49, Issue11November 2003Pages 2984-2987 RelatedInformation

DNA probe attachment on plastic surfaces and microfluidic hybridization array channel devices with sample oscillation

DNA probe immobilization on plastic surfaces and device assembly are both critical to the fabrication of microfluidic hybridization array channel (MHAC) devices. Three oligonucleotide (oligo) probe immobilization procedures were investigated for attaching oligo probes on four different types of plastic surfaces (polystyrene, polycarbonate, poly(methylmethacrylate), and polypropylene). These procedures are the Surmodics procedure, the cetyltrimethylammonium bromide (CTAB) procedure, and the Reacti-Bind procedure. To determine the optimal plastic substrate and attachment chemistry for array fabrication, we investigated plastic hydrophobicity, intrinsic fluorescence, and oligo attachment efficiency. The Reacti-Bind procedure is least effective for attaching oligo probes in the microarray format. The CTAB procedure performs well enough to use in array fabrication, and the concentration of CTAB has a significant effect on oligo immobilization efficiency. We also found that use of amine-modified oligo probes resulted in better immobilization efficiency than use of unmodified oligos with the CTAB procedure. The oligo probe immobilization on plastic surfaces by the Surmodics procedure is the most effective with regard to probe spot quality and hybridization sensitivity. A DNA hybridization assay on such a device results in a limit of detection of 12 pM. Utilizing a CO 2 IR laser machining and adhesive layer approach, we have developed an improved procedure for realizing a DNA microarray inside a microfluidic channel. This device fabrication procedure allows for more feasible spot placement in the channel and reduced sample adsorption by adhesive tapes used in the fabrication procedure. We also demonstrated improved hybridization kinetics and increased detection sensitivity in MHAC devices by implementing sample oscillation inside the channel. A limit of detection of 5 pM has been achieved in MHAC devices with sample oscillation.

An integrated fluorescence detection system in poly(dimethylsiloxane) for microfluidic applications.

This paper describes a prototype of an integrated fluorescence detection system that uses a microavalanche photodiode (microAPD) as the photodetector for microfluidic devices fabricated in poly(dimethylsiloxane) (PDMS). The prototype device consisted of a reusable detection system and a disposable microfluidic system that was fabricated using rapid prototyping. The first step of the procedure was the fabrication of microfluidic channels in PDMS and the encapsulation of a multimode optical fiber (100-microm core diameter) in the PDMS; the tip of the fiber was placed next to the side wall of one of the channels. The optical fiber was used to couple light into the microchannel for the excitation of fluorescent analytes. The photodetector, a prototype solid-state microAPD array, was embedded in a thick slab (1 cm) of PDMS. A thin (80 microm) colored polycarbonate filter was placed on the top of the embedded microAPD to absorb scattered excitation light before it reached the detector. The microAPD was placed below the microchannel and orthogonal to the axis of the optical fiber. The close proximity (approximately 200 microm) of the microAPD to the microchannel made it unnecessary to incorporate transfer optics; the pixel size of the microAPD (30 microm) matched the dimensions of the channels (50 microm). A blue light-emitting diode was used for fluorescence excitation. The microAPD was operated in Geiger mode to detect the fluorescence. The detection limit of the prototype (approximately 25 nM) was determined by finding the minimum detectable concentration of a solution of fluorescein. The device was used to detect the separation of a mixture of proteins and small molecules by capillary electrophoresis; the separation illustrated the suitability of this integrated fluorescence detection system for bioanalytical applications.

Biosystem for the culture and characterisation of epithelial cell tissues

We have designed and realised a new type of microsystem for the electrical characterisation of epithelial cell layers for biomedical diagnostic purposes. We have used deep plasma and other micromachining procedures for the fabrication of vias and microfluidic channels in silicon and glass substrates. Miniaturised cell culture devices have been realised by gluing nano-porous polycarbonate membranes in between two structured wafers and by combining these with glass wafers to provide integrated microfluidic channels. We have characterised the impedimetric properties of our microsystem, demonstrated epithelial cell layer growth within it, and have done the initial electrical characterisations of epithelial cell layers. We believe that our devices will open new perspectives for cell-based diagnostic applications, especially for those where available cell quantities pose a limiting factor.

Fabrication of a novel microsystem for the electrical characterisation of cell arrays

We have designed and realised a new type of microsystem for the electrical characterisation of arrays of living cells for biomedical diagnostic purposes. We have used deep plasma etching for the fabrication of microholes and micro-fluidic channels in silicon substrates. After oxidation and electrical contact fabrication, these structured silicon wafers have been anodically bonded with Pyrex wafers. The fabrication is completed by the gluing of micro-patterned polyimide foils on top of the silicon. We have tested the electrical characteristics of our microsystems using NaCl salt solutions of various molarities. We believe that our device will open new perspectives for biochemical sensor applications.

Plasma-deposited amorphous silicon carbide films for micromachined fluidic channels

The stress properties of the a-SiC:H films on Si by plasma-enhanced chemical vapor deposition (PECVD) are investigated. It is found that the stability of the a-SiC:H films relates to Si–H bonds breaking and changes the stress toward tensile. No evident reduction in the content of Si–H bonds after thermal cycles was found in the carbon-rich samples. Moreover, a new method to fabricate microchannels by through-hole etching with subsequent planarization is proposed. The process is based on etching out the deep grooves through a perforated a-SiC:H membrane, where poly-Si is used as a sacrificial layer to define the channel structure, followed by PECVD sealing the SiC:H membrane. In order to improve the etching performance, the agitated KOH etch is performed at low temperatures (<50°C). The process technology is demonstrated on the fabrication of microfluidic channels with the low-stress (<0.1 GPa) a-SiC:H membranes.

Buried microchannels in photopolymer for delivering of solutions to neurons in a network

A simple and efficient technique for the fabrication of buried microfluidic channels is presented. Microchannels made using a contribution of thick liquid and laminated photopolymers are used for the realization of smart microchips for culture, stimulation and recording of neural cell arrays.

Photochemical decomposition mechanisms for AZ-type photoresists : J. Pacansky and J. R. Lyeria. IBM J. Res. Dev.23, (1) 42 (January 1979)

Photolithography has been applied to biological applications such as cell and protein micropatterning and the fabrication of microfluidic channels. However, the preparation of photomasks for projecting micropattern lighting images is often time consuming and costly. Therefore, we have developed maskless photolithography devices by modifying the optics of commercially available liquid crystal display (LCD) projectors from extended to reduced projection. The developed second and third devices produce practically a centimeter-scale micropattern by dividing an original large mask pattern into several patterns, which are individually and synchronously exposed to substrates with a motorized XY-stage, applying them to cell micropatterning and polydimethylsiloxane (PDMS) microfluidic device production. The first part of this chapter describes the developments of the maskless photolithography devices. The second part describes the exposure control system with a motorized XY-stage. The third part describes the applications of devices to cell micropatterning. The last part describes the application of the devices to the fabrication of the PDMS microfluidic channel. Maskless photolithography with an LCD projector has a large advantage with no requirement for a photomask. In particular, the maskless photolithography devices show a greater power by optimizing the conditions of pattern size and shape.

Packaging with laser welding : J. E. Jackson, SCP and Solid St. Technology, May (1966), p. 21

Photolithography has been applied to biological applications such as cell and protein micropatterning and the fabrication of microfluidic channels. However, the preparation of photomasks for projecting micropattern lighting images is often time consuming and costly. Therefore, we have developed maskless photolithography devices by modifying the optics of commercially available liquid crystal display (LCD) projectors from extended to reduced projection. The developed second and third devices produce practically a centimeter-scale micropattern by dividing an original large mask pattern into several patterns, which are individually and synchronously exposed to substrates with a motorized XY-stage, applying them to cell micropatterning and polydimethylsiloxane (PDMS) microfluidic device production. The first part of this chapter describes the developments of the maskless photolithography devices. The second part describes the exposure control system with a motorized XY-stage. The third part describes the applications of devices to cell micropatterning. The last part describes the application of the devices to the fabrication of the PDMS microfluidic channel. Maskless photolithography with an LCD projector has a large advantage with no requirement for a photomask. In particular, the maskless photolithography devices show a greater power by optimizing the conditions of pattern size and shape.