Manufacturing Of Microfluidic Devices Research Articles

Rapid Laser Manufacturing of Microfluidic Devices from Glass Substrates.

Conventional manufacturing of microfluidic devices from glass substrates is a complex, multi-step process that involves different fabrication techniques and tools. Hence, it is time-consuming and expensive, in particular for the prototyping of microfluidic devices in low quantities. This article describes a laser-based process that enables the rapid manufacturing of enclosed micro-structures by laser micromachining and microwelding of two 1.1-mm-thick borosilicate glass plates. The fabrication process was carried out only with a picosecond laser (Trumpf TruMicro 5×50) that was used for: (a) the generation of microfluidic patterns on glass, (b) the drilling of inlet/outlet ports into the material, and (c) the bonding of two glass plates together in order to enclose the laser-generated microstructures. Using this manufacturing approach, a fully-functional microfluidic device can be fabricated in less than two hours. Initial fluid flow experiments proved that the laser-generated microstructures are completely sealed; thus, they show a potential use in many industrial and scientific areas. This includes geological and petroleum engineering research, where such microfluidic devices can be used to investigate single-phase and multi-phase flow of various fluids (such as brine, oil, and CO2) in porous media.

Bonding and in‐channel microfluidic functionalization using the huisgen cyclization

ABSTRACTThe bonding of layers of silicone elastomers during the manufacturing of microfluidic devices is often accomplished using plasma oxidation. The process can be costly, may require a clean room and materials that ensure the flatness of the bonding layers and, as a consequence of hydrophobic recovery, can lead to high variability in the degree of adhesion. As importantly, the process precludes incorporation of chemical functionalities that work as anchors to immobilize biomolecules within the microfluidic channel. We hypothesized that it would be possible to fabricate microfluidic channels using the Huisgen 1,3‐dipolar cycloaddition of azides to alkynes to crosslink silicones and form PDMS elastomers and, in a subsequent step, bond one PDMS layer to another simply by heating, with the added advantage of producing microfluidic channels with embedded chemical functionalities. After thermal bonding, the microfluidic devices underwent cohesive failure (rupture of the elastomer layer) at ∼145 kPa during pressure tests, but did not exhibit adhesive failure (delamination), showing that the azide–alkyne reaction provides a strong bond between elastomer layers. Furthermore, the internal microfluidic channel surfaces retained alkyne and azide functionality during the process, as shown by the grafting of one or more fluorescent dyes, through Huisgen cyclization. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 589–597

IOT and Industry 4.0 – Gateway towards improving Energy Efficiency

Energy efficiency (EE) has become an important benchmark in manufacturing industry due the increasing concerns about climate change and tightening of environmental regulations. However, most manufacturing and production industries today are only able to monitor aggregated energy consumption and lack the real-time visibility of EE on the shop floors. The ability to access energy information and effectively analyse such real-time data to extract key indicators is a crucial factor for successful energy management. While enabling real-time online monitoring of Energy Efficiency, it also applies data gathering analysis to detect abnormal energy consumption patterns and quantify energy efficiency gaps. Through a case study of a microfluidic device manufacturing line, we demonstrate how the application can assist energy managers in embedding best energy management practices in their day-to-day operations and improve Energy Efficiency by eliminating possible energy wastages on manufacturing shop floors.

One-Step Fabrication of a Microfluidic Device with an Integrated Membrane and Embedded Reagents by Multimaterial 3D Printing.

One of the largest impediments in the development of microfluidic-based smart sensing systems is the manufacturability of integrated, complex devices. Here we propose multimaterial 3D printing for the fabrication of such devices in a single step. A microfluidic device containing an integrated porous membrane and embedded liquid reagents was made by 3D printing and applied for the analysis of nitrate in soil. The manufacture of the integrated, sealed device was realized as a single print within 30 min. The body of the device was printed in transparent acrylonitrile butadiene styrene (ABS) and contained a 400 μm wide structure printed from a commercially available composite filament. The composite filament can be turned into a porous material through dissolution of a water-soluble material. Liquid reagents were integrated by briefly pausing the printing before resuming for sealing the device. The devices were evaluated by the determination of nitrate in a soil slurry containing zinc particles for the reduction of nitrate to nitrite using the Griess reagent. Using a consumer digital camera, the linear range of the detector response ranged from 0 to 60 ppm, covering the normal range of nitrate in soil. To ensure that the sealing of the reagent chamber is maintained, aqueous reagents should be avoided. When using the nonaqueous reagent, the multimaterial device containing the Griess reagent could be stored for over 4 days but increased the detection range to 100-500 ppm. Multimaterial 3D printing is a potentially new approach for the manufacture of microfluidic devices with multiple integrated functional components.

Internet of Things for Real-time Waste Monitoring and Benchmarking: Waste Reduction in Manufacturing Shop Floor

In today's manufacturing IT system (e.g. ERP), waste streams in operations are rarely tracked in real-time. Therefore, operational decision that is based on late and incomplete information becomes untimely and not optimal. This paper presents an approach for real-time waste monitoring, analysis and discovers waste reduction potential in manufacturing shop floor. The objective of this study is to learn the waste performance in manufacturing shop floor. Data Envelope Analysis (DEA) is conducted to perform waste benchmarking analysis and the outcome is presented as relative efficiency. The efficiency values are then classified using quartile into 3 performance classes: normal, warning and abnormal. With the performance status, it leads manager to discover achievable waste reduction targets and hence empowers optimization of operational efficiency. A case study using microfluidic device manufacturing line is studied to demonstrate real-time waste monitoring and benchmarking.

Internet-of-Things Enabled Real-time Monitoring of Energy Efficiency on Manufacturing Shop Floors

Energy efficiency (EE) has become an important indicator in manufacturing industry due the rising concerns about climate change and tightening of environmental regulations. However, most manufacturing companies today are only able to monitor aggregated energy consumption and lack the real-time visibility of EE on the shop floors. The ability to access energy information and effectively analyze such real-time data to extract key indicators is a crucial factor for successful energy management. Therefore, in this paper, we introduce an internet-of-things (IoT) enabled software application for real-time monitoring of EE on manufacturing shop floors. While enabling real-time monitoring of EE, it also applies data envelopment analysis (DEA) technique to detect abnormal energy consumption patterns and quantify energy efficiency gaps. Through a case study of a microfluidic device manufacturing line, we demonstrate how the application can assist energy managers in embedding best energy management practices in their day-to-day operations and improve EE by eliminating possible energy wastages on manufacturing shop floors.

Additive manufacturing of microfluidic devices

This paper presents the additive manufacturing process in the manufacture of micro fluidic devices. In a growth scenario of point of care diagnosis and miniaturization of chemical analysis systems is necessary the implementation and analysis of new manufacturing processes of micro fluidic devices. A proposal for additive manufacturing of a Lab on a Chip prototype was done. Preliminary tests concerning dimensional control and real application were performed with the prototype and showed the benefits and limitations of the three dimensional printing application.

Stress Reduction of Amorphous Silicon Deposited by PECVD

ABSTRACTAmorphous silicon (α-Si) was deposited on glass substrates by PECVD at different deposition conditions in order to characterize the residual stress on the film. Subsequently, a thermal-annealing was applied for different times at 400 °C in a N2 atmosphere, aiming to reduce the stress in the films. The deposition power was between 15 and 30 W at 13.56 MHz, the pressure in the chamber was adjusted in a range from 600 to 900 mTorr, and the temperature was varied from 140 to 200 °C. The stress was determined by using the Stoney equation, measuring the curvature and thickness of the α-Si films with a stylus profilometer. A deposition rate between 7-24 nm/min was obtained, and the time for thermal-annealing needed to reduce the stress was reduced from 10 to 2-4 h, obtaining a minimum compressive stress of 17 MPa. With this value of stress, it was possible to use the α-Si as masking material for wet etching of glass during the manufacturing of microfluidic devices, in order to obtain microstructures in the glass with 150 μm in depth.

Synthesis and characterization of a photosensitive organic–inorganic, hybrid positive resin type material: application to the manufacture of microfluidic devices by laser writing

A chemically amplified photosensitive organic–inorganic hybrid material based on PAA polymer, TVEB as a crosslinking dissolution inhibitor, a VEPTES pre-hydrolysed as an organic–inorganic material and a PAG photoacid generator was developed.

Three-Dimensional Printing Based Hybrid Manufacturing of Microfluidic Devices.

Microfluidic platforms offer revolutionary and practical solutions to challenging problems in biology and medicine. Even though traditional micro/nanofabrication technologies expedited the emergence of the microfluidics field, recent advances in advanced additive manufacturing hold significant potential for single-step, stand-alone microfluidic device fabrication. One such technology, which holds a significant promise for next generation microsystem fabrication is three-dimensional (3D) printing. Presently, building 3D printed stand-alone microfluidic devices with fully embedded microchannels for applications in biology and medicine has the following challenges: (i) limitations in achievable design complexity, (ii) need for a wider variety of transparent materials, (iii) limited z-resolution, (iv) absence of extremely smooth surface finish, and (v) limitations in precision fabrication of hollow and void sections with extremely high surface area to volume ratio. We developed a new way to fabricate stand-alone microfluidic devices with integrated manifolds and embedded microchannels by utilizing a 3D printing and laser micromachined lamination based hybrid manufacturing approach. In this new fabrication method, we exploit the minimized fabrication steps enabled by 3D printing, and reduced assembly complexities facilitated by laser micromachined lamination method. The new hybrid fabrication method enables key features for advanced microfluidic system architecture: (i) increased design complexity in 3D, (ii) improved control over microflow behavior in all three directions and in multiple layers, (iii) transverse multilayer flow and precisely integrated flow distribution, and (iv) enhanced transparency for high resolution imaging and analysis. Hybrid manufacturing approaches hold great potential in advancing microfluidic device fabrication in terms of standardization, fast production, and user-independent manufacturing.

Process parameter effects on dimensional accuracy of a hot embossing process for polymer-based micro-fluidic device manufacturing

The embossing of polymeric materials is widely used for manufacturing of micro-parts. The thermoplastic amorphous polymers are always selected to get micro-components. The paper consists to characterise the thermal mechanical properties of three amorphous polymers: polystyrene (PS), poly(methyl methacrylate) (PMMA) and polycarbonate (PC). A set of experiments such as differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) have been carried out with PS, PMMA and PC. The thermoplastic polymers’ behaviours have been characterised above their glass transition temperature. Then, flexible micro-fluidic devices have been manufactured with the polymers by hot embossing process. The surface topography of mould die cavity insert and the micro-fluidic devices have been observed and analysed by a 3D optical microscopy viewing and measurement system in order to compare the replication accuracy for polymeric replicas. The surface roughness of the micro-fluidic devices has been measured to characterise the effect of the compression load and temperature in the hot embossing process. The paper is mainly concentrated on the effect of the process parameters with different amorphous thermoplastic polymers to achieve the process optimization. The results concerning the micro- and nano-scale cavities filling provide information on the reliability about the facilities to replicate complex surface topographies. In this paper, the flow behaviour of polymer during forming process thus process parameters would be investigated. The mould instrumented with micro-structured patterns will be presented. The relationship between embossing conditions and parts quality will be established.

Rapid mold-free manufacturing of microfluidic devices with robust and spatially directed surface modifications

A new method that allows for mold-free, rapid and easy-to-use proto- typing of micro uidic devices comprising channels, access holes and surface modied patterns, is presented. The innovative method ...

Fabrication of Microfluidic Devices for Forensic Molecular Diagnostics

There have been considerable advances in the development of microfluidic devices that can carry out the automated and sophisticated processing necessary for DNA analysis and forensic biology. Polymer substrates with high replication techniques are often used in the manufacture of microfluidic devices that are single use, low cost and disposable. High replication techniques require the creation of a master mould from which the devices are subsequently fabricated. This review will describe the use of high replication techniques for device fabrication, with a focus on creation of the master mould manufacture and application of these devices in molecular diagnostics for forensic applications.

3D Ceramic Microfluidic Device Manufacturing

Today, semiconductor processing serves as the backbone for the bulk of micromachined devices. Precision lithography and etching technology used in the semiconductor industry are also leveraged by alternate techniques like electroforming and molding. The nature of such processing is complex, limited and expensive for any manufacturing foundry. This paper details the technology elements developed to manufacture cost effective and versatile microfluidic devices for applications ranging from medical diagnostics to characterization of bioassays. Two applications using multilayer ceramic technology to manufacture complex 3D microfluidic devices are discussed.

Correction of a coherent image during KrF excimer laser ablation using a mask projection

Using masks for laser ablation has proven useful in the fabrication of prototypes for the manufacturing of micro-fluidic devices. In this work, an excimer laser was used to engrave microscopic channels on the surface of polyethylene terephthalate (PET), which showed a high absorption ratio for an excimer laser beam with a wavelength of 248 nm. When 50 μm wide rectangular microscopic channels were made using a 500×500 μm square mask and a magnification ratio of 1/10, ditch-shaped defects were found at both corners. The calculation of the laser beam intensity showed that a coherent image in the PET specimen caused the defects. An analysis based on the Fourier diffraction theory enabled the prediction of a coherent shape at the image plane, as well as a diffracted beam between the mask and the image plane. The analysis also showed that the diameter of the aperture was a predominant factor toward the elimination of ditch-shaped defects in the rectangular microscopic channels on the PET produced by an excimer laser ablation.

Microfluidic devices obtained by thermal toner transferring on glass substrate

A new process for the manufacture of microfluidic devices based on deposition of laser-printing toner on glass substrates is described. It is an alternative method to the toner on polyester film (toner-polyester) one, previously introduced. Commercial laser printers cannot print directly on glass, thus the toner must first be printed on a special paper and then transferred by heating under pressure to the glass surface. Although this procedure is more complex than the toner-polyester one, it can be repeated several times, yielding multiple toner layers. Even without special alignment equipment, up to four layers could be satisfactorily piled up. Characterization tests revealed that the toner-glass devices have similar behavior as toner-polyester ones regarding the toner layer porosity. The main advantages of the toner-glass technology are improved mechanical stability, possibility of multiple toner layers, augmented electroosmotic flow (EOF), and improved heat transfer. On the other hand, toner adhesion to glass is weaker than to polyester, which limits the device lifetime and usable liquid media. The measured EOF mobility (3.5 x 10(-4) cm2.V(-1).s(-1) for pH 7) suggests that it is mainly determined by the glass surface, being little influenced by the toner walls. Microchip electrophoresis with contactless conductivity detection and photometric detection were implemented using toner-glass devices.

Polyimide and SU-8 microfluidic devices manufactured by heat-depolymerizable sacrificial material technique.

The following paper describes a sacrificial layer method for the manufacturing of microfluidic devices in polyimide and SU-8. The technique uses heat-depolymerizable polycarbonates embedded in polyimide or SU-8 for the generation of microchannels and sealed cavities. The volatile decomposition products originating from thermolysis of the sacrificial material escape out of the embedding material by diffusion through the cover layer. The fabrication process was studied experimentally and theoretically with a focus on the decomposition of the sacrificial materials and their diffusion through the polyimide or SU-8 cover layer. It is demonstrated that the sacrificial material removal process is independent of the actual channel geometry and advances linearly with time unlike conventional sacrificial layer techniques. The fabrication method provides a versatile and fast technique for the manufacturing of microfluidic devices for applications in the field of microTAS and Lab-on-a-Chip.

Low-cost thermoforming of micro fluidic analysis chips

We present a new method for the low-cost manufacture of micro fluidic devices from polymers for single use. Within a one-step or two-step process inside a hot embossing press, micro channels are thermoformed into a thin plastic film and welded on to a thicker plastic film or sheet. Sterile, hermetically sealed micro fluidic structures were fabricated from polystyrene for easy opening immediately before use. It even appears to be possible to produce micro fluidic analysis chips from polymers on a coil from which single devices are cut off for use.