Experimental Analysis of Laser Micromachining of Microchannels in Common Microfluidic Substrates (original) (raw)

Effect of Process Parameters and Material Properties on Laser Micromachining of Microchannels

Micromachines, 2019

Laser micromachining has emerged as a promising technique for mass production of microfluidic devices. However, control and optimization of process parameters, and design of substrate materials are still ongoing challenges for the widespread application of laser micromachining. This article reports a systematic study on the effect of laser system parameters and thermo-physical properties of substrate materials on laser micromachining. Three dimensional transient heat conduction equation with a Gaussian laser heat source was solved using finite element based Multiphysics software COMSOL 5.2a. Large heat convection coefficients were used to consider the rapid phase transition of the material during the laser treatment. The depth of the laser cut was measured by removing material at a pre-set temperature. The grid independent analysis was performed for ensuring the accuracy of the model. The results show that laser power and scanning speed have a strong effect on the channel depth, whi...

Studies on CO2 Laser Micromachining on PMMA to Fabricate Micro Channel for Microfluidic Applications

Topics in Mining, Metallurgy and Materials Engineering, 2015

Microfluidic devices are in great demand in the field of biomedical technology,point of care diagnostics and chemical analysis. The rapid and low cost manufacturing of these devices have been a challenge. CO 2 laser micromachining plays an important role in machining although it renders the machined surfaces with high roughness.This study is an attempt to do process optimization of laser micromachining technique which may produce smooth machined surfaces. Herein, the impact of process parameters like raster speed ,laser power, print resolution etc. are optimized using two target functions ofdimensional precision and surface roughness on microchannels made in PMMA (Poly methyl metha acrylate) substrates. The laser machined PMMA samples are analyzed using 3D-profilometry and Field emission scanning electron microscope (FESEM) for surface quality and dimensional precision.To investigate optimum process parameters of CO 2 laser for fabricating the microchannel on PMMA with dimensional accuracy and good surface quality, Analysis of variance (ANOVA) and regression analyses is conducted. It is found that optimum surface roughness of this process is around7.1µm at theoptimum values of the process parameters 7.5 mm /sec (50% of maximum machine limit)raster speed, 17.9Watt (51% of maximum machine limit) laser power and 1200 DPI (100% of maximum machine limit)printing resolution. The static contact angle of the micro-machined surface has also been observedfor analyzing the amenability of these channels to flow of water like fluids for micro-fluidic applications.

Rapid fabrication of tooling for microfluidic devices via laser micromachining and hot embossing

Journal of Micromechanics and Microengineering, 2008

This paper presents a new method for rapid fabrication of polymeric micromold masters for the manufacture of polymer microfluidic devices. The manufacturing method involves laser micromachining of the desired structure of microfluidic channels in a thin metallic sheet and then hot embossing the channel structure onto poly(methyl methacrylate) PMMA substrate to form the mold master. The channeled layer of the microfluidic device is then produced by pouring the polydimethylsiloxane (PDMS) elastomer over the mold and curing it. The method is referred to as LHEM (laser micromachining, hot embossing and molding). Polymers like PDMS are preferred over silicon as the material for building microfluidic devices because of their biocompatibility properties as well as because of their lower cost. The proposed manufacturing method involves fewer processing steps than the conventional soft lithography process and enables manufacture of non-rectangular channels in microfluidic devices. To test the method, a mold for a micro capillary electrophoresis microfluidic chip was fabricated. The experimental results confirmed that high quality (Ra 10 to 100 nm) molds can be fabricated quickly and inexpensively. Advantages and limitations of the proposed method are discussed in the concluding section of the paper.

Rapid Laser Manufacturing of Microfluidic Devices from Glass Substrates

Micromachines

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 micros...

UV Laser Micromachining of Polymers for Microfluidic Applications

Journal of the Association for Laboratory Automation, 2002

W e have recently begun to explore the use of UV laser ablation micromachining to construct microfluidic devices in polymers. This technique can create microchannels rapidly and modify the resulting polymer surface in a single step. By ablating under different atmospheres, it is possible to alter both the surface chemistries and physical surface morphologies of the microchannels. We have employed electroosmotic flow measurements, chemical mapping, and optical microscopy to characterize the microfluidic devices. In addition, we have studied the parameters affecting the ablation, such as the laser wavelength, laser fluence, laser firing repetition rate, and the material being ablated.

Nanosecond pulsed laser micromachining of PMMA-based microfluidic channels

Journal of Manufacturing Processes, 2012

This paper reports an investigation on the effects of nanosecond laser processing parameters on the depth and width of microchannels fabricated from polymethylmethacrylate (PMMA). The Nd:YAG solid-state pulsed laser has a wavelength of 1064 nm and a measured maximum power of 4.15 W. The laser processing parameters are varied in a scanning speed range of 400 to 800 pulses/mm, a pulse frequency range of 5 to 11 Hz, a Q-switch delay time range of 170 to 180 µs. Main effects plots and microchannel images are utilized to identify the effects of the process parameters for improving material removal rate and surface quality simultaneously for laser micromachining of microchannels in PMMA polymer. It is observed that channel width and depth decreased linearly with increasing Q-switch delay time (hence average power) and increased nonlinearly with increasing scanning rate and not much affected by the increase in pulse frequency.

Improved Manufacturing Quality and Bonding of Laser Machined Microfluidic Systems

Procedia Technology, 2015

Laser micro-machining offers a versatile tool for the rapid manufacturing of polymeric microfluidics systems, with a typical turnaround-time in the order of minutes. However, the chaotic nature of the thermal evaporative ablation process can yield a significant number of defects in the surface of the manufactured microchannels, in the form of residual condensed material. In this work we have investigated the use of solvent evaporation by which to not only laminate bond the laser machined structures but to remove a significant number of the defect formed by the condensation of residual polymer. Results are presented of the surface profiling of the bonded channel structures and demonstrations of the bonding of the microchips to produce autonomous capillary microchannels.

Optimization of laser micromachining process for biomedical device fabrication

The International Journal of Advanced Manufacturing Technology, 2015

Laser machining is commonly used for fabrication of medical devices with microscale features, including vascular stents, drug delivery devices, and scaffolds for tissue engineering with controlled pore size and porosity. The process can also be used to produce structured scaffolds for controlling cell growth, orientation, and location. Moreover, lasers may be used to fabricate complex channel nets in which cells are subsequently seeded or to pattern channels for microfluidic devices. Traditionally, these micro devices were fabricated using silicon substrates, but recently the use of titanium allowed to produce more robust devices at a reasonable cost. In particular, the high quality surfaces that can be obtained with laser machining reduce the liquid flow turbulence and avoid micro cavities formation, critical for bacteria proliferation. The present research reports the results of an investigation on the process capability of laser ablation to produce micro pockets fabricated on titanium sheet (0.5 mm thick). A first experimental campaign was designed for identifying a set of laser ablation cycles able to realize the micro pockets by changing the process parameters as scanning speed, laser power, q-switch frequency, loop number, and duty cycle. Moreover, a process optimization was executed in order to produce the pockets with a highly flat surface. The results were acquired by a confocal laser scanning microscope (CLSM) to obtain high-resolution images with depth selectivity and were analyzed with statistic methods for the identification of the best parameter configuration.

Effect of laser processing parameters and glass type on topology of micro-channels

2010

Traditional processes to manufacture micro-fluidic devices include standard lithography, electron beam writing and photo-patterning. These techniques are well established but most are limited to surface micro-fabrication. Laser micro-machining provides an alternative for microfabrication of devices. This paper presents Design of Experiment models for the fabrication of micro-channel structures with four different types of glass, soda-lime, fused-silica, borosilicate and quartz. A 1.5kW CO 2 laser with 90 µm spot size was used to fabricate micro-channels on the surface of glass sheets. Power, P, pulse repetition frequency, PRF, and translation speed, U, were set as control parameters. The resulting geometry of the channel (depth and width) and transmission capabilities were measured and analyzed. A comparison of the results of this experimental testing with the four glass types showed that quartz and fused-silica glasses would have better channel topologies for chemical sensing applications.

Microfluidics-based laser cell-micropatterning system

Biofabrication, 2014

The ability to place individual cells into an engineered microenvironment in a cell-culture model is critical for the study of in vivo relevant cell-cell and cell-extracellular matrix interactions. Microfluidics provides a high-throughput modality to inject various cell types into a microenvironment. Laser guided systems provide the high spatial and temporal resolution necessary for single-cell micropatterning. Combining these two techniques, the authors designed, constructed, tested and evaluated (1) a novel removable microfluidics-based cell-delivery biochip and (2) a combined system that uses the novel biochip coupled with a laser guided cellmicropatterning system to place individual cells into both two-dimensional (2D) and three-dimensional (3D) arrays. Cell-suspensions of chick forebrain neurons and glial cells were loaded into their respective inlet reservoirs and traversed the microfluidic channels until reaching the outlet ports. Individual cells were trapped and guided from the outlet of a microfluidic channel to a target site on the cell-culture substrate. At the target site, 2D and 3D pattern arrays were constructed with micron-level accuracy. Single-cell manipulation was accomplished at a rate of 150 μm s −1 in the radial plane and 50 μm s −1 in the axial direction of the laser beam. Results demonstrated that a single-cell can typically be patterned in 20-30 s, and that highly accurate and reproducible cellular arrays and systems can be achieved through coupling the microfluidics-based cell-delivery biochip with the laser guided system.