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In this work, total 1592 individual leakage-free polymethylmethacrylate (PMMA) microfluidic devices as laboratory-on-a-chip systems are fabricated by maskless lithography, hot embossing lithography, and direct bonding technique. Total 1094 individual Audio Video Interleave Files as experimental outputs related to the surface-driven capillary flow have been recorded and analyzed. The influence of effective viscosity, effect of surface wettability, effect of channel aspect ratio, and effect of centrifugal force on the surface-driven microfluidic flow of aqueous microparticle suspensions have been successfully and individually investigated in these laboratory-on-a-chip systems. Also, 5 micron polystyrene particles have been separated from the aqueous microparticle suspensions in the microfluidic lab-on-a-chip systems of modified design with 98% separation efficiency, and 10 micron polystyrene particles have been separated with 100% separation efficiency. About the novelty of this work, the experimental investigations have been performed on the surface-driven microfluidic flow of aqueous microparticle suspensions with the investigations on the separation time in particle-size based separation mechanism to control these suspensions in the microfluidic lab-on-a-chip systems. This research work contains a total of 10,112 individual experimental outputs obtained using total 30 individual instruments by author’s own hands-on completely during more than three years continuously. Author has performed the experimental investigations on both the fluid statics and fluid dynamics to develop an automated fluid machine.

In this paper, we review ongoing progress in the development of novel on-chip, low loss planar molecular sensors that address the emerging need in the field of biochemical sensing. Chalcogenide glasses were identified as the material of choice for sensing due to their wide infrared transparency window. We report the details of manufacturing processes used to realize novel high-index-contrast, compact micro-disk resonators. Our findings demonstrate that our device can operate in dual modalities, for detection of the infrared optical absorption of a binding event using cavity enhanced spectroscopy, or sensing refractive index change due to surface molecular binding and extracting micro-structural evolution information via cavity enhanced refractometry.

Young Innovators under 35 - 2016 Asia's TR35 Innovators (EmTech Asia 2016)

New Biomedical R&D Centre Set Up by Lite-On Group in Singapore

The Philippines Initiates the World's First Public Dengue Vaccination Programme

In this paper, endeavor has been made to design and analyze different Y-type micromixers by characterizing the mixing and flow behavior in ultra-low Reynolds number region. The effects of different geometric and flow parameters on the mixing and pressure drop are studied through computational fluid dynamics (CFD) simulations using COMSOL Multiphysics software. The parameters investigated are obstacle geometry, obstacle arrangement, obstacle depth, aspect ratio (AR), entrance angle ($E_{\theta })$, Reynolds number (Re) and obstacle packing factor (OPF). The simulation results reveal that rectangular shaped obstacles in staggered arrangement gives the best mixing. Increasing obstacle depth and OPF increases both mixing and pressure drop whereas increasing entrance angle enhances mixing but has negligible effect on pressure drop. Also both the mixing and pressure drop performance enhances with decreasing AR and lower Reynolds number gives better mixing in the lower laminar flow region.

During the last decade, pocket-size analytical equipment based on the "lab-on-a-chip" approach has become available. These chips, in combination with portable electronic equipment, are applicable in e.g. "point-of-care" ion analysis of body fluids, forensics, identification of explosives, tracking of pollution in environmental or waste waters, monitoring nutrients in agricultural or horticultural water, controlling quality in food production, or process control in chemical industry. This paper discusses several demonstrators with applications in these fields.

In microchip electrophoresis (μ-CE), sample injection is generally achieved through cross, double-T, or T-form injector structures. In these reported approaches, the separation efficiency and detection sensitivity of μ-CE is significantly influenced by the shape and size of the sample plug introduced into the separation channel or sample leakage in separation phase. Here, we present a sandwich-injection method for controlling discrete sample injection in μ-CE. This method involves four accessory arm channels in which symmetrical potentials are loaded to form a unique parallel electric field distribution at the intersection of sample and separation channels. The parallel electric field effectuate a virtual wall to confine the shape of a sample plug and depress the spreading of the sample plug at the junction of sample and separation channels, and also prevent sample leakage during separation step. The key features of this method are the ability to inject well-defined sample plugs at the original sample concentration and the ability to control the sample plug size. The virtues of the novel injection technique were demonstrated with numerical models and validated with fluorescence visualizations of electrophoretic experiments.

Loop-mediated isothermal amplification (LAMP) is a novel nucleic acid amplification method. Compared with the widely utilized polymerase chain reaction (PCR), LAMP has higher speed and efficiency as well as lower requirement for system temperature control because the whole amplification process is isothermal and no efforts are needed to switch between different temperatures. In this paper, we designed and fabricated different kinds of polycarbonate (PC) microfluid chips, explored appropriate reaction condition for LAMP in microenvironment (1 nL → 10 μL), and developed a microfluidic isothermal amplification detection system. The DNA optimal amplification temperature is obtained; the starting time of exponential amplification of DNA is put forward farther. The optimal condition of DNA amplification in microenvironment, with a little reaction materials and early starting exponential amplification time of DNA are very important for clinic DNA detection and the application of Lab-on-a-Chip.

Micromilling has great potential in producing microdevices for lab-on-a-chip and organ-on-a-chip applications, but has remained under-utilized due to the high machinery costs and limited accessibility. In this paper, we assessed the machining capabilities of a low-cost 3-D mill in polycarbonate material, which were showcased by the production of microfluidic devices. The study demonstrates that this particular mill is well suited for the fabrication of multi-scale microdevices with feature sizes from micrometers to centimeters.

Microfluidic devices are constructed from polydimethylsiloxane (PDMS) due to their biocompatibility, fabrication ease, well-established protocols, and simplicity. PDMS-based microfluidic devices are constructed by (i) applying liquid PDMS to a negative mold (usually a silicon or 3D-printed mold) and (ii) curing the PDMS with heat exposure over a set time period. Unreacted resin monomers in 3D-printed molds prevent PDMS from fully curing, resulting in improper channel formation in PDMS and reducing the PDMS device’s efficacy. An in-house protocol that uses SU-8 as a “non-stick” coating on 3D-printed molds facilitates the successful casting of PDMS. Contact angle, surface profile, optical profile, and force testing prove that PDMS cast from SU-8-treated molds resembles pristine PDMS, unlike PDMS cast from untreated molds. Further, this method is generalized to commercial 3D prints using different 3D printing resins. To demonstrate this technique’s viability in microfluidic devices, a microfluidic tree using PDMS from treated 3D prints shows vibrant colors and clear lines. This is absent from an untreated PDMS.