Microfluidic Channel Fabrication With Tailored Wall Roughness

Author(s):  
Jing Ren ◽  
Sriram Sundararajan

Realistic random roughness of channel surfaces is known to affect the fluid flow behavior in microscale fluidic devices. This has relevance particularly for applications involving non-Newtonian fluids, such as biomedical lab-on-chip devices. In this study, a surface texturing process was developed and integrated into microfluidic channel fabrication. The process combines colloidal masking and Reactive Ion Etching (RIE) for generating random surfaces with desired roughness parameters on the micro/nanoscale. The surface texturing process was shown to be able to tailor the random surface roughness on quartz. A Large range of particle coverage (around 6% to 67%) was achieved using dip coating and drop casting methods using a polystyrene colloidal solution. A relation between the amplitude roughness, autocorrelation length, etch depth and particle coverage of the processed surface was built. Experimental results agreed reasonably well with model predictions. The processed substrate was further incorporated into microchannel fabrication. Final device with designed wall roughness was tested and proved a satisfying sealing performance.

Biosensors ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 65
Author(s):  
Puneet Manocha ◽  
Gitanjali Chandwani

Molecular communication is a bioinspired communication that enables macro-scale, micro-scale and nano-scale devices to communicate with each other. The molecular communication system is prone to severe signal attenuation, dispersion and delay, which leads to performance degradation as the distance between two communicating devices increases. To mitigate these challenges, relays are used to establish reliable communication in microfluidic channels. Relay assisted molecular communication systems can also enable interconnection among various entities of the lab-on-chip for sharing information. Various relaying schemes have been proposed for reliable molecular communication systems, most of which lack practical feasibility. Thus, it is essential to design and develop relays that can be practically incorporated into the microfluidic channel. This paper presents a novel design of passive in-line relay for molecular communication system that can be easily embedded in the microfluidic channel and operate without external energy. Results show that geometric modification in the microfluidic channel can act as a relay and restore the degraded signal up-to 28%.


2016 ◽  
Vol 78 (8-4) ◽  
Author(s):  
Ummikalsom Abidin ◽  
Jumril Yunas ◽  
Burhanuddin Yeop Majlis

Microfluidics channel of micron- to millimeter in dimension has been widely used for fluid handling in transporting, mixing and separating biological cells in Lab-on-Chip (LoC) applications. In this research, fabrication and testing of Polydimethylsiloxane (PDMS) microfluidic channel for Lab-on-chip magnetically-labelled biological cells separation is presented. The microchannel is designed with one inlet and outlet. A reservoir or chamber is proposed as an extra component of the microchannel design for ease of trapping the intended biological cells in LoC magnetic separator system. The PDMS microchannel of circular-shaped chamber geometry has been successfully fabricated using replica molding technique from SU-8 negative photoresist mold. An agglomerate-free microbeads flowing has been observed using the fabricated PDMS microchannel. Trapping of microbeads in the trapping chamber with 2.0 A current supply in the continuous microfluidics flow > 100 mL/min has also been demonstrated. In conclusion, a separation of biological cells labelled with magnetic microbeads is expected to be realized using the fabricated PDMS microchannel.


Author(s):  
Nazmul Islam

As the world becomes increasingly concerned with endocrine disruptor from estrogenic activity, and since the threat of estrogen can be substantially mitigated if detected early, the demand for real-time/on-site detection of estrogen is expanding quickly. However, current technology is expensive, technically complicated and not available for estrogen level determination at the contamination sites. The primary objective of this research is to develop and validate a robust, rapid lab-on-chip for detecting estrogen in environmental water samples. Anti-estrogen antibodies can be layered to the microcantilever (MC) surface through passive adsorption using a dilute solution of antibody. The estrogen in the water will bind/react with antibody, which will result in a strain in the cantilever. The strain of the cantilever can ultimately be measured as a resistance change in the microsystem. MC will be integrated with AC electokinetic to produce a lab-on-a-chip that can concentrate measure and differentiate viable estrogen.


2016 ◽  
Vol 819 ◽  
pp. 420-424
Author(s):  
Ummikalsom Abidin ◽  
Burhanuddin Yeop Majlis ◽  
Jumril Yunas

Microchannel of micron-to milimeter in dimension has been immensely used for fluid handling in transporting, mixing and separating biological cells in Lab-on-Chip (LoC) applications. In this paper, design, simulation and fabrication of Polydimethylsiloxane (PDMS) microfluidic channel are presented. The microchannel is designed with one inlet and outlet. A reservoir or chamber is proposed as an extra component in the microchannel design for ease of separating the intended biological cells as used in LoC magnetic separator and micro-incubator. Finite Element Analysis (FEA) shows laminar flow characteristic is maintained in the proposed microchannel design operating at volumetric flow rate between 0.5 to 1000 μL/min. In addition, pressure drop data across the microchannel are also been obtained from the FEA in determining the safe operation limit of the microchannel. The PDMS microchannels of two different chamber geometries have been successfully fabricated using replica molding technique from SU-8 negative photoresist mold. The fabricated SU-8 mold and the PDMS microchannel structure dimension are characterized using Scanning Electron Microscopy (SEM). Reversible bonding of PDMS microchannel layer and PDMS tubing layer has successfully accomplished by activating the PDMS surfaces using corona discharge. The preliminary testing of the microchannel confirmed its function for LoC continuous flow applications.


Author(s):  
K Karthikeyan ◽  
L Sujatha

AbstractThis paper deals with design, simulation, fabrication, analysis of mixing efficiency and thin film bonding stability of the micromixer devices with different flow rates used for lab on chip applications. The objective of the present study is to achieve complete mixing with low flow rate and less pressure drop in low cost polymer microfluidic devices. This paper emphasis the design, simulation and fabrication of straight channel micromixer, serpentine channel micromixer with and without quadrant shaped grooves to study the mixing behavior by the effect of structural dimensions of the microfluidic channel at different flow rates. The designed micromixers were tested with varying rates of flow such as 1, 10, 25, 50, 75 and 100 µL/min.


2013 ◽  
Vol 832 ◽  
pp. 84-88
Author(s):  
Veeradasan Perumal ◽  
U. Hashim ◽  
Tijjani Adam

A simple design and simulation of microwire, contact pad and microfluidic channel on computer aided design (CAD) for chrome mask fabrication are described.The integration of microfluidic and nanotechnology for miniaturized lab-on-chip device has received a large research attention due to its undisputable and widespread biomedical applications. For the development of a micro-total analytical system, the integration of an appropriate fluid delivery system to a biosensing apparatus is required. In this study, we had presented the new Lab-On-Chip design for biomedical application. AutoCAD software was used to present the initial design/prototype of this Lab-On-Chip device. The microfluidic is design in such a way, that fluid flow was passively driven by capillary effect. Eventually, the prototype of the microfluidics was simulated using Comsol Multiphysics software for design validation.The complete design upon simulation is then used for mask fabrication. Hence, three mask is fabricated which consist of microwire, contact pad and microfluidics for device fabrication using photolithography process.


2021 ◽  
pp. 2004101
Author(s):  
Marco Giacometti ◽  
Francesca Milesi ◽  
Pietro Lorenzo Coppadoro ◽  
Alberto Rizzo ◽  
Federico Fagiani ◽  
...  
Keyword(s):  

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1113
Author(s):  
Mohammed Asadullah Khan ◽  
Jürgen Kosel

An integrated polymer-based magnetohydrodynamic (MHD) pump that can actuate saline fluids in closed-channel devices is presented. MHD pumps are attractive for lab-on-chip applications, due to their ability to provide high propulsive force without any moving parts. Unlike other MHD devices, a high level of integration is demonstrated by incorporating both laser-induced graphene (LIG) electrodes as well as a NdFeB magnetic-flux source in the NdFeB-polydimethylsiloxane permanent magnetic composite substrate. The effects of transferring the LIG film from polyimide to the magnetic composite substrate were studied. Operation of the integrated magneto hydrodynamic pump without disruptive bubbles was achieved. In the studied case, the pump produces a flow rate of 28.1 µL/min. while consuming ~1 mW power.


Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ali Rostamian ◽  
Ehsan Madadi-Kandjani ◽  
Hamed Dalir ◽  
Volker J. Sorger ◽  
Ray T. Chen

Abstract Thanks to the unique molecular fingerprints in the mid-infrared spectral region, absorption spectroscopy in this regime has attracted widespread attention in recent years. Contrary to commercially available infrared spectrometers, which are limited by being bulky and cost-intensive, laboratory-on-chip infrared spectrometers can offer sensor advancements including raw sensing performance in addition to use such as enhanced portability. Several platforms have been proposed in the past for on-chip ethanol detection. However, selective sensing with high sensitivity at room temperature has remained a challenge. Here, we experimentally demonstrate an on-chip ethyl alcohol sensor based on a holey photonic crystal waveguide on silicon on insulator-based photonics sensing platform offering an enhanced photoabsorption thus improving sensitivity. This is achieved by designing and engineering an optical slow-light mode with a high group-index of n g  = 73 and a strong localization of modal power in analyte, enabled by the photonic crystal waveguide structure. This approach includes a codesign paradigm that uniquely features an increased effective path length traversed by the guided wave through the to-be-sensed gas analyte. This PIC-based lab-on-chip sensor is exemplary, spectrally designed to operate at the center wavelength of 3.4 μm to match the peak absorbance for ethanol. However, the slow-light enhancement concept is universal offering to cover a wide design-window and spectral ranges towards sensing a plurality of gas species. Using the holey photonic crystal waveguide, we demonstrate the capability of achieving parts per billion levels of gas detection precision. High sensitivity combined with tailorable spectral range along with a compact form-factor enables a new class of portable photonic sensor platforms when combined with integrated with quantum cascade laser and detectors.


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