Manufacturing Issues and Considerations in Thermal Bonding of Polymer Based Lab-on-a-Chip

2009 ◽  
Vol 74 ◽  
pp. 175-178
Author(s):  
Yu Xin Koh ◽  
Sum Huan Ng ◽  
Khin Thet May ◽  
Cong Zhi Chan ◽  
Zhi Ping Wang
Keyword(s):  
Bond Strength ◽  
Surface Topography ◽  
Lab On A Chip ◽  
Microfluidic Devices ◽  
Thermal Bonding ◽  
Bonding Pressure ◽  
Bonding Quality ◽  
Viscoelastic Effect ◽  
Common Technique

The sealing of microchannels is a key step in the fabrication of microfluidic devices and thermal bonding is a common technique used. Here, major manufacturing issues and considerations in thermal bonding are investigated, including bonding quality and microchannel deformations. Flatness of substrate is extremely crucial to the uniformity in bonding. While increased bonding pressure helps to overcome problems related to surface topography and to enhance bond strength, its significant impact on geometrical changes of microchannel due to viscoelastic effect should also be taken into consideration.

scholarly journals Emerging Lab-on-a-Chip Approaches for Liquid Biopsy in Lung Cancer: Status in CTCs and ctDNA Research and Clinical Validation

Cancers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 2101
Author(s):  
Ângela Carvalho ◽  
Gabriela Ferreira ◽  
Duarte Seixas ◽  
Catarina Guimarães-Teixeira ◽  
Rui Henrique ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Liquid Biopsy ◽  
Residual Disease ◽  
Lab On A Chip ◽  
Microfluidic Devices ◽  
Early Recurrence ◽  
Circulating Tumor Dna ◽  
Clinical Validation ◽  
Liquid Biopsies ◽  
Lung Cancer Patients

Despite the intensive efforts dedicated to cancer diagnosis and treatment, lung cancer (LCa) remains the leading cause of cancer-related mortality, worldwide. The poor survival rate among lung cancer patients commonly results from diagnosis at late-stage, limitations in characterizing tumor heterogeneity and the lack of non-invasive tools for detection of residual disease and early recurrence. Henceforth, research on liquid biopsies has been increasingly devoted to overcoming these major limitations and improving management of LCa patients. Liquid biopsy is an emerging field that has evolved significantly in recent years due its minimally invasive nature and potential to assess various disease biomarkers. Several strategies for characterization of circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) have been developed. With the aim of standardizing diagnostic and follow-up practices, microfluidic devices have been introduced to improve biomarkers isolation efficiency and specificity. Nonetheless, implementation of lab-on-a-chip platforms in clinical practice may face some challenges, considering its recent application to liquid biopsies. In this review, recent advances and strategies for the use of liquid biopsies in LCa management are discussed, focusing on high-throughput microfluidic devices applied for CTCs and ctDNA isolation and detection, current clinical validation studies and potential clinical utility.

scholarly journals Recent Advances in Continuous-Flow Particle Manipulations Using Magnetic Fluids

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 744 ◽  
Author(s):  
Xiangchun Xuan
Keyword(s):  
Continuous Flow ◽  
Lab On A Chip ◽  
Microfluidic Devices ◽  
Magnetic Fluids ◽  
Label Free ◽  
Particle Manipulation ◽  
The Past ◽  
Recent Advances ◽  
Medium Exchange ◽  
Flow Particle

Magnetic field-induced particle manipulation is simple and economic as compared to other techniques (e.g., electric, acoustic, and optical) for lab-on-a-chip applications. However, traditional magnetic controls require the particles to be manipulated being magnetizable, which renders it necessary to magnetically label particles that are almost exclusively diamagnetic in nature. In the past decade, magnetic fluids including paramagnetic solutions and ferrofluids have been increasingly used in microfluidic devices to implement label-free manipulations of various types of particles (both synthetic and biological). We review herein the recent advances in this field with focus upon the continuous-flow particle manipulations. Specifically, we review the reported studies on the negative magnetophoresis-induced deflection, focusing, enrichment, separation, and medium exchange of diamagnetic particles in the continuous flow of magnetic fluids through microchannels.

Gas-assisted thermal bonding of thermoplastics for the fabrication of microfluidic devices

2019 ◽  
Vol 25 (10) ◽  
pp. 3923-3932 ◽  
Author(s):  
S. R. Mahmoodi ◽  
P.-K. Sun ◽  
M. Mayer ◽  
R. S. Besser
Keyword(s):  
Microfluidic Devices ◽  
Thermal Bonding

Comparison of Nickel Nanoparticle-Assisted Diffusion Brazing of Stainless Steel to Conventional Diffusion Brazing and Bonding Processes

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
S. K. Tiwari ◽  
B. K. Paul
Keyword(s):  
Stainless Steel ◽  
Bond Strength ◽  
Diffusion Bonding ◽  
Transient Liquid Phase ◽  
Bond Line ◽  
Scanning Electron Micrographs ◽  
Secondary Phases ◽  
Bonding Pressure ◽  
Nickel Nanoparticle ◽  
Diffusion Brazing

Transient liquid phase diffusion brazing is used in precision, hermetic joining applications as a replacement for diffusion bonding to reduce cycle times, reduce bonding pressure, and improve yields. In the present study, stainless steel 316L laminae are diffusion brazed with an interlayer of nickel nanoparticles and compared with samples joined by conventional diffusion bonding and electroplated nickel-phosphorous diffusion brazing. Comparison is made with regard to microstructural evolution, diffusional profile, and bond strength. All bonding was carried out in a uni-axial vacuum hot press at 1000°C with a heating rate of 10°C/min, a dwell time of 2 h and a bonding pressure of 10 MPa. Bond strength measurements show that the sample brazed with a nickel nanoparticle interlayer has the lowest void fraction at 4.8±0.9% and highest shear strength at 141.3±7.0 MPa. Wavelength dispersive spectroscopic analysis of sample cross-sections shows substantial diffusion of Ni and Fe across the nickel nanoparticle bond line. Scanning electron micrographs show no secondary phases along the nickel nanoparticle bond line.

A Microfluidic Mixer Fabricated From Compliant Thermoplastic Films

2008 ◽  
Vol 2 (1) ◽  
Author(s):  
N. Paya ◽  
T. Dankovic ◽  
A. Feinerman
Keyword(s):  
Reynolds Number ◽  
Lab On A Chip ◽  
Microfluidic Devices ◽  
Reynolds Numbers ◽  
Mixing Efficiency ◽  
Minimal Amount ◽  
Microfluidic Mixer ◽  
Mixing Performance ◽  
Rapid Mixing ◽  
Microfluidic Flows

Mixing is often crucial to the operation of various microfluidic devices. And the most common objective is rapid mixing between two initially segregated fluid streams in a minimal amount of space. In microfluidic flows characterized by incompressibility and low Reynolds number, however, turbulence is almost entirely absent and mixing generally relies on diffusion. Therefore, based on the properties of the fluids involved, it can take impractically long to achieve high mixing efficiency in some cases. To resolve this problem, this paper demonstrates a novel compliant micromixer made of thermoplastic films for lab-on-a-chip applications. The microfluidic mixer utilizes self-rotation effects to achieve high mixing efficiency at Reynolds numbers below 100. In addition, a possible design is suggested for a thermoplastic voltage-actuated micromixer which can lead to even better mixing performance at Reynolds numbers below 1.

Effect of the Organic Acid Surface Modification on Bond Strength of Tin and Copper

2011 ◽  
Author(s):  
Shinji Koyama ◽  
Yukinari Aoki ◽  
Ikuo Shohji
Keyword(s):  
Surface Modification ◽  
Citric Acid ◽  
Solid State ◽  
Bond Strength ◽  
Organic Acid ◽  
Vacuum Chamber ◽  
Bonding Temperature ◽  
Bonded Joints ◽  
Bonding Pressure ◽  
Bonded Interface

The effect of citric-acid surface modification on the bond strength of the solid-state bonded interface of tin and copper has been investigated by SEM observation of the interfacial microstructures and fractured surfaces. Citric-acid surface modification was carried out in a vacuum chamber at a bonding temperature of 383–473 K and a bonding pressure of 7 MPa (bonding time: 1800 s). The citric-acid surface modification decreased bonding temperature by 70 K at which bonded joints could be obtained and bond strength comparable with the base metal was achieved.

EXPERIMENTAL INVESTIGATIONS ON THE INTERACTIONS BETWEEN LIQUIDS AND STRUCTURES TO PASSIVELY CONTROL THE SURFACE-DRIVEN CAPILLARY FLOW IN MICROFLUIDIC LAB-ON-A-CHIP SYSTEMS TO SEPARATE THE MICROPARTICLES FOR BIOENGINEERING APPLICATIONS

2016 ◽  
Vol 24 (06) ◽  
pp. 1750075 ◽  
Author(s):  
SUBHADEEP MUKHOPADHYAY
Keyword(s):  
Surface Area ◽  
Capillary Flow ◽  
Separation Efficiency ◽  
Volume Ratio ◽  
Lab On A Chip ◽  
Microfluidic Devices ◽  
Research Paper ◽  
Novel Approach ◽  
The Individual ◽  
Effect Of Surface

In this research paper, total 246 individual microfluidic devices have been fabricated by maskless lithography, hot embossing lithography and direct bonding technique. The effect of surface area to volume ratio on the surface-driven capillary flow of different liquids has been experimentally investigated in these microfluidic devices fabricated by polymethylmethacrylate (PMMA). Also, the individual effects of liquid viscosity and surface wettability on the surface-driven capillary flow of different liquids are experimentally investigated. The polystyrene particles of 10[Formula: see text][Formula: see text]m diameters have been separated from the aqueous microparticle suspensions in the microfluidic lab-on-a-chip systems with 100% separation efficiency. Also, the polystyrene particles of 5[Formula: see text][Formula: see text]m diameters have been separated from a different set of aqueous microparticle suspensions in the microfluidic lab-on-a-chip systems with 100% separation efficiency. The individual designs of the microfluidic lab-on-a-chip systems are a novel approach in this research paper. The effect of surface area to volume ratio on the separation time is experimentally investigated as another novel approach of this research paper.

scholarly journals Shear bond resistance and enamel surface comparison after the bonding and debonding of ceramic and metallic brackets

2014 ◽  
Vol 19 (1) ◽  
pp. 77-85 ◽  
Author(s):  
José Maurício da Rocha ◽  
Marco Abdo Gravina ◽  
Marcio José da Silva Campos ◽  
Cátia Cardoso Abdo Quintão ◽  
Carlos Nelson Elias ◽  
...  
Keyword(s):  
Bond Strength ◽  
Surface Topography ◽  
Level Set ◽  
Shear Bond Strength ◽  
Enamel Surface ◽  
Tissue Loss ◽  
Significance Level ◽  
Mineral Particles ◽  
Significant Difference ◽  
Ceramic Brackets

OBJECTIVE: To evaluate, in vitro, the shear bond strength presented by three brands of polycrystalline ceramic brackets and one brand of metallic bracket; verify the adhesive remnant index (ARI) after the tests, and analyze, through scanning electron microscopy (SEM) the enamel surface topography after debonding, detecting the release of mineral particles. METHODS: Sixty bovine lower incisors were used. Three ceramic brackets (Allure(r), InVu(r), and Clarity(r)) and one metallic bracket (Geneus(r)) were bonded with Transbond XT(r). Kruskal-Wallis's test (significance level set at 5%) was applied to the results of share bond and ARI. Mann Whitney's test was performed to compare the pairs of brackets in relation to their ARI. Brown-Forsythe's test (significance level set at 5%) was applied to the results of enamel chemical composition. Comparisons between groups were made with Games-Howell's and the Post-hoc tests. RESULTS: No statistically significant difference was observed in relation to the shear bond strength loads. Clarity(r) brackets were the most affected in relation to the surface topography and to the release of mineral particles of enamel (calcium ions). CONCLUSION: With regard to the ARI, there was a prevalence of score 4 (40.4%). As for enamel surface topography, the Geneus(r) bracket was the only one which did not show superficial tissue loss. The InVu(r) and Clarity(r) ones showed cohesive fractures in 33.3% and the Allure(r) in 50%, the latter being the one that presented most fractures during removal.

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