scholarly journals Fabrication of a Monolithic Lab-on-a-Chip Platform with Integrated Hydrogel Waveguides for Chemical Sensing

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4333 ◽  
Author(s):  
Maria Leilani Torres-Mapa ◽  
Manmeet Singh ◽  
Olga Simon ◽  
Jose Louise Mapa ◽  
Manan Machida ◽  
...  
Keyword(s):  
Chemical Sensing ◽  
Fluorescence Emission ◽  
Microfluidic Channel ◽  
Lab On A Chip ◽  
Fluorescence Signal ◽  
Excitation Light ◽  
Optical Signals ◽  
Polyethylene Glycol Diacrylate ◽  
Glycol Diacrylate ◽  
Chain Lengths

Hydrogel waveguides have found increased use for variety of applications where biocompatibility and flexibility are important. In this work, we demonstrate the use of polyethylene glycol diacrylate (PEGDA) waveguides to realize a monolithic lab-on-a-chip device. We performed a comprehensive study on the swelling and optical properties for different chain lengths and concentrations in order to realize an integrated biocompatible waveguide in a microfluidic device for chemical sensing. Waveguiding properties of PEGDA hydrogel were used to guide excitation light into a microfluidic channel to measure the fluorescence emission profile of rhodamine 6G as well as collect the fluorescence signal from the same device. Overall, this work shows the potential of hydrogel waveguides to facilitate delivery and collection of optical signals for potential use in wearable and implantable lab-on-a-chip devices.

scholarly journals Shear Stress-Triggered Deformation of Microparticles in a Tapered Microchannel

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 55
Author(s):  
Cheolheon Park ◽  
Junghyun Bae ◽  
Yeongjae Choi ◽  
Wook Park
Keyword(s):  
Shear Stress ◽  
Void Fraction ◽  
Applied Pressure ◽  
Microfluidic Channel ◽  
Volume Index ◽  
Effective Volume ◽  
Particle Deformation ◽  
Polyethylene Glycol Diacrylate ◽  
Glycol Diacrylate ◽  
Deformation Ratio

We demonstrate that it is possible to produce microparticles with high deformability while maintaining a high effective volume. For significant particle deformation, a particle must have a void region. The void fraction of the particle allows its deformation under shear stress. Owing to the importance of the void fraction in particle deformation, we defined an effective volume index (V*) that indicates the ratio of the particle’s total volume to the volumes of the void and material structures. We chose polyethylene glycol diacrylate (Mn ~ 700) for the fabrication of the microparticles and focused on the design of the particles rather than the intrinsic softness of the material (E). We fabricated microparticles with four distinct shapes: discotic, ring, horseshoe, and spiral, with various effective volume indexes. The microparticles were subjected to shear stress as they were pushed through a tapered microfluidic channel to measure their deformability. The deformation ratio R was introduced as R = 1−Wdeformed/Doriginal to compare the deformability of the microparticles. We measured the deformation ratio by increasing the applied pressure. The spiral-shaped microparticles showed a higher deformation ratio (0.901) than those of the other microparticles at the same effective volume index.

Femtosecond Laser Fabrication of a Lab-on-a-Chip in Glass for Enhancing Detection Sensitivity

2006 ◽  
Author(s):  
Y. Cheng ◽  
Tracy E. Hockenhull ◽  
H. L. Tsai
Keyword(s):  
Femtosecond Laser ◽  
Fluorescence Emission ◽  
Microfluidic Channel ◽  
Lab On A Chip ◽  
Green Laser ◽  
Detection Sensitivity ◽  
Output Beam ◽  
Quantitative Characterization ◽  
Fluidic Channel ◽  
Optical Mirrors

Lab-on-a-chip devices offer faster, cheaper, and better ways of doing chemical and biological analyses. In this paper, we will show that both 3D micro-fluidic and 3D micro-optical structures can be directly formed in photosensitive glass using a femtosecond laser and an annealing and etching process. Particularly, we will demonstrate the fabrication and examine the function of lab-on-a-chip biosensors integrated with micro-optical loops for enhancing detection sensitivity. The fabricated lab-on-a-chip biosensors are composed of a micro-fluidic channel into which sample under test will be injected. Five micro-optical mirrors are distributed on both sides of the micro-channel to form a zigzag optical path, which forces a micro-optical beam to cross the micro-fluidic channel three times before entering into a photodetector. This design can effectively extend the absorption path length and result in enhanced detection sensitivity of photoabsorption spectroscopic analysis. To examine the function of the micro-device, we filled the microfluidic channel with a dye solution (Rhodamine 640 dissolved in methanol) and shone a green laser beam (532nm) from a laser pointer into the microstructure. The fluorescence emission from the dye solution indicated that the light beam passed through the microchannel; however, due to the strong absorption, the output beam was not obvious. Quantitative characterization is under way for evaluating the detection limit of the lab-on-a-chip micro-device.

Quantitative Measurement of Fluorescent Layers with Respect to Spatial Thickness Variations and Substrate Properties

2020 ◽  
Vol 74 (4) ◽  
pp. 439-451
Author(s):  
Philipp Holz ◽  
Christoph Pönisch ◽  
Albrecht Brandenburg
Keyword(s):  
Manufacturing Industry ◽  
Quantitative Measurement ◽  
Fluorescence Emission ◽  
Fluorescence Analysis ◽  
Thin Layers ◽  
Fluorescence Signal ◽  
Functional Coatings ◽  
Custom Made ◽  
Substrate Properties ◽  
Thickness Variations

Imaging fluorescence spectroscopy proves to be a fast and sensitive method for measuring the thickness of thin coatings in the manufacturing industry. This encouraged us to systematically study, theoretically and experimentally, parameters that influence the fluorescence of thin layers. We analyzed the fluorescence signal as a function of the scattering and reflectance properties of the sample substrate. In addition, we investigated effects of the layer properties on fluorescence emission. A ray-tracing software is used to describe the influence of these parameters on the fluorescence emission of thin layers. Experiments using a custom-made system for imaging fluorescence analysis verify the simulations. This work shows a factor five variation of fluorescence intensity as a function of the reflectance of the sample substrate. Simulations show variations by a factor of up to eight for samples with different surface roughness. Results on tilted samples indicate a significant increase of the detected fluorescence signal, for fluorescent droplets on reflective substrates, if illuminated and coaxially observed at angles greater than 25°. These findings are of utmost relevance for all applications which utilize the fluorescence emission to quantify thin layers. These applications range from in-line lubricant monitoring in press plants to monitoring of functional coatings in medical technology and the detection of filmic contaminations.

scholarly journals Elucidating the Molecular Mechanisms for the Interaction of Water with Polyethylene Glycol-Based Hydrogels: Influence of Ionic Strength and Gel Network Structure

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 845
Author(s):  
Xin Yang ◽  
Bronwin Dargaville ◽  
Dietmar Hutmacher
Keyword(s):  
Polyethylene Glycol ◽  
Ionic Strength ◽  
Molecular Mechanisms ◽  
Repeat Unit ◽  
Bound Water ◽  
Weight Fraction ◽  
Swelling Ratio ◽  
Polyethylene Glycol Diacrylate ◽  
Glycol Diacrylate ◽  
Hydrogel System

The interaction of water within synthetic and natural hydrogel systems is of fundamental importance in biomaterial science. A systematic study is presented on the swelling behavior and states of water for a polyethylene glycol-diacrylate (PEGDA)-based model neutral hydrogel system that goes beyond previous studies reported in the literature. Hydrogels with different network structures are crosslinked and swollen in different combinations of water and phosphate-buffered saline (PBS). Network variables, polyethylene glycol (PEG) molecular weight (MW), and weight fraction are positively correlated with swelling ratio, while “non-freezable bound water” content decreases with PEG MW. The presence of ions has the greatest influence on equilibrium water and “freezable” and “non-freezable” water, with all hydrogel formulations showing a decreased swelling ratio and increased bound water as ionic strength increases. Similarly, the number of “non-freezable bound water” molecules, calculated from DSC data, is greatest—up to six molecules per PEG repeat unit—for gels swollen in PBS. Fundamentally, the balance of osmotic pressure and non-covalent bonding is a major factor within the molecular structure of the hydrogel system. The proposed model explains the dynamic interaction of water within hydrogels in an osmotic environment. This study will point toward a better understanding of the molecular nature of the water interface in hydrogels.

scholarly journals Generation of Photopolymerized Microparticles Based on PEGDA Using Microfluidic Devices. Part 1. Initial Gelation Time and Mechanical Properties of the Material

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 293
Author(s):  
José M. Acosta-Cuevas ◽  
José González-García ◽  
Mario García-Ramírez ◽  
Víctor H. Pérez-Luna ◽  
Erick Omar Cisneros-López ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Gelation Time ◽  
Mesh Size ◽  
Microfluidic Devices ◽  
Future Generation ◽  
Mechanical Tests ◽  
Continuous Systems ◽  
Polyethylene Glycol Diacrylate ◽  
Glycol Diacrylate ◽  
Close Relationship

Photopolymerized microparticles are made of biocompatible hydrogels like Polyethylene Glycol Diacrylate (PEGDA) by using microfluidic devices are a good option for encapsulation, transport and retention of biological or toxic agents. Due to the different applications of these microparticles, it is important to investigate the formulation and the mechanical properties of the material of which they are made of. Therefore, in the present study, mechanical tests were carried out to determine the swelling, drying, soluble fraction, compression, cross-linking density (Mc) and mesh size (ξ) properties of different hydrogel formulations. Tests provided sufficient data to select the best formulation for the future generation of microparticles using microfluidic devices. The initial gelation times of the hydrogels formulations were estimated for their use in the photopolymerization process inside a microfluidic device. Obtained results showed a close relationship between the amount of PEGDA used in the hydrogel and its mechanical properties as well as its initial gelation time. Consequently, it is of considerable importance to know the mechanical properties of the hydrogels made in this research for their proper manipulation and application. On the other hand, the initial gelation time is crucial in photopolymerizable hydrogels and their use in continuous systems such as microfluidic devices.

Drug-eluting microneedles for self-administered treatment of keloids

TECHNOLOGY ◽  
2014 ◽  
Vol 02 (02) ◽  
pp. 144-152 ◽  
Author(s):  
Peng Xue ◽  
David Chen Loong Yeo ◽  
Yon Jin Chuah ◽  
Hong Liang Tey ◽  
Yuejun Kang ◽  
...  
Keyword(s):  
Clinical Supervision ◽  
Fibrous Tissue ◽  
Polyethylene Glycol Diacrylate ◽  
Glycol Diacrylate ◽  
Keloid Fibroblast ◽  
Culture Models ◽  
Drug Eluting ◽  
Good Potential ◽  
Microneedle Patch

Keloid is a long-term dermatological scarring disease characterized by disfiguring lesions resulting from overgrowth of dense fibrous tissue. Current therapeutics are ineffective, require clinical supervision and can be costly. This study investigated the use of microneedle technology in the self-management of keloid lesions. Specifically, a microneedle patch comprising of polyethylene glycol diacrylate (PEGDA) and encapsulating 5-fluorouracil (5-FU) has been developed for transdermal delivery. The microneedle patches showed requisite mechanical strength (hardness 45 ± 11 MPa, elastic modulus 0.66 ± 0.16 GPa) and were able to puncture porcine epidermis. The choice of PEGDA substrate enabled conformability to non-planar anatomical regions (e.g. elbow), with about 50% of the loaded 5-FU released during the first 12 hours. Thereafter, the microneedle efficacy was evaluated on in vitro keloid fibroblast culture models, where 5-FU loaded microneedles effectively abolished keloid fibroblast proliferation activity. In summary, we have developed a microneedle device with a good potential as an effective, economical and self-applied therapy for keloid scars.

scholarly journals More natural more better: triple natural anti-oxidant puerarin/ferulic acid/polydopamine incorporated hydrogel for wound healing

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Qianmin Ou ◽  
Shaohan Zhang ◽  
Chuanqiang Fu ◽  
Le Yu ◽  
Peikun Xin ◽  
...  
Keyword(s):  
Wound Healing ◽  
Ferulic Acid ◽  
Natural Antioxidants ◽  
Wound Dressings ◽  
Polyethylene Glycol Diacrylate ◽  
Glycol Diacrylate ◽  
Antioxidant Function ◽  
Healing Tissue ◽  
Anti Oxidant ◽  
Gel Network

Abstract Background During wound healing, the overproduction of reactive oxygen species (ROS) can break the cellular oxidant/antioxidant balance, which prolongs healing. The wound dressings targeting the mitigation of ROS will be of great advantages for the wound healing. puerarin (PUE) and ferulic acid (FA) are natural compounds derived from herbs that exhibit multiple pharmacological activities, such as antioxidant and anti-inflammatory effects. Polydopamine (PDA) is made from natural dopamine and shows excellent antioxidant function. Therefore, the combination of natural antioxidants into hydrogel dressing is a promising therapy for wound healing. Results Hydrogel wound dressings have been developed by incorporating PUE or FA via PDA nanoparticles (NPs) into polyethylene glycol diacrylate (PEG-DA) hydrogel. This hydrogel can load natural antioxidant drugs and retain the drug in the gel network for a long period due to the presence of PDA NPs. Under oxidative stress, this hydrogel can improve the activity of superoxide dismutase and glutathione peroxidase and reduce the levels of ROS and malondialdehyde, thus preventing oxidative damage to cells, and then promoting wound healing, tissue regeneration, and collagen accumulation. Conclusion Overall, this triple antioxidant hydrogel accelerates wound healing by alleviating oxidative injury. Our study thus provides a new way about co-delivery of multiple antioxidant natural molecules from herbs via antioxidant nanoparticles for wound healing and skin regeneration. Graphic Abstract

Low-Cost Microfluidic Channel Fabrication for Lab-on-a-Chip Application Using Optimized SU-8 Soft Lithography

2021 ◽  
Author(s):  
Md. Fazlay Rubby ◽  
Varsha Namboodiri ◽  
Mohammad Salman Parvez ◽  
Nazmul Islam
Keyword(s):  
Soft Lithography ◽  
Low Cost ◽  
Microfluidic Channel ◽  
Lab On A Chip
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