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Yuning Zhang, Xu Liu, Yanan Zhao, Jen-Kan Yu, Walter Reisner, William B Dunbar
A nanofluidic device is presented that, enables independent sensing and resensing of a single DNA molecule translocating through two nanopores with sub-micrometer spacing. The device concept is based upon integrating a thin nitride membrane with microchannels etched in borosilicate glass. Pores, coupled to each microchannel, are connected via a fluid-filled half-space on the device backside, enabling translocation of molecules across each pore in sequence. Critically, this approach allows for independent application of control voltage and measurement of trans-pore ionic current at each of the two pores, leading to 1) controlled assessment of molecular time of flight, 2) voltage-tuned selective molecule recapture, and 3) ability to acquire two correlated translocation signatures for each molecule analyzed...
October 17, 2018: Small
Fei Tian, Lili Cai, Jianqiao Chang, Shanshan Li, Chao Liu, Tiejun Li, Jiashu Sun
Label-free, high-throughput, and efficient separation and enrichment of rare tumor cells, such as circulating tumor cells (CTCs), from untreated whole blood is a challenging task, owing to extremely rare events of CTCs and an enormous amount of blood cells. Current strategies for CTC separation always require pre-processing steps including lysis of blood or labeling of CTCs, leading to loss or damage of CTCs. Here, we report an interfacial viscoelastic microfluidic system for size-selective separation of tumor cells directly from whole blood, without the need of cell labeling and other treatments...
October 17, 2018: Lab on a Chip
Kieu The Loan Trinh, Yu Zhang, Nae Yoon Lee
In this study, we demonstrate a simple and facile method to enable DNA purification and amplification in a continuous step inside a thermoplastic microdevice. The innate property of thermoplastics was adopted to simplify DNA purification because negatively charged DNA can electrostatically interact with the induced positively charged surfaces of thermoplastics as a sample flows inside a microchannel; thus, the DNA purification step can be eliminated. We report the use of natural plastics for the selective adsorption of DNA and conduct a subsequent flow-through polymerase chain reaction (PCR) using a thermoplastic microdevice...
December 21, 2018: Analytica Chimica Acta
Gang Chen, Hui Hui Chai, Ling Yu, Can Fang
A smartphone-based image analysis system is advantageous for point-of-care testing applications. However, the processes of observation and image recording rely heavily on an external attachment that includes additional light sources. Moreover, microfluidic point-of-care devices are highly miniaturized, and can be clearly observed only under magnification. To address these issues, the present work proposes a novel imaging box for converting the built-in light source of a smartphone into uniform backlight illumination to avoid interference arising from reflections...
October 1, 2018: Biomedical Optics Express
Lingyan Gong, Wei Ouyang, Zirui Li, Jongyoon Han
A novel ion concentration polarization-based microfluidic device is proposed for continuous extraction of Li+ from high Mg2+ /Li+ ratio brines. With simultaneous application of the cross-channel voltage that drives electroosmotic flow and the cross-membrane voltage that induces ion depletion, Li+ is concentrated much more than other cations in front of the membrane in the microchannel. The application of external pressure produces a fluid flow that drags a portion of Li+ (and Na+ ) to flow through the microchannel, while keeping most of Mg2+ (and K+ ) blocked, thus implementing continuous Li+ extraction...
June 15, 2018: Journal of Membrane Science
Quang Nghia Pham, Kieu The Loan Trinh, Nguyen Khoi Song Tran, Tae-Sik Park, Nae Yoon Lee
We fabricate a three-dimensional (3D) microdevice operated with minimal peripheral accessories, including a portable pump for semi-automated sample delivery and a single heater for temperature control, for performing reverse transcription polymerase chain reaction (RT-PCR) integrated with a downstream fluorescence detection module for semi-quantitative assessment of gene expression. The microdevice was fabricated by wrapping a polytetrafluoroethylene (PTFE) tube around a pre-designed polycarbonate mold to create a seamless microchannel for both the reverse transcription (RT) of RNA and the amplification of complementary DNA...
October 15, 2018: Analyst
Bun Yamawaki, Ryuki Mori, Kazuhiko Tsukagoshi, Katsumi Tsuchiya, Kenichi Yamashita, Masaharu Murata
No abstract text is available yet for this article.
October 12, 2018: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Xuejia Huang, Jianlin Tang, Lanlan Hu, Ruyu Bian, Ming Liu, Wenxuan Cao, Huijing Zhang
Circulating tumor cells (CTCs) from peripheral blood of cancer patients are considered as one of the most promising pharmacodynamic (PD) biomarkers due to its non-invasive property in disease diagnosis and prognosis. However, the detection of extremely low number of CTCs in patient blood requires methods with high sensitivity and accuracy. We fabricated an arrayed geometrically enhanced mixing (GEM) chip with a "dislocation herringbone" layout based on cell immunoaffinity. By optimizing the injection and rinsing flow rate, an average cell capture rate of 87...
October 9, 2018: Analytical Biochemistry
Liangti Qu, Hongya Geng, Ke Zhou, Jiajia Zhou, Hongyun Ma, Cunjing Lv, Zhiping Xu, Chun Li
Fast and controllable water transport in microchannels implicates multifarious applications. A combination of stimuli-responsive asymmetrical changes in the geometry and gradient in the surface wettability offers the possibility to accelerate the transport and realize controllability. Herein, we introduce a meters-long sunlight-powered reconfigurable water pump constructed by tubular poly(dimethylsiloxane) (PDMS) premixed with chemically reduced graphene oxide (rGO), where the inner wall is modified with thermal-sensitive poly(N-isopropylacrylamide) hydrogel (PNIPAm)...
October 12, 2018: Angewandte Chemie
Jing Nie, Qing Gao, Yidong Wang, Jiahui Zeng, Haiming Zhao, Yuan Sun, Jian Shen, Hamed Ramezani, Zhenliang Fu, Zhenjie Liu, Meixiang Xiang, Jianzhong Fu, Peng Zhao, Wei Chen, Yong He
Hydrogel structures equipped with internal microchannels offer more in vivo-relevant models for construction of tissues and organs in vitro. However, currently used microfabrication methods of constructing microfluidic devices are not suitable for the handling of hydrogel. This study presents a novel method of fabricating hydrogel-based microfluidic chips by combining the casting and bonding processes. A twice cross-linking strategy is designed to obtain a bonding interface that has the same strength with the hydrogel bulk, which can be applied to arbitrary combinations of hydrogels...
October 11, 2018: Small
Rebecca A Moriarty, Kimberly M Stroka
Tumor cells experience physical confinement on one or multiple axes, both in the primary tumor and at multiple stages during metastasis. Recent work has shown that confinement in a 3D spheroid alters nucleus geometry and delays cell division, and that vertical confinement impairs mitotic spindle rounding, resulting in abnormal division events. Meanwhile, the effects of bi-axial confinement on cell cycle progression has received little attention. Given the critical role of nuclear shape and mechanics in cell division, we hypothesized that bi-axial physical confinement of the cell body and nucleus would alter cell cycle progression...
October 10, 2018: Cell Cycle
Sung Bong Kim, KunHyuck Lee, Milan S Raj, Boram Lee, Jonathan T Reeder, Jahyun Koo, Aurélie Hourlier-Fargette, Amay J Bandodkar, Sang Min Won, Yurina Sekine, Jungil Choi, Yi Zhang, Jangryeol Yoon, Bong Hoon Kim, Yeojeong Yun, Seojin Lee, Jiho Shin, Jeonghyun Kim, Roozbeh Ghaffari, John A Rogers
Sweat excretion is a dynamic physiological process that varies with body position, activity level, environmental factors, and health status. Conventional means for measuring the properties of sweat yield accurate results but their requirements for sampling and analytics do not allow for use in the field. Emerging wearable devices offer significant advantages over existing approaches, but each has significant drawbacks associated with bulk and weight, inability to quantify volumetric sweat rate and loss, robustness, and/or inadequate accuracy in biochemical analysis...
October 9, 2018: Small
Theodore Christoforidis, Tom G Driver, Jalees Rehman, David T Eddington
Hydrogen sulfide (H2 S) plays an important role as an intercellular and intracellular signaling molecule, yet its targets are not well understood. As a molecule it easily evaporates and it is hard to acquire stable concentration for in vitro studies, constituting a major problem for the field to identify its downstream targets and function. Here we develop a microfluidic system that can provide consistent and controllable H2 S levels in contrast to the current method of delivering large bolus doses to cells...
2018: RSC Advances
Jia Ming Zhang, Qinglei Ji, Ying Liu, Jianyong Huang, Huiling Duan
The development of integrated microfluidic systems/platforms concerns many fields. Current remarkable integrated systems based on stacking multi-layer polydimethylsiloxane (PDMS) require complicated fabrication and operation and still remain challenging. We propose a novel micro-millifluidic processing system (MPS) comprising three core modules: a motherboard, a control panel and microfluidic chips. Fluids are handled in sub-millichannels in a motherboard and functional operations occur in microchannels in microfluidic chips...
October 3, 2018: Lab on a Chip
C Caiazza, V Preziosi, G Tomaiuolo, D O'Sullivan, V Guida, S Guido
HYPOTHESIS: Shear-banding of branched wormlike solutions is a topic of active investigation which has not been fully elucidated. Here, we surmise that flow-induced microstructuring in the shear banding regime is associated with spatial concentration gradients. EXPERIMENTS: The experiments focus on the flow-induced behavior of a CTAB/NaSal wormlike micellar system. A unique approach based on a microfluidic-spitter geometry, combined with particle-image velocimetry and high-speed video microscopy, is used to separate the streams flowing out from the core and the near wall zones of the microchannel...
September 18, 2018: Journal of Colloid and Interface Science
Kai Zhao, Dongqing Li
A novel AC-dielectrophoretic (DEP) device for tunable manipulation and characterization of particles and droplets is presented in this work. To induce the dielectrophoretic forces, the AC electric field is applied via two embedded microelectrodes to generate a local non-uniform electric field perpendicular to the channel length through a pair of asymmetric orifices on the opposite microchannel walls. The droplets experience the DEP effects only when passing through the vicinity of the small orifice, where the strongest gradient of the non-uniform electric field exists...
September 28, 2018: ACS Applied Materials & Interfaces
Nasire Uluc, Mehmet Burcin Unlu, Gultekin Gulsen, Hakan Erkol
The dynamic response behavior of red blood cells holds the key to understanding red blood cell related diseases. In this regard, an understanding of the physiological functions of erythrocytes is significant before focusing on red blood cell aggregation in the microcirculatory system. In this work, we present a theoretical model for a photoacoustic signal that occurs when deformed red blood cells pass through a microfluidic channel. Using a Green's function approach, the photoacoustic pressure wave is obtained analytically by solving a combined Navier-Stokes and photoacoustic equation system...
June 1, 2018: Biomedical Optics Express
Yongjian Li, Xiangyu Hu, Shuaishuai Liang, Jiang Li, Haosheng Chen
When an immiscible fluid is flowing over a fluid-infused surface with transverse grooves in a microchannel, the infused fluid is either left in or cleaned away from the grooves by the flowing fluid. The cleaning status depends on the geometric parameters of the groove and the contact angle of the flowing fluids. The critical width of the grooves for the infused fluid enclosed in or driven out of the grooves are derived. This study helps to understand the stability of the Cassie status in a low shear flow where the surface tension plays the key role...
September 26, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Lor Huai Chong, Huan Li, Isaac Wetzel, Hansang Cho, Yi-Chin Toh
Drug-induced skin sensitization is prevalent worldwide and can trigger life-threatening health conditions, such as Stevens Johnson Syndrome. However, existing in vitro skin models cannot adequately predict the skin sensitization effects of drugs administered into the systemic circulation because dermal inflammation and injury are preceded by conversion of parent drugs into antigenic reactive metabolites in the liver and subsequent activation of the immune system. Here, we demonstrate that recapitulation of these early tandem cellular processes in a compartmentalized liver-immune coculture array is sufficient to predict the skin sensitization potential of systemic drugs...
September 25, 2018: Lab on a Chip
Fan Luo, Fei Feng, Bin Zhao, Bowen Tian, Xuelei Yang, Haimei Zhou, Xinxin Li
Miniaturization of gas chromatography (GC) columns is one of the key problems associated with microminiaturization of a chromatograph. In this study, a GC column with high-aspect-ratio microchannel based on micro-electro-mechanical system (MEMS) technology has been designed and manufactured. Simulation and analysis by the COMSOL software revealed that the GC column has even velocity field distribution, which is crucial for improving the separation efficiency of the column. The results show that heavy hydrocarbons (C6-C10) and compounds of benzene series can be successfully separated...
September 8, 2018: Se Pu, Chinese Journal of Chromatography
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