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Biomedical Microdevices

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https://www.readbyqxmd.com/read/28929363/all-in-one-low-intensity-pulsed-ultrasound-stimulation-system-using-piezoelectric-micromachined-ultrasonic-transducer-pmut-arrays-for-targeted-cell-stimulation
#1
Wonjun Lee, Seungjun Yoo, Joontaek Jung, Woojin Kang, Wei Wang, Cheil Moon, Hongsoo Choi
A novel cell-stimulation system was fabricated using 10 × 29 piezoelectric micromachined ultrasonic transducer (pMUT) arrays for targeted ultrasonic cell stimulation. Both the diameter of a single pMUT element and the edge-to-edge gap were 120 μm, and the size of a pMUT array was 2.27 × 6.84 mm, to be placed at the bottom of a Transwell. The measured resonance frequency of a single pMUT element was 1.48 ± 0.13 MHz and the measured acoustic intensity of the pMUT array was 0.15 ± 0.03 MPa at 1 mm away from the transducer...
September 19, 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28929304/embryonic-body-culturing-in-an-all-glass-microfluidic-device-with-laser-processed-4%C3%A2-%C3%AE-m-thick-ultra-thin-glass-sheet-filter
#2
Y Yalikun, N Tanaka, Y Hosokawa, T Iino, Y Tanaka
In this paper, we report the development and demonstration of a method to fabricate an all-glass microfluidic cell culturing device without circulation flow. On-chip microfluidic cell culturing is an indispensable technique for cellular replacement therapies and experimental cell biology. Polydimethylsiloxane (PDMS) have become a popular material for fabricating microfluidic cell culture devices because it is a transparent, biocompatible, deformable, easy-to-mold, and gas-permeable. However, PDMS is also a chemically and physically unstable material...
September 19, 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28929244/analyzing-polymeric-matrix-for-fabrication-of-a-biodegradable-microneedle-array-to-enhance-transdermal-delivery
#3
Kuo-Yuan Hwa, Vincent H S Chang, Yao-Yi Cheng, Yue-Da Wang, Pey-Shynan Jan, Boopathi Subramani, Min-Ju Wu, Bo-Kai Wang
Traditional drug delivery systems, using invasive, transdermal, and oral routes, are limited by various factors, such as the digestive system environment, skin protection, and sensory nerve stimulation. To improve the drug delivery system, we fabricated a polysaccharide-based, dissolvable microneedle-based array, which combines the advantages of both invasive and transdermal delivery systems, and promises to be an innovative solution for minimally invasive drug delivery. In this study, we designed a reusable aluminum mold that greatly improved the efficiency and convenience of microneedle fabrication...
September 19, 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28894955/a-flexible-cell-concentrator-using-inertial-focusing
#4
Chunglong Tu, Jian Zhou, Yitao Liang, Bobo Huang, Yifeng Fang, Xiao Liang, Xuesong Ye
Cell concentration adjustment is intensively implemented routinely both in research and clinical laboratories. Centrifuge is the most prevalent technique for tuning biosample concentration. But it suffers from a number of drawbacks, such as requirement of experienced operator, high cost, low resolution, variable reproducibility and induced damage to sample. Herein we report on a cost-efficient alternative using inertial microfluidics. While the majority of existing literatures concentrate on inertial focusing itself, we identify the substantial role of the outlet system played in the device performance that has long been underestimated...
September 11, 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28887730/an-exploration-of-the-reflow-technique-for-the-fabrication-of-an-in-vitro-microvascular-system-to-study-occlusive-clots
#5
Yang Li, Chuer Pan, Yunfeng Li, Eugenia Kumacheva, Arun Ramachandran
Embolic ischemia and pulmonary embolism are health emergencies that arise when a particle such as a blood clot occludes a smaller blood vessel in the brain or the lungs, and restricts flow of blood downstream of the vessel. In this work, the reflow technique (Wang et al. Biomed. Microdevices 2007, 9, 657) was adapted to produce a microchannel network that mimics the occlusion process. The technique was first revisited and a simple geometrical model was developed to quantitatively explain the shapes of the resulting microchannels for different reflow parameters...
September 8, 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28884359/development-of-a-shear-stress-free-microfluidic-gradient-generator-capable-of-quantitatively-analyzing-single-cell-morphology
#6
David Barata, Giulia Spennati, Cristina Correia, Nelson Ribeiro, Björn Harink, Clemens van Blitterswijk, Pamela Habibovic, Sabine van Rijt
Microfluidics, the science of engineering fluid streams at the micrometer scale, offers unique tools for creating and controlling gradients of soluble compounds. Gradient generation can be used to recreate complex physiological microenvironments, but is also useful for screening purposes. For example, in a single experiment, adherent cells can be exposed to a range of concentrations of the compound of interest, enabling high-content analysis of cell behaviour and enhancing throughput. In this study, we present the development of a microfluidic screening platform where, by means of diffusion, gradients of soluble compounds can be generated and sustained...
September 7, 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28779376/development-of-a-co-culture-device-for-the-study-of-human-tenocytes-in-response-to-the-combined-stimulation-of-electric-field-and-platelet-rich-plasma-prp
#7
Chih-Hao Chiu, Kin Fong Lei, Wen-Ling Yeh
One of the objectives of rotator cuff repairs is to achieve biological healing and recovery in the tendon-bone zone. Some clinical evaluations reported the feasibility of tendon healing based on the stimulations of electric field and platelet-rich plasma (PRP). However, because of lack of appropriate tool for in vitro primary culture under complicated conditions, the efficacy and standard protocol of these healing approaches are still controversial among clinical experts. In this study, a novel co-culture device was developed for the study of tenocytes proliferation under single and combined stimulations of electric field and PRP...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28779375/rapid-prototyping-and-parametric-optimization-of-plastic-acoustofluidic-devices-for-blood-bacteria-separation
#8
R Silva, P Dow, R Dubay, C Lissandrello, J Holder, D Densmore, J Fiering
Acoustic manipulation has emerged as a versatile method for microfluidic separation and concentration of particles and cells. Most recent demonstrations of the technology use piezoelectric actuators to excite resonant modes in silicon or glass microchannels. Here, we focus on acoustic manipulation in disposable, plastic microchannels in order to enable a low-cost processing tool for point-of-care diagnostics. Unfortunately, the performance of resonant acoustofluidic devices in plastic is hampered by a lack of a predictive model...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28776236/multifractal-based-nuclei-segmentation-in-fish-images
#9
Nikola Reljin, Marijeta Slavkovic-Ilic, Coya Tapia, Nikola Cihoric, Srdjan Stankovic
The method for nuclei segmentation in fluorescence in-situ hybridization (FISH) images, based on the inverse multifractal analysis (IMFA) is proposed. From the blue channel of the FISH image in RGB format, the matrix of Holder exponents, with one-by-one correspondence with the image pixels, is determined first. The following semi-automatic procedure is proposed: initial nuclei segmentation is performed automatically from the matrix of Holder exponents by applying predefined hard thresholding; then the user evaluates the result and is able to refine the segmentation by changing the threshold, if necessary...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28776235/an-array-of-porous-microneedles-for-transdermal-monitoring-of-intercellular-swelling
#10
Kuniaki Nagamine, Jun Kubota, Hiroyuki Kai, Yoshinobu Ono, Matsuhiko Nishizawa
An array of porous microneedles was developed for minimally-invasive transdermal electrolytic connection through the human skin barrier, the stratum corneum. The length of microneedle was designed to be 100 μm so that it penetrates into the epidermis layer without pain. Each microneedle was supported by a thicker cylindrical post protruding from a planar substrate to realize its effective penetration even into elastic human skin. Since this support (post and substrate) was equally porous as the needles, the needle chip was entirely permeable for electrolyte...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28776234/combination-of-antibody-coated-physical-based-microfluidic-chip-with-wave-shaped-arrays-for-isolating-circulating-tumor-cells
#11
Hongmei Chen, Baoshan Cao, Hongda Chen, Yu-Sheng Lin, Jingjing Zhang
Circulating tumor cells (CTCs) are found in the peripheral blood of patients with metastatic cancers, which have critical significance in cancer prognosis and diagnostics. Enumeration is significantly valuable since number of CTCs is strongly correlated to severity of disease. This article is proposed and demonstrated an antibody-coated, size-based microfluidic chip with wave-shaped arrays could efficiently capture CTCs combining two separation methods of both size- and deformability-based and affinity-based segregation...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28710644/non-electrolytic-microelectroporation
#12
Chenang Lyu, Jianping Wang, Boris Rubinsky
Micro and nano technologies are of increasing importance in microfluidics devices used for electroporation (electroporation - the permeabilization of the cell membrane with brief high electric field pulses). Electrochemical reactions of electrolysis occur whenever an electric current flows between an electrode and an ionic solution. It can have substantial detrimental effects, both on the cells and solutions during the electroporation. As electrolysis is a surface phenomenon, between electrodes and solution, the extent of electrolysis is increased in micro and nano electroporation over macro-electroporation, because the surface area of the electrodes in micro and nano electroporation is much larger...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28695382/point-of-care-coagulation-monitoring-first-clinical-experience-using-a-paper-based-lateral-flow-diagnostic%C3%A2-device
#13
Michael A Hegener, Hua Li, Daewoo Han, Andrew J Steckl, Giovanni M Pauletti
Vitamin K antagonists such as warfarin are the most widely used class of oral anticoagulants. Due to a narrow therapeutic window, patients on warfarin require regular monitoring. Self-testing using point-of-care (POC) diagnostic devices is available, but cost makes this monitoring method beyond reach for many. The main objective of this research was to assess the clinical utility of a low-cost, paper-based lateral flow POC diagnostic device developed for anticoagulation monitoring without the need for a separate electronic reader...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28688071/study-of-the-behavior-of-euglena-viridis-euglena-gracilis-and-lepadella-patella-cultured-in-all-glass-microaquarium
#14
Agnieszka Podwin, Wojciech Kubicki, Jan A Dziuban
In the paper, the microaquarium fabricated in a form of entirely glass lab-on-a-chip for culturing and microscale study of microorganisms has been presented. A new approach towards cellular studies that brings a significant improvement over commonly utilized - polymer-based solutions has been shown. For the first time, all-borosilicate glass chip was applied for the culturing of the selected microorganisms and enabled notable population growth and behaviorism investigation. The chip fabrication method in comparison to typical glass chip technology was notably simplified, including quick patterning and low temperature bonding in 80 °C...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28688070/long-term-performance-of-porous-platinum-coated-neural-electrodes
#15
M Leber, R Bhandari, J Mize, D J Warren, M M H Shandhi, F Solzbacher, S Negi
Over the last several years, there has been a growing interest in neural implants for the study and diagnostics of neurological disorders as well as for the symptomatic treatment of central nervous system related diseases. One of the major challenges is the trade-off between small electrode sizes for high selectivity between single neurons and large electrode-tissue interface areas for excellent stimulation and recording properties. This paper presents an approach of increasing the real surface area of the electrodes by creating a surface microstructure...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28681238/impedance-feedback-control-of-microfluidic-valves-for-reliable-post-processing-combinatorial-droplet-injection
#16
Brant Axt, Yi-Fan Hsieh, Divya Nalayanda, Tza-Huei Wang
Droplet microfluidics has found use in many biological assay applications as a means of high-throughput sample processing. One of the challenges of the technology, however, is the ability to control and merge droplets on-demand as they flow through the microdevices. It is in the interest of developing lab-on-chip devices to be able to combinatorically program additive mixing steps for more complex multistep and multiplex assays. Existing technologies to merge droplets are either passive in nature or require highly predictable droplet movement for feedforward control, making them vulnerable to errors during high throughput operation...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28677098/integration-of-solid-state-nanopores-into-a-functional-device-designed-for-electrical-and-optical-cross-monitoring
#17
Raphaël Marchand, Christophe Thibault, Franck Carcenac, Christophe Vieu, Emmanuelle Trévisiol
We present a new strategy for fabricating a silicon nanopore device allowing straightforward fluidic integration and electrical as well as optical monitoring. The device presents nanopores of diameters 10 nm to 160 nm, and could therefore be used to obtain solvent-free free-standing lipid bilayers from small unilamellar vesicles (SUV) or large unilamellar vesicles (LUV). The silicon chip fabrication process only requires front side processing of a silicon-on-insulator (SOI) substrate. A polydimethylsiloxane (PDMS) microfluidic interface is assembled on the silicon chip for fluidic handling and electrical addressing...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28667400/microfluidic-device-flow-field-characterization-around-tumor-spheroids-with-tunable-necrosis-produced-in-an-optimized-off-chip-process
#18
James Baye, Casey Galvin, Amy Q Shen
Tumor spheroids are a 3-D tumor model that holds promise for testing cancer therapies in vitro using microfluidic devices. Tailoring the properties of a tumor spheroid is critical for evaluating therapies over a broad range of possible indications. Using human colon cancer cells (HCT-116), we demonstrate controlled tumor spheroid growth rates by varying the number of cells initially seeded into microwell chambers. The presence of a necrotic core in the spheroids could be controlled by changing the glucose concentration of the incubation medium...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28646280/bubble-removal-with-the-use-of-a-vacuum-pressure-generated-by-a-converging-diverging-nozzle
#19
Theodore Christoforidis, Carlos Ng, David T Eddington
Bubbles are an intrinsic problem in microfluidic devices and they can appear during the initial filling of the device or during operation. This report presents a generalizable technique to extract bubbles from microfluidic networks using an adjacent microfluidic negative pressure network over the entire microfluidic channel network design. We implement this technique by superimposing a network of parallel microchannels with a vacuum microfluidic channel and characterize the bubble extraction rates as a function of negative pressure applied...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28634847/carbon-nanotubes-embedded-in-embryoid-bodies-direct-cardiac-differentiation
#20
Samad Ahadian, Shukuyo Yamada, Mehdi Estili, Xiaobin Liang, Ramin Banan Sadeghian, Ken Nakajima, Hitoshi Shiku, Tomokazu Matsue, Ali Khademhosseini
We embedded carbon nanotubes (CNTs) in mouse embryoid bodies (EBs) for modulating mechanical and electrical cues of the stem cell niche. The CNTs increased the mechanical integrity and electrical conductivity of the EBs. Measured currents for the unmodified EBs (hereafter, EBs) and the EBs-0.25 mg/mL CNTs were 0.79 and 26.3 mA, respectively, at voltage of 5 V. The EBs had a Young's modulus of 20.9 ± 6.5 kPa, whereas the Young's modulus of the EB-0.1 mg/mL CNTs was 35.2 ± 5.6 kPa. The EB-CNTs also showed lower proliferation and greater differentiation rates compared with the EBs as determined by the expression of pluripotency genes and the analysis of EB sizes...
September 2017: Biomedical Microdevices
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