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Biomedical Microdevices

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https://www.readbyqxmd.com/read/28710644/non-electrolytic-microelectroporation
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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
#9
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
https://www.readbyqxmd.com/read/28620782/role-of-key-genetic-mutations-on-increasing-migration-of-brain-cancer-cells-through-confinement
#10
Loan Bui, Sayem H Bhuiyan, Alissa Hendrick, Cheng-Jen Chuong, Young-Tae Kim
Uncontrolled invasive cancer cell migration is among the major challenges for the treatment and management of brain cancer. Although the genetic profiles of brain cancer cells have been well characterized, the relationship between the genetic mutations and the cells' mobility has not been clearly understood. In this study, using microfluidic devices that provide a wide range of physical confinements from 20 × 5 μm(2) to 3 × 5 μm(2) in cross sections, we studied the effect of physical confinement on the migratory capacity of cell lines with different types of mutations...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28612283/cell-laden-microgel-prepared-using-a-biocompatible-aqueous-two-phase-strategy
#11
Yang Liu, Natalia Oshima Nambu, Masahito Taya
Microfluidic methods are frequently used to produce cell-laden microgels for various biomedical purposes. Such microfluidic methods generally employ oil-water systems. The poor distribution of crosslinking reagents in the oil phase limits the available gelation strategies. Extracting the microgel from the oil-phase also reduces its production efficiency. In this study, an aqueous two-phase system (ATPS) involving dextran (DEX) and polyethylene glycol (PEG) was used to prepare cell-laden microgel. This avoided the problems associated with an oil phase...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28612282/probing-of-peripheral-blood-mononuclear-cells-anchoring-on-tnf-alpha-challenged-vascular-endothelia-in-an-in-vitro-model-of-the-retinal-microvascular
#12
Yuan Li, Yao Lu, Qiong Chen, Yuejun Kang, Ling Yu
Retinopathy is a complication of diabetes that affects the eyes; it stems from damage to the microvasculature of the retina and eventually compromises vision. The diagnosis of retinopathy is difficult to make because there are no early symptoms or warning signs. Dysfunction of the retina's microvascular networks is believed to be associated with inflammatory cytokines and tumor necrosis factor alpha (TNF-α). To investigate the effect of these cytokines, such as TNF-α, a polydimethylsiloxane (PDMS)/glass hydride microfluidic device reflecting the physiological structure of the retina's microvasculature was developed...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28608128/fabrication-of-highly-modulable-fibrous-3d-extracellular-microenvironments
#13
Xixiang Zhang, Fangfei Han, Ahad Syed, Ebtihaj M Bukhari, Basil Chew Joo Siang, Shan Yang, Bingpu Zhou, Wei-Jia Wen, Dechen Jiang
Three-dimensional (3D) in vitro scaffolds that mimic the irregular fibrous structures of in vivo extracellular matrix (ECM) are critical for many important biological applications. However, structural properties modulation of fibrous 3D scaffolds remains a challenge. Here, we report the first highly modulable 3D fibrous scaffolds self-assembled by high-aspect-ratio (HAR) microfibers. The scaffolds structural properties can be easily tailored to incorporate various physical cues, including geometry, stiffness, heterogeneity and nanotopography...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28597392/packaging-of-implantable-accelerometers-to-monitor-epicardial-and-endocardial-wall-motion
#14
Luigi Brancato, Tristan Weydts, Wouter Oosterlinck, Paul Herijgers, Robert Puers
Acceleration signals, collected from the inner and the outer heart wall, offer a mean of assessing cardiac function during surgery. Accelerometric measurements can also provide detailed insights into myocardial motion during exploratory investigations. Two different implantable accelerometers to respectively record endocardial and epicardial vibrations, have been developed by packaging a commercially available capacitive transducer. The same coating materials have been deposited on the two devices to ensure biocompatibility of the implants: Parylene-C, medical epoxy and Polydimethylsiloxane (PDMS)...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28577265/on-the-injectability-of-free-standing-magnetic-nanofilms
#15
Silvia Taccola, Virginia Pensabene, Toshinori Fujie, Shinji Takeoka, Nicola M Pugno, Virgilio Mattoli
Free-standing films with sub-micrometric thickness, composed of soft polymers and functional nanostructures are promising candidates for many potential applications in the biomedical field, such as reduced port abdominal surgery. In this work, freely suspended poly(L-lactic acid) nanofilms with controlled morphology embedding superparamagnetic iron oxide nanoparticles were fabricated by spin-coating deposition. The mechanical properties of magnetic nanofilms were investigated by Strain-Induced Elastic Buckling Instability for Mechanical Measurements (SIEBIMM) test...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28560702/hybrid-intracerebral-probe-with-integrated-bare-led-chips-for-optogenetic-studies
#16
Suleman Ayub, Luc J Gentet, Richárd Fiáth, Michael Schwaerzle, Mélodie Borel, François David, Péter Barthó, István Ulbert, Oliver Paul, Patrick Ruther
This article reports on the development, i.e., the design, fabrication, and validation of an implantable optical neural probes designed for in vivo experiments relying on optogenetics. The probes comprise an array of ten bare light-emitting diode (LED) chips emitting at a wavelength of 460 nm and integrated along a flexible polyimide-based substrate stiffened using a micromachined ladder-like silicon structure. The resulting mechanical stiffness of the slender, 250-μm-wide, 65-μm-thick, and 5- and 8-mm-long probe shank facilitates its implantation into neural tissue...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28560701/nano-calorimetry-based-point-of-care-biosensor-for-metabolic-disease-management
#17
Evan Kazura, Brad R Lubbers, Elliott Dawson, John A Phillips, Franz Baudenbacher
Point of care (POC) diagnostics represents one of the fastest growing health care technology segments. Developments in microfabrication have led to the development of highly-sensitive nanocalorimeters ideal for directly measuring heat generated in POC biosensors. Here we present a novel nano-calorimeter-based biosensor design with differential sensing to eliminate common mode noise and capillary microfluidic channels for sample delivery to the thermoelectric sensor. The calorimeter has a resolution of 1.4 ± 0...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28560700/an-improved-design-of-optical-sensor-for-long-term-measurement-of-arterial-blood-flow-waveform
#18
Biljana Djurić, Slavica Suzić, Bojana Stojadinović, Zorica Nestorović, Marija Ivanović, Jelena Suzić-Lazić, Dejan Nešić, Sanja Mazić, Tamar Tenne, Dragoslav Zikich, Dejan Žikić
We present here the improved design and development of optical sensor for non-invasive measurements of arterial blood flow waveform. The sensor is based on a physical principle of reflective photoplethysmography (PPG). As the light source we used serially connected infrared diodes whereas NPN silicon phototransistors were used as light detectors. The electronic components were molded into square package and poured with silicone. Such preparation produced an elastic superficies that allowed excellent attachment of the sensor on the skin's surface...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28540469/a-3d-microfluidic-perfusion-system-made-from-glass-for-multiparametric-analysis-of-stimulus-secretioncoupling-in-pancreatic-islets
#19
Torben Schulze, Kai Mattern, Eike Früh, Lars Hecht, Ingo Rustenbeck, Andreas Dietzel
Microfluidic perfusion systems (MPS) are well suited to perform multiparametric measurements with small amounts of tissue to function as an Organ on Chip device (OOC). Such microphysiolgical characterization is particularly valuable in research on the stimulus-secretion-coupling of pancreatic islets. Pancreatic islets are fully functional competent mini-organs, which serve as fuel sensors and transduce metabolic activity into rates of hormone secretion. To enable the simultaneous measurement of fluorescence and oxygen consumption we designed a microfluidic perfusion system from borosilicate glass by 3D femtosecond laser ablation...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28536859/accelerated-life-test-methods-and-results-for-implantable-electronic-devices-with-adhesive-encapsulation
#20
Xuechen Huang, Petcharat May Denprasert, Li Zhou, Adriana Nicholson Vest, Sam Kohan, Gerald E Loeb
We have developed and applied new methods to estimate the functional life of miniature, implantable, wireless electronic devices that rely on non-hermetic, adhesive encapsulants such as epoxy. A comb pattern board with a high density of interdigitated electrodes (IDE) could be used to detect incipient failure from water vapor condensation. Inductive coupling of an RF magnetic field was used to provide DC bias and to detect deterioration of an encapsulated comb pattern. Diodes in the implant converted part of the received energy into DC bias on the comb pattern...
September 2017: Biomedical Microdevices
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