scholarly journals Thermally-actuated microfluidic membrane valve for point-of-care applications

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Muhsincan Sesen ◽  
Christopher J. Rowlands
Keyword(s):  
Point Of Care ◽  
Microfluidic Channels ◽  
Peristaltic Pumping ◽  
65 H ◽  
Valve Opening ◽  
Arduino Microcontroller ◽  
Thermally Actuated ◽  
Valve Operation ◽  
Microfluidic Valves ◽  
Scaling Out

AbstractMicrofluidics has enabled low volume biochemistry reactions to be carried out at the point-of-care. A key component in microfluidics is the microfluidic valve. Microfluidic valves are not only useful for directing flow at intersections but also allow mixtures/dilutions to be tuned real-time and even provide peristaltic pumping capabilities. In the transition from chip-in-a-lab to lab-on-a-chip, it is essential to ensure that microfluidic valves are designed to require less peripheral equipment and that they are transportable. In this paper, a thermally-actuated microfluidic valve is presented. The valve itself is fabricated with off-the-shelf components without the need for sophisticated cleanroom techniques. It is shown that multiple valves can be controlled and operated via a power supply and an Arduino microcontroller; an important step towards transportable microfluidic devices capable of carrying out analytical assays at the point-of-care. It is been calculated that a single actuator costs less than $1, this highlights the potential of the presented valve for scaling out. The valve operation is demonstrated by adjusting the ratio of a water/dye mixture in a continuous flow microfluidic chip with Y-junction channel geometry. The power required to operate one microfluidic valve has been characterised both theoretically and experimentally. Cyclical operation of the valve has been demonstrated for 65 h with 585 actuations. The presented valve is capable of actuating rectangular microfluidic channels of 500 μm × 50 μm with an expected temperature increase of up to 5 °C. The fastest actuation times achieved were 2 s for valve closing (heating) and 9 s for valve opening (cooling).

scholarly journals Nano-Interstice Driven Powerless Blood Plasma Extraction in a Membrane Filter Integrated Microfluidic Device

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1366
Author(s):  
Jaehoon Kim ◽  
Junghyo Yoon ◽  
Jae-Yeong Byun ◽  
Hyunho Kim ◽  
Sewoon Han ◽  
...  
Keyword(s):  
Blood Plasma ◽  
Microfluidic Device ◽  
Blood Cells ◽  
Extraction Method ◽  
Membrane Filter ◽  
Point Of Care ◽  
Extraction Yield ◽  
Microfluidic Channels ◽  
Point Of Care Testing ◽  
Plasma Extraction

Blood plasma is a source of biomarkers in blood and a simple, fast, and easy extraction method is highly required for point-of-care testing (POCT) applications. This paper proposes a membrane filter integrated microfluidic device to extract blood plasma from whole blood, without any external instrumentation. A commercially available membrane filter was integrated with a newly designed dual-cover microfluidic device to avoid leakage of the extracted plasma and remaining blood cells. Nano-interstices installed on both sides of the microfluidic channels actively draw the extracted plasma from the membrane. The developed device successfully supplied 20 μL of extracted plasma with a high extraction yield (~45%) in 16 min.

scholarly journals Towards a “Sample-In, Answer-Out” Point-of-Care Platform for Nucleic Acid Extraction and Amplification: Using an HPV E6/E7 mRNA Model System

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Anja Gulliksen ◽  
Helen Keegan ◽  
Cara Martin ◽  
John O'Leary ◽  
Lars A. Solli ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Sample Preparation ◽  
Clinical Sample ◽  
Point Of Care ◽  
Fluorescent Detection ◽  
Clinical Samples ◽  
Microfluidic Channels ◽  
Acid Extraction ◽  
Nucleic Acid Extraction ◽  
Hpv E6

The paper presents the development of a “proof-of-principle” hands-free and self-contained diagnostic platform for detection of human papillomavirus (HPV) E6/E7 mRNA in clinical specimens. The automated platform performs chip-based sample preconcentration, nucleic acid extraction, amplification, and real-time fluorescent detection with minimal user interfacing. It consists of two modular prototypes, one for sample preparation and one for amplification and detection; however, a common interface is available to facilitate later integration into one single module. Nucleic acid extracts (n=28) from cervical cytology specimens extracted on the sample preparation chip were tested using the PreTect HPV-Proofer and achieved an overall detection rate for HPV across all dilutions of 50%–85.7%. A subset of 6 clinical samples extracted on the sample preparation chip module was chosen for complete validation on the NASBA chip module. For 4 of the samples, a 100% amplification for HPV 16 or 33 was obtained at the 1 : 10 dilution for microfluidic channels that filled correctly. The modules of a “sample-in, answer-out” diagnostic platform have been demonstrated from clinical sample input through sample preparation, amplification and final detection.

In Vitro Determination of the Curvatures and Bending Strains Acting on the Leaflets of Polyurethane Trileaflet Heart Valves During Leaflet Motion

1995 ◽  
Vol 209 (4) ◽  
pp. 243-253 ◽  
Author(s):  
J Corden ◽  
T David ◽  
J Fisher
Keyword(s):  
High Speed ◽  
Heart Valves ◽  
Video Camera ◽  
Casting Technique ◽  
Modes Of Failure ◽  
Bending Strain ◽  
High Speed Video Camera ◽  
Valve Opening ◽  
Valve Operation

Leaflet tears originating from the free leaflet edge and calcification around the commissural region are common modes of failure exhibited by explanted bioprosthetic trileaflet heart valves. These may be a result of the cyclic bending and high levels of curvature that affect the leaflets within these areas during normal valve operation. These high leves of curvature occur in a short time period (approximately 20 ms) during rapid leaflet opening and to a lesser degree during leaflet closure. The curvatures that occur at the free leaflet edge of two designs of polyurethane trileaflet heart valve were determined in vitro at various stages during a cardiac cycle using a high-speed video camera (1000 frames/s). Significant deformations at the free leaflet edge were observed and bending radii as low as 0.55 ± 0.125 mm (mean ± standard deviation) were present during leaflet opening, 0.76 ± 0.24 mm during leaflet closure and 1.01 ± 0.27 mm while the valve was fully open during peak systole. The values of curvature were used to determine the values of bending strain and bending stress acting at the free leaflet edge using thin shell bending theory. The calculated values of bending strain were a maximum during the leaflet flexure associated with valve opening. These high levels of bending strain, which occur for short periods of time, are likely to be an important determinant of the valve's durability. It has been shown that the method of manufacture significantly influenced the level of bending strain in the valve leaflets. Valves manufactured using a dip-casting technique resulted in open leaflet bending strains up to 31 per cent lower than valves manufactured from solvent-cast sheets of polyurethane.

Transient Modelling of Pneumatic Valves in Centrifugal Microfluidic Devices

2016 ◽  
Author(s):  
Michael R. Moon ◽  
Lin Lin
Keyword(s):  
Surface Tension ◽  
Point Of Care ◽  
Low Cost ◽  
Microfluidic Devices ◽  
Novel Technologies ◽  
Fluid Handling ◽  
Pneumatic Valves ◽  
Microfluidic Valves ◽  
And Control ◽  
Micrometer Scale

Point of care medical instruments benefit from compact fluid handling systems in the microliter range. To handle fluid volumes this small, many novel technologies have been studied. Pneumatic valves offer advantages over other microfluidic valves, including robustness and low cost. These valves are used in centrifugal microfluidic devices, a very active area of research, and take advantage of pneumatic and centrifugal pressure to aliquot and control the flow of fluid. The physics of fluids at the micrometer scale are complex and modelling their behavior using CFD software is challenging. Representing adhesion, surface tension, and other multiphase interactions is critical to accurately model microfluidic behavior. Centrifugal devices must also consider Coriolis, centrifugal, and Euler effects. In this study, a pneumatic valve was designed and simulated using commercial CFD software. The device was also fabricated for verification of the simulation. The simulation demonstrated the multiphase interactions of fluid and air within the rotating device. In a transient analysis of the model, a 6 μl volume of water is held in stable equilibrium by a compressed volume of air at low RPM, while at a higher RPM, the fluid is observed to displace the compressed air as a result of Rayleigh-Taylor instability. Actual devices with comparable geometry were built and tested. The behavior of the valve predicted in the model was in agreement with experimental results produced from the actual devices. The results of the simulation captured the stabilizing effect of both pneumatic pressure and surface tension at low RPM, as well as the instability that results from increased centrifugal and Euler pressure at higher RPM.

Biocontractile microfluidic channels for peristaltic pumping

2017 ◽  
Vol 19 (4) ◽  
Author(s):  
Angelina V. Shutko ◽  
Vasily S. Gorbunov ◽  
Konstantin G. Guria ◽  
Konstantin I. Agladze
Keyword(s):  
Microfluidic Channels ◽  
Peristaltic Pumping

scholarly journals Review of Integrated Optical Biosensors for Point-of-Care Applications

Biosensors ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 209
Author(s):  
Yung-Tsan Chen ◽  
Ya-Chu Lee ◽  
Yao-Hsuan Lai ◽  
Jin-Chun Lim ◽  
Nien-Tsu Huang ◽  
...  
Keyword(s):  
Optical Sensors ◽  
Point Of Care ◽  
Future Perspective ◽  
Optical Biosensors ◽  
Microfluidic Channels ◽  
Point Of Care Testing ◽  
Electrical Control ◽  
Semiconductor Chip ◽  
Integrated Optical ◽  
Signal Readout

This article reviews optical biosensors and their integration with microfluidic channels. The integrated biosensors have the advantages of higher accuracy and sensitivity because they can simultaneously monitor two or more parameters. They can further incorporate many functionalities such as electrical control and signal readout monolithically in a single semiconductor chip, making them ideal candidates for point-of-care testing. In this article, we discuss the applications by specifically looking into point-of-care testing (POCT) using integrated optical sensors. The requirement and future perspective of integrated optical biosensors for POC is addressed.

scholarly journals Performance Study of Air Driven Engine Being Modified From Conventional Four Stroke Engine without Cam Modification

2020 ◽  
Vol 10 (2) ◽  
pp. 250-254
Keyword(s):  
Air Pollution ◽  
Pressure Ratio ◽  
Compressed Air ◽  
Maximum Speed ◽  
Exhaust Manifold ◽  
Performance Study ◽  
Valve Opening ◽  
Valve Operation ◽  
Stroke Engine

This research presents a novel mechanism to convert a conventional100-cc four stroke driven engine into a 2 stroke compressed air driven engine without doing any modifications in the cam shaft. This allows for a faster valve operation & also helping the existing engines to be converted into air driven engines with removal of intake and exhaust manifold and also provides a platform to curb the growing menace of air pollution by using the existing old engines to be used as air driven engine. Also, cycle of operation of the Air Engine has been representedon P-V diagram and theoretical efficiency has been calculated which is a function of pressure ratio and temperature, and comes out to be around 80 percent (@ Prr. Ratio of 10& Temp of 550K). Variation of rpm with percentage valve opening is seen at different pressure ratios and the maximum speed of the engine (after doing said modifications and running through compressed air)is observed to be 1573 rpm at a pressure of 9 bar with the developed mechanism for the existing 4 stroke maestro engine.

scholarly journals A Compact, Syringe-Assisted, Vacuum-Driven Micropumping Device

Micromachines ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 543 ◽  
Author(s):  
Anyang Wang ◽  
Domin Koh ◽  
Philip Schneider ◽  
Evan Breloff ◽  
Kwang W. Oh
Keyword(s):  
Microfluidic Device ◽  
Point Of Care ◽  
Microfluidic Devices ◽  
Microfluidic Channels ◽  
Constant Flow ◽  
Proof Of Concept ◽  
Point Of Care Testing ◽  
Microfluidic Mixing ◽  
Pumping System ◽  
Dead End

In this paper, a simple syringe‑assisted pumping method is introduced. The proposed fluidic micropumping system can be used instead of a conventional pumping system which tends to be large, bulky, and expensive. The micropump was designed separately from the microfluidic channels and directly bonded to the outlet of the microfluidic device. The pump components were composed of a dead‑end channel which was surrounded by a microchamber. A syringe was then connected to the pump structure by a short tube, and the syringe plunger was manually pulled out to generate low pressure inside the microchamber. Once the sample was loaded in the inlet, air inside the channel diffused into the microchamber through the PDMS (polydimethylsiloxane) wall, acting as a dragging force and pulling the sample toward the outlet. A constant flow with a rate that ranged from 0.8 nl · s − 1 to 7.5 nl · s − 1 was achieved as a function of the geometry of the pump, i.e., the PDMS wall thickness and the diffusion area. As a proof-of-concept, microfluidic mixing was demonstrated without backflow. This method enables pumping for point-of-care testing (POCT) with greater flexibility in hand-held PDMS microfluidic devices.

Studies on the Variation of Flow Parameters through a Ball Valve

2013 ◽  
Vol 321-324 ◽  
pp. 1799-1804 ◽  
Author(s):  
Iulian Florescu ◽  
Daniela Florescu ◽  
Dragoş Nedelcu
Keyword(s):  
Power Flow ◽  
Ball Valve ◽  
Power Lines ◽  
Flow Simulations ◽  
Operation Analysis ◽  
Flow Parameters ◽  
Valve Opening ◽  
Flow Through ◽  
Valve Operation ◽  
Loan Losses

This paper aims to highlight the current line of flow through a ball valve for opening its different angles. We chose to study the values of values 30o, 45o, 60o and 75o as represented in figures. Flow simulations were performed using Fluent 6.3 software, power lines are marked by their tangent vectors speed. For a default value of power flow and pressure were represented power lines following the turbulence and hence the increased loan losses occur. This ball valve operation analysis may reveal different hydraulic energy losses given conditions different valve opening and leads to a modern design and dynamic analysis of operation.

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