scholarly journals Controlling Capillary Flow Rate on Lateral Flow Test Substrates by Tape

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 562
Author(s):  
Zhiqing Xiao ◽  
Yuqian Yang ◽  
Xingwei Zhang ◽  
Weijin Guo
Keyword(s):  
Flow Rate ◽  
Rate Control ◽  
Capillary Flow ◽  
Lateral Flow ◽  
Average Flow Rate ◽  
Average Flow ◽  
Flow Test ◽  
Lateral Flow Test ◽  
Lateral Flow Tests ◽  
Flow Rate Control

Controlling capillary flow rate of sample liquid is of high interest for lateral flow tests, since the flow rate can affect the dissolution and mixing of the immunoreagents and the efficiency of immunoreactions. Here we develop a facile method to adjust the capillary flow rate on lateral flow test substrates by using tape to cover the surface of substrates. We test this method on the traditional lateral flow test substrate—nitrocellulose and a novel lateral flow test substrate—synthetic paper, which is a porous media made by interlocked off-stoichiometry thiol-ene (OSTE) micropillars. We found that after the surface was covered by tape, the average flow rate decreased to 61% of the original flow rate on nitrocellulose, while the average flow rate increased to at least 320% of the original flow rate on synthetic paper. More interesting, besides the increase of flow rate, the volume capacity of synthetic paper also increases after covered by tape. Furthermore, we investigated the influence of length and position of tape on the capillary flow rate for nitrocellulose. A longer tape will lead to a smaller flow rate. The influence of tape of same length on the flow rate is bigger when the tape is placed closer to the loading pad. These results can help in the flow rate control on lateral flow test substrates, and potentially improve the performance of lateral flow tests.

scholarly journals Eliminating viscosity bias in lateral flow tests

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Daniel M. Kainz ◽  
Bastian J. Breiner ◽  
Susanna M. Früh ◽  
Tobias Hutzenlaub ◽  
Roland Zengerle ◽  
...  
Keyword(s):  
Point Of Care ◽  
Lateral Flow ◽  
Nitrocellulose Membrane ◽  
Widespread Application ◽  
Significant Challenge ◽  
Microfluidic Flow ◽  
Flow Test ◽  
Lateral Flow Test ◽  
Lateral Flow Tests ◽  
Viscosity Dependence

AbstractDespite the widespread application of point-of-care lateral flow tests, the viscosity dependence of these assay results remains a significant challenge. Here, we employ centrifugal microfluidic flow control through the nitrocellulose membrane of the strip to eliminate the viscosity bias. The key feature is the balancing of the sample flow into the cassette of the lateral flow test with the air flow out of the cassette. A viscosity-independent flow rate of 3.01 ± 0.18 µl/min (±6%) is demonstrated for samples with viscosities ranging from 1.1 mPas to 24 mPas, a factor greater than 20. In a model human IgG lateral flow assay, signal-intensity shifts caused by varying the sample viscosity from 1.1 mPas to 2.3 mPas could be reduced by more than 84%.

scholarly journals Analysis of free chlorine in aqueous solution at very low concentration with lateral flow tests

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
K. Uta Schwenke ◽  
Dieter Spiehl ◽  
Marcel Krauße ◽  
Laura Riedler ◽  
Anna Ruppenthal ◽  
...  
Keyword(s):  
Reaction Zone ◽  
Sample Volume ◽  
Lateral Flow ◽  
Free Chlorine ◽  
Test Strips ◽  
Flow Test ◽  
Lateral Flow Test ◽  
Lateral Flow Tests ◽  
User Friendly ◽  
Dip Test

AbstractTest strips are convenient tools for rapid, semi-quantitative analysis of a variety of parameters by dipping them for a few seconds in a sample solution followed by a simple colorimetric read-out. Their sensitivity is mainly determined by the reactivity of the test dyes on the reaction zone and is not sufficient for some applications. The detection limit of commercially available free chlorine test strips, for example, is at present not low enough to confirm the absence of this analyte as disinfectant in rinsing solutions after disinfection or to control required residual amounts of chlorine in drinking water. Therefore, we developed a user-friendly lateral flow test which is capable to detect very low amounts of free chlorine. The latter relies on a larger sample volume passing the reaction zone as compared to simple dip test strips. An amount of as low as 0.05 ppm chlorine can, however, only be detected if oxidation stable flow test substrates are used. The eventually developed flow test reaches a 10x higher sensitivity than a commercial dip test. The result is obtained within 4–5 min flow time, whereby no action is required by the user during this analysis time.

scholarly journals Point-of-Care Diagnoses and Assays Based on Lateral Flow Test

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Miroslav Pohanka
Keyword(s):  
Quality Of Life ◽  
Point Of Care ◽  
Lateral Flow ◽  
Improve Quality ◽  
New Materials ◽  
Flow Test ◽  
Lateral Flow Test ◽  
Lateral Flow Tests

Analytical devices for point-of-care diagnoses are highly desired and would improve quality of life when first diagnoses are made early and pathologies are recognized soon. Lateral flow tests (LFTs) are such tools that can be easily performed without specific equipment, skills, or experiences. This review is focused on the use of LFT in point-of-care diagnoses. The principle of the assay is explained, and new materials like nanoparticles for labeling, new recognition molecules for interaction with an analyte, and new additional instrumentation like signal scaling by a smartphone camera are described and discussed. Advantages of the LFT devices as well as their limitations are described and discussed here considering actual papers that are properly cited.

Continuous separation of particles using a microfluidic device equipped with flow rate control valves

2006 ◽  
Vol 1127 (1-2) ◽  
pp. 214-220 ◽  
Author(s):  
Yuushi Sai ◽  
Masumi Yamada ◽  
Masahiro Yasuda ◽  
Minoru Seki
Keyword(s):  
Microfluidic Device ◽  
Flow Rate ◽  
Rate Control ◽  
Continuous Separation ◽  
Control Valves ◽  
Flow Rate Control

Variable Powder Flow Rate Control in Laser Metal Deposition Processes

2008 ◽  
Author(s):  
Lie Tang ◽  
Jianzhong Ruan ◽  
Robert G. Landers ◽  
Frank Liou
Keyword(s):  
Transport System ◽  
Flow Rate ◽  
Rate Control ◽  
Metal Deposition ◽  
Powder Flow ◽  
Laser Metal Deposition ◽  
Motion System ◽  
Powder Flow Rate ◽  
Deposition Processes ◽  
Flow Rate Control

This paper proposes a novel method, called Variable Powder Flow Rate Control (VPFRC), for the regulation of powder flow rate in laser metal deposition processes. The idea of VPFRC is to adjust the powder flow rate to maintain a uniform powder deposition per unit length even when disturbances occur (e.g., the motion system accelerates and decelerates). Dynamic models of the powder delivery system motor and the powder transport system (i.e., five–meter pipe, powder dispenser, and cladding head) are constructed. A general tracking controller is then designed to track variable powder flow rate references. Since the powder flow rate at the nozzle exit cannot be directly measured, it is estimated using the powder transport system model. The input to this model is the DC motor rotation speed, which is estimated on–line using a Kalman filter. Experiments are conducted to examine the performance of the proposed control methodology. The experimental results demonstrate that the VPFRC method is successful in maintaining a uniform track morphology, even when the motion system accelerates and decelerates.

A Design Method for Thermosyphon Solar Domestic Hot Water Systems

1987 ◽  
Vol 109 (2) ◽  
pp. 150-155 ◽  
Author(s):  
M. P. Malkin ◽  
S. A. Klein ◽  
J. A. Duffie ◽  
A. B. Copsey
Keyword(s):  
Flow Rate ◽  
Design Method ◽  
Water Systems ◽  
Hot Water ◽  
Average Flow Rate ◽  
Domestic Hot Water ◽  
Average Flow ◽  
Solar Fraction ◽  
Wide Range ◽  
Flow Circuit

A modification to the f-Chart method has been developed to predict monthly and annual performance of thermosyphon solar domestic hot water systems. Stratification in the storage tank is accounted for through use of a modified collector loss coefficient. The varying flow rate throughout the day and year in a thermosyphon system is accounted for through use of a fixed monthly “equivalent average” flow rate. The “equivalent average” flow rate is that which balances the thermosyphon buoyancy driving force with the frictional losses in the flow circuit on a monthly average basis. Comparison between the annual solar fraction predited by the modified design method and TRNSYS simulations for a wide range of thermosyphon systems shows an RMS error of 2.6 percent.

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