Influence of Contact Force on Electrochemical Responses of Redox Species Flowing in Nitrocellulose Membrane at Micropyramid Array Electrode

Iwasaki, Wataru; Sathuluri, Ramachandra Rao; Niwa, Osamu; Miyazaki, Masaya

doi:10.2116/analsci.31.729

Cited by 10 publications

(9 citation statements)

References 12 publications

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“…(7) First, a photoresist was spin-coated on a silicon wafer with a 1-μm-thick thermal oxide silicon film and patterned by photolithography with the electrode pattern. The widths of the WE and RE were 1 mm and that of CE was 2 mm.…”

Section: Electrochemical Immunochromatography Platformmentioning

confidence: 99%

“…In the case of electrochemical methods, the working electrode (WE), counter electrode (CE), and reference electrode (RE) are attached or printed on the paper, and are used to measure the electrochemical species flowing through a paper membrane. (7)(8)(9) The placements of WE, CE, and RE are very important for electrochemical measurement. However, the effects of the electrode placement on the detection signal in the paper-based analysis were not investigated.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Electrode Placement and Measurement Time on Electrochemical Signal of Redox Species Flowing through Porous Material

2016

Sensors and Materials

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We have studied the construction of an electrochemical immunochromatography platform as one of the point-of-care testing devices from both experimental and theoretical aspects. In the electrochemical immunochromatography measurement, the layout of working, reference, and counter electrodes and the flow rate in a porous membrane are important in obtaining a highly sensitive and stable electrochemical signal. In this manuscript, we report the effects of the layout of the three electrodes and the elapsed time after sample injection on electrochemical signals. We found that the working electrode should be placed upstream of the reference electrode because an unfavorable electrochemical signal from a Ag + ion from the reference electrode was observed on the working electrode when it was located downstream of the reference electrode. Furthermore, we found that the electrochemical signal was inversely proportional to the sixth root of time. Experimental and theoretical results are consistent with each other, exhibiting a high correlation coefficient of 0.99.

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Section: Electrochemical Immunochromatography Platformmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Electrode Placement and Measurement Time on Electrochemical Signal of Redox Species Flowing through Porous Material

2016

Sensors and Materials

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“…We have previously developed an electrochemical immunochromatography platform as a µPAD [ 16 , 17 ]. Usually, electrodes are printed on a paper when an electrochemical method is introduced into µPADs [ 9 , 18 , 19 ].…”

Section: Introductionmentioning

confidence: 99%

A Simple, Low Cost, Sensitive, and Portable Electrochemical Immunochromatography Sensing Device to Measure Estrone-3-Sulfate

Iwasaki

Kataoka²,

Sawadaishi³

et al. 2020

Sensors

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In livestock production, point-of-care testing (POCT) technology that enables easy on-site analysis of sex hormones is desired to improve reproductive efficiency. In this context, low-molecular-weight endogenous steroids are particularly important for perinatal management. Therefore, we attempted to use a simple method that combines electrochemical techniques with immunochromatography to measure estrone-3-sulfate (E1S), one of the low-molecular-weight endogenous steroids that is an estrogen ester. The limit of detection (LOD) for E1S achieved by electrochemical immunochromatography was 570.5 ng/mL, which was one to two orders of magnitude lower than that of small molecule compounds analyzed by other POCT techniques (Primpray et al., Anal. Chim. Acta, 2019). In addition, it was indicated by a colorimetric analysis that the sensitivity of the electrochemical immunochromatographic technique could be enhanced by improving the method of application of the antibodies on the nitrocellulose membrane and the contact between the electrochemical detector and the nitrocellulose membrane.

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“…Other groups have developed wearable wireless estrus detection sensors (12) and portable estrus intensity detection sensors. (13) In this study, we focused on a photoplethysmographic (PPG) sensor.…”

Section: Introductionmentioning

confidence: 99%

Relationship between AC/DC Ratio and Light-blocking Structure for Reflective Photoplethysmographic Sensor

Nogami¹,

Iwasaki

Morita

et al. 2018

Sensors and Materials

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Photoplethysmographic (PPG) sensors are suitable for wearable devices, and they can provide a wide range of information such as stress level (calculated from the heart rate interval), respiration rate, heart rate, and blood vessel stiffness. Of particular importance is that reflective PPG sensors can be easily attached anywhere on the body with low wearer constraint. However, PPG sensors are susceptible to body motion artifacts. The output signal of PPG sensors is composed of alternating current (AC), originating from the heart cycle, and direct current (DC), originating from veins and stationary tissue. Motion artifacts affect DC signals, making it difficult to detect AC signals. Thus, it is important to reduce DC signals and increase the AC/DC ratio. In this study, we investigated the effect of a light-blocking structure on the AC/DC ratio. In addition, the AC/DC ratio was estimated when the gap between the light source (LED) and the photodetector was small (3.2 mm) and large (8.0 mm). In this experiment, the measurement part was a fingertip, and the AC/DC ratio was estimated when AC had the highest output with the force from step-by-step contact. As a result, the AC/DC ratio of the light-blocking structure was 2.4%, and the AC/DC of the non-light-blocking type was 0.9%. Also, the AC/DC of the small-gap PPG sensor was 2.4%, and the AC/DC of the large-gap sensor was 7.5%. Thus, the light-blocking structure was effective in increasing the AC/DC ratio, and a larger distance between the LED and photodetector was useful.

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Influence of Contact Force on Electrochemical Responses of Redox Species Flowing in Nitrocellulose Membrane at Micropyramid Array Electrode

Cited by 10 publications

References 12 publications

Effects of Electrode Placement and Measurement Time on Electrochemical Signal of Redox Species Flowing through Porous Material

Effects of Electrode Placement and Measurement Time on Electrochemical Signal of Redox Species Flowing through Porous Material

A Simple, Low Cost, Sensitive, and Portable Electrochemical Immunochromatography Sensing Device to Measure Estrone-3-Sulfate

Relationship between AC/DC Ratio and Light-blocking Structure for Reflective Photoplethysmographic Sensor

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