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Article

Enhancement of Sensitivity and Accuracy of Micro/Nano Water Droplets Detection Using Galvanic-Coupled Arrays

1
Center for Functional Sensor & Actuator, Electrochemical Sensors Group, Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
2
Graduate School of Engineering, Chiba Institute of Technology, 2-17-1, Tsudanuma, Narashino, Chiba 275-0016, Japan
*
Author to whom correspondence should be addressed.
Sensors 2019, 19(20), 4500; https://doi.org/10.3390/s19204500
Received: 11 September 2019 / Revised: 2 October 2019 / Accepted: 10 October 2019 / Published: 17 October 2019
(This article belongs to the Section Physical Sensors)
A moisture sensor has been reported that detects invisibly small water droplets and distinguishes their particle size with high accuracy and high speed. This sensor uses narrow lines of dissimilar metals as electrodes, arranged with gaps of 0.5 to 10 μm. The working principle for this sensor is that it measures the galvanic current generated when a water droplet forms a bridge-like structure between the electrodes. In addition, the surface of the sensor was controlled by using hydrophilic polymer, GL, and hydrophobic polymer, PMMA. The study of the relationship between the contact angle, projected area of water droplets and current response from the sensor with a modified surface showed that in the case of GL, the contact angle was small (wettability increased) and the average value and distribution of the projected water droplet area and the sensor’s response increased. This enhanced the sensor’s sensitivity. On the other hand, in the case of PMMA, the contact angle was large (wettability decreased), the area of the water droplet and its distribution became small and the accuracy of discriminating the water droplet’s diameter by the sensor enhanced. Therefore, by rendering sensor’s surface hydrophilic and hydrophobic, the sensitivity and accuracy of the sensor could be enhanced. View Full-Text
Keywords: galvanic current; electrodes; moisture; polymer; contact angle galvanic current; electrodes; moisture; polymer; contact angle
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MDPI and ACS Style

Shrestha, R.G.; Ando, T.; Sakamoto, Y.; Kawakita, J. Enhancement of Sensitivity and Accuracy of Micro/Nano Water Droplets Detection Using Galvanic-Coupled Arrays. Sensors 2019, 19, 4500. https://doi.org/10.3390/s19204500

AMA Style

Shrestha RG, Ando T, Sakamoto Y, Kawakita J. Enhancement of Sensitivity and Accuracy of Micro/Nano Water Droplets Detection Using Galvanic-Coupled Arrays. Sensors. 2019; 19(20):4500. https://doi.org/10.3390/s19204500

Chicago/Turabian Style

Shrestha, Rekha G., Tatsuya Ando, Yukihiro Sakamoto, and Jin Kawakita. 2019. "Enhancement of Sensitivity and Accuracy of Micro/Nano Water Droplets Detection Using Galvanic-Coupled Arrays" Sensors 19, no. 20: 4500. https://doi.org/10.3390/s19204500

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