A Microfabricated Amperometric Moisture Sensor
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Authors
Su, Xiao-Li
Dallas, Tim
Gangopadhyay, Shubhra
Temkin, Henryk
Wang, Xuejun
Walulu, Richard
Li, Jianzhong
Dasgupta, Purnendu K.
Xiong, Xingguo
Issue Date
2002-02-11
Type
Article
Language
Keywords
Moisture sensor , Water sensor , Microfabricated sensor , Amperometric sensor , Computer science , Robotics
Alternative Title
Abstract
We describe a microfabricated moisture sensor with interdigitated Au or Pt electrodes on a silicon substrate. The sensor active area is covered with a spin-coated, baked-on layer of Nafion® perfluorosulfonate ionomer of submicron thickness. The sensor responds to moisture with a 10–90% rise time of 50–100 ms and a 90–10% fall time of 20–30 ms, faster than any other presently available sensor. The logarithm of the sensor current is related to the cube root of the moisture level at a given temperature. At 23 °C, the sensor easily measures relative humidities as low as 10%. The sensor response at a given absolute humidity level decreases exponentially with increasing temperature. The film is stable up to a temperature of 150 °C, permitting elevated temperature moisture measurement. Since sorbed water is actively decomposed electrolytically, the sensors exhibit negligible hysteresis. Response reproducibility of an individual sensor is <1%, that between identically made sensors is <5%, suggesting mass production techniques without individual calibration will be acceptable for all but the most demanding situation.
Description
Citation
X. Su, T. Dallas, S. Gangopadhyay, H. Temnik, X. Wang, R. Walulu, J. Li, P. K. Dasgupta, X. Xiong, "A Microfabricated Amperometric Moisture Sensor," Talanta, vol.56, no. 2, Feb. 2002.
Publisher
Elsevier