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Journal of Sensors
Volume 2014, Article ID 238350, 7 pages
http://dx.doi.org/10.1155/2014/238350
Research Article

Using Capacitance Sensor to Extract Characteristic Signals of Dozing from Skin Surface

1Department of Electronic Engineering, National Chin-Yi University of Technology, Taichung 41170, Taiwan
2Department of Information Engineering, I-Shou University, Kaohsiung 84001, Taiwan
3Department of Electronic Engineering, National Kaohsiung University, Kaohsiung 811, Taiwan
4Department of Computer Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan
5Department of Management of Information System, National Chung Hsing University, Taichung 402, Taiwan
6Department of Electronic Engineering, I-Shou University, Kaohsiung 84001, Taiwan
7Department of Electrical Engineering, I-Shou University, Kaohsiung 84001, Taiwan
8Department of Electronic Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 811, Taiwan
9Department of Computer Science and Information Technology, National Chin-Yi University of Technology, Taichung 41170, Taiwan

Received 21 May 2014; Revised 20 October 2014; Accepted 23 October 2014; Published 13 November 2014

Academic Editor: Chengkuo Lee

Copyright © 2014 Po-Ying Chen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Skin is the largest organ of the human body and a physiological structure that is directly exposed to the environment. From a theoretical perspective, numerous physiological and psychological signals use the skin as a medium for input and output with the outside world. Therefore, the skin is considered an optimal signal interception point when developing noninvasive, direct, and rapid signal exploration devices. To date, skin signal interceptions are predominantly performed by measuring skin impedance. However, this method is prone to interference such as sweat secretion, salt accumulation on the skin, and muscle contractions, which may result in a substantial amount of interference and erroneous results. The present study proposes novel and effective methods for skin signal interception, such as using a nested probe as a sensor to measure capacitance to be further processed as physiological and psychological signals. The experimental results indicate that the capacitance curve for the transition between wakefulness and dozing exhibits significant changes. This change in the curve can be analyzed by computer programs to clearly and rapidly determine whether the subject has entered the initial phases of sleep.