ZHAO Zhen-gang, LIU Xiao-wei, WANG Xin, JIN Hai-yan, TAN Xiao-yun. Carbon nanotube sensors based on 555 multivibrators[J]. Editorial Office of Optics and Precision Engineering, 2010,19(1): 118-123
ZHAO Zhen-gang, LIU Xiao-wei, WANG Xin, JIN Hai-yan, TAN Xiao-yun. Carbon nanotube sensors based on 555 multivibrators[J]. Editorial Office of Optics and Precision Engineering, 2010,19(1): 118-123 DOI: 10.3788/OPE.20111901.0118.
Carbon nanotube sensors based on 555 multivibrators
The capacitive signals of capacitive carbon nanotube humidity sensors are usually tested by measuring instruments
which restricts the uses and developments of the sensors seriously. Focusing on this problem
one kind of capacitive carbon nanotube humidity sensor based on a 555 multivibrator was presented. Firstly
the principle of the sensor and the detecting circuit were discussed
and the sensor was designed and fabricated. Then
the sensor was tested by both the RCL apparatus and the proposed circuit
respectively. Finally
the response and recovery time of the sensor was tested. The testing results demonstrate that when the Relative Humidities (RH) surrounding the sensor change from 11% to 97%
the capacitive sensitivity and the output frequency sensitivity of the sensor are 905% and 889%
respectively. The frequency sensitivity is closed to the capacitive sensitivity
which means the circuit can well change capacitive signals to frequency signals.Furthermore
the adesorption and desorption time of the sensor is about 4 s and 18 s
respectively
which shows the sensor can offer low power consumption and fast response and has potential application prospects.
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references
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