The Development of Inkjet-Printing Humidity Sensing Device
Date Issued
2012
Date
2012
Author(s)
Lin, Shih-Hui
Abstract
Since the ancient times, the rain and humidity of the weather has been a great concern in daily life. Simple tools were used to detect the humidity in the air. People in the old times used hanging feather, the weight change of the charcoals, and the tune change of the instruments to observe the humidity change in times. In recent times, conventional bulb hygrometers and hair hygrometers are invented to measure the humidity. Until the late 90’s, the technical boost has given the development of electrical hygrometers a chance to become intelligent and multifunctional.
Polymers are attractive materials in electronic field for their easy fabrication processes, low cost, room temperature operation, etc. Herein, with the combination of semiconductor process and ink-jet printing system, we have developed the innovative humidity sensing materials based on the nanoparticles of silicon dioxide and Al-doped zinc oxide as dopants to improve the doped poly(3,4-ethylenedioxythiophene)-poly(4-styrenesulfonate) sensitivity and stability to the humidity.
In this work, we presented three humidity sensing devices by inkjet printing, the relationship between their resistance and relative humidity is highly exponential dependent. All devices have been proved to be highly sensitive and repeatable. We have also proved that after the doping of nano-SiO2 particles into PEDOT:PSS, the sensitivity can be improved to 106%; after doping the Al-doped zinc oxide, the sensitivity to water vapor can be risen up to 67%. Further, by taking the advantages of inkjet printing system, different sensing materials can be printed on one chip. While each of the sensing devices possesses its own solving equations, the gas sensor chip has the potential to be applied to various aspects by solving the equations of each sensing device simultaneously. Consequently, the extension of application of the sensing devices can be expanded, increasing the industrial values at the same time.
Subjects
humidity sensor
Ink-jet printing
Poly(3,4-ethylenedioxythiophene) Poly(4-styrenesulfonate) (PEDOT:PSS)
SiO2
Al-doped ZnO (AZO)
Type
thesis
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