Low Cost Humidity Sensor Based on PANI/PEDOT:PSS Printed on Paper

Abstract

The production of low cost sensors to monitor environment in some industrial sectors is a current need. In aviculture centers, for example, the concentration of ammonia gas is related to humidity, and it is necessary to control it to avoid contamination. With this need in mind, this paper presents the preparation and characterization of a low cost humidity sensor based on poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) and polyaniline fully printed onto paper by a commercial HP printer. Using electrochemical impedance spectroscopy, an equivalent circuit containing resistive and capacitive parameters was proposed. The resistive parameter R1 is related to values of ambient humidity. The R1 values showed a sensitive response of 200% when relative humidity changes 80%, taking 10 min to reach saturation point. Moreover, the device showed good stability when humidity remained constant. These results indicate that the proposed device is suitable for applying as a humidity sensor that costs less than 1 Euro cent.

Recent Advances in Graphene-Based Humidity Sensors

“…According to the change of the physical parameters after interacting with water molecules, humidity sensors can be categorized into many types, such as the capacitive type, resistive type, impedance type, optic-fiber type, quartz crystal microbalance (QCM) type, surface acoustic wave (SAW) type, resonance type, and so on [3]. Many materials sensitive to water molecules have been developed as sensing materials in humidity sensors, including ceramics, such as Al 2 O 3 , SiO 2 , and spinel compounds [2]; semiconductors, such as TiO 2 [5,6], SnO 2 [7,8,9,10], ZnO [11,12,13,14], In 2 O 3 , Si [15], and perovskite compounds [16,17]; polymers, such as polyelectrolytes [18,19], conducting and semiconducting polymers [20], and hydrophilic polymers [21,22,23,24]; 2D materials, such as MoS 2 [25,26,27], WS 2 [28,29,30], and black phosphorus [31,32,33,34]; and carbon materials, such as porous carbon [35], carbon nanotubes [36,37], and graphene [38,39].…”

Electrohydrodynamic jet printed conducting polymer for enhanced chemiresistive gas sensors

“…Examples of such devices have been produced. 2,12,13 Existing preparation techniques for depositing conducting polymers are based on inkjet printing 14,15 , spin-coating, drop-casting 16 , electrospinning 17 , Langmuir-Blodgett films 18 and electrochemical polymerization [19][20][21][22] . Most of these techniques require a significant amount of polymer to bridge the electrodes in a chemiresistor type gas sensor and do not allow discrete conducting polymer bridges.…”

Effect of Humidity on the Electrical Properties of Poly (3, 4‐Ethylenedioxythiophene) – Poly (Styrenesulfonate) and its Carbon Nanotube Composites

“…The conducting polymers and their nanomaterials and nanocomposites have also been extensively investigated for sensing temperature, relative humidity, chemical vapors, gases, etc. because of their light weight, low‐cost solution processing and easy fabrication of devices [16–20] . It is well known that carbon nanotubes (CNTs) exhibit extraordinary electrical, optical, chemical and mechanical properties and when mixed together with conducting polymer complement each other in the nanocomposites form.…”

“…Further, flexible thin films of conducting polymers can be easily deposited by various techniques, such as spin‐coating, dip coating, electrochemical deposition and polymerization. Thereafter, conducting polymers have widely been used in various device applications such as organic light emitting diode, [3–5] organic field effect transistors, [6,7] organic memory devices, [8,9] photovoltaic applications, [9–11] sensors, [12–18] etc.…”