Surface Acoustic Wave Humidity Sensors Based on Graphene Oxide Thin Films Deposited with the Surface Acoustic Wave Atomizer

Abstract

Submicron-thick films of graphene oxide and polyvinyl alcohol (PVA) were deposited onto the surface of 160 MHz quartz surface acoustic wave (SAW) delay lines, and manufactured devices were used as humidity sensors. Films were obtained by consecutive atomization of 0.35 μl droplets of 0.33 mg/ml graphene oxide water suspension or 5.00 mg/ml PVA water solution using 25 MHz SAW atomizers. During measurements authors did not observe additional attenuation of the surface acoustic wave propagating along the surface of the sensors, which confirms that deposited films have low thickness and good uniformity. It was shown that SAW quartz humidity sensors with graphene oxide films, PVA thin films and uncoated surface have sensitivity of 1.54 kHz/%RH, 0.47 kHz/%RH and 0.13 kHz/%RH respectively. Sensors with graphene oxide thin films showed the best sensitivity and dynamic response. It was concluded that they can be used as sensitive coatings in humidity sensors for industrial environment.

Surface acoustic wave devices for chemical sensing and microfluidics: a review and perspective

“…35 This problem can be overcome by the use of semiconducting metal oxide-based sensing layers such as ZnO, CdO, SnO 2 , TiO 2 , CuO and WO 3 . 36 Several nanomaterials such as silver nanoparticles 37 , zinc oxide nanorods 38 , carbon nanotubes 39 , metal oxide nanowires 40,41 , electrospun nanofibers 42 and palladium nanoparticles 43 have also been successfully used due to their high surface to volume ratio. 44,45 More recently, graphene oxide, which has a similarly larger surface area to volume ratio along with hydrophilic functional groups, has been used for humidity sensing applications.…”

High sensitivity and fast response graphene oxide capacitive humidity sensor with computer-aided design

“…So we can apply this theory to improve the sensitivity of the sensor after considering these factors. Compared with previous work [14,[34][35][36][37][38], Table 3 presents the related characteristics of the proposed humidity sensor. This comparison provides a clear perspective to observe the merits of adjusting the comb electrode parameters and achieve an ideal measure for building humidity sensors.…”

Influence of the deposition parameters of graphene oxide nanofilms on the kinetic characteristics of the SAW humidity sensor

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“…GO thin films are known to be very promising candidates for the sensitive elements of various types of fast and reliable humidity sensors [1][2][3]. The fast response and recovery of the films make possible to use GO-based sensors when relative humidity (RH) of the atmosphere changes significantly during a few seconds [4].…”

“…The fast response and recovery of the films make possible to use GO-based sensors when relative humidity (RH) of the atmosphere changes significantly during a few seconds [4]. The simplest ways of deposition of such films are spray or spin coating [1][2][3]. Although these methods allow one to obtain the films with the thickness in nanometer range, it is not always convenient to use them because they can require a significant area of deposition or produce films with the thickness difficult to control.…”