A Novel Surface Acoustic Wave Sensor Array Based on Wireless Communication Network

Abstract

A novel surface acoustic wave (SAW) sensor array based on wireless communication network is prepared. The array is composed of four SAW sensors, a wireless communication network module, and a global positioning system (GPS) module. The four SAW sensors of the array are coated with triethanolamine, polyepichlorohydrin, fluoroalcoholpolysiloxane, and L-glutamic acid hydrochloride to detect hydrogen sulfide (H2S), 2-chloroethyl ethyl sulfide (CEES), dimethylmethylphosphonate (DMMP), and ammonia (NH3) at film thicknesses of 50–100 nm. The wireless communication network module consists of an acquisition unit, a wireless control unit, and a microcontroller unit. By means of Zigbee and Lora technologies, the module receives and transmits the collected data to a PC work station in real-time; moreover, the module can control the sensor array’s working mode and monitor the working status. Simultaneously, the testing location is determined by the GPS module integrated into the SAW sensor array. H2S, CEES, DMMP, and NH3 are detected in 300 m at different concentrations. Given the practical future application in environment in the future, the low, safe concentrations of 1.08, 0.59, 0.10, and 5.02 ppm for H2S, CEES, DMMP, and NH3, respectively, are detected at the lowest concentration, and the sensitivities of different sensors of the sensor array are 32.4, 14.9, 78.1 and 22.6 Hz/ppm, respectively. With the obtained fingerprints and pattern recognition technology, the detected gases can be recognized.

Effects of temperature and humidity on the performance of a PECH polymer coated SAW sensor

“…The PECH lm thickness could be estimated by monitoring the frequency shi. 31 The optical and SEM picture of the sensing device was shown in Fig. 3, in which, the widths of the electrodes in SPUDTs are measured by $5.2 and 2.6 mm, and a spacing among them is 4 mm, agreeing well with the set parameters.…”

“…The use of SAW devices for detecting HD and CEES have been studied in some articles, 17,18 as one kind of mass sensitive detector, the basic operating principle of SAW sensors must be the reversible adsorption of chemical vapor by adsorbent coatings which are sensitive and selective to the vapor being detected, so many lms are selected as the coatings to detect HD and CEES previously, and the related mechanism of adsorption kinetics and the preparation of sensitive membrane materials have also been studied, such as ethyl cellulose (ECEL), poly(epichlorohydrin) (PECH), poly(ethylenimine), CdSnO 3 , etc, and PECH is considered to be the best lm for the detection of HD or CEES, while the inuencing factors including temperature, humidity, and interfering gases are seldom reported. [19][20][21] However, SAW microsensor systems designed and fabricated to date have also shown several potential limitations, primarily involving chemical selectivity of the coatings and their reduced sensitivity due to temperature or humidity. The problems of sensitivity and selectivity of lms depend on reversible interaction (e.g.…”

Acoustic Wave Sensors for Detection of Blister Chemical Warfare Agents and Their Simulants

“…In the work from 2018 [ 65 ], the sensor array for the remote detection of CWAs and other toxic gases was described. The array was composed of four two-port SAW resonators coated with: PECH, SXFA, TEA (triethylamine), and L-glutamic acid hydrochloride (the film thicknesses ranged from 50 to 100 nm).…”

Bulk and Surface Acoustic Wave Sensor Arrays for Multi-Analyte Detection: A Review

“…Another five-channel two-port SAW resonator array was provided with four sensors carrying coatings from different classes (triethanolamine, polyepichlorohydrin, fluoroalcoholpolysiloxane, and L-glutamic acid hydrochloride) and an uncoated reference sensor. This array was successfully used for the highly selective detection of two harmful inorganic gases and two CWA simulants by wireless communication technology within a communication distance of 300 m. The sensor array system was also equipped with a GPS (global positioning system) module to determine the location of the measurement [154].…”