Development of a SAW poly(epichlorohydrin) gas sensor for detection of harmful chemicals

Abstract

The uniformity and compactness of the surface of a viscoelastic sensitive film are among the most important factors that influence the characteristics of a surface acoustic wave (SAW) gas sensor....

A passive wireless surface acoustic wave (SAW) sensor system for detecting warfare agents based on fluoroalcohol polysiloxane film

“…13 , no monotonically increasing change is observed between the sensor response signal and the film thickness, but an optimal thickness is found because of the viscoelastic effect of SXFA as a polymer-sensitive material. As SXFA used in this manuscript is a kind of multiple molecular layer, according to linear solvation energy relations (LSERs) and gas‒liquid equilibrium theory 7 , 8 , 53 , at a certain temperature, the ratio of the concentration of molecules in the gas phase C v to the concentration on the membrane surface C s is a constant K. When the concentration of molecules in the gas phase is constant, under its pressure drive, if the membrane is very thin, it will quickly reach equilibrium. If the membrane is too thick, the permeation of gas molecules in it leads to a longer equilibrium time.…”

Highly Selective Ionic Gel-Based Gas Sensor for Halogenated Volatile Organic Compound Detection: Effect of Dipole–Dipole Interaction

“…The distance between the IDTs is 2.56 mm, and the area provided (white dashed box) is the sensing area coated with the ionic gel film. To reduce the propagation loss of SAW, both the single-phase unidirectional transducers (SPUDTs) and pseudofingers are used in IDTs, , as shown in the enlarged view. Finally, the SAW device is packaged on a base and connected with the pins via wire bonding.…”

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

“…The PECH glass transition temperature (T g ) values reported in the literature range from −22.4 °C [ 55 ] to −14.5 °C [ 56 ]. Such low values of T g confirm the definitely elastomeric nature of PECH at typical operating temperatures of SAW sensors.…”

“…The solvation properties of PECH are determined by dipolar chloromethyl groups and slightly basic ether linkages. The interaction of PECH with sulfur mustard is likely to be Van der Waals interactions and the formation of hydrogen bonds in which PECH is donor of hydrogen [ 55 , 57 ]. However, the contribution of formation of hydrogen bonds of this type has been questioned in some work [ 58 ].…”

“…In 2022, the same research team published another paper on the use of a PECH sensor to detect CEES [ 55 ]. This time, a SAW delay line with a center frequency of 200 MHz was used.…”