Abstract
A polymer-coated surface acoustic wave (SAW)-based chemical sensor for organophosphorous compound sensing at extremely low concentrations was developed, in which a dual-delay-line oscillator coated with fluoroalcoholpolysiloxane (SXFA) acted as the sensor element. Response mechanism analysis was performed on the SXFA-coated chemical sensor, resulting in the optimal design parameters. The shear modulus of the SXFA, which is the key parameter for theoretical simulation, was extracted experimentally. New designs were done on the SAW devices to decrease the insertion loss. Referring to the new phase modulation approach, superior short-term frequency stability (±2 Hz in seconds) was achieved from the SAW oscillator using the fabricated 300 MHz delay line as the feedback element. In the sensor experiment on dimethylmethylphosphonate (DMMP) detection, the fabricated SXFA-coated chemical sensor exhibited an excellent threshold detection limit up to 0.004 mg/m3 (0.7 ppb) and good sensitivity (∼485 Hz/mg/m3 for a DMMP concentration of 2∼14 mg/m3).
Highlights
Due to the threat of terrorism and environmental pollution there is great demand for chemical sensors with high sensitivity and good stability towards organophosphorous compounds for real-time monitoring
Chemical sensor, composed of a dual-delay-line oscillator and a chemical interface coated onto the acoustic path of a surface acoustic wave (SAW) device
Hoyt et al presented a way to improve the frequency stability of the oscillator, in which both of the dual delay line oscillators were modified with chemically sensitive interface materials to compensate for the noise and drift in SAW oscillator frequency and frequency associated with temperature effects on wave velocity in coating films [19]
Summary
Due to the threat of terrorism and environmental pollution there is great demand for chemical sensors with high sensitivity and good stability towards organophosphorous compounds for real-time monitoring. Wang et al presented some meaningful advances in sensor response mechanism analysis considering the effect of the metal film under such case, optimal design parameters like polymer thickness, and operation frequency were extracted theoretically [15]. Referring to the Wang model [15], the response mechanism of the SXFA-coated chemical sensor was depicted in detail, including the polymer thickness and frequency effect on vapor adsorption, allowing optimal design parameter extraction. Hoyt et al presented a way to improve the frequency stability of the oscillator, in which both of the dual delay line oscillators were modified with chemically sensitive interface materials to compensate for the noise and drift in SAW oscillator frequency and frequency associated with temperature effects on wave velocity in coating films [19]. The fabricated oscillator with good stability results and superior threshold detection limits, which was confirmed in the gas sensing experiment, in which, the SXFA with optimal thickness was used as the sensor material for DMMP detection
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
