Advances in SXFA-Coated SAW Chemical Sensors for Organophosphorous Compound Detection

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).

A simple route to functionalize siloxane polymers for DMMP sensing

“…Because the molecular structure of the sorbent polymer LSFA was much similar to that of SXFA and PLF (see Figure ), its sensitivity to DMMP was compared with SXFA and PLF, based on polymer coated SAW sensors published previously in the literature . To make the comparison feasible, several key factors should be taken into account and normalized.…”

Enhanced Sensitivity of Surface Acoustic Wave-Based Rate Sensors Incorporating Metallic Dot Arrays

“…The SPUDT and comb structure will improve the frequency stability of the oscillator effectively [13]. The SAW velocity on the X-112°Y LiTaO 3 substrate with 110 nm Al metallization ( v x ) was 3,295 m/s.…”

An experimental research of love wave sensor based on LiTaO<inf>3</inf>/SiO<inf>2</inf> structure

“…Then, an experiment was performed to evaluate the frequency stability of the fabricated Love Wave oscillator at room temperature (20 °C). The oscillation was also modulated at the frequency point with lowest insertion loss by a strategically phase modulation [9]. The typical medium-term frequency stability in hours of the developed oscillators with operation frequency of 150MHz is measured as ±30Hz/h.…”