A Noncontact Dibutyl Phthalate Sensor Based on a Wireless-Electrodeless QCM-D Modified with Nano-Structured Nickel Hydroxide

Abstract

Dibutyl phthalate (DBP) is a widely used plasticizer which has been found to be a reproductive and developmental toxicant and ubiquitously existing in the air. A highly sensitive method for DBP monitoring in the environment is urgently needed. A DBP sensor based on a homemade wireless-electrodeless quartz crystal microbalance with dissipation (QCM-D) coated with nano-structured nickel hydroxide is presented. With the noncontact configuration, the sensing system could work at a higher resonance frequency (the 3rd overtone) and the response of the system was even more stable compared with a conventional quartz crystal microbalance (QCM). The sensor achieved a sensitivity of 7.3 Hz/ppb to DBP in a concentration range of 0.4–40 ppb and an ultra-low detection limit of 0.4 ppb of DBP has also been achieved.

Quartz Crystal Microbalance Electronic Interfacing Systems: A Review

“…On the other hand, electrodeless QCM-D based systems are also recently reported in the literature. The electrodeless crystal configuration significantly boosts its sensitivity and limits of detection [ 42 ], in addition to overcoming the metallic electrode’s biotoxicity to certain bioactive coating films by directly applying them to the bare crystal. QCM-D is advantageous for such films to assess their real-time viscoelastic changes through dissipation monitoring.…”

“…QCM-D is advantageous for such films to assess their real-time viscoelastic changes through dissipation monitoring. Several electrodeless QCM characterization systems are reported in the literature [ 42 , 43 , 44 , 45 , 46 ]. The work presented in [ 42 ] utilizes a bare-crystal separately placed in a test chamber.…”

“…The received signal is conditioned, amplified and processed for and extraction. For the reported work, an interrogation distance of 3 mm was achieved, allowing to place the bare crystal in closed environments for characterization [ 42 ]. Another inherent advantage for the electrodeless setup is the parallel plates capacitance absence and thus minimizing the interference with MSRF determination.…”

“…Electrodeless QCM biosensors operating at a fundamental resonance frequency of 170–180 MHz are also newly reported [ 41 ]. Specifically, recent works introduced wireless-electrodeless QCM operation to increase the resonator’s sensitivity and detection limits [ 42 , 43 , 44 , 45 , 46 ]. This is because parallel electrodes deteriorate the overall QCM sensitivity and range since they are also considered as deposited adlayers [ 42 ].…”

“…Specifically, recent works introduced wireless-electrodeless QCM operation to increase the resonator’s sensitivity and detection limits [ 42 , 43 , 44 , 45 , 46 ]. This is because parallel electrodes deteriorate the overall QCM sensitivity and range since they are also considered as deposited adlayers [ 42 ]. The effect of parallel electrodes geometry and distribution on the resonator’s sensitivity is recently discussed in [ 47 ], in addition to the effect of adlayers radial distribution.…”