Sniff Species: SURMOF-Based Sensor Array Discriminates Aromatic Plants beyond the Genus Level

Abstract

Lamiaceae belong to the species-richest family of flowering plants and harbor many species that are used as herbs or in medicinal applications such as basils or mints. The evolution of this group has been driven by chemical speciation, mainly volatile organic compounds (VOCs). The commercial use of these plants is characterized by adulteration and surrogation to a large extent. Authenticating and discerning this species is thus relevant for consumer safety but usually requires cumbersome analytics, such as gas chromatography, often coupled with mass spectroscopy. Here, we demonstrate that quartz-crystal microbalance (QCM)-based electronic noses provide a very cost-efficient alternative, allowing for fast, automated discrimination of scents emitted from the leaves of different plants. To explore the range of this strategy, we used leaf material from four genera of Lamiaceae along with lemongrass, which is similarly scented but from an unrelated outgroup. To differentiate the scents from different plants unambiguously, the output of the six different SURMOF/QCM sensors was analyzed using machine learning (ML) methods together with a thorough statistical analysis. The exposure and purging of data sets (four cycles) obtained from a QCM-based, low-cost homemade portable e-Nose were analyzed using a linear discriminant analysis (LDA) classification model. Prediction accuracy with repeated test measurements reached values of up to 0%. We show that it is possible not only to discern and identify plants at the genus level but also to discriminate closely related sister clades within a genus (basil), demonstrating that an e-Nose is a powerful device that can safeguard consumer safety against dangers posed by globalized trade.

Electrochemical fabrication of long-range ordered macro-microporous metal–organic framework films

“…Combined with the PCA approach, the 3DOM ZIF-8 film was able to discriminate single-component vapors and vapor mixtures. A comparison of the MOF-based vapor sensors is shown in Table S3 † 60–63.…”

“…A comparison of the MOF-based vapor sensors is shown in Table S3. † [60][61][62][63] Reversibility is also an important property of sensing devices. We established that the sensing process could be repeated up to ve times without damaging the sensor, thus demonstrating the robustness and reusability of the 3DOM ZIF-8 lm sensor.…”

Non-injective gas sensor arrays: identifying undetectable composition changes

“…Nanogram-scale changes in the adsorbed mass of gas in the MOF film can be inferred from changes in the resonant frequency of the piezoelectric quartz crystal, forced by an alternating voltage [9,10]. Several gravimetric, MOF-based sensors have been experimentally demonstrated using QCMs [15,[26][27][28][29][30][31][32] and surface acoustic wave devices [33][34][35] as electromechanical signal transducers [36].…”