Fig. 1. (Color online) The bimodal sensor to detect insect wingbeat^[28].

Fig. 2. (Color online) (a) A schematic view of the electronic nose system. (b) Cylindrical sensor chamber with 6 metal–oxide–semiconductor sensors. (c) System procedure diagram with pump flow work that will control the sensor response in a specific cycle^[31].

Fig. 3. (Color online) The principle of the e-nose detection for citrus fruits infested byB. dorsalis^[39].

Fig. 4. (Color online) (a) Optical images of the flexible wearable sensor mounted on a single plant leaf. (b) Exploded view illustration of the sap flow sensor^[53]. (c) Schematic illustration of the fabrication process of the flexible humidity sensor^[59]. (d) Schematic of the integrated device attached onto the lower epidermis of the leaf to monitor transpiration processes. (e) Photo of the front view of the multimodal flexible plant healthcare device integrated with a room humidity sensor, leaf-surface humidity sensor, optical sensor, and temperature sensor^[62].