Piezoelectric sensor front-end for energy-efficient acquisition of ultrasonic emissions related to water-stress in plants

Formation of embolisms in plant’s xylem water transport vessels is considered a major cause of plant mortality due to water-stress. Passive ultrasonic acoustic emissions (AE) monitoring shows the most potential for field-quantification of embolism level. However, this requires designing energy-efficient embedded hardware for autonomous high-speed ultrasonic AE acquisition, processing, and storage. In this paper we present a piezoelectric sensor interface for triggered AE acquisition at 2 MS/s. Its design requirements were assessed by laboratory dehydration experiments on grapevine pot-plants. An embedded prototype was design and characterized. The proposed architecture enables event-based acquisition of AE within 120-550 kHz band, at 5.7 mW average power, and 717 ns wakeup-latency.