IoT-Enabled Stretchable Piezoresistive Sensor for Real-Time Monitoring of Fruit Growth and Human Physiology

Ensuring quality control by identifying issues such as nutrient deficiencies and pest infestations helps in crop yield estimation for effective planning and resource management. However, the development of sensors for real-time continuous monitoring of fruit growth in an open environment has been a challenge. Herein, we propose a hydrophobic and stretchable piezoresistive sensor to monitor real-time fruit growth using graphene-silicone-based screen-printable paste (GSiCP) remotely. Graphene has been synthesized with a green approach utilizing an electrochemical exfoliation process, wherein no hazardous or strong acids were employed. The synthesized graphene has been characterized using X-ray (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman spectroscopy, and dynamic light scattering. The developed (GSiCP) sensors have shown a high sensitivity, stretchability, and cyclic durability of 2050, 125%, and 5000 cycles, respectively. The sensors show an exceptional minimal detection limit of 0.04%, which shows the capability of monitoring the slowest fruit growth. The GSiCP sensors have been used to monitor on-field the continuous real-time growth of fruit (brinjal) for 15 days using the Internet of Things (IoT). Further, the impact of an excess amount of fertilizer (urea) on fruit growth and plants has been investigated. Owing to the sensor's merits, GSiCP sensors have shown applicability in monitoring physiological signals (radial artery pulse rate) and physical activities.