I. Agir, T. Özer
Istanbul Medeniyet University; Yildiz Technical University,
Keywords: internet of things, potassium, sodium, nitrate, hydroponic, greenhouse, ion selective electrodes
Summary:Here, we introduce a portable and low-cost device in the concept of the Internet of Things for continuous monitoring of potassium, sodium and nitrate in hydroponic greenhouse. The amount of dissolved nutrients is required to be controlled for plant health and agricultural applications since any imbalance in nutrient levels adversely affect crop quality and yield. Traditional methods of measuring Na, K and NO3- includes atomic absorption spectroscopy, inductively coupled plasma mass spectroscopy, which require bulky instruments, laborious sample pretreatment steps, specialized personnel and sample transportation to laboratory environment. Thus, these conventional methods are not suitable for on-site detection of the nutrients in hydroponic system. We developed a sensing platform that integrates ion-selective electrodes with potentiometric method for real-time monitoring of Na, K and NO3-. The ion-selective electrodes were fabricated using in-house screen-printing method. Then, they were modified with carbon black nanomaterial to prevent formation of water layer between ion-selective membrane and solid-contact. The ion-selective membranes were optimized to improve electrode performance. Under optimized conditions, the ion-selective electrodes exhibited Nernstian response with a short response time (11 s). They showed linear working range between 0.1 M- 10-4 M with limit of detection of 1× 10-5 M. Our sensing platform is able to make an auto-calibration after sampling process via micropumps and a microfluidic device for rapid detection in the field. In addition, the device can also implement long-range wireless networking (up to 10 kilometers) in terms of data access and remote connection. We have also developed a smartphone application interface to be easily operated by end-users. This sensing platform has low-power consumption due to its customized power unit using solar electric panels (20 W). We applied the developed device and obtained an average of 98% recovery in real sample analysis. Consequently, our device will help farmers to sensitively and continuously monitor the nutrients including potassium, sodium and nitrate for efficient crop growth in hydroponic cultivation.