Technological watch

Abstract This work brings in an eco-friendly, smart integrated miniaturized sensor system to determine the temperature of aqueous solution and soil in a more affordable way to yield quality farming, small-scale agricultural farming, greenhouse farming, domestic gardening, and hydroponics. Carbon-Graphite hybrid electrode-based planar disposable sensor strip is used for sensing the temperature over a range of 27 to 50°C. The temperature sensor element is compared to four distinct structures, and the meander geometrical structure is deduced as a result. The temperature sensing element is fabricated utilizing a prudent, efficacious, and inexpensive microfabrication methodology of screen printing. The temperature and resistance characteristics are plotted for the carbon-graphite electrode on PET and paper. The temperature coefficient of resistance is determined to be 1%/°C for PET and 0.8%/°C paper substrate in soil. Test experiment was carried out in water, oven and on field to find out the characteristic equation of study. The temperature sensor strip is integrated with a Wi-Fi SoC-assisted nodeMCU processor that is used in IoT platforms. An app is created using MIT app inventor user interface and is launched on an android smartphone. The app gives the suitable temperature range for sowing seed and germination of the plant growth information. The instantaneous temperature of soil or water is measured, and status information for plant cultivation is also provided by the app.

Graphical abstract