Performance Analysis of a Molybdenum Disulphide (MoS2) Based Soil Moisture Sensor for in-situ Agriculture Applications

Abstract

In-situ moisture sensing is a highly active field of research and commercial importance owing to its direct application in automation of precision irrigation. The work is in continuation to [3], and further cements MoS2 as a highly viable, sensitive and robust option for deposition on the inter-digitated electrode (IDE) structure in a capacitive soil moisture sensor design. This is an investigative work where different concentrations, i.e. 10mg/10uL, 10mg/100uL, 10mg/1mL and 10mg/10mL; where 10mg of MoS2 is added to the appropriate volume of aprotic solvent, i.e. ethyl acetate (Wt. per ml at 20°C: 0.899-0.902g), and the sensor’s operability under various moisture profiles for a silt loamy and black soil is tested, along with its selectivity and temperature dependence. Initially, the designed sensor with 10mg/1mL gave us the best results with sensitivity of 454.87 % for 20 % gravimetric moistened soil, temperature variance of 2.81 % °C-1 for the temperature range (25°C-55°C) and 0.4 % average ion selectivity dependence on the soil infused with 10 mg ions (Cu2+, Cd2+, K+ and Na+). In direct comparison to [3], these numbers are better in every regards, and therefore inclines towards MoS2 as a suitable nanomaterial candidate. We have further seen that on an average 10mg/100uL concentration is a suitable candidate and conducted our experiments suitably for the respective sensor.