United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 Korimoto, Kagoshima-shi, Kagoshima 890-0065, Japan.
Department of Agricultural Engineering, Faculty of Agriculture, University of Ruhuna, Kamburupitiya 81100, Sri Lanka.
Sensors (Basel). 2021 Feb 8;21(4):1189. doi: 10.3390/s21041189.
This research presents a low-cost, easy-to-assemble nondispersive infrared (NDIR) device for monitoring NO gas concentration in agricultural soils during field and laboratory experiments. The study aimed to develop a cost-effective instrument with a simple optic structure suitable for detecting a wide range of soil NO gas concentrations with a submerged silicone diffusion cell. A commercially available, 59 cm path-length gas cell, microelectromechanical systems (MEMS)-based infrared emitter, pyroelectric detector, two anti-reflective (AR) coated optical windows, and one convex lens were assembled into a simple instrument with secure preciseness and responsivity. Control of the IR emitter and data recording processes was achieved through a microcontroller unit (MCU). Tests on humidity tolerance and the saturation rate of the diffusion cell were carried out to test the instrument function with the soil atmosphere. The developed calibration model was validated by repeatability tests and accuracy tests. The soil NO gas concentration was monitored at the laboratory level by a specific experimental setup. The coefficient of determination (R) of the repeatability tests was more than 0.9995 with a 1-2000 ppm measurability range and no impact of air humidity on the device output. The new device achieved continuous measuring of soil NO gas through a submerged diffusion cell.
本研究提出了一种低成本、易于组装的非分散型红外（NDIR）设备，用于在田间和实验室实验中监测农业土壤中的 NO 气体浓度。该研究旨在开发一种具有简单光学结构的经济型仪器，适用于检测具有浸没式硅扩散池的广泛土壤 NO 气体浓度。将市售的 59 厘米光路长度气体池、基于微机电系统（MEMS）的红外发射器、热电探测器、两个抗反射（AR）涂层光学窗和一个凸透镜组装成一个具有精确性和响应性的简单仪器。通过微控制器单元（MCU）实现对 IR 发射器和数据记录过程的控制。对湿度容限和扩散池的饱和度进行了测试，以测试仪器在土壤气氛中的功能。通过重复性测试和准确性测试验证了所开发的校准模型。通过特定的实验装置在实验室水平监测土壤 NO 气体浓度。重复性测试的决定系数（R）大于 0.9995，可测量范围为 1-2000 ppm，且空气湿度对设备输出无影响。新设备通过浸没式扩散池实现了土壤 NO 气体的连续测量。
