The importance of Carbon dioxide (CO2) gas detection as a greenhouse and exhale breathe gas is an undeniable issue. This study aims to propose a new miniaturized, low cost and portable no dispersive infrared (NDIR) system for detecting CO2 gas.,Poly(methyl methacrylate) (PMMA)-based channels with Au coating because of its high reflection properties in IR region were used in this work. The optical windows were fabricated using PDMS polymer which is cost effective and novel in comparison to other conventional methods. The effects of channel dimensions, lengths and entrance angle of light on optical path length and losses were analyzed with four types of channel using both simulation and experimental tests.,The simulation results indicate that the 0 degree light entrance angle is the most efficient angle among different investigated conditions. The experimental data are in agreement with the simulation results regarding the loss and optical path length in different types of channel. The experimental tests were performed for the 0.5% up to 20% of CO2 concentration under constant temperature and humidity condition. The results show that the device with 5 and 2 cm channels length were saturated in 4% and 8% concentration of CO2 gas, respectively. Response and recovery times were depending on gas concentration and channels specifications that in average found to be 10 S and 14 S, respectively, for the largest size channel. Moreover, the environment humidity effect on detection system performance was investigated which had no considerable influence. Also, the saturation fraction absorbance value for devices with various dimensions were 0.62 and 0.8, respectively.,According to the performed curve fitting for practical situation and selected CO2 concentration range for experimental tests, the device is useful for medical and environmental applications.,PMMA with Au deposition layer was used as a basic material for this NDIR system. Besides, a novel PDMS optical window helps to have a low cost device. The effects of channel dimensions, lengths and entrance angle of light on optical path length and losses were analyzed using both simulation and experimental tests. Using narrowband optical filter (100 nm bandwidth) helps to have a system with good CO2 selectivity. In addition, experimental tests with different channel dimensions and lengths covered a considerable range of CO2 concentration useful for medical and environmental applications. Finally, curve fitting was adopted for a modified Beer–Lambert law as a practical situation.

中文翻译：

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用于 CO2 检测应用的低成本和小型化 NDIR 系统

二氧化碳 (CO2) 气体检测作为温室气体和呼出呼吸气体的重要性是一个不可否认的问题。本研究旨在提出一种新的小型化、低成本和便携式无色散红外 (NDIR) 系统，用于检测 CO2 气体。具有 Au 涂层的聚甲基丙烯酸甲酯 (PMMA) 基通道因其在红外区域的高反射特性而被在这项工作中使用。光学窗口是使用 PDMS 聚合物制造的，与其他传统方法相比，它具有成本效益和新颖性。通过仿真和实验测试，分析了四种通道的通道尺寸、长度和光入射角对光路长度和损耗的影响。仿真结果表明，0度光入射角是最有效的角度。不同的调查条件。实验数据与不同类型信道的损耗和光路长度的模拟结果一致。在恒温恒湿条件下，对0.5%~20%的CO2浓度进行了实验测试。结果表明，具有 5 cm 和 2 cm 通道长度的装置分别在 4% 和 8% 的 CO2 气体浓度下饱和。响应和恢复时间取决于气体浓度和通道规格，对于最大尺寸的通道，平均分别为 10 S 和 14 S。此外，还研究了环境湿度对检测系统性能的影响，但没有显着影响。此外，不同尺寸器件的饱和分数吸光度值分别为 0.62 和 0.8。根据对实际情况进行的曲线拟合和为实验测试选择的 CO2 浓度范围，该装置可用于医疗和环境应用。具有 Au 沉积层的 PMMA 被用作该 NDIR 系统的基础材料。此外，新型 PDMS 光学窗口有助于降低设备成本。使用模拟和实验测试分析了通道尺寸、长度和光入射角对光路长度和损耗的影响。使用窄带滤光片（100 nm 带宽）有助于使系统具有良好的 CO2 选择性。此外，具有不同通道尺寸和长度的实验测试涵盖了可用于医疗和环境应用的相当大范围的 CO2 浓度。最后，