基于VO2的超表面双气体传感器设计

Design of metasurface dual-gas sensor based on VO2

  • 摘要: 针对传统矿用气体传感器易受温度和环境湿度等因素的影响而导致稳定性不高的问题,基于局域表面等离子共振原理和二氧化钒(VO2)的相变特性,设计了一种基于VO2的超表面双气体传感器。该传感器结构由上下三层组成,表面由多层金属−介电−金属(MDM)结构组成。根据VO2的相变特点,通过改变施加的偏置电压,以电阻加热的形式加热金属板,精细控制VO2的温度,通过改变VO2的电导率来模拟VO2的不同状态。当VO2呈高温金属态时,上三层形成MDM结构, VO2表现出金属性质,并在1 721.3 nm激发局域表面等离子体共振(LSPR),实现甲烷检测,传感器的吸收率为94.3 %,甲烷灵敏度为4.21 nm/%。当VO2呈低温绝缘态时,下三层形成MDM结构,在2 694.6 nm激发LSPR,实现氢气检测,传感器的吸收率为95.9 %,氢气灵敏度为2.10 nm/%。当环境折射率发生变化时,VO2在2种状态下的吸收峰均发生了红移,且呈线性关系,可以用来检测环境折射率的变化。为验证该传感器的可行性,对6种不同体积分数的甲烷、氢气和4种不同的环境折射率进行了仿真和分析,结果表明:基于VO2的超表面双气体传感器可有效检测出较低浓度的甲烷和氢气,且灵敏度较现有的气体传感器有较大提升;谐振峰偏移量与环境折射率变化量和甲烷体积分数变化量的计算值和理论值误差很小,说明该传感器具有很高的准确性;通过分析环境折射率和谐振波长的关系,得出该传感器对环境折射率的变化同样具有较高的检测灵敏度。

     

    Abstract: The traditional mine gas sensor is vulnerable to the influence of temperature and ambient humidity and other factors, resulting in low stability. In order to solve the above problem, based on the principle of local surface plasmon resonance (LSPR) and the phase change characteristics of vanadium dioxide (VO2), a kind of metasurface dual-gas sensor based on VO2 is designed. The sensor structure is composed of three layers, and the surface is composed of multi-layer metal-dielectric-metal (MDM) structure. According to the phase change characteristics of VO2, the metal plate is heated in the form of resistance heating by changing the applied bias voltage. The temperature of VO2 is carefully controlled, and the different states of VO2 are simulated by changing the conductivity of VO2. When VO2 is in a high-temperature metal state, the upper three layers form MDM structure. VO2 shows metal properties and excites local surface plasmon resonance (LSPR) at 1721.3 nm to realize methane detection. The sensor's absorptance reaches 94.3%, and the methane sensitivity reaches 4.21 nm/%. When VO2 is in a low-temperature insulation state, the lower three layers form MDM structure. LSPR is excited at 2694.6 nm to realize hydrogen detection. The sensor's absorptance reaches 95.9%, and the hydrogen sensitivity reaches 2.10 nm/%. When the environmental refractive index changes, the absorption peaks of VO2 in both states are red-shifted and linear,which can be used to detect the change of the environmental refractive index. In order to verify the feasibility of the sensor, six different concentrations of methane, hydrogen and four different environmental refractive indexes are simulated and analyzed. The results show that the metasurface dual-gas sensor based on VO2 can effectively detect methane and hydrogen with lower concentration. The sensitivity is greatly improved compared with the existing gas sensors. The error between the calculated and theoretical values of the resonant peak shift and the environmental refractive index change and the methane volume fraction change is very small. This indicates that the sensor has high accuracy. By analyzing the relationship between the environmental refractive index and the resonant wavelength, it is concluded that the sensor also has high detection sensitivity when the environmental refractive index changes.

     

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