基于DSP的集成谐振式微悬臂梁便携式气体检测仪

DSP-Based Portable Gas Detector with Integrated Resonant Microcantilever

针对集成谐振式微悬臂梁气体检测仪小型化的问题,利用DSP(数字信号处理)设计和实现了可快速现场检测的便携式气体检测仪。该仪器基于DSP28335开发,采用开环自动扫频与闭环锁相检测相结合的方式。闭环测试核心是软件锁相环的设计,其中采用DFT(离散傅里叶变换)算法提取相位差,提高了运算的速度和计算相位差的精度。软件设计跟踪算法使其能够一直跟踪频率变化,使锁相更快,精度更高。结合实验室研制的微悬臂梁传感器制备了便携式二甲苯气体检测仪,并对浓度低至30 ppm的二甲苯气体进行了实测,验证了该仪器具有快速的响应速度和检测重复性。

For purpose of miniaturization of the integrated resonant microcantilever gas detector,a DSP-based interface circuit was designed.The interface circuit was developed with DSP28335.Open loop frequency sweep was combined with the closed loop phase lock detection with a software phase-locked loop.The core of the closed-loop test was the design of the software phase-locked loop,which used DFT(Discrete Fourier Transform)algorithm to extract the phase difference,improving the speed of operation and the accuracy of phase difference.By using the software designed frequency tracking algorithm,the process of phase lock is faster with a higher precision.A portable xylene gas detector was developed with alab-made microcantilever sensor,and used to detect xylene gas with alow concentration of 30 ppm.The experiment results show that the gas detector has a fast response and good repeatability.