甲醛是一种重要的化工原料和有机溶剂，是制造油漆、塑料、橡胶、染料等的原料。近年来，随着出行的需要和城市车辆的增长，人们在车内度过的时间越来越多，车内甲醛污染已成为影响人体健康的一个重要因素。甲醛气体会对人体造成极大的危害，为了保障人们的身体健康，发展高性能、低成本的传感器与智能技术相结合的检测系统具有重要的现实意义。本文通过甲醛气体传感器构建智能检测系统，检测甲醛的浓度，该系统具有数据采集、实时显示、声光报警、串口通讯等功能，并对甲醛传感器进行了标定，提高了整个系统的测量精度。 首先，论文分析了半导体甲醛传感器的原理，简要地介绍了传感器的线性度和直线拟合的定义，然后对甲醛传感器进行了标定。文中用三种方法对传感器的实验数据进行拟合，以观察拟合的结果之间的差异。在传感器组成的检测系统中，直线拟合的方法直接决定了线性度的高低。因此，在检测系统的组建中，若检测系统线性度和精度要求不高，尽量采用简单的拟合方法；若检测系统线性度和精度要求较高，拟合尽量采用最小二乘法。本系统线性度和精度要求都比较高，最终采用非线性的最小二乘法进行拟合。 随之，根据要求提出并实现了系统整体方案，完成了甲醛检测系统的硬、软件设计。系统硬件主要分为4部分：一是电源系统部分，主要实现±5V和+3.3V的电压输出；二是传感器信号的检测电路与调理电路部分；三是TMS320LF2407控制器部分的电路，包括DSP最小系统、甲醛气体浓度的采集、液晶显示电路、声光报警等；四是下位机通讯电路。系统软件包括2个部分：一是用C和汇编语言混合编写的下位机程序，主要完成系统初始化、中断采样、数据实时显示、声光报警和数据通讯等工作；二是由VC语言上位机软件程序，主要完成数据实时传输、数据保存等功能。 实验表明系统性能稳定，系统硬件和软件设计合理，测量精度达到预定的要求，具有很好的应用前景。

Formaldehyde is the important chemical raw materials and organic solvents，It is used to make paint, plastics, rubber, dyes and other products. In recent years, people spent more and more time in the car with the growth of city vehicles and the needs for travel. So formaldehyde pollution in car has become an important factor which affects human health. Formaldehyde gas would cause great harm to the human body. Therefore, the developing of a monitoring system with a high-performance, low-cost multi-sensor technology combined with intelligence has the important practical significance in order to protect people's health. In this thesis, a intelligent monitoring system is built to detect the concentration of formaldehyde by using formaldehyde gas sensor. The system comprises the data acquisition part, the real-time display part, the sound-light alarm part, the serial port communication part and other functions. In addition, formaldehyde sensor was calibrated to improve the accuracy of the system. First of all, the thesis deeply analyzes the principle of the semiconductor sensor of formaldehyde, briefly introduces the definitions of linearity and straight line fitting of the sensor. Then the formaldehyde sensor is calibrated. Three ways are used to fit the experimental data of the gas sensor, so as to observe the differences among the results of fitting. In the test system consisting of the sensors, the linear fitting method directly determines the level of linearity. Therefore, if the linearity and the precision are less demanding in the formation of the test system, the fitting method is as simple as possible;if the linearity and precision are high demanding, the least square method may be used to the fitting. The linearity and precision of our test system is high, so the least square algorithm which is nonlinear is used finally in our system. Secondly, the overall program are proposed and implemented, and the designing of hardware and software of the formaldehyde monitoring device is performed according to the requirements. The hardware includes three parts. The first one is power section where the±5V and the +3.3V voltage output supplied. The second one is the detection circuit and the signal conditioning circuit part. The third one is the part of TMS320LF2407 controller circuit, including the formaldehyde gas concentration acquisition, liquid crystal display circuit, sound-light alarm and so on. The last one is the position machine communication circuit. The software section consists of two parts. One is the program with C language and hybrid language which are used for the lower computer. In this part, the performances of the system initialization, the interrupt sampling, the data real-time displaying, the acousto-optic alarm and the data communications are realized. The other is the upper computer software based on VC language. It mainly achieves the real-time transmission, the data reservation and the displaying gas concentration. In the end, the real experiments show that the hardware and software are reasonable; the system has a steady quality and high accuracy as required. The system is of a bright future.