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Portable Formaldehyde Detector Based on MSP430 Microprocessor

Author: MaoRan
Tutor: GongYiMin
School: Jilin University
Course: Radio Physics
Keywords: Formaldehyde Testing Portable MSP430
CLC: TP368.12
Type: Master's thesis
Year: 2009
Downloads: 343
Quote: 2
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Abstract

Formaldehyde is a colorless, strong irritating smells of gas .It is a strong toxic chemicals and carcinogenic, teratogenic-type material. The formaldehyde and other indoor air pollution from interior decoration and furniture has become a major source of serious impact on human health. Therefore, the analysis of formaldehyde detection is particularly important. Phenol reagent spectrophotometric assay is in line with the national indoor air quality standards commonly used methods of detection of formaldehyde content. The main principle is that through the spectrophotometer absorbance of the sample solution for testing to determine the formaldehyde content of the air sampling. To simplify the testing process and improve the detection accuracy and reduce the difficulty of detection, we developed a portable, low-power detection system.The detection system is mainly to replace the traditional methods of detection and concentration calculation of absorbance detection link. First of all, using the 630nm wavelength red LED irradiation on the sample solution, frequency of the sensor light is absorbed by the solution of the light intensity signals are collected and converted to frequency signals. In a large number of different concentrations of test solution, the combination of traditional detection methods on the same batch of test data solution, the concentration of - and related formula for the frequency curve. In the detection range, the curve can be divided into three parts, namely, the frequency of the signal once, twice, three curves. By the curve can be treated after the test solution-side. Through optical frequency sensor light is absorbed by the test solution has been transformed into the frequency signal in the scope of its formula for calculating, then we get the concentration of the solution.Because the testing result of the temperature, pressure, humidity and other factors can cause changes in solution volume and temperature drift, the system also measures the three environmental factors to improve the detection accuracy. By system size, weight, low power requirements, etc., system use two patches of this sensor to measure the three kind of data. The resolution of temperature, humidity, pressure test data is 0.1℃、1%RH、1mbar, and the measurement accuracy is 0.5℃(5~40℃)、5%RH、5mbar. Using the data results of the solution concentration of the rectification can be more accurate concentration.All the testing, calculation and other functions, all is based on a set of intelligent, portable, low-power single-chip microcomputer system, which is the core of the detection system.MSP430F435 single-chip microcomputer system as the core model, make full use of its various functions, including the provision of low-power applications, LCD driver, Flash memory, serial communications, analog-to-digital conversion and other functions in support of the system on a number of sensor-driven, the driver of the LCD screen on battery power detection and support the operation of the entire software system.This system provides a low-power, portable applications the concentration of formaldehyde solution under the new method of detection, the introduction of the optical frequency detection module, at the same time testing the impact of environmental factors in the measurement, to improve the measurement accuracy and simplify the detection process, to achieve the detection, automation of the calculation process.

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