| Concentration measurement of rock salt aerosol is the foundation to improve the accuracy of salt aerosol's concentration control in Halotherapy. The accuracy of concentration control has great meanings to the improvement of treatment with respiratory diseases. So this paper proposes a design scheme of concentration measurement to realize the rock salt aerosol's accurate concentration measurement in real time and on line.This paper mainly introduces the design and realization of the concentration measurement system, which is based on AVR Single Chip Microcomputer (AVR SCM for short). The concentration measurement system gets the rock salt aerosol's concentration information by converting the light signal to electrical signal, elementary processing on analog voltage, then converting analog voltage signal to digital signal, and at last synthetical analyzing and processing work through AVR SCM.The rock salt aerosol concentration measurement system measures rock salt aerosol's concentration by measuring the scattering intensity caused by salt particles'Mie scattering when a laser passes through rock salt aerosol. This paper first introduces commonly used aerosol's concentration measurement method, then states the concentration measurement principle of Mie scattering, meanwhile, analyzes the realization processs using Mie scattering to measure rock salt aerosol's concentration, and finally designed and debugged the hardware and software of the system.With AVR MCU as the data processing part, the rock salt aerosol concentration measurement system includes two parts: one is the analog singnal acquirement and processing part, with impulse-modulated Semiconductor Laser Module as the light source, NE555 to generate impulse-modulated signal, five phototransistors distributed at the light receiving terminal to receive scattering light intensity, CA3140 with small leakage current to realize photoelectric conversion, high precision analog bandpass filter designed by MAX274, quad bilateral switch CD4066 to realize peak value's sampling and holding. The other part is digital signal processing realized by ATmega128, which is produced by ATMEL company. This part samples the photovoltage, which is corresponded with the change of rock salt aerosol's concentration, transfers the anolog voltage to digital signal, and also is responsible for digital filter realization and synthetical software processing.In addition, AVRStudio and WinAVR are used as the software development platform to realize programming and debugging.The results show that the design scheme of this measurement system can correctly measure rock salt aerosol's concentration in real time and on line. |
PDF Full Text Request