Portable Smart Aids Testing Instrument

AIDS(Acquired Immunodeficiency Syndrome) is a disease that is quickly spread and cannot be cured at present. A human being who infects with HIV(Human Immunodeficiency Virus) catches the disease. In order to handily and quickly detect the HIV in human blood qualitatively and quantificationally, a handy intelligent AIDS-detecting instrument is developed according to the NASBA(Nucleic Acid Sequence-based Amplification) principle.In the detecting process of this instrument, HIV in a sample is amplified according to the NASBA principle, and the change of fluorescence signal in the sample is detected using the real time fluorescence detection technique. Then qualitative and quantificational conclusions are achieved according to the change. The temperature of the samples is controlled at 41\0.5℃.The AIDS-detecting instrument is designed as a small volume, low power consumption and low cost intelligent instrument based on a 16 bit microcontroller-M16C/62. It automatically controls the process and can store data and retrieve data. It can also communicate with the PC by a serial communication port.Weak fluorescence signals are converted into current signals using silicon photodiodes, then are amplified using a precision amplification circuit and is converted into digital value at last. Corresponding methods are used to reduce the noise. Signal-to-Noise ratio is improved and the requirement on measuring signal of NASBA technique is met.The temperature of samples is controlled by heating a metallic pedestal in which the test tubes are placed with the metallic electrothermal film. We design a digital temperature control system combined with a thermometer utilizing a DS18B20, a heater utilizing a metallic electrothermal film and a controller utilizing a M16C/62 microcontroller. Two methods, digital PID control and fuzzy control, are tested. The temperature fluctuations of the two methods are ?0.125℃:.A series of tests is made. The results indicate the AIDS-detecting instrument basically realize scheduled functions.