The Study Of Rapid Detection Of Pathogenic Bacteria With Serial Piezoelectric Bulk Acoustic Wave Bio-sensor

Series piezoelectric crystal sensor, known as a kind of none-mess responsive sensor, can respond the change of conductivity of solution. When microorganisms were cultured in the medium, the metabolism of them could change the ingredients of the medium, and change its electrochemical characters. Series piezoelectric crystal sensor could detect this change sensitively. On the other hand, how to detect the microorganisms in food and medical specimens quickly and accurately was a hot-point of scientist's study in several decades. An automated detection instrument based on series piezoelectric crystal sensor was constructed. The main work of the thesis could be summarized as follows.1. Determination of the sensitivity intervalE.coli was detected as sample under different cell constants, and the values of signal to noise were different too. When the cell constant was 0.506 cm, the value of signal to noise was biggest, so it was the best cell constant. Keeping best cell constant, added different concentrations of NaCl solutions into detection cells, detected the frequency shift of series piezoelectric crystal sensor. The results showed that the conductivity of solution changed from 544.05 s to 607.35 s, the response of series piezoelectric crystal sensor was most sensitive. This was the sensitivity interval of our instrument.2. Accurate determination of FDTMathematical treatment was done on the experimental results with mathematical analysis software, Origin 6.0. FDT was defined based on this treatment. This method eliminated the subjective effect, overcame the defect of previous method. FDT could be gained utilize Origin 6.0 conveniently.3. Development of amino acid brothA kind of novel medium, amino acid broth was developed based on nutrient broth and glucose broth. It was nutrient and low conductivity, satisfied the requirement of series piezoelectric crystal sensor. The frequency shift was twice as the result of no amino acid solution added. 4. Detection of several common bacteriaFour species of bacteria, E.coli, S.aureus, S.dysenteriae, and P.aeruginosa were detected with the detection instrument based on series piezoelectric crystal sensor. Their typical frequency shift curves were gained. The relationship between the frequency detection time (FDT) and the logarithm of the initial number of bacteria was linear. The corresponding equations were derived and applied to determine the number of cells in culture. The detection ranges were from 100 to 106 cells ml-1. Results were in good agreement with those obtained by standard pour plate method. 5. Detection of model blood specimenModel blood specimen which was added P.aeruginosa was detected with our instrument. It was optimum that 0.5 ml blood specimen added into every 10 ml AaB. The results shown that the instrument could detect the bacteria in the blood sample. This instrument would be applied in the next step experiment.