The Construction And Application Research On Series Piezoelectric Microbial Sensor

The multi-channel series piezoelectric quartz crystal sensor (MSPQC) wasdesigned based on the principle of series piezoelectric quartz crystal. It can detectmulti-samples at one time. This sensor can respond to the parameter changes (such asconductance and capacitance) of aqueous solutions sensitively. MSPQC has attractedmany analysts due to its high sensitivity, easy operation, broad sensing spectrum andlow cost. Based on the study of our group and the special response of MSPQC, somenew detection methods were presented in this dissertation. These new methods hadbroadened the application of MSPQC in clinic. The main research work could besummarized as follows:1. A new phage-modified piezoelectric sensor system was constructed forspecific detection of mycobacterium. In this system, lytic phages were immobilizedon the interdigital gold electrodes via chemical adsorption. Interdigital gold electrodeimmobilized with lytic phage was used as probe in place of steel electrode inmulti-channel series piezoelectric quartz crystal (MSPQC) system. Mycobacteriumwas specifically captured to phage-modified electrode and then lysed by immobilizedphage, which caused the electrode electrical properties change. This change can besensitively monitored by piezoelectric detection system. The detection ofMycobacterium smegmatis required1-2hours and a detection limit of103cfu/ml wasobtained. Additionally, it was successfully used to detect Mycobacterium tuberculosis.Compared with MSPQC system, proposed system was simpler， faster and morespecific.2. A simple, rapid, and new method was proposed for identification andquantification of urease-producing bacteria according the metabolic features ofbacteria. Urease-producing bacteria grew well in the proposed medium. During thegrowth, the pH of the medium was increased firstly, and then decreased, which causedtheir response signals in MSPQC system distinctive and specific. Their specificsignals can be differentiated from other strains in clinical common bacteria, such asEscherichia coli, Pseudomonas aeruginosa and Salmonella spp by this method.Urease-producing bacteria, such as Proteus mirabilis can be quantitatively detectedbased on the fact that frequency detection time (FDT) detected by MSPQC indeveloped medium had a linear relationship with the logarithm of its initial concentration in the range of10-107cfu/ml. The detection limit was low to10cfu/ml.3. A new piezoelectric microbial sensor has been fabricated based on semi-solidconduction. The proposed sensor can be sensitively responded to stable impedancechanges due to the growth of bacteria. Compared with MSPQC method, the proposedsensor is quicker and more sensitive. When it was used to quantitatively determinePseudomonas aeruginosa, the accuracy was the same to PPC method. In the range of10-106cfu/ml, a good linear relationship between the frequency detection times (FDT)with the logarithm values of initial concentration was obtained with a detection limitof10cfu/ml. Besides, it was more sensitive to detect the clinic microorganisms inblood compared with MSPQC method.