The study and application of a new IDE–PQC sensor

A new interdigital electrode–piezoelectric quartz crystal (IDE–PQC) sensor was proposed here. It was constructed using an interdigital electrode (IDE) and a piezoelectric quartz crystal in series. The response was studied theoretically and experimentally. Proposed sensor was more sensitive than series piezoelectric quartz crystal sensor (SPQC) to changes in electrical parameters of solution in certain conditions. Factors affecting the response of the IDE–PQC were discussed in detail. Proposed method was used to detect Pseudomonas aeruginosa. The logarithm of the initial concentration of P. aeruginosa had a linear relationship with frequency detection time (FDT) in the range of 10–106 cfu ml−1. The detection limit could be as low as 10 cfu ml−1. Pour plate counts (PPC) and SPQC methods were used for comparing with proposed method. Escherichia coli and Staphylococcus aureus were also detected successfully with proposed method.