A new sensor method based on series piezoelectric quartz crystal (SPQC) sensing technique was proposed for studying the effect of surfactants on the growth of Pseudomonas aeruginosa in media. The frequency shift curves under different growth conditions were obtained and compared with each other. By tting frequency shift ( F) curves, three kinetic parameters (m , λ and A) were gained to describe the growth of microorganisms. When the F became small and frequency detection time (FDT) prolonged, surfactants had an inhibitory effect to the growth of bacteria. At the same time, the lag time (λ) was prolonged; the maximum specic growth rate (m ) and the asymptote (A) were decreased. By using the proposed method, the inuence of the concentration and ion type of surfactants, hydrophilic group and the number of ethoxyl of nonionic surfactants on the growth of bacteria was investigated in detail. 2005 Elsevier B.V. All rights reserved.

The bulk acoustic wave impedance biosensor was set up and used to monitor the growth of Mycobacterium tuberculosis (M.TB). This sensor is rapid, simple, sensitive (lower limit is 2 )/103 cells ml (1) and cheap (easy to generalize). The typical response curve was different from other bacteria’s, such as Escherichia coli , Staphylococcus aureus , Proteus mirabilis . The frequency detection time was used to quantitatively determine M.TB. It was proportional to logarithm of the initial concentration of M.TB in the range of 2 )/103 /3)/107 cells ml (1. The set up sensor was applied to the direct diagnosis of M.TB samples. The interference of other bacteria was eliminated by pretreatment. Our results confirmed that the use of the set up biosensor was reliable, sensitive. It gives out the potential use for determining M.TB.