A highly sensitive QCM sensor coated with Ag+-ZSM-5 film for medical diagnosis

The application of quartz crystal microbalance (QCM) modified with Ag+-ZSM-5 zeolite to diagnosis of diabetes is presented in this paper. Such sensor is utilized in detecting the acetone in nitrogen and the concentration of acetone in diabetics’ breath. The experimental results demonstrate high sensitivity and selectivity with good repeatability. A test for minimum detectable concentration of acetone vapor has been stopped at 1.2 ppm and the lower detection limit of acetone vapor is convinced to be much lower, e.g. 0.26 ppm has been identified in the following example for application in diagnosis of diabetes. The breath between diabetics and healthy persons are well distinguished. An average of 90 s response time has been observed. The frequency shift of QCM along with temperature is studied as well.