Higher order sensing using QCM sensor array and preconcentrator with variable temperature

We proposed the higher order sensing method using a preconcentrator with variable temperature in combination with the quartz-crystal microbalance sensor array to extract many features of the samples. The temperature of the preconcentrator tube packed with hydrophobic adsorbent was gradually raised to 200/spl deg/C. The rough separation among the compounds along the time axis enhanced the discrimination capability of the sensor array system. The results of the second-order sensing, such as images of the sensor responses and the loci on the principal component analysis space, gave us information about the apple flavors with different recipes. Moreover, the low-concentration flavors, such as apple and banana in water, were successfully discriminated using the proposed method. It was found that the system was robust against the sample concentration change under the environment of the large humidity.