Fabrication of a Sensor Array Based on Quartz Crystal Microbalance and the Application in Egg Shelf Life Evaluation

Abstract. Egg has become an indispensable food product in our daily life. An effective, convenient and nondestructive technique on egg quality evaluation is in great need. Quartz crystal microbalance (QCM) sensors provide a simple and nondestructive method to test egg samples by sensing the volatiles released by eggs. QCM technique has been widely used in the field of gas detection because of its high sensitivity and low operating temperature. In this study, a QCM sensor array with four different surface modified QCM sensors (i.e., multi-walled carbon nanotube, graphene, nanostructured copper oxide and polyaniline nanocomposite) was fabricated and analyzed by field-emission scanning electron microscope (FE-SEM). The frequency shift of sensors in the process of absorption and desorption was monitored by a home-made frequency measurement system. Particularly, these four sensors exhibited a relatively good reversibility, reproducibility and long-term stability. In application, the sensor array was applied to detect eggs with different shelf life. Principal Component Analysis (PCA) was employed and the first two PCs explained 84.8% of total variations. Linear Discriminant Analysis (LDA) exhibited a good classification accuracy with 100% and 98.8%. Partial Least Square Regression (PLSR) was used to establish a regression model and the fitting correlation coefficients (R²) of PLSR increased from 0.8119 to 0.9547 after KPCA method was introduced. It could be concluded that the QCM sensor array is effective for the detection of eggs with different shelf life, offering an alternative method to evaluate the shelf life of eggs.