Angular Sensing and Chemical Identification with Quartz Crystal Oscillator Sensor

Gas sensors coated with mixed lipid film, mist sensors coated with lipid film, and angular sensors with an AT-cut quartz crystal oscillator were investigated. Mixed lipid film on the quartz crystal increased the sensitivity of the quartz crystal microbalance (QCM) gas sensors for Volatile Organic Compounds (VOCs). The approximate curves were created from the frequency shift curves of the gas sensors. The differential coefficients of the approximate curves at 25 and 50 sec showed better classification of the VOCs. The mist sensors coated with lipid film had a different sensitivity to the volatile mists, where the fine mist of the volatile liquid was produced by an ultrasonic vibration of the atomizer. The angular sensor can detect a rotation angle by gravity sensitivity, where a hydroxyapatite thin layer has been deposited on an electrode of the oscillator in order to increase the gravity sensitivity. The frequency deviation caused by the rotation of oscillator shifted between -0.4 and 0.8 ppm.