How does quartz work in the temperature sensor inside the vial in freeze dryer?

A quartz temperature sensor inside a vial in a freeze dryer works by measuring the frequency of the quartz crystal. The quartz crystal is designed to vibrate at a specific frequency when it is exposed to a certain temperature. As the temperature inside the vial changes, the frequency of the quartz crystal changes as well. The frequency is then measured by the temperature sensor and compared to a reference temperature, allowing the freeze dryer to accurately measure and control the temperature of the vial.