Quartz plates show a mechanical movement or strain when subjected to an electrical charge and conversely, they show a difference of potential between faces when subjected to a mechanical stress.
Tactile Switches are used in many devices, including ventilators, CPAP machines, ultrasound machines, EEG/ECG machines, blood glucose testers, electronic inhalers, patient monitors, pulse oximeters, and insulin pumps.
TCXOs supply the design engineer with a device that bridges the stability gap between standard XO or VCXO and an OCXO [Oven Controlled Crystal Oscillator], sometimes equaling the performance of a low grade OCXO design.