![]() ![]() One way to satisfy these interface requirements is to connect the piezo sensor to a junction field-effect transistor (JFET). This impedance matching is a consequence of the power-transfer law, where the impedance of a source and its load must be complex conjugates to achieve maximum power transfer. Due to its inherently high electrical impedance, it can only deliver a sufficiently strong signal to the electronic circuitry if the interfacing signal-conditioning circuit also has very high impedance. Using Piezo Devices as Strain SensorsĪs a basic transducer, the piezo-based unit is very simple and rugged, but it has a unique electrical aspect. Depending on material, these sensors can withstand and work at accelerations of several thousand g. For this reason, they are often used as transducers for sensing pressure-related physical parameters, which includes pressure itself, as well as its related manifestations: acceleration, impact, altitude (air pressure), and vibration. Since they have a crystalline structure, many piezoelectric materials are quite hard and can withstand a great deal of stress without changing their basic characteristics or failing. This spark ignites the gas and initiates a flame (but the current level is so low that there is no danger of shock). (Source: Seiko Epson Corp.)Įven a gas-fired grill can have a piezoelectric element, using a built-in crystal that generates a spark of several hundred volts when the user turns a knob and so squeezes the crystal. Piezo materials are also used as actuators that can be directed to move in precise nanometer-size steps, such as for micromotors in applications ranging from high-end scientific instruments down to autofocusing in mass-market consumer cameras.įigure 1: The piezoelectric effect has a dual nature: a) applying stress on a crystal causes it to generate a voltage while b) applying a voltage to the crystal causes it to deform, both in predictable and repeatable relationships. These two principles have been adapted to many applications the best-known one is use of quartz as a resonant element in an oscillator circuit. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |