Look at the picture which shows typical piezoelectric pressure sensor and fill in the gaps in the text with appropriate words.

When , force or acceleration is applied to a , a charge is developed across the crystal that is proportional to the force applied. The fundamental difference between these crystal sensors and static-force devices such as is that the electric signal generated by the crystal decays rapidly. This characteristic makes these unsuitable for the measurement of static forces or pressures but useful for dynamic measurements

Piezoelectric devices can further be classified according to whether the crystal's electrostatic charge, its , or its resonant frequency electrostatic charge is measured. Depending on which phenomenon is used, the crystal sensor can be called electrostatic, piezoresistive, or resonant.
When pressure is applied to a crystal, it is elastically deformed. This deformation results in a flow of (which lasts for a period of a few seconds). The resulting electric signal can be measured as an indication of the pressure which was applied to the crystal. These sensors cannot detect , but are used to measure rapidly changing pressures resulting from blasts, explosions, (in rocket motors, engines, compressors) or other sources of shock or vibration. Some of these rugged sensors can detect pressure events having "rise times" on the order of a millionth of a second.

13. Complete the sentences by adding the reason given. Using to + verb is the easiest way to link them.

Reasons:

· cover an extremely wide pressure range

· isolate two fluidic pressures

· move a magnetic core inside a coil assembly

· convert the pressure induced diaphragm deflection into an electric resistance change

· give a calibrated measurement of the pressure

· convert the pressure induced diaphragm deflection into an electric resistance change

1. The most direct way of measuring pressure is to isolate an area on an elastic mechanical element for the force to act on.

2. The basic requirements for a pressure-sensing element are a means … .

3. Strain gages made of silicon diffused resistors are typically integrated on the diaphragm … .

4. The deformation of the sensing element produces displacements and strains that can be precisely sensed… .

5. The displacement of a Bourdon tube or capsule is used … .

6. Capacitive pressure sensors can be designed … .

7. Strain gages made of silicon diffused resistors are typically integrated on the diaphragm … .

Date: 2016-04-22; view: 839