*3.8.2 Electricity generators*

Some applications require the harvesting of energy from pressure changes, vibrations, or mechanical impulses. The harvesting of energy is possible by using piezoelectric materials to convert deflections or displacements into electrical energy that can either be used or stored for later use.

**Figure 11.** *(a) Piezoelectric buzzer block diagram. (b) Piezoelectric buzzer.*

are usually inexpensive and require little power to produce relatively large sound volumes. Thus, piezoelectric speakers (**Figure 10**) are often found in devices such

as the following:

**Figure 8.**

**Figure 9.**

**Figure 10.** *Piezoelectric speakers.*

*Inkjet printer working.*

*A dot-matrix printer.*

*Multifunctional Ferroelectric Materials*

• Earbuds

**84**

• Cell phones

• Sound-producing toys

• Musical greeting cards

• Musical balloons
