How does Epson’s Micro Piezo print head work?

In the Epson Micro Piezo print head, microscopic piezoelectric elements (like crystals and ceramics) are built behind the print nozzles. When an electrical charge is applied to them, these elements bend backward, forcing precise amounts of ink onto the substrate (see Diagram 1). Because electrical charges can be turned on and off like a switch, there is a vast amount of control over the rate of ink being ejected through the nozzle while also creating perfectly spherical dots at different droplet sizes.

Different from Piezo print head, there is another print head, thermal print head, what the comparison between them?
Piezo print head: 
Pros: 

• Precise and Variable Droplet Sizes
• Can use wide range of inks due to low temperature (solvent, UV, pigment, dye) 
• Droplet sizes down to 1.5 picoliter
• Run longer due to cooler temperature

Cons: 

• More Expensive Heads 
• Fewer Print Heads Per Printer

Thermal print head:
Pros:

• Less Expensive Print Heads 
• More Print Heads Per Printer

Cons: 

• Only 2 different droplet sizes
• Larger droplet size
• Limited ink options due to extreme heat
• Need to be replaced more often due to high heat

More info:
Website：www.skyimagepaper.com
Company Name: Fei Yue Paper Industrial Co.,LTD
E-mail: sales@feiyuepaper.com 
Tel: 86-025-83228884
Whatsapp: +86 18252072197
Address: Central Road 323, Nanjing, Jiangsu, China