Micropump Classification and Piezoelectric Micropump

Classification of micropumps

Micropumps can broadly be classified as:

1. Mechanical/non-dynamic displacement pumps: diaphragm, peristaltic and reciprocating types.
2. Dynamic or non-mechanical pumps: electroosmotic, electrohydrodynamic, magnetohydrodynamic and other field-driven pumps.

They may also be described as externally actuated or self-actuated, depending on the actuation mechanism.

Piezoelectric micropump

A piezoelectric micropump uses a piezoelectric actuator bonded to or coupled with a flexible diaphragm.

Basic structure:
Piezo actuator → flexible diaphragm → pump chamber → inlet valve → outlet valve

Working

1. Applying an alternating voltage causes the piezoelectric element to expand/contract or bend.
2. This deflects the diaphragm and changes the chamber volume.
3. During one stroke, chamber expansion lowers pressure and draws fluid through the inlet valve.
4. During the opposite stroke, chamber compression raises pressure and pushes fluid through the outlet valve.
5. Repeated electrical excitation produces continuous pumping.

Advantages

• Small size.
• Fast response.
• Low power requirements in suitable designs.
• Precise flow control.
• Easy electrical control.

Applications include drug delivery, microfluidic transport, cooling and Lab-on-Chip systems.