The BP7 Micropump: A Practical Microfluidic Workhorse

To see how microfluidic principles come to life in real-world systems, let’s take a closer look at the Bartels Pump | BP7. Developed by Bartels Mikrotechnik, this piezoelectric diaphragm pump showcases how compact design and microscale fluid handling can work together with high precision and reliability.

Working Principle and Pumping Technology

The Bartels Pump | BP7 operates using a piezoelectric actuation mechanism. A ceramic piezo element is bonded to a flexible diaphragm. When alternating voltage is applied, the element flexes and moves the diaphragm in a rhythmic up-and-down motion. This deformation creates alternating pressure conditions in the pump chamber:

• Inhalation phase: The diaphragm lifts, lowering pressure and drawing fluid in through the inlet valve
• Exhalation phase: The diaphragm pushes down, increasing pressure and forcing fluid out through the outlet valve

Through this oscillating motion, the Bartels Pump | BP7 moves discrete volumes of fluid with exceptional accuracy and repeatability.

The Passive Valve Sheet

A core innovation of the Bartels Pump | BP7 is its passive valve system, usually made from a polymer valve sheet with microstructured flaps or membranes. These valves:

• Operate passively, without external actuation
• Ensure unidirectional flow from inlet to outlet
• Respond quickly and reliably to changes in chamber pressure
• Are robust, low-maintenance, and clog-resistant under standard conditions

This design supports long-term operation while reducing complexity in microfluidic setups.

Air Bubbles in Microfluidics

As with all microfluidic systems, air bubbles can present a challenge. Even with the precision of the Bartels Pump | BP7, bubbles may occur due to small channel sizes and low flow rates. Air bubbles can:

• Disrupt steady flow or cause backflow
• Interfere with valve sealing
• Add compressibility, affecting flow control
• Lead to component stress or cavitation

To minimize these effects, users should degas liquids and prime the system carefully. While the Bartels Pump | BP7 is designed to tolerate small amounts of air, best results are achieved in bubble-free conditions.

Internal Structure and Technical Highlights

Internally, the Bartels Pump | BP7 consists of three core layers:

1. Pump housing: Connects to fluid channels and secures internal components
2. Piezo actuator: Forms the upper chamber wall and drives the diaphragm
3. Valve sheet: Directs flow between inlet and outlet

Key specifications include:

• Compact size: Fits within a few centimeters, ideal for portable and embedded applications
• Low weight: Approximately 2 grams, suitable for mobile or battery-powered systems
• Internal dead volume: Around 30 µL
• Flow rate: Reaches several milliliters per minute, depending on system parameters
• Operating frequency: Optimized between 100 and 300 Hz
• Microscale valves: Channel and flap dimensions in the hundreds of micrometers, enabling accurate control

The Bartels Pump | BP7 combines precision, portability, and integration in one reliable microfluidic component. Its robust design and performance make it a trusted solution in diagnostics, life sciences, and microreactor technologies.