Bubble pressure measurement of micropipet tip outer diameter

Area of Science:

• Biophysics
• Materials Science
• Scientific Instrumentation

Background:

• Micropipet tip outer diameter is critical for microinjection, intracellular recording, and patch-clamp experiments.
• Accurate measurement of tip dimensions is essential for experimental reproducibility.
• Existing methods may be destructive or less precise.

Purpose of the Study:

• To evaluate bubble pressure measurement as a technique for determining micropipet tip outer diameter.
• To assess the influence of glass type and tip modifications on bubble pressure measurements.
• To establish the reliability and accuracy of bubble pressure for micropipet characterization.

Main Methods:

• Measuring the minimum transmural pressure required to expel bubbles from submerged micropipet tips.
• Comparing experimental bubble pressures with theoretical predictions based on surface tension.
• Analyzing the relationship between bubble pressure and tip outer diameter for different glass wall thicknesses and tip modifications.

Main Results:

• Bubble pressure correlates closely with tip outer diameter for thin-wall glass micropipets, aligning with surface tension predictions.
• Glass composition and shank geometry do not significantly affect this relationship for thin-wall pipets.
• Tip outer diameter is larger for thick-wall glass pipets at equivalent bubble pressures.
• Measurements are reproducible, enabling accurate size determination.
• Fire-polishing and beveling can be monitored, though with reduced accuracy.

Conclusions:

• Bubble pressure measurement is a simple, accurate, and non-destructive method for determining micropipet tip outer diameter.
• The technique is reliable for various glass types and can track tip modifications.
• This method offers a valuable tool for quality control and experimental preparation in micro- and nano-manipulation.