Capillary Tubes - Draw up liquids by capillary action


These thin high-precision glass tubes use capillary action to draw up a controlled volume of liquid. The capillary action is the result of the liquid's inherent surface adhesion (intermolecular attraction to dissimilar molecules) and cohesion (attraction to similar molecules). The liquid's adhesion to the inner wall of the tube causes an upward force on the liquid at the tube walls. The cohesion holds the liquid together, causing it to be dragged upward until the gravitational force becomes too strong.

Used for:
The tubes are commonly used in medical and research fields for liquid measurement, liquid transfer, and sample collection. A major application is in collecting and handling samples for blood analysis.

The tubes can be manufactured with different inner diameters and wall thicknesses. The capillary action works only with liquids that will wet the surface of the glass.

The sample:
You get a couple of tubes in a small transparent container. Dip the tip of the sample in a liquid. Take care, as the tubes are fragile and can break easily.

All samples come with a laminated information card, which includes contact details for the supplier.