In recent years there has been a developing interest in fabricating micropipettes from aluminosilicate glass. Like silicon, aluminum combines with oxygen to form tetrhbedral networks and the Al-O bonds are very strong. In comparison with borosilicate glass, aluminosilicate provides increased hardness, improved chemical durability, reduced electrical conductivity and a lower coefficient of thermal expansion. Also, while the original ratio of a borosilicate capillary’s inner to outer diameter will remain unchanged over its total taper length, aluminosilicate glass demonstrates a marked tendency to thin out as it is drawn to a tip. This behavior allows extremely fine tips to be formed.

For more information, see:
1. Na/H Exchange, Vaughan-Jones, RD.; Grinstein Press, Ch.1 p.8;
2. Effects of intracellular and extracellular pH on contraction in isolated
mammalian cardiac muscle, Bountra, C. & Vaughan-Jones, R.D.; Journal of Physiology Volume 418 (1989)