Blog – Page 2754

Getting glue to stick in dry conditions is relatively easy, but having it maintain a bond underwater is much more difficult. That said, a new bio-based glue not only works underwater, it actually gets stronger when immersed.

The nontoxic adhesive is being developed by Assoc. Prof. Gudrun Schmidt and colleagues at Indiana’s Purdue University. It’s made mainly of zein – which is a protein extracted from corn – and tannic acid, which is obtained from galls in oak tree bark.

When the glue is sandwiched between two objects which are subsequently placed underwater, a thin skin initially forms on it. That skin can be broken simply by piercing it with a finger or something similarly pokey. The surrounding water is then able to get into the glue, increasing its bond strength. Maximum bonding takes place at a water temperature of about 30 ºC (86 ºF).

A small team of engineers at Eindhoven University of Technology in the Netherlands, working with a colleague from the Max Planck Institute for Intelligent Systems in Germany, has found a way to create tiny artificial cilia that work at the microscale. Their study is reported in the Proceedings of the National Academy of Sciences.

Cilia are tiny appendages that microscopic organisms use to move through a fluid. Prior research has shown that they are efficient—some paramecia are able to move at a rate of 10 times their own length per second. Prior research has also shown that cilia also move fluid. In the human lung, they work to clear away mucus.

Because of their usefulness, scientists have been studying cilia looking for a way to replicate them for use in desired applications. Such efforts have until now been stymied by the problem of creating working cilia at the microscale. In this new effort, the researchers have overcome such problems and created the first artificial microscale working cilia.