US scientists have developed a cheaper and quicker way of making three-dimensional microstructures. 

Samuel Sia's team at Columbia University, New York, used light from a microscope to polymerise specific areas of a fluid inside a microfluidic channel.  This process, which causes the fluid to harden and stick to the surface of the channel, is known as photocuring.  The unpolymerised material was then washed away and a second material was injected into the channel to be photocured.  By repeating this process, Sia built up a three-dimensional microstructure made up of 24 different materials in less than one hour, far quicker than conventional methods. 

Sia says that the technique, which combines microscopy with microfluidics, will be useful for studying cell behaviour because the microstructures can mimic complex biological tissues.

Victor Ugaz, an expert in microfluidics at Texas A&M University, College Station, US, welcomes this development. 'This technique allows you to polymerise different materials to create structures with spatial variations in material properties.  This may be the most exciting aspect; there is a lot of interest in patterning cells in microenvironments that incorporate these kinds of variations since they may more closely mimic in vivo conditions.'

Sia believes the technique has many potential applications. 'An important next step will be to exploit this capability to make new discoveries, for example in cell-cell communication for the patterning of biocompatible hydrogels,' he said.

Joanne Thomson