Shrinky-Dink microfluidics

I grew up in Hawaii, where apparently Shrinky-Dinks never quite made it as the icon of childhood craftiness that it seems to be for others of my peers, but I recently heard about them in the journal Chemical Technology. Check it out:

Shrinky-Dink microfluidics

A children's toy has been turned into a microfluidic research tool in the hands of US engineers.

Michelle Khine's team from the University of California, Merced, printed microfluidic mould patterns onto Shrinky-Dinks and used them to make patterns of channels for mixing fluids and moving cells about. The technique allows the whole process - from device design conception to working device - to be completed with very simple tools within minutes.

Shrinky-Dinks are thermoplastic sheets of polystyrene which have been pre-heated and stretched. When they are reheated they shrink to their original size, also shrinking anything drawn on them. The drawn features become narrower and more raised as the ink lines are compressed.

Using only a laserjet printer and a toaster oven, the team printed a device layout on a Shrinky-Dink sheet and shrunk it down to make a mould. The ink lines printed on their Shrinky-Dinks were raised by over 500% to form a series of small walls with slightly rounded edges, ideal for making channels for use with microfluidic valves. The polydimethylsiloxane plastic used to make the devices could then be simply poured onto the mould, cured, and peeled off.

'Many researchers are excited about this, because it dramatically lowers the barrier to entry into the microfluidics field,' said Khine. 'There are no tooling costs - all you need is a printer and a toaster oven.'

'I am not a patient person,' explained Khine, 'and being a new faculty member at a brand new university, I did not have the cleanroom facilities I am accustomed to. As I was brainstorming solutions, I remembered my favourite childhood toy and decided to try it in my kitchen one night, and it worked amazingly well!' The Shrinky-Dink moulds can be used more than ten times, and different heights of channel can be made by running the Shrinky-Dink sheets through the printer more than once.

'We are using the microfluidic chips for chemotaxis experiments and cell culture experiments,' she added, 'and we definitely have a couple more projects based on this in the oven.'

Clare Boothby

Link to journal article

Shrinky-Dink microfluidics: rapid generation of deep and rounded patterns
Anthony Grimes, David N. Breslauer, Maureen Long, Jonathan Pegan, Luke P. Lee and Michelle Khine, Lab Chip, 2008