New Parts For Old

The fabrication of complex objects took a big leap forward when 3-D printing became a practical possibility. The printer works rather like your conventional inkjet, but builds up an object layer by layer. The important bits of the object are polymerizable, that is their molecules can be encouraged to join with their neighbors to form a solid material.

The price of a printer is now down to about $10k, so still too expensive to have on our desks to print out unique toys for our kids, but maybe soon. There is a huge potential for customizable manufacturing.

A BBC report by Moskvitch (1) on the BioRap project at the Fraunhofer Institute, Stuttgart, brings some exciting news in the artificial organ domain (2). The idea is to print out the spare part with capillaries built in to provide blood flow through so that the plumbing job becomes a matter of connection.

Biocompatible materials are, of course, a must, but there is a big challenge in polymerizing these components with the accuracy and efficiency required on this small scale. The solution comes in the form of two-photon polymerization, a technique already showing great promise in micro-fabrication of bio-scaffolding materials that can be used to encourage regrowth of tissue (3).

Light initiated polymerization normally requires ultraviolet light, but two-photon polymerization uses light at twice the wavelength, which goes much deeper into a material. It can be focused very finely and so can work on the material printed to make the fine capillaries. High energy pulsed lasers are used, so the polymerization is complete.

The great thing about 3-D printing is the customizable aspect. The spare part can be built to fit exactly. With things like matched plumbing, one can imagine the day, with surgical techniques such as the Da Vinci robotic system, that the human input would be at the computer screen with just a drag and drop on a touch screen so that the freshly printed part would be slipped into place with the minimum of contact.


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