CUHK showcased over ten technological research projects at the International ICT Expo 2014 at the Hong Kong Convention and Exhibition Centre from 13 to 16 April. One of the featured projects is the 'Precision Roll to Roll Microcontact Printing' technology which is developed for cost-effective and high-throughout fabrication of flexible photonic devices.

Optical gratings and transparent electrodes, which are produced with submicron technology, are essential components in a wide range of optoelectronics devices. The conventional approach for fabricating submicron resolution patterns is photolithography or electron-beam lithography, which can create extremely precise patterns (50 nanometers). However, these processes are expensive, complex and need to be performed in a cleanroom. To solve this problem, researchers have developed the Microcontact Printing (MCP) technique in the hope of replacing the conventional production processes. However, MCP still has a lot to overcome for large scale manufacturing, including speed, accuracy, stability, and control of printing force.

Prof. Chen Shih-Chi, Department of Mechanical and Automation Engineering, and his team have recently developed and constructed a flexure-based precision roll-to-roll (R2R) printing system that demonstrates multi-axis submicron level precision and repeatability. The technology enables fabrication of transparent gold microelectrodes to be performed in a non-cleanroom environment. The system rollers roll continuously just like printing paper, and large area transparent gold microelectrodes can be produced within a minute.

The developed technology could be widely applied to mass manufacture cost-effective flexible photonic devices and it is ready to commercialize for production. In the future, foldable electronic devices like tablets and LCD displays can be produced in low cost, and become our common daily accessories.

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