MEMS micro-contact printing engines

Abstract

This thesis investigates micro-contact printing (µCP) engines using micro-electro-mechanical systems (MEMS). Such engines are self-contained and do not require further optical alignment and precision manipulation equipment. Hence they provide a low-cost and accessible method of multilevel surface patterning with sub-micron resolution. Applications include the field of biotechnology where the placement of biological ligands at well controlled locations on substrates is often required for biological assays, cell studies and manipulation, or for the fabrication of biosensors. A miniaturised silicon µCP engine is designed and fabricated using a wafer-scale MEMS fabrication process and single level and bi-level µCP are successfully demonstrated. The performance of the engine is fully characterised and two actuation modes, mechanical and electrostatic, are investigated. In addition, a novel method of integrating the stamp material into the MEMS process flow by spray coating is reported. A second µCP engine formed by wafer-scale replica moulding of a polymer is developed to further drive down cost and complexity. This system carries six complementary patterns and allows six-level µCP with a layer-to-layer accuracy of 10 µm over a 5 mm x 5 mm area without the use of external aligning equipment. This is the first such report of aligned multilevel µCP. Lastly, the integration of the replica moulded engine with a hydraulic drive for controlled actuation is investigated. This approach is promising and proof of concept has been provided for single-level patterning