Manufacture of SU-8 Micro-Grippers for Mechanical Characterization of Gut Epithelial Cells

摘要

This paper describes the manufacture of an integrated micro-electro-mechanical system (MEMS) to be used for small scale tissue manipulation. The micro-grippers are to be used to test the mechanical cell adhesion properties of the gut epithelium. In the majority of sporadic colon cancers the Adenomatous Polyopsis Coli (APC) protein is mutated or missing. Mutations of APC occur extremely early in the development of cancer, before formation of polyps. The following paper looks at the manufacturing processes for SU-8 micro-grippers. The micro-gripper structure has been successfully fabricated as a single structure not incorporating conduction paths. A number of sacrificial layers have been examined for compatibility with the SU-8 development. The sacrificial layer will be removed to leave a suspended structure. Stiction is a challenge to overcome in wet etch processes. An electroless coating process for Ni-P sacrificial layer has been developed. Coating Ni-P onto bare silicon substrates is a challenging problem. Sensitization and activation steps are needed to coat non-conductive surfaces. Sensitizers for Ni-P coatings of SnCl_2 and 3-aminopropyltriethoxysilane were tested to look at adhesion of Ni-P to the substrate. Results have shown Ni-P can be applied to SiO_2 surfaces at a thickness high enough to be utilized as a sacrificial layer for micro-grippers.