Micromachining of Parylene C for bioMEMS

Recent advances in the micromachining of poly(p‐xylylenes), commercially known as Parylenes, have enabled the development of novel structures and devices for microelectromechanical systems (MEMS). In particular, Parylene C (poly[chloro‐p‐xylylene]) has been explored extensively for biomedical applications of MEMS given its compatibility with micromachining processes, proven biocompatibility, and many advantageous properties including its chemical inertness, optical transparency, flexibility, and mechanical strength. Here we present a review of often used and recently developed micromachining process for Parylene C, as well as a high‐level overview of state‐of‐the‐art Parylene hybrid and free film devices for biomedical MEMS (bioMEMS) applications, including a discussion on its challenges and potential as a MEMS material. Copyright © 2015 John Wiley & Sons, Ltd.     

Spatial and Temporal Control Over Multilayer Bio‐Polymer Film Assembly and Composition

Biosensing applications have taken advantage of lab‐on‐a‐chip technologies for sample handling and sensors integration for highly sensitive, specific detection with high throughput. These systems are based on 2.5D fabrication principles with sensing elements restricted to an array format in two dimensions. In this report, a sensing platform that recovers biosensing capabilites in three spatial dimensions is presented. This is achieved by leveraging chitosan, a stimulus responsive polyaminosaccharide that undergoes a sol–gel transition driven by a change of pH. This process can be repeated, resulting in a multilayered hydrogel stack where each layer carries a unique chemical identity. In addition, the functionality of chitosan can be modified prior to or during the assembly process. This is demonstrated by introducing both a carboxylic acid functionality and additional primary amines to the base chitosan polymer. The assembly process is shown to be compatible with microfluidic dimensions.     

AFM analysis of organic silane thin films for bioMEMS applications

Designing surfaces that elicit the desirable response is essential for bioMEMS (biological microelectromechanical systems) applications. To this end, we have developed two different types of silane film—hydrophobic and hydrophilic—using vinyltrichlorosilane and poly(ethylene glycol) silane, respectively. As the surface topography plays a very important role in governing protein or cell interactions, these films were characterized extensively using atomic force microscopy. All the films developed were found to have a very low root‐mean‐square roughness value (<1.3 nm). Furthermore, the topography of protein‐adsorbed silane‐modified surfaces was investigated because cell adhesion is mediated primarily by proteins. Three‐dimensional and section plots were able to differentiate the way in which protein interacts with hydrophobic and hydrophilic surfaces. Copyright © 2003 John Wiley & Sons, Ltd.