Fiber-based pumpless flexible drug delivery system for implantable prosthesis

Abstract

This thesis describes the design, fabrication and characterization of a novel, flexible, LCP-based implantable probe with integrated fiber-embedded drug drug-delivery channel. The novel design integrates fibers to fabricate monolithic probe with electrical components to achieve local drug delivery with minimum increase in implantable prosthesis thickness. The fabrication process for integrated drug delivery channel is described. Electrical performance and fluid delivery via characteristic of fluidic channel was also thoroughly tested. The key characteristic of the system is simple fabrication process that involves monolithic thermal bonding of fibers between flexible probes instead of complicated patterning and etching steps. Kevlar fibers were sandwiched between two LCP (liquid crystal polymer) film-based MEA (multiple electrode array probes) probes to serve as drug delivery channel. A custom thermal press mold was developed to bond electrode patterned LCP films and i fiber-containing films without damaging fragile MEA (micro electrode array) and interconnections during fabrication. We have measured the cyclic voltammetry, impedance spectroscopy of the integrated probe which has 64 electrodes, and the result shows a good compatibility of fabrication process. The embedded Kevlar-fiber channel provides self-driven fluid transport via the gap around the fiber bundle and capillary wicking via the interfilament space, respectively. The flow rate via the single fiber channel was characterized using 1% agarose gel as a brain phantom and the flow rate was 10-2~10-1 μl/min. Drug delivery to brain can be modeled as an absorptivity competitive system. The mathematical modeling of diffusion behavior in brain phantom has been established, and the model was correlated and verified with experimental results successfully. The flow rate via fiber-embedded channel is a function of concentration and molecular weight of the drug, the absorptivity of target tissue and the geometrical factor of the fiber. Finally, drug reservoir module compatible with fiber inlet has been developed and introduced. To solve a tight fitting joint with fiber, selective capillary flow technique using hydrophobic barrier was developed. This thesis has potential for application in a number of implantable medical devices.