Active micromixing and in-vivo protection of sensors with gold/polypyrrole actuators.

摘要

This thesis presents the work carried out in the fabrication of gold/polypyrrole (Au/PPy) polymer actuators for in-vivo sensor protection and active micromixing applications. These actuators are fabricated as thin bilayer structures, the bottom layer constructed in Au and the top one in PPy. When the PPy polymer is doped in a particular fashion and it is submerged inside a specific electrolytic solution, in application of an electronic bias to these systems PPy experiences changes in volume due to ion exchanges between the polymer matrix and the ionic solution. The alteration in volume of the PPy translates into stresses on the top surface of the volume-preserving subjacent Au layer, and these stresses induce a bending on the Au/PPy structure.;These actuators are fabricated and analyzed in this work for use in two different applications. The first application aims at constructing reliably operating structures for periods of several months, so that these devices can be used for long term in-vivo applications (such as implantable devices incorporating biosensors for uses such as constant glucose monitoring). The second application involves generating mixing in the microscale (volumes with characteristic sizes smaller than 1mm).;We demonstrate in this work that Au/PPy actuators can be fabricated such that they remain active for extended periods of time under simulated in-vivo conditions, therefore providing an alternative solution to extend the operability of devices with current short term implantable life spans (such as biosensors).;Aiming at testing these actuators as viable means for generating micromixing, several sets of devices were fabricated and tested under different conditions. These experiments provide proof that Au/PPy actuators can behave as efficient micromixing devices, an accomplishment that is made more relevant by the low power requirements of actuation needed and the possibility of mixing in confined, stagnant microvolumes of aqueous solutions.