Conjugated Polymer Actuators for Articulating Neural Probes and Electrode Interfaces.

[摘要] This thesis investigated the potential use of polypyrrole (PPy) doped with dodecylbenzenesulfonate (DBS) to controllably articulate (bend or guide) flexible neural probes and electrodes.PPy(DBS) actuation performance was characterized in the ionic mixture and temperature found in the brain.Nearly all the ions in aCSF were exchanged into the PPy – the cations Na+, K+, Mg2+, Ca2+, as well as the anion PO43-;Cl- was not present.Nevertheless, deflections in aCSF were comparable to those in NaDBS and they were monotonic with oxidation level:strain increased upon reduction, with no reversal of motion despite the mixture of ionic charges and valences being exchanged.Actuation depended on temperature.Upon warming, the cyclic voltammograms showed additional peaks and an increase of 70% in the consumed charge.Actuation strain was monotonic under these conditions, demonstrating that conducting polymer actuators can indeed be used for neural interface and neural probe applications.In addition, a novel microelectro-mechanical system (MEMS) was developed to measure previously disregarded residual stress in a bilayer actuator.Residual stresses are a major concern for MEMS devices as that they can dramatically influence their yield and functionality.This device introduced a new technique to measure micro-scaled actuation forces that may be useful for characterization of other MEMS actuators.Finally, a functional movable parylene-based neural electrode prototype was developed.Employing PPy(DBS) actuators, electrode projections were successfully controlled to either remain flat or actuate out-of-plane and into a brain phantom during insertion.An electrode projection 800 µm long and 50 µm wide was able to deflect almost 800 µm away from the probe substrate.Applications that do not require insertion into tissue may also benefit from the electrode projections described here.Implantable neural interface devices are a critical component to a broad class of emerging neuroprosthetic and neurostimulation systems aimed to restore functionality, or abate symptoms related to physical impairments, loss of sensory abilities, and neurological disorders.The therapeutic outcome and performance of these systems hinge to a large degree on the proximity, size, and placement of the device or interface with respect to the targeted neurons or tissue.

[发布机构] University of Michigan

[效力级别] Conjugated and Conducting Polymer Actuators

[关键词] Neural Probes and Electrodes;Conjugated and Conducting Polymer Actuators;Movable Probes;Biomedical Engineering;Engineering;Biomedical Engineering