Browsing by Author "Ecker, Melanie"
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Item Conformal Electrode Arrays to Enable in Vivo Recordings of the Enteric Nervous System(Society for Biomaterials) Ecker, Melanie; Guerrero, Edgar; Flores, Pedro Emanuel Roca; Voit, Walter E.; 0000-0003-0135-0531 (Voit, WE); Ecker, Melanie; Guerrero, Edgar; Flores, Pedro Emanuel Roca; Voit, Walter E.Statement of Purpose: The enteric nervous system (ENS) has the largest population of neurons in the peripheral nervous system, but it is not well understood and is less investigated than the central nervous system. Most of the information on the function and electrophysiology of the ENS was collected ex vivo, either on pathological samples or in cell cultures. Major problems when attaching neural electrodes to the gut, e.g. the small intestine, are that the tissue is of soft muscle, the geometry and its surface topology are complex, and it is constantly moving. Thus, conventional stiff electrodes and nerve cuffs cannot conform to the gut surface and are susceptible to motion artifacts since they will be moving relative to the bowel. Here, we demonstrate that the problems caused by conventional, stiff electrodes can be solved with the use of a thin-film electrode array fabricated on a self-softening polymeric substrate material. The hypothesis is that the polymer is capable of softening and changing its shape, so that the device can adapt to the shape and surface topology of its surroundings. It will wrap tightly around the gut, securing the electrodes in place to enable continuous periodic in vivo recordings of neurons from the myenteric and submucosal plexus within the small intestine. © 2019 Omnipress - All rights reserved.Item Electrical Properties of Thiol-ene-Based Shape Memory Polymers Intended For Flexible Electronics(MDPI AG, 2019-05-17) Frewin, Christopher L.; Ecker, Melanie; Joshi-Imre, Alexandra; Kamgue, Jonathan; Waddell, Jeanneane; Danda, Vindhya Reddy; Stiller, Alison M.; Voit, Walter E.; Pancrazio, Joseph J.; 0000-0002-0603-6683 (Ecker, M); 0000-0002-4271-1623 (Joshi-Imre, A); 0000-0003-0135-0531 (Voit, WE); 0000-0001-8276-3690 (Pancrazio, JJ); Frewin, Christopher L.; Ecker, Melanie; Joshi-Imre, Alexandra; Kamgue, Jonathan; Waddell, Jeanneane; Danda, Vindhya Reddy; Stiller, Alison M.; Voit, Walter E.; Pancrazio, Joseph J.Thiol-ene/acrylate-based shape memory polymers (SMPs) with tunable mechanical and thermomechanical properties are promising substrate materials for flexible electronics applications. These UV-curable polymer compositions can easily be polymerized onto pre-fabricated electronic components and can be molded into desired geometries to provide a shape-changing behavior or a tunable softness. Alternatively, SMPs may be prepared as a flat substrate, and electronic circuitry may be built directly on top by thin film processing technologies. Whichever way the final structure is produced, the operation of electronic circuits will be influenced by the electrical and mechanical properties of the underlying (and sometimes also encapsulating) SMP substrate. Here, we present electronic properties, such as permittivity and resistivity of a typical SMP composition that has a low glass transition temperature (between 40 and 60 °C dependent on the curing process) in different thermomechanical states of polymer. We fabricated parallel plate capacitors from a previously reported SMP composition (fully softening (FS)-SMP) using two different curing processes, and then we determined the electrical properties of relative permittivity and resistivity below and above the glass transition temperature. Our data shows that the curing process influenced the electrical permittivity, but not the electrical resistivity. Corona-Kelvin metrology evaluated the quality of the surface of FS-SMP spun on the wafer. Overall, FS-SMP demonstrates resistivity appropriate for use as an insulating material. © 2019 by the authors.Item Environmental Dynamic Mechanical Analysis to Predict the Softening Behavior of Neural Implants(NLM (Medline)) Hosseini, Seyed Mahmoud; Voit, Walter E.; Ecker, Melanie; Hosseini, Seyed Mahmoud; Voit, Walter E.; Ecker, MelanieWhen using dynamically softening substrates for neural implants, it is important to have a reliable in vitro method to characterize the softening behavior of these materials. In the past, it has not been possible to satisfactorily measure the softening of thin films under conditions mimicking body environment without substantial effort. This publication presents a new and simple method that allows dynamic mechanical analysis (DMA) of polymers in solutions, such as phosphate buffered saline (PBS), at relevant temperatures. The use of environmental DMA allows measurement of the softening effects of polymers due to plasticization in various media and temperatures, which therefore allows a prediction of the materials behavior under in vivo conditions.Item A Mosquito Inspired Strategy to Implant Microprobes into the Brain(Nature Publishing Group, 2018-11-05) Shoffstall, Andrew J.; Srinivasan, Suraj; Willis, Mitchell; Stiller, Allison M.; Ecker, Melanie; Voit, Walter E.; Pancrazio, Joseph J.; Capadona, Jeffrey R.; 0000-0002-0603-6683 (Ecker, M); 0000-0003-0135-0531 (Voit, WE); 0000-0001-8276-3690 (Pancrazio, JJ); Stiller, Allison M.; Ecker, Melanie; Voit, Walter E.; Pancrazio, Joseph J.Mosquitos are among the deadliest insects on the planet due to their ability to transmit diseases like malaria through their bite. In order to bite, a mosquito must insert a set of micro-sized needles through the skin to reach vascular structures. The mosquito uses a combination of mechanisms including an insertion guide to enable it to bite and feed off of larger animals. Here, we report on a biomimetic strategy inspired by the mosquito insertion guide to enable the implantation of intracortical microelectrodes into the brain. Next generation microelectrode designs leveraging ultra-small dimensions and/or flexible materials offer the promise of increased performance, but present difficulties in reliable implantation. With the biomimetic guide in place, the rate of successful microprobe insertion increased from 37.5% to 100% due to the rise in the critical buckling force of the microprobes by 3.8-fold. The prototype guides presented here provide a reproducible method to augment the insertion of small, flexible devices into the brain. In the future, similar approaches may be considered and applied to the insertion of other difficult to implant medical devices.