Ashley N. Dalrymple

Ashley N. Dalrymple
Carnegie Mellon University | CMU · Department of Mechanical Engineering

PhD

About

22
Publications
2,840
Reads
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190
Citations
Additional affiliations
October 2020 - present
Carnegie Mellon University
Position
  • PostDoc Position
Description
  • Transcutaneous spinal cord stimulation to reduce spinal cord excitability in amputees, in vivo testing of Injectrode
September 2019 - September 2020
University of Pittsburgh
Position
  • PostDoc Position
Description
  • Transcutaneous spinal cord stimulation to reduce spinal cord excitability, in vivo testing of Injectrode
January 2019 - July 2019
Bionics Institute
Position
  • PostDoc Position
Description
  • Testing novel materials and safety stimulation limits for cochlear implants

Publications

Publications (22)
Preprint
In the United States, over 1.5 million people live with lower-limb amputation. Existing prosthetic limbs do not restore somatosensory feedback from the limb, resulting in functional impairments including balance deficits and an increased risk of falls. Further, these prostheses do not alleviate the severe phantom limb pain that often follows amputa...
Preprint
Spinal cord neuromodulation has gained much attention for demonstrating improved motor recovery in people with spinal cord injury, motivating the development of clinically applicable technologies. Among them, transcutaneous spinal cord stimulation (tSCS) is attractive because of its non-invasive profile. Many tSCS studies employ a high-frequency (1...
Article
Full-text available
Minimally invasive neuromodulation technologies seek to marry the neural selectivity of implantable devices with the low-cost and non-invasive nature of transcutaneous electrical stimulation (TES). The Injectrode ® is a needle-delivered electrode that is injected onto neural structures under image guidance. Power is then transcutaneously delivered...
Article
Full-text available
Objective . The goal of this work was to compare afferent fiber recruitment by dorsal root ganglion (DRG) stimulation using an injectable polymer electrode (Injectrode ® ) and a more traditional cylindrical metal electrode. Approach . We exposed the L6 and L7 DRG in four cats via a partial laminectomy or burr hole. We stimulated the DRG using an In...
Preprint
Full-text available
Minimally invasive neuromodulation technologies seek to marry the neural selectivity of implantable devices with the low-cost and non-invasive nature of transcutaneous electrical stimulation (TES). The Injectrode ® is a needle-delivered electrode that is injected onto neural structures under image guidance. Power is then transcutaneously delivered...
Preprint
Full-text available
Objective The goal of this work was to compare afferent fiber recruitment by dorsal root ganglion (DRG) stimulation using an injectable polymer electrode (Injectrode ® ) and a more traditional cylindrical metal electrode. Approach We exposed the L6 and L7 DRG in four cats via a partial laminectomy or burr hole. We stimulated the DRG using an Injec...
Conference Paper
Full-text available
Chronic pain affects millions of people in the United States and pharmacological treatments have been ineffective. Dorsal root ganglion (DRG) stimulation is a neuromodulation method that delivers electrical stimulation to the DRG to relieve pain. DRG electrodes are rigid and cylindrical. The implantation of DRG electrodes requires a technically-cha...
Article
Full-text available
Objective: Established guidelines for safe levels of electrical stimulation for neural prostheses are based on a limited range of the stimulus parameters used clinically. Recent studies have reported particulate platinum (Pt) associated with long-term clinical use of these devices, highlighting the need for more carefully defined safety limits. We...
Article
Objective: Cochleae of long-term cochlear implant users have shown evidence of particulate platinum (Pt) corroded from the surface of Pt electrodes. The pathophysiological effect of Pt within the cochlea has not been extensively investigated. We previously evaluated the effects of Pt corrosion at high charge densities and reported negligible patho...
Article
This review focuses on the development of intelligent, intuitive control strategies for restoring walking using an innovative spinal neural prosthesis called intraspinal microstimulation (ISMS). These control strategies are inspired by the control of walking by the nervous system and are aimed at mimicking the natural functionality of locomotor-rel...
Article
Objective: To evaluate the electrochemical properties, biological response, and surface characterization of an electrodeposited Platinum-Iridium (Pt-Ir) electrode coating on cochlear implants subjected to chronic stimulation in vivo. Approach: Electrochemical impedance spectroscopy (EIS), charge storage capacity (CSC), charge injection limit (CI...
Article
Objective: Neuromodulation technologies are increasingly used for improving function after neural injury. To achieve a symbiotic relationship between device and user, the device must augment remaining function, and independently adapt to day-to-day changes in function. The goal of this study was to develop predictive control strategies to produce...
Article
Objective: Evaluate electrochemical properties, biological response, and surface characterization of a conductive hydrogel (CH) coating following chronic in vivo stimulation. Approach: Coated CH or uncoated smooth platinum (Pt) electrode arrays were implanted into the cochlea of rats and stimulated over a 5 week period with more than 57 million...
Article
Objective: To systematically compare the in vitro electrochemical and mechanical properties of several electrode coatings that have been reported to increase the efficacy of medical bionics devices by increasing the amount of charge that can be delivered safely to the target neural tissue. Approach: Smooth platinum (Pt) ring and disc electrodes...
Preprint
Full-text available
Objective: Neural interface technologies are more commonly used in people with neural injury. To achieve a symbiotic relationship between device and user, the control system of the device must augment remaining function and adapt to day-to-day changes. The goal of this study was to develop predictive control strategies to produce alternating, over-...
Thesis
Full-text available
Walking is a locomotor task that integrates information from all over the nervous system. The lumbosacral spinal cord houses neural networks that contribute to locomotion. These networks dominate locomotor activity during development and may provide suitable targets for restoring function after injury. Motor activity of the developing spinal cord u...
Article
Full-text available
Objective: The goal of this study was to develop control strategies to produce alternating, weight-bearing stepping in a cat model of hemisection spinal cord injury (SCI) using intraspinal microstimulation (ISMS). Approach: Six cats were anesthetized and the functional consequences of a hemisection SCI were simulated by manually moving one hind-...
Article
Full-text available
The growth of TiO2 nanotube arrays (TNTAs) on non-native substrates is essential for exploiting the full potential of this nanoarchitecture in applications such as gas sensing, biosensing, antifouling coatings, low-cost solar cells, drug-eluting bimedical implants and stem-cell differentiators. The direct formation of anodic TNTAs on non-native sub...
Chapter
Full-text available
This chapter surveys the different control methods developed for spinal cord stimulation to restore walking after neural injury or disease. We start by exploring the networks within the spinal cord that control or modulate walking. Next we introduce the different modes of stimulating the spinal cord: intraspinal microstimulation, epidural spinal co...
Article
Full-text available
Shape irregularity and size dispersion exhibited by TiO2 nanotube arrays (TNAs) is a disadvantage for size-selective applications such as flow-through membranes, cell differentiation and drug delivery, and for photonic applications such as photonic crystals and metallodielectric metamaterials, where size and shape dispersity are sources of defects...
Article
Full-text available
Exploitation of anodically formed self-organized TiO2 nanotube arrays in mass-manufactured, disposable biosensors, rollable electrochromic displays and flexible large-area solar cells would greatly benefit from integration with transparent and flexible polymeric substrates. Such integration requires the vacuum deposition of a thin film of titanium...

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Projects

Projects (4)
Project
Improve cochlear implants and related technology for better performance
Project
Apply machine learning techniques to solve neuroscience problems
Project
Develop intelligent control strategies to restore walking using neural interfaces