1,053 research outputs found
Neuromorphic hardware for somatosensory neuroprostheses
In individuals with sensory-motor impairments, missing limb functions can be restored using neuroprosthetic devices that directly interface with the nervous system. However, restoring the natural tactile experience through electrical neural stimulation requires complex encoding strategies. Indeed, they are presently limited in effectively conveying or restoring tactile sensations by bandwidth constraints. Neuromorphic technology, which mimics the natural behavior of neurons and synapses, holds promise for replicating the encoding of natural touch, potentially informing neurostimulation design. In this perspective, we propose that incorporating neuromorphic technologies into neuroprostheses could be an effective approach for developing more natural human-machine interfaces, potentially leading to advancements in device performance, acceptability, and embeddability. We also highlight ongoing challenges and the required actions to facilitate the future integration of these advanced technologies
Development of a SQUID magnetometry system for cryogenic neutron electric dipole moment experiment
A measurement of the neutron electric dipole moment (nEDM) could hold the key to understanding why the visible universe is the way it is: why matter should predominate over antimatter. As a charge-parity violating (CPV) quantity, an nEDM could provide an insight into new mechanisms that address this baryon asymmetry. The motivation for an improved sensitivity to an nEDM is to find it to be non-zero at a level consistent with certain beyond the Standard Model theories that predict new sources of CPV, or to establish a new limit that constrains them.
CryoEDM is an experiment that sought to better the current limit of cm by an order of magnitude. It is designed to measure the nEDM via the Ramsey Method of Separated Oscillatory Fields, in which it is critical that the magnetic field remains stable throughout. A way of accurately tracking the magnetic fields, moreover at a temperature K, is crucial for CryoEDM, and for future cryogenic projects.
This thesis presents work focussing on the development of a 12-SQUID magnetometry system for CryoEDM, that enables the magnetic field to be monitored to a precision of pT. A major component of its infrastructure is the superconducting capillary shields, which screen the input lines of the SQUIDs from the pick up of spurious magnetic fields that will perturb a SQUID's measurement. These are shown to have a transverse shielding factor of , which is a few orders of magnitude greater than the calculated requirement.
Efforts to characterise the shielding of the SQUID chips themselves are also discussed. The use of Cryoperm for shields reveals a tension between improved SQUID noise and worse neutron statistics. Investigations show that without it, SQUIDs have an elevated noise when cooled in a substantial magnetic field; with it, magnetostatic simulations suggest that it is detrimental to the polarisation of neutrons in transport. The findings suggest that with proper consideration, it is possible to reach a compromise between the two behaviours.
Computational work to develop a simulation of SQUID data is detailed, which is based on the Laplace equation for the magnetic scalar potential. These data are ultimately used in the development of a linear regression technique to determine the volume-averaged magnetic field in the neutron cells. This proves highly effective in determining the fields within the pT requirement under certain conditions
Beam scanning by liquid-crystal biasing in a modified SIW structure
A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium
Diagnostic Methods for the Characterization of a Helicon Plasma Thruster
Programa de Doctorado en Mecánica de Fluidos por la Universidad Carlos III de Madrid; la Universidad de Jaén; la Universidad de Zaragoza; la Universidad Nacional de Educación a Distancia; la Universidad Politécnica de Madrid y la Universidad Rovira iPresidente: José Javier Honrubia Checa.- Secretario: José Miguel Reynolds Barredo.- Vocal: Eduardo de la Ca
Maintaining the Integrity Over Wear Time of a Hydrocolloid-based Ostomy Adhesive Whilst Maintaining Skin Barrier Function
In this extensive body of work, a thorough exploration delves into hydrocolloid based adhesives, with a focus on addressing challenges faced by stoma patients, particularly the susceptibility of ostomy adhesives to breakdown upon exposure to liquids. Stoma patients, compelled to wear pouching systems continuously, encounter issues like the compromise of skin barrier integrity, leading to medical adhesive-related skin injuries. The primary objective of this thesis is to reinforce the structural integrity of ostomy adhesives while preserving the skin barrier during pouching system use, an aspect often overlooked in current literature due to the hydrophilic nature of hydrocolloid based adhesives. The study introduces novel aims, examining the potential link between handedness and the preferred direction of adhesive removal, and its impact on peristomal skin complications as well as a novel skin capacitive imagery stitching technique. Another goal involves developing hierarchical structures on adhesive surfaces to enhance integrity, initial tack, and minimize skin contact for optimal skin health. The introduction provides a detailed breakdown of hydrocolloid-based ostomy adhesives, stoma anatomy, and the purpose of pouching systems. A comprehensive literature review, utilizing the PICO approach, encompasses stoma anatomy, physiology, indications for stoma surgery, and methods for assessing skin health. The review explores various methodologies to improve the durability of hydrocolloid-based adhesives, incorporating hydrodynamics, crosslinking, and layering systems. The potential influence of handedness on adhesive removal techniques is examined, considering its impact on peristomal skin complications. Results reveal the consistent performance of Welland Medical Ltd.'s hydrocolloid based adhesive but highlight the need for improved integrity over wear time. Strategies include modifying sodium-carboxymethylcellulose degree of substitution and increasing pectin degree of esterification, resulting in enhanced fluid handling capabilities and reduced susceptibility to degradation. Residual testing indicates that residual particles on the skin can impair the barrier function, remedied by a silicone-based adhesive remover. Surveys show that a patient's dominant hand and following the skin's natural langer lines during adhesive removal may minimize skin trauma. The results also show that structured surface profiles on hydrocolloid-based adhesive surfaces impact the skin's functional barrier recovery time. The research goal of this project and its objectives have been reached, the approaches have been explained clearly and implementations have been assessed using experimental findings. This project's findings contribute to advancements in ostomy care by enhancing adhesive performance, understanding patient behaviour, and improving the overall user experience. It also facilitates the efficient detachment of the adhesive from the skin surface
Advanced Materials and Technologies in Nanogenerators
This reprint discusses the various applications, new materials, and evolution in the field of nanogenerators. This lays the foundation for the popularization of their broad applications in energy science, environmental protection, wearable electronics, self-powered sensors, medical science, robotics, and artificial intelligence
Analysis, Design and Fabrication of Micromixers, Volume II
Micromixers are an important component in micrototal analysis systems and lab-on-a-chip platforms which are widely used for sample preparation and analysis, drug delivery, and biological and chemical synthesis. The Special Issue "Analysis, Design and Fabrication of Micromixers II" published in Micromachines covers new mechanisms, numerical and/or experimental mixing analysis, design, and fabrication of various micromixers. This reprint includes an editorial, two review papers, and eleven research papers reporting on five active and six passive micromixers. Three of the active micromixers have electrokinetic driving force, but the other two are activated by mechanical mechanism and acoustic streaming. Three studies employs non-Newtonian working fluids, one of which deals with nano-non-Newtonian fluids. Most of the cases investigated micromixer design
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