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Extracellular pH monitoring for use in closed-loop vagus nerve stimulation

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Title: Extracellular pH monitoring for use in closed-loop vagus nerve stimulation
Authors: Cork, SC
Eftekhar, A
Mirza, KB
Gardiner, JV
Bloom, SR
Toumazou, C
Item Type: Journal Article
Abstract: Objective: Vagal nerve stimulation (VNS) has shown potential benefits for obesity treatment; however, current devices lack physiological feedback, which limit their efficacy. Changes in extracellular pH (pHe) have shown to be correlated with neural activity, but have traditionally been measured with glass microelectrodes, which limit their in vivo applicability. Approach. Iridium oxide has previously been shown to be sensitive to fluctuations in pH and is biocompatible. Iridium oxide microelectrodes were inserted into the subdiaphragmatic vagus nerve of anaesthetised rats. Introduction of the gut hormone cholecystokinin (CCK) or distension of the stomach was used to elicit vagal nerve activity. Main results. Iridium oxide microelectrodes have sufficient pH sensitivity to readily detect changes in pHe associated with both CCK and gastric distension. Furthermore, a custom-made Matlab script was able to use these changes in pHe to automatically trigger an implanted VNS device. Significance. This is the first study to show pHe changes in peripheral nerves in vivo. In addition, the demonstration that iridium oxide microelectrodes are sufficiently pH sensitive as to measure changes in pHe associated with physiological stimuli means they have the potential to be integrated into closed-loop neurostimulating devices.
Issue Date: 1-Feb-2018
Date of Acceptance: 26-Jul-2017
URI: http://hdl.handle.net/10044/1/51866
DOI: 10.1088/1741-2552/aa8239
ISSN: 1741-2552
Publisher: IOP Publishing
Start Page: 1
End Page: 11
Journal / Book Title: Journal of Neural Engineering
Volume: 15
Issue: 1
Copyright Statement: Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Sponsor/Funder: Commission of the European Communities
Engineering & Physical Science Research Council (EPSRC)
Biotechnology and Biological Sciences Research Council (BBSRC)
Engineering & Physical Science Research Council (EPSRC)
National Institute for Health Research
National Institute for Health Research
Funder's Grant Number: 319818
EP/N002474/1
BB/L018268/1
EP/K009842/1
NF-SI-0507-10337
NF-SI-0513-10080
Keywords: Science & Technology
Technology
Life Sciences & Biomedicine
Engineering, Biomedical
Neurosciences
Engineering
Neurosciences & Neurology
iridium oxide
extracellular pH
neuromodulation
obesity
closed-loop control
vagal nerve stimulation (VNS)
ELECTRICAL-STIMULATION
WEIGHT-LOSS
OBESITY
BRAIN
MODULATION
TRANSIENTS
RESPONSES
BLOCKADE
FILM
CCK
Animals
Extracellular Fluid
Iridium
Male
Microelectrodes
Rats
Rats, Wistar
Vagus Nerve
Vagus Nerve Stimulation
Vagus Nerve
Extracellular Fluid
Animals
Rats
Rats, Wistar
Iridium
Microelectrodes
Male
Vagus Nerve Stimulation
Biomedical Engineering
0903 Biomedical Engineering
1103 Clinical Sciences
1109 Neurosciences
Publication Status: Published
Open Access location: https://doi.org/10.1088/1741-2552/aa8239
Article Number: 016001
Online Publication Date: 2017-12-01
Appears in Collections:Department of Metabolism, Digestion and Reproduction
Electrical and Electronic Engineering
Faculty of Medicine
Faculty of Engineering