Imperial College London


Faculty of EngineeringDepartment of Electrical and Electronic Engineering

Visiting Professor



+44 (0)20 7594 1594k.nikolic




Bessemer 420CBessemer BuildingSouth Kensington Campus






BibTex format

author = {Cork, SC and Eftekhar, A and Mirza, KB and Gardiner, JV and Bloom, SR and Toumazou, C},
doi = {1741-2552/aa8239},
journal = {Journal of Neural Engineering},
title = {Extracellular pH monitoring for use in closed-loop vagus nerve stimulation.},
url = {},
volume = {15},
year = {2017}

RIS format (EndNote, RefMan)

AB - 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 (pH<sub>e</sub>) 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 pH<sub>e</sub> associated with both CCK and gastric distension. What's more, custom made Matlab script was able to use these changes in pH<sub>e</sub> to automatically trigger an implanted VNS device. SIGNIFICANCE: This is the first study to show pH<sub>e</sub> changes in peripheral nerves in vivo. Furthermore, the demonstration that iridium oxide microelectrodes are sufficiently pH sensitive as to measure changes in pH<sub>e</sub> associated with physiological stimuli means they have the potential to be integrated into closed-loop neurostimulating devices.
AU - Cork,SC
AU - Eftekhar,A
AU - Mirza,KB
AU - Gardiner,JV
AU - Bloom,SR
AU - Toumazou,C
DO - 1741-2552/aa8239
PY - 2017///
SN - 1741-2552
TI - Extracellular pH monitoring for use in closed-loop vagus nerve stimulation.
T2 - Journal of Neural Engineering
UR -
UR -
VL - 15
ER -