Change search
ReferencesLink to record
Permanent link

Direct link
Investigation of Interfacial Capacitance of Pt, Ti and TiN Coated Electrodes by Electrochemical Impedance Spectroscopy
KTH, Superseded Departments, Materials Science and Engineering.
KTH, Superseded Departments, Materials Science and Engineering.ORCID iD: 0000-0002-4431-0671
KTH, Superseded Departments, Materials Science and Engineering.ORCID iD: 0000-0002-9453-1333
2002 (English)In: Biomolecular Engineering, ISSN 1389-0344, E-ISSN 1878-559X, Vol. 19, no 2-6, 67-71 p.Article in journal (Refereed) Published
Abstract [en]

Electrochemical processes at the electrode-electrolyte (body fluid) interface are of ultimate importance for stimulating/sensing electrode function. A high electrode surface area is desirable for safe stimulation through double-layer charging and discharging. Pt and Pt-Ir alloys have been the most common electrode materials. The use of TiN coating as the surface layer on the electrode has found increasing interest because of its metal-like conductivity, excellent mechanical and chemical properties, and the fact that it can be deposited with a high surface area. In this work, electrochemical impedance spectroscopy (EIS), which is a sensitive and non-destructive technique and widely used for characterization of electrical properties of electrode-electrolyte interfaces, was applied to investigate pure Pt and Ti, and TiN coated electrodes exposed to a phosphate-buffered-saline (PBS) solution. Platinized Pt and Ti were also studied for comparison. The capacitance value of the electrodes in PBS was obtained through quantitative analysis of the EIS spectra. The results reveal that the capacitance of the TiN coated electrodes with a rough surface is several hundreds times higher than that of a smooth Pt surface. Platinization of Ti can also increase the capacitance to the same extent as platina. EIS has been shown to be a powerful technique for characterization of stimulating/sensing electrodes.

Place, publisher, year, edition, pages
2002. Vol. 19, no 2-6, 67-71 p.
Keyword [en]
Effective surface area, Electrochemical impedance spectroscopy, Interfacial capacitance, Platinization, Stimulating/sensing electrodes, TiN coating
National Category
Physical Chemistry
URN: urn:nbn:se:kth:diva-5060DOI: 10.1016/S1389-0344(02)00013-8ISI: 000178266800007OAI: diva2:7743
QC 20100920Available from: 2005-04-25 Created: 2005-04-25 Last updated: 2010-09-20Bibliographically approved
In thesis
1. Investigation of electrochemical properties and performance of stimulation/sensing electrodes for pacemaker applications
Open this publication in new window or tab >>Investigation of electrochemical properties and performance of stimulation/sensing electrodes for pacemaker applications
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

People suffering from certain types of arrhythmia may benefit from the implantation of a cardiac pacemaker. Pacemakers artificially stimulate the heart by applying short electrical pulses to the cardiac tissue to restore and maintain a steady heart rhythm. By adjusting the pulse delivery rate the heart is stimulated to beat at desired pace. The stimulation pulses are transferred from the pacemaker to the heart via an electrode, which is implanted into the cardiac tissue. Additionally, the electrode must also sense the cardiac response and transfer those signals back to the electronics in the pacemaker for processing. The communication between the electrode and the tissue takes place on the electrode/electrolyte (tissue) interface. This interface serves as the contact point where the electronic current in the electrode is converted to ionic currents capable to operate in the body. The stimulation/sensing signals are transferred across the interface via three electrochemical mechanisms: i) non-faradaic charging/discharging of the electrochemical double layer, ii) reversible and iii) irreversible faradaic reactions. It is necessary to study the contribution of each mechanism to the total charge transferred to evaluate the pacing/sensing performance of the pacemaker electrode.

In this thesis, the electrochemical properties and performance of stimulation/sensing electrodes for pacemaker applications have been investigated by electrochemical impedance spectroscopy, cyclic voltammetry and transient electrochemical techniques. All measurements were performed in synthetic body fluid with buffer capacity. Complementary surface analysis was performed with scanning electron microscopy, energy dispersive spectroscopy and X-ray photoelectron spectroscopy.

The results reveal different interfacial behaviour and stability for electrode materials such as Pt, TiN, porous carbon, conducting oxides (RuO2 and IrO2 and mixed oxides) and porous Nb2O5 oxide. The influence of the charge/discharge rate on the electrode characteristics also has been evaluated. Although the rough and porous electrodes provide a high interfacial capacitance, the maximum capacitance cannot be fully employed at high charge/discharge rates because only a small part of the effective surface area is accessible. The benefit of pseudo-capacitive material properties on charge delivery was observed. However, these materials suffer similar limitations at high charge/discharge rate and, hence, are only utilising the surface bound pseudo-capacitive sites. Porous Nb2O5 electrodes were investigated to study the performance of capacitor electrodes. These electrodes predominantly deliver the charge via reversible non-faradaic mechanisms and hence do not produce irreversible by-products. They can deliver very high potential pulses while maintaining high impedance and, thus, charge lost by faradaic currents are kept low. By producing Nb oxide by plasma electrolysis oxidation a porous surface structure is obtained which has the potential to provide a biocompatible interface for cell adherence and growth.

This thesis covers a multidisciplinary area. In an attempt to connect diverse fields, such as electrophysiology, materials science and electrochemistry, the first chapters have been attributed to explaining fundamental aspects of the respective fields. This thesis also reviews the current opinion of pacing and sensing theory, with special focus on some areas where detailed explanation is needed for the fundamental nature of electrostimulation/sensing.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. vii, 119 p.
Physical chemistry, pacemaker electrode, interfacial property, biomaterial, electrostimulation charge transfer mechanism, electrochemical impedance spectroscopy, transient processes, plasma electrolysis anodisation, porous niobium oxide, ruthenium oxide, nano-porous carbon, iridium oxide, titanium nitride, platinum, surface roughness, porous electrode, pacing impedance, electrode polarisation, Fysikalisk kemi
National Category
Physical Chemistry
urn:nbn:se:kth:diva-176 (URN)91-7283-994-5 (ISBN)
Public defence
2005-04-29, Kollegiesalen, Administrationsbyggnaden, Valhallavägen 79, Stockholm, 14:00 (English)
QC 20101014Available from: 2005-04-25 Created: 2005-04-25 Last updated: 2012-03-14Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Norlin, AnnaPan, JinshanLeygraf, Christopher
By organisation
Materials Science and Engineering
In the same journal
Biomolecular Engineering
Physical Chemistry

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 81 hits
ReferencesLink to record
Permanent link

Direct link