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F Risacher

Publications and source records attributed to F Risacher.

3 recordsLinked to original sources

Factors affecting electrode-gel-skin interface impedance in electrical impedance tomography.

The magnitude, mismatch and temporal variations of the electrode-gel-skin interface impedance can cause problems in electrical impedance tomography (EIT) measurement. It is shown that at the high frequencies generally encountered in EIT the capacitive properties of the electrode interface, and especially those of the skin, are of primary importance. A wide range of techniques are reviewed that could possibly be used to minimise these problems. These techniques include the use of skin preparation, penetration enhancers, temperature and electrical impulses. Although several of these techniques appear very attractive, they are not without serious potential drawbacks. A combination of some of these techniques may well hold the key to success.

Electric Impedance↗

A high frequency electrical impedance tomograph using distributed parallel input channels.

Electrical Impedance Tomography (EIT) is an imaging technique based on multiple impedance measurements using electronically multiplexed surface electrodes. The present study describes an EIT prototype tomograph which uses two frequencies of applied signal: 31.25 kHz (within the frequency range originally used in early EIT studies) and 250 kHz. The use of the latter frequency was made possible as a result of several technical innovations including the use of separate groups of electrodes for current injection and for differential voltage measurement and the use of parallel input channels distributed around the object. In vitro images were successfully obtained using the system at the above two frequencies. It is concluded from this study that Electrical Impedance Tomography can be used at sufficiently high frequencies to enable bio-electrical tissue characterisation.

Electric Conductivity↗