Focused Impedance Measurement (FIM) is a recent technique for quantifying the

electrical resistance The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares some conceptual paralle ...

in tissues of the human body with improved zone localization compared to conventional methods. This method was proposed and developed by Department of ''Biomedical Physics and Technology'' of

University of Dhaka The University of Dhaka (also known as Dhaka University, or DU) is a public research university located in Dhaka, Bangladesh. It is the oldest university in Bangladesh. The university opened its doors to students on July 1st 1921. Currently i ...

under the supervision of Prof. Khondkar Siddique-e-Rabbani;BAS Gold Medal Award Ceremony 2011
, Bangladesh Academy of Sciences who first introduced the idea. FIM can be considered a bridge between Four

Electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials d ...

Impedance Measurement (FEIM) and Electrical impedance Tomography (EIT), and provides a middle ground in terms of simplicity and accuracy. Many biological parameters and processes can be detected and monitored through their effects on bioimpedance. Bioimpedance measurement can be performed with a few simple instruments and non-invasively. Measurement of electrical impedance to obtain physiological or diagnostic information has been of interest to researchers for many years. However, the human body is geometrically and conductively uneven, with variation between individuals and phases of normal body activity, and bioimpedance results from many factors, including

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

concentrations, cell geometry, extra-cellular fluids, intra-cellular fluids, and organ geometry. This makes accurate analysis of results from a small number of electrodes difficult and unreliable. Identifying zones with specific impedances can provide greater certainty regarding the factors behind the impedance. Conventional Four Electrode or Tetra-polar Impedance Measurement (TPIM) is simple, but the zone of sensitivity is not well defined and may include organs other that those of interest, making interpretation difficult and unreliable. On the other hand,

Electrical impedance tomography Electrical impedance tomography (EIT) is a noninvasive type of medical imaging in which the electrical conductivity, permittivity, and impedance of a part of the body is inferred from surface electrode measurements and used to form a tomographic ...

(EIT) offers reasonable resolution, but is complex and require many electrodes. By placing two FEIM systems perpendicular to each other over a common zone at the center and combining the results, it is possible to obtain enhanced sensitivity over this central zone. This is the basis of FIM, which may be useful for impedance measurements of large organs like stomach, heart, and lungs. Being much simpler in comparison to EIT, multifrequency systems can be simply built for FIM. FIM may be useful in other fields where impedance measurements are performed, like geology.

References

{{reflist Medical tests Electrophysiology Impedance measurements Bangladeshi inventions

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