Omd551 types of electrodes

Types of electrodes in BBMI

1. OMD551- BASICS OF BIOMEDICAL INSTRUMENTATION TYPES OF ELECTRODES

2. ELECTRODES Electrodes are used to pickup the electric signals of the body. Electrodes serve as a transducer to convert ionic current into electronic current. Devices that converts ionic potential into electronic potential are called as electrodes. Used to measure the potentials from ECG,EEG,EMG

3. PURPOSE OF ELCTROLYTES Outer skin is non conductive Conductivity of the skin directly proportional to moisture of the skin represents the body fluid containing ions

4. ELECTROLYTE INTERFACE To Measure and record the potentials, necessary to provide interface between body and electronic measuring apparatus. Electrolyte interface is used to examine the electric current from body to an electrode

5. ELECTROLYTE INTERFACE The net current that crosses the interface, passing from electrode to electrolyte , consists of Electrons moving in the direction opposite to that of the current in the electrode. Cations (C+) moving same direction of current Anions (A-) moving opposite direct ion of current

6. ELECTRODES &ELECTRODE POTENTIAL Devices that convert ionic potential into electronic potential are called electrodes. The interface of metallic ions in solution with their associated metals in an electrical potential is called electrode potential.

7. Half cell potentials voltage developed at an electrode- electrolyte interface is called half cell potential

8. ELECTROLYTE CHARACTERISTICS Perfect polarized electrode charges not transfer across metal electrolyte interface. Perfect non-polarized electrode infinite charges transfer across metal electrolyte interface. Artifacts non-polarized electrode will create variable noise termed as artifacts

9. Types of elctrodes

10. TYPES OF ELECTRODES   Surface Electrode Needle Electrode Micro Electrode Depth Electrode Chemical Electrode

11. SURFACE ELECTRODE Surface electrodes are used to measure the potential available from surface of skin and to sense potential from heart and brain.

12. Metal plate electrode

13. Metal plate electrode One of most frequently used bio potential electrode Consists of metallic conductor in contact with skin Electrolyte gel is used to establish and maintain connection between skin and electrode This electrode is made of German silver(nickel silver alloy)

14. Suction cup elctrode –Flat surface of body

15. Suction cup electrode –Flat surface of body Modification of metal plate electrode Does not require straps or adhesives for holding in a place Used in ECG Used for short period of time and quite large Suction and pressure of contact surface against skin causes irritation.

16. Adhesive tape - metallic screen backed by a pad - holds the electrodes in place Delays the evaporation of electrolyte

17. Used for any environmental conditions

18. Flexible Electrodes

19. R- Gas constant T- Absolute temperature in kelvin n – valence of ions F-Faradays constant C1,C2- Concentration of selected ion on two sides of membrane F1,f2-Activity co-efficient of ions on two sides of membrane