4 - Electrode Design For The Recording Of Bioelectrical Signals Flashcards
What are the different classification for electrodes ?
Application (fundamental or clinical, in vivo, in vitro,…) Site (extra corporal, intra : percutaneous, implanted) Duration oriented (chronic, a cute, synchronic) Material oriented classification (glass, metal salt electrolyte or Nobel metals)
Pro cons : extra corporal
Low selectivity
No trauma
Pro cons : percutaneous
Low invasive ness
Skin injury
Pro cons : implanted
No hindrance (=obstacle) due to cables High selectivity Surgery (-)
Site Time for chronic, sub chronic and acute application.
Acute : <1 day or 60 minutes
Sub chro : <29d
Chro: >30d
Site three main classes of material oriented application.
Glass pipette, métal/métal salt/electrolyte or noble metals (platinum, iridium, stainless steel)
Site the five general requirements for electrodes
Generation of irreversible electrochemical inflammatory reaction products should be as low as possible
Low Polarisability
Low and long term stable interface impedance
Phase boundary impedance should exhibit a low frequency response
As less artefacts as possible (eg electrochemical noise)
Define polarisabilty
Ability of a material to change due to an electric field
What are the materials for micro electrodes ?
Glass or metal
Site the three parts of a glass micro electrode
Shaft shoulder and tip
What kinds of recording for micro electrode
Tissue slices
Cell cultures
Single cell
How can a piece of metal in a salt water can be modélisés as a circuit ?
Capacitor and resistor in parallel
How act the glass mantle in the glass micro electrode ?
As a capacity
What is the total capacity of the glass micro electrode ?
Common mode capacity at the amplifier input (Cgl)
Stray capacity in the cable (Cl)
Electrode capacity (Csf)
Describe the principle of metal microelectrode
Metal wire finely extruded
Insulation everywhere except at the tip
Application in in vivo diagnostic
