BME 732 - Abiotic Analysis for Microelectrode Characterization

medicineman's version from 2015-10-04 00:43


Question Answer
Abiotic factorsMaterials, geometry, impedance, and SNR
Insertion effectsBreakage of the blood-brain barrier, inflammation, microglial cells activated
Where do action potentials originate in a neuron?The axon hillock
What is the recovery phase also called?The black out period because the electrophysiological signal quality is very poor
What layer of the brain are electrodes typically implanted?Layer 5 of the neocortex. Neurons in this layer send information outside of the brain
Why is Iridium used in microelectrode wires?It gives rigidity to the wire
What is a problem with using Tungsten in microelectrode wires?Tungsten corrodes easily
Why is blood in the body in blood vessels and not free-floating?Because the Iron in red blood cells would cause corrosion
Impedance spectroscopySending small voltages at various frequencies to measure impedance
Frequency and impedanceAt low frequencies, the capacitive component of impedance is small so impedance is based on resistance
Listening sphereHow far away from an electrode signals can be recorded. Based on impedance (higher impedance > smaller listening sphere)
Surface area and impedance A larger surface area results in a smaller impedance (R=ρL/A)
Detecting problems based on impedanceIf impedance is 0 there is a break in the wire. If impedance is very high, there is a problem with the electrode
Insulation damage and its effects Insulation damage increases surface area which results in a larger listening sphere
Thermal noiseHigh impedance causes thermal noise
Corrosion effectsCorrosion results in deterioration of electrode recording sites in the form of recording surfaces becoming more recessed within the insulation

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