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AUD spring 2020 CI > Week 2 Electronics > Flashcards

Week 2 Electronics Flashcards

1
Q

valence electrons

A

the outer most ring of electrons which try and become a full orbit by losing or gaining electrons

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2
Q

what makes a good or bad conductor

A

poor conductors= full outer ring of electrons; good conductors= not full ring (atom has positive, negative, or neutral number of electrons depending on losing or gaining electrons)

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3
Q

coulomb

A

what electric charge is measured in

  • 1 coulomb= 6.14*10 to the 18th power electrons
  • more electrons= larger electric charge
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4
Q

what does electricity result from

A
  • the movement of electrons

* could result from the movement of ions

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5
Q

voltage (V)

A
  • the work needed to move electrons from one point to the other (volts)
  • –which is the result of difference in charge
  • —–what creates a voltage difference? power source
  • ——–voltage=0.75- (-0.75)=1.5V
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6
Q

electric gradient

A

the electromotive force that will drive electrons from where they are to where they need to be

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7
Q

amperes (Amp)

A

the rate at which electrons travel through a medium

—current could travel even in poor conductive materials (example is lightening)

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8
Q

direct current (DC)

A

current travels in one direction of a circuit (example=battery current)

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9
Q

alternating current (AC)

A

current direction alternate back and forth at a specific rate
*example=outlet current

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10
Q

ionic current

A

charge and concentration gradient

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11
Q

impedance (Ohm)

A

opposition of current flow when a voltage i applied

  • this is important to control the flow of electrons from high to low concentration
  • –associated with AC
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12
Q

resistance

A

opposition of current flow when a voltage is applied

—associated with DC

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13
Q

Ohm’s law

A

current= voltage/impedance

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14
Q

electrical circuit

A

a network (resistors, capacitors, etc) consisting of a closed loop, giving a return path for the current

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15
Q

resistors (R)

A

a piece of conducting material of a particular resistance to reduce the current flow in a circuit

  • –the thinner and longer, the more resistance
  • –example: light bulb tungsten wire
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16
Q

capacitor (C)

A

capacitance is the ability of a body to store electric charge

  • DC–blocked
  • AC–back and forth charging (charge balance)
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17
Q

factors affecting a capacitor

A
  • area (A)
  • spacing (d)
  • dielectric material–insulator
  • –dielectric constant (E): air (1), distilled water (80)
  • ****C=(EA)/d
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18
Q

electromagnetic induction

A
  • electric current generates a magnetic field
  • magnetic field generates an electric current
  • –stimulation in CIs is done using electromagnetic induction
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19
Q

telemetry

A

when the processor sends signal to the headpiece which generates current in the internal device where it is then used to stimulate the cochlea
*when the internal device delivers info back=bidirectional telemetry

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20
Q

2 types of electric signals which can be used with CI

A
  • analog

* pulsatile

21
Q

analog signals with CI

A
  • continuous over time
  • leads to “truer speech”
  • need more voltage to have continuous current which leads to battery drain, and the electrodes which are being stimulated are going to effect and cancel out one another which leads to signal distortion
22
Q

pulsatile signals with CI

A
  • current is on then off; this is what is currently used with CI
  • never stimulate with one pulse, but use different pulses
  • –polarity is anodic and cathodic
  • duration (width) of the pulse is a characteristic
  • greater amplitude means greater current
  • intensity is controlled with pulsatile signals by:
  • –increase in amplitude (increases intensity)
  • –increase in duration (increase intensity)
23
Q

anodic pulse signal

A

the positive pulse

24
Q

cathodic pulse signal

A

the negative pulse

25
Q

how can you change the intensity of a pulsatile signal

A
  • increase amplitude to increase intensity

* increase duration to increase intensity

26
Q

monophasic pulsatile signal

A

either anodic or cathodic (not used in CI)

27
Q

pseudomonophasic pulsatile signal

A

cathodic and anodic but 1 is longer in duration

28
Q

biphasic pulsatile signal

A

equal cathodic and anodic

29
Q

triphasic pulsatile signal

A

amplitude of 2 cathodic or anodic is equal to that of 1 of the opposite

30
Q

interphase gap

A

pause between cathodic and anodic, the little break allows the change to stay a little longer in the electrode thus resulting in a slightly better threshold

31
Q

charge balance

A

trying to ensure not causing damage to the auditory system or electrode by sending charge through
—need to make sure that if you send a certain amount of charge through, you bring the same amount back (this is why you can’t use monophasic because it is not charge balances which pseudo, bi, and triphasic are)

32
Q

pulse rate

A

1/period, can be modulated to represent the speech signal/ speech envelope

33
Q

sequential (nonsimultaneous stimulation)

A

only one electrode is stimulated at a time (the stimulus timing used most today)

  • pulsatile only
  • too short an interval may cause channel interaction
34
Q

simultaneous stimulation

A

pulsatile or analog stimulation

  • each electrode needs separate current source
  • if the signals are in phase or out of phase they can sum or cancel out each other
35
Q

partially simultaneous stimulation

A

pulsatile only

  • each electrode needs a separate current source
  • cans stimulate 2 electrodes at the same time, but they need to be far apart so they do not affect each other (add or cancel)
36
Q

electrode

A

the physical contact used to deliver the electric current to tissue

37
Q

channel

A

the resulting field of stimulation (frequency range) from electrode

38
Q

virtual channel

A

frequency ranges to be stimulated that are created through different patterns of stimulation of electrodes which stimulates the area between electrodes

39
Q

Sequential stimulation to make a virtual channel

A
  • short interval (<0.5ms) between the stimulation of 2 electrodes, will allow for 3-6 virtual channels between the 2 electrodes
  • –the amount of current sent to each electrode will determine the location of channel
40
Q

current steering stimulation to make a virtual channel

A
  • commonly used
  • certain amount of current sent to each electrode and uses simultaneous stimulation therefore needs separate current sources, will crease 4-6 virtual channels
  • –the electrode that receives the larger % of the current will be the frequency the VC is closer to (50/50 would be halfway between)
41
Q

dual electrode stimulation to make a virtual channel

A

*can only stimulate the area halfway between the 2 electrodes and is done by connecting the 2 electrodes together (Cochlear can do this, but really isnt used)

42
Q

electrode configuration/ coupling

A
  • how the circuit is formed to create a closed loop for current
  • how do we decide what electrode will deliver the current and what electrode will serve as the return path for the current
  • broader stimulation created wider excitation pattern and lower threshold
43
Q

list the 6 methods of electrode coupling

A
  • monopolar
  • pseudomonopolar
  • bipolar/ variable bipolar
  • tripolar
  • partial tripolar
  • common ground
44
Q

monopolar electrode coupling

A

uses electrodes inside cochlea as the active to send the current and the return path is the extracochlear electrode

  • all signal is sent to 1 electrode
  • results in the widest range of stimulation (larger excitement of fibers and thus lower threhsolds)
  • all Cochlear implant stimulation is happening using monopolar stimulation right now
45
Q

pseudomonopolar electrode coupling

A

modifies monopolar and is used when there is no electrocochlear electrode (if it isnt working)
*designates the most basal electrode as the return path

46
Q

bipolar electrode coupling

A
  • available with Cochlear and uses the very next apical electrode to the electrode stimulated as the return path
  • issue is that this creates a very narrow field of stimulation (which can be good because it allows for more specific stimulation) which requires a larger current to stimulate
  • modifications:
  • –BP+1 which means there is the active electrode and one electrode between this and the return and so on with BP+2 and up
  • —-this acts to increase the range so not as much current would be seeded to stimulate
  • –variable bipolar is when more than one form of bipolar is used, ex:BP and BP+1 in the same CI and would use this in cases if one electrode is damaged and thus would not be able to act as return path for its neighbor
47
Q

tripolar electrode coupling

A
  • active electrode and the 2 electrodes on the side function as return path (one electrode on either side)
  • again gives a very narrow area of excitation and results in needing larger current to stimulate
  • the need for more current causes voltage compliance problem
48
Q

partial tripolar electrode coupling

A
  • uses monopolar and tripolar to try to get the narrow stimulation without needing so much voltage to stimulate
  • sends half the current as a return through the neighboring electrodes and the other half through the extracochlear electrode
  • –the monopolar portion recruits a bit more to make it less narrow stimulation
49
Q

common ground electrode coupling

A
  • availabel through cochlear= not used for stimulation but used for testing to evaluate the internal device
  • activates one electrode and all the other electrodes act as a return path
  • –used for diagnostics
  • –common ground cannot be done if each electrode has its own power source hence why it is only for Cochlear

AUD spring 2020 CI (16 decks)

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