BPK 407 - Biometrics; Basic Electricity and Tenets of Electrical Safety (Pages 13-26)

Define Biometrics

A branch of science that includes measurements of physiological variables and parameters

What factors should be considered in design or specification using Biometrics? (8)

- Range

- Sensitivity

- Linearity

- Hysteresis

- Frequency Response

- Accuracy

- Signal:Noise Ratio

- Stability

Define Range in biometrics

all levels of input amplitude and frequency that a device operates over.

Define Sensitivity in biometrics

determines how small a variation of a variable or parameter can be reliably measured.

Define Linearity in biometrics

the degree to which output variation of an instrument follows input variation. the degree of change. should have equal degrees of change at all absolute amounts of input change

Define Hysteresis in biometrics

characteristic of some instruments whereby a given value of a measured variable results in different reading when reached through ascending or descending directions. I.e. friction

Define Frequency response in biometrics

the variation of an instruments sensitivity over the frequency range it operates in.

Define Accuracy in biometrics

A measure of systematic errors

- Errors of tolerance of electronic components

- Mechanical errors in meter movements

- Component errors due to drift, temp var, atmospheric changes

- Errors due to poor frequency response

- Instruments not zero'd

- Proper parameter measurement

Define Signal:Noise ratio in biometrics

Higher ratio = better

Define stability in biometrics

Ability of a system to return to / resume a steady state condition following disturbance at the input rather than be driven into uncontrollable oscillation.

- Factor of amplification, feedback, etc

Define Current

The movement of electrons. Amperes (Amps, A)

- Circuit must be complete for current to flow

Define Voltage

The force which causes current to flow. Volts (V)

- Battery and wall outlet are voltage sources

- Voltage source is also a current source

Define Direct Current

A current that only flows in one direction (DC).

- A cell (battery) is DC voltage source

Define Alternating Current

A current that reverses its direction of flow at regular intervals

- A wall outlet is a source of AC voltage

Define Resistance and explain insulators and conductors

The limit or control of the flow of current

- Insulators = Materials that do not easily give off electrons (Rubber, glass)

- Conductors = material that give off electrons (Copper, silver)

Explain Ohm's Law

I = V/R

V = IR

Explain a capacitor

A device which controls electricity by regulating the flow of AC. Stores electrical charge which opposes any change in current (Capacitance). Farads (C)

- Constructed by sandwiching an insulating material between two conductors

What is grounding

A pathway for electrons to flow into the earth or ground. Grounding prevents electrocution when your body is a circuit

Why are 3 prong plugs safer than 2 prong plugs?

-

What are the effects of a 60Hz electrical shock?

- Impacted myocardium function (TMP of 60mV)

- Lowers RMP by 15-20mV leading to spontaneous reversal of the TMP.

When the heart the most vulnerable to electrical shock

Apex of the T-wave

What Current is the lethal zone?

50ma - 2.5 amp

What are the methods of electrical shock? (3)

- Victim in series

- Victim in parallel as a common path to ground

- "Hot" Chassis