Lecture 3 Flashcards
Converts energy from one form to another
transducer
Converts physical parameter to electrical output
sensor
Interested in converting three physiological events to electrical signals
chemical, thermal, mechanical
advantage of electrical signal:
facilitates storage and subsequent data processing
Refers to the ability of a transducer to produce an output signal that is directly proportional to the input amplitude
Amplitude linearity
measures the ability of the transducer to produce an output that follows the input independently of a direction change of input
Hysteresis
Apply physiologic event of known amplitude
calibration
sensor is precalibrated at factory
standization
Resistive Sensors: resistance depends on:
material properties, geometric configuration, and temperature
Change in resistance is converted to:
Change in voltage
Resistance changes with change in______ with strain gauges.
geometry
Resistive element is cemented onto a packing approx. the size of postage stamp. The backing is then cemented onto the structure to be deformed.
bonded strain gauge
resistance wire is stretched between supporting members
unbounded
R = (Formula)
pL/A
strain=(Formula)
(L-L0)/L0
true strain=(formula)
ln(L/L0)
Actual displacement in a strain gauge is dependent on the ______of the gauge wire
material properties
Maximum strain=(formula)
f/E
Change in R/ R =
Gf/E or G*dL/L
Strain gauges output varies as a function of:
temperature
generally use strain gauges in ____ in a bridge circuit
in pairs
the second gauge in a wheatstone is subjected to ______ variation but not _______
temperature; strain
A wheatstone bridge minimizes ______ and increases______
thermal effects; output(4x)
