Sensors
ElectronicsResistive Sensors
Terry Sturtevant
Wilfrid Laurier University
May 31, 2017
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Introduction to transducers
convert one form of energy to anotherelectrical input transducer;output is some form of electrical property(i,v,r,c,l,nu, etc.)input transducer = sensoroutput transducer = actuator
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Introduction to transducers
convert one form of energy to another
electrical input transducer;output is some form of electrical property(i,v,r,c,l,nu, etc.)input transducer = sensoroutput transducer = actuator
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Introduction to transducers
convert one form of energy to anotherelectrical input transducer;
output is some form of electrical property(i,v,r,c,l,nu, etc.)input transducer = sensoroutput transducer = actuator
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Introduction to transducers
convert one form of energy to anotherelectrical input transducer;output is some form of electrical property
(i,v,r,c,l,nu, etc.)input transducer = sensoroutput transducer = actuator
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Introduction to transducers
convert one form of energy to anotherelectrical input transducer;output is some form of electrical property(i,v,r,c,l,nu, etc.)
input transducer = sensoroutput transducer = actuator
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Introduction to transducers
convert one form of energy to anotherelectrical input transducer;output is some form of electrical property(i,v,r,c,l,nu, etc.)input transducer = sensor
output transducer = actuator
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Introduction to transducers
convert one form of energy to anotherelectrical input transducer;output is some form of electrical property(i,v,r,c,l,nu, etc.)input transducer = sensoroutput transducer = actuator
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistive sensors
A resistive sensor is a resistor which changes according to somephysical change in its environment. Some examples would be:
Potentiometer; the resistance varies with physical movementPhotoresistor; the resistance varies with lightThermistor; the resistance varies with heatStrain gauge (or gage); the resistance varies with stress orcompressionForce-dependent resistor; the resistance varies with appliedpressure
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistive sensors
A resistive sensor is a resistor which changes according to somephysical change in its environment.
Some examples would be:Potentiometer; the resistance varies with physical movementPhotoresistor; the resistance varies with lightThermistor; the resistance varies with heatStrain gauge (or gage); the resistance varies with stress orcompressionForce-dependent resistor; the resistance varies with appliedpressure
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistive sensors
A resistive sensor is a resistor which changes according to somephysical change in its environment. Some examples would be:
Potentiometer; the resistance varies with physical movementPhotoresistor; the resistance varies with lightThermistor; the resistance varies with heatStrain gauge (or gage); the resistance varies with stress orcompressionForce-dependent resistor; the resistance varies with appliedpressure
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistive sensors
A resistive sensor is a resistor which changes according to somephysical change in its environment. Some examples would be:
Potentiometer;
the resistance varies with physical movementPhotoresistor; the resistance varies with lightThermistor; the resistance varies with heatStrain gauge (or gage); the resistance varies with stress orcompressionForce-dependent resistor; the resistance varies with appliedpressure
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistive sensors
A resistive sensor is a resistor which changes according to somephysical change in its environment. Some examples would be:
Potentiometer; the resistance varies with physical movement
Photoresistor; the resistance varies with lightThermistor; the resistance varies with heatStrain gauge (or gage); the resistance varies with stress orcompressionForce-dependent resistor; the resistance varies with appliedpressure
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistive sensors
A resistive sensor is a resistor which changes according to somephysical change in its environment. Some examples would be:
Potentiometer; the resistance varies with physical movementPhotoresistor;
the resistance varies with lightThermistor; the resistance varies with heatStrain gauge (or gage); the resistance varies with stress orcompressionForce-dependent resistor; the resistance varies with appliedpressure
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistive sensors
A resistive sensor is a resistor which changes according to somephysical change in its environment. Some examples would be:
Potentiometer; the resistance varies with physical movementPhotoresistor; the resistance varies with light
Thermistor; the resistance varies with heatStrain gauge (or gage); the resistance varies with stress orcompressionForce-dependent resistor; the resistance varies with appliedpressure
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistive sensors
A resistive sensor is a resistor which changes according to somephysical change in its environment. Some examples would be:
Potentiometer; the resistance varies with physical movementPhotoresistor; the resistance varies with lightThermistor;
the resistance varies with heatStrain gauge (or gage); the resistance varies with stress orcompressionForce-dependent resistor; the resistance varies with appliedpressure
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistive sensors
A resistive sensor is a resistor which changes according to somephysical change in its environment. Some examples would be:
Potentiometer; the resistance varies with physical movementPhotoresistor; the resistance varies with lightThermistor; the resistance varies with heat
Strain gauge (or gage); the resistance varies with stress orcompressionForce-dependent resistor; the resistance varies with appliedpressure
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistive sensors
A resistive sensor is a resistor which changes according to somephysical change in its environment. Some examples would be:
Potentiometer; the resistance varies with physical movementPhotoresistor; the resistance varies with lightThermistor; the resistance varies with heatStrain gauge (or gage);
the resistance varies with stress orcompressionForce-dependent resistor; the resistance varies with appliedpressure
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistive sensors
A resistive sensor is a resistor which changes according to somephysical change in its environment. Some examples would be:
Potentiometer; the resistance varies with physical movementPhotoresistor; the resistance varies with lightThermistor; the resistance varies with heatStrain gauge (or gage); the resistance varies with stress orcompression
Force-dependent resistor; the resistance varies with appliedpressure
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistive sensors
A resistive sensor is a resistor which changes according to somephysical change in its environment. Some examples would be:
Potentiometer; the resistance varies with physical movementPhotoresistor; the resistance varies with lightThermistor; the resistance varies with heatStrain gauge (or gage); the resistance varies with stress orcompressionForce-dependent resistor;
the resistance varies with appliedpressure
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistive sensors
A resistive sensor is a resistor which changes according to somephysical change in its environment. Some examples would be:
Potentiometer; the resistance varies with physical movementPhotoresistor; the resistance varies with lightThermistor; the resistance varies with heatStrain gauge (or gage); the resistance varies with stress orcompressionForce-dependent resistor; the resistance varies with appliedpressure
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Here’s an example of how a strain gauge works.
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistance
R = ρ LA
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistance
6
?
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistance
6
?
R ′ = ρ (L−∆L)(A+∆A) < R
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistance
R = ρ LA
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistance -?
6
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistance -?
6
R ′ = ρ (L+∆L)(A−∆A) > R
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Thermistors
Resistance
(Ω)
Temperature (C)
This is the resistance/temperature curve for a thermistor.
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Thermistors
Resistance
(Ω)
Temperature (C)
(High temperature; Rmin)
This is the resistance/temperature curve for a thermistor.
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Thermistors
Resistance
(Ω)
Temperature (C)
(High temperature; Rmin)
(Low temperature; Rmax )
This is the resistance/temperature curve for a thermistor.
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
Resistive sensors in voltage dividers
R1 I
R2 I
Vin
Vout = Vin(
R2R1+R2
)
True if Iout ≡ 0
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
If we want to put a variable resistor in a voltage divider, thenwe need to choose the other resistor.
To make the output vary over as large a range as possible asthe variable resistor goes from Rmin to Rmax , it turns out wewant to choose the other resistor, R so thatR =
√Rmin × Rmax
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
If we want to put a variable resistor in a voltage divider, thenwe need to choose the other resistor.To make the output vary over as large a range as possible asthe variable resistor goes from Rmin to Rmax , it turns out wewant to choose the other resistor, R so that
R =√
Rmin × Rmax
Terry Sturtevant Electronics Resistive Sensors
Sensors Resistive sensorsResistive sensors in voltage dividers
If we want to put a variable resistor in a voltage divider, thenwe need to choose the other resistor.To make the output vary over as large a range as possible asthe variable resistor goes from Rmin to Rmax , it turns out wewant to choose the other resistor, R so thatR =
√Rmin × Rmax
Terry Sturtevant Electronics Resistive Sensors