测量与信号基础英文PPT (37).pdf

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1、Appendix C Introduction to Arduino8.1 Overview of sensor technology8.2 Resistive sensor8.3 Inductive sensor8.4 Capacitance sensor8.5 Magnetoelectric tranducer8.6 Piezoelectric transducer8.7 Hall sensorChapter 8 Principles of sensorsFundamentals of Measurement and Signal Analysis8.8 Photoelectric sen

2、sor8.9 Image sensor8.10 Thermocouple8.11 Fiberoptic sensor8.12 Grating8.13 Biosensor8.14 How to select a sensor8.2 Resistive sensor2.Other resistive sensors1）Resistance thermometer(resistance temperature detector,RTD)It is made of metal wires,typically platinum,nickel and copper.Its resistance chang

3、es with temperature.Relationship between platinum resistance and temperature:(0640)1(20BtAtRRt)100(1 320ttCBtAtRRt(2400)8.2 Resistive sensor2）ThermistorIt is made of ceramic or polymer materials.Its resistance changes with temperature.It can be divided into three categories:positive temperature coef

4、ficient thermistor(PTC),negative temperature coefficient thermistor(NTC),critical temperature coefficient thermistor(CTR).NTC 0-100C,R=10K-5008.2 Resistive sensorExample:Measuring resistance of a thermistor8.2 Resistive sensorExample:Temperature controlled fan8.2 Resistive sensorResistive temperatur

5、e sensors are widely used in daily life,including:thermometers,air conditionings,refrigerators,rice cookers,electric fans and computers.8.2 Resistive sensor3）PhotoresistorWhen the semiconductor material is exposed to light,under the effect of light quantum,it absorbs energy and releases electrons in

6、side,which increases the carrier density or mobility,and leads to an increase in conductivity and a decrease in resistance.The stronger the light,the lower the resistance.1-100lux R:100K-2k8.2 Resistive sensorExample:Photoresistance measurement8.2 Resistive sensorPhotoresistor sensors have been wide

7、ly used in life/work.8.2 Resistive sensorExample:LED controlled by photoresistor8.2 Resistive sensorDIY:measuring the gravitational acceleration with a pendulumgL2T LT224g8.2 Resistive sensor4）MagnetoresistorIt uses the magnetoresistance effect of semiconductor materials,such as InSb or InAs.When th

8、e magnitude or direction of the magnetic field changes,the resistance or the magnetoresistor will also change.mRRObC0HHNS8.2 Resistive sensorApplication of magnetoresistor:Electronic compass:magnetoresistive sensor+fluxgate8.2 Resistive sensorApplication of magnetoresistor:8.2 Resistive sensorExampl

9、e:Measuring bicycle speed by magnetoresistorMagnet+magnetoresistive sensor8.2 Resistive sensor5)Gas-sensitive resistive sensorThe detection of gas is an indispensable way to protect and improve the ecological environment,in which gas sensors play an important role.If the concentration of carbon mono

10、xide in the living environment reaches 0.8 to 1.15 ml/L,shortness of breath,rapid pulse,and even syncope may occur.The gas sensors can also be used in the detection of flammable,explosive gases,alcohol,etc.CO2 sensorAlcohol sensorSmoke detector8.2 Resistive sensorMQ-135 air quality sensorGas sensors

11、 are made of gas-sensitive semiconductor materials,such as tin oxide and manganese oxide.When they absorb carbon monoxide,carbon dioxide,etc.,a chemical reaction will occur,releasing heat,increasing the temperature of the element and changing the resistance.8.2 Resistive sensorMQ-3 alcohol sensor8.2

12、 Resistive sensorGas leakage detectorSmoke detectorDrunk driving test8.2 Resistive sensorExample:Gas leakage detection8.1 Overview of sensor technologyHomework1.Please list resistive sensor modules that can be find on the Internet,and summarize their functions and prices.2.Choose two types of resistive sensors(such as thermistor,photoresistor),try to use Arduino to do some measurements.