Stephanie PitcherStephanie PitcherGK-12GK-12

SENSORSSENSORS

Are devices capable of detecting change:Are devices capable of detecting change: TemperatureTemperature PressurePressure HumidityHumidity SpeedSpeed And Many more …And Many more …

There are many types of sensors used for various There are many types of sensors used for various applications that detect different types of measurandsapplications that detect different types of measurands Example:Example:

Area of applicationArea of application Environment – monitor air pollutionEnvironment – monitor air pollution

Type of measurandsType of measurands Chemical – gas type and concentrationChemical – gas type and concentration Thermal – temperature Thermal – temperature

HUMAN SENSESHUMAN SENSES[Vision, hearing, smell, taste, touch][Vision, hearing, smell, taste, touch]

Human senses help detect changeHuman senses help detect change How they enhance our ability to detect changeHow they enhance our ability to detect change

Your senses consist of a very narrow band of what is possible, Your senses consist of a very narrow band of what is possible, but there are devices that help people sense things beyond but there are devices that help people sense things beyond their capabilities or limitationstheir capabilities or limitations

Examples:Examples: Each of our senses need a certain amount of energy to work properly Each of our senses need a certain amount of energy to work properly

Light must be a certain brightness to see Light must be a certain brightness to see sound must be loud enough to hearsound must be loud enough to hear The pressure on our skin must be great enough to feel. The skin must be The pressure on our skin must be great enough to feel. The skin must be

sensitive enough to detect the difference in temperature--hot or cold. sensitive enough to detect the difference in temperature--hot or cold.

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HUMAN VISIONHUMAN VISION

Human Eye 4,100Human Eye 4,100Å (violet) to Å (violet) to 6,6006,600Å (red)Å (red)

(400-600nm)(400-600nm)

VISION TESTSVISION TESTS

““VISION” SENSORSVISION” SENSORS

Importance:Importance: Sight is limited to the visible light spectrum Sight is limited to the visible light spectrum Devices are used to detect waves beyond the human rangeDevices are used to detect waves beyond the human range

Night vision goggles – creates images in the infra-red rangeNight vision goggles – creates images in the infra-red range

X-ray machines – creates images with the very short x-ray X-ray machines – creates images with the very short x-ray wavelengthswavelengths

There are environmental parameters that are important to our There are environmental parameters that are important to our welfare and survival that cannot be sensed by the human welfare and survival that cannot be sensed by the human senses senses An example: radioactivity, UV exposure, etc.An example: radioactivity, UV exposure, etc.

SOUND SENSORSSOUND SENSORS

Importance:Importance: human hearing is limited human hearing is limited

Microphones can detect sound at extremely low Microphones can detect sound at extremely low volumesvolumes

Ultrasound devices detect sounds at very high Ultrasound devices detect sounds at very high frequenciesfrequencies

CommunicationCommunication Whales, submarinesWhales, submarines

SMELL SENSORSSMELL SENSORS

Human smell is limited to a certain number of chemical Human smell is limited to a certain number of chemical compounds in the aircompounds in the air

Electronic NosesElectronic Noses Air quality (NASA project, industry – medical)Air quality (NASA project, industry – medical) Foods (fish, fruit, etc.)Foods (fish, fruit, etc.) WinesWines

Smoke detectorsSmoke detectors

There are environmental parameters that are important to There are environmental parameters that are important to our welfare and survival that cannot be sensed by the our welfare and survival that cannot be sensed by the human senses examples:human senses examples: carbon monoxide, radon, etc.carbon monoxide, radon, etc.

HUMAN BODYHUMAN BODY-TASTE--TASTE-

There are four tastes that can be recognized by There are four tastes that can be recognized by the tongue: sweet, sour, bitter, and salty.the tongue: sweet, sour, bitter, and salty.

Most of what we experience as taste is actually Most of what we experience as taste is actually from our sense of smell.from our sense of smell.

Particular scents and tastes are due to different Particular scents and tastes are due to different molecules that bind to smell and taste receptors. molecules that bind to smell and taste receptors.

Our smell receptors can recognize thousands of Our smell receptors can recognize thousands of different scent molecules. different scent molecules.

TASTE SENSORSTASTE SENSORS

Human taste requires direct contact with the Human taste requires direct contact with the compoundcompound

Taste sensor Taste sensor Example: Litmus paper – can tell if a compound is acidic or a Example: Litmus paper – can tell if a compound is acidic or a

basebase Water quality (sensors that sample the water)Water quality (sensors that sample the water)

-pollution, ecoli, etc.-pollution, ecoli, etc. Fish freshnessFish freshness

Females have more taste buds than males Females have more taste buds than males Taste is the weakest of the five sensesTaste is the weakest of the five senses

FEEL SENSORSFEEL SENSORS

Humans can detect change in temperature relative Humans can detect change in temperature relative to the environmentto the environment A human or a sensor needs to be "calibrated." There are differences A human or a sensor needs to be "calibrated." There are differences

between people and between cultures in the way the human between people and between cultures in the way the human "sensors" are "calibrated." For example, an Eskimo might call a room "sensors" are "calibrated." For example, an Eskimo might call a room "too hot" that a person from New York calls "just right." "too hot" that a person from New York calls "just right."

Sensors relating to - pressure, temperature and gravitySensors relating to - pressure, temperature and gravity Thermometers, wind speed, motion detectors, etc.Thermometers, wind speed, motion detectors, etc.

Magnetic field sensorsMagnetic field sensors Some birds and fish can sense the earth’s magnetic field, humans Some birds and fish can sense the earth’s magnetic field, humans

seem unable to (we use compasses)seem unable to (we use compasses) Electric FieldsElectric Fields

Sharks and eels seem to be able to, humans cannot (electrometers)Sharks and eels seem to be able to, humans cannot (electrometers)

IMPORTANCE OF SENSORSIMPORTANCE OF SENSORS

There are inventions or devices that can extend the There are inventions or devices that can extend the human physical senses of sight, hearing, taste, smell, human physical senses of sight, hearing, taste, smell, touch (pressure, temperature and gravity).touch (pressure, temperature and gravity).

To appreciate the role of the environmental sensors by To appreciate the role of the environmental sensors by considering them as an extension of human senses. considering them as an extension of human senses. Sensors sense the same phenomena as human Sensors sense the same phenomena as human senses, but: senses, but: they are there 24 hours a day they are there 24 hours a day they are there 365 days a yearthey are there 365 days a year their measurements are more precise (sensitive & selective)their measurements are more precise (sensitive & selective) their measurements are reproducible their measurements are reproducible

SENSORS IN EVERYDAY LIFESENSORS IN EVERYDAY LIFE

AutomobilesAutomobiles Cell PhonesCell Phones Remote ControlsRemote Controls Traffic LightsTraffic Lights Appliances (stove, refrigerator, furnace, Appliances (stove, refrigerator, furnace,

thermometer)thermometer) Motion SensorsMotion Sensors Smoke DetectorsSmoke Detectors Gas DetectorsGas Detectors

VERNIER LABPRO OVERNIER LABPRO O22 SENSOR SENSOR

VERNIER LABPRO OVERNIER LABPRO O22 SENSOR SENSOR

How it worksHow it works OO22 Gas Sensor Gas Sensor measures oxygen levels using an measures oxygen levels using an

electrochemical sensor (electrochemical sensor (meaning it detects a meaning it detects a chemical change by measuring electrical propertieschemical change by measuring electrical properties))

Chemical reaction generates a current that is proportional Chemical reaction generates a current that is proportional to the oxygen level to the oxygen level current is measured across a current is measured across a resistance to generate a small voltage output resistance to generate a small voltage output voltage voltage output is conditioned and read by the Vernier interfaceoutput is conditioned and read by the Vernier interface

Questions???Questions???