Stephanie Pitcher

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What is a Sensor?

• Stephanie Pitcher
• GK-12

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SENSORS

• Are devices capable of detecting change
• Temperature
• Pressure
• Humidity
• Speed
• And Many more
• There are many types of sensors used for various
  applications that detect different types of
  measurands
• Example
• Area of application
• Environment monitor air pollution
• Type of measurands
• Chemical gas type and concentration
• Thermal temperature

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HUMAN SENSESVision, hearing, smell, taste,
touch

• Human senses help detect change
• How they enhance our ability to detect change
• Your senses consist of a very narrow band of what
  is possible, but there are devices that help
  people sense things beyond their capabilities or
  limitations
• Examples
• Each of our senses need a certain amount of
  energy to work properly
• Light must be a certain brightness to see
• sound must be loud enough to hear
• 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.

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HUMAN VISION

• Human Eye 4,100Å (violet) to 6,600Å (red)
• (400-600nm)

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VISION TESTS
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VISION SENSORS

• Importance Sight is limited to the visible light
  spectrum
• Devices are used to detect waves beyond the human
  range
• Night vision goggles creates images in the
  infra-red range
• X-ray machines creates images with the very
  short x-ray wavelengths
• There are environmental parameters that are
  important to our welfare and survival that cannot
  be sensed by the human senses
• An example radioactivity, UV exposure, etc.

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SOUND SENSORS

• Importance human hearing is limited
• Microphones can detect sound at extremely low
  volumes
• Ultrasound devices detect sounds at very high
  frequencies
• Communication
• Whales, submarines

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SMELL SENSORS

• Human smell is limited to a certain number of
  chemical compounds in the air
• Electronic Noses
• Air quality (NASA project, industry medical)
• Foods (fish, fruit, etc.)
• Wines
• Smoke detectors
• There are environmental parameters that are
  important to our welfare and survival that cannot
  be sensed by the human senses examples
• carbon monoxide, radon, etc.

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HUMAN BODY-TASTE-

• There are four tastes that can be recognized by
  the tongue sweet, sour, bitter, and salty.
• Most of what we experience as taste is actually
  from our sense of smell.
• Particular scents and tastes are due to different
  molecules that bind to smell and taste receptors.
  
• Our smell receptors can recognize thousands of
  different scent molecules.

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TASTE SENSORS

• Human taste requires direct contact with the
  compound
• Taste sensor
• Example Litmus paper can tell if a compound is
  acidic or a base
• Water quality (sensors that sample the water)
• -pollution, ecoli, etc.
• Fish freshness
• Females have more taste buds than males
• Taste is the weakest of the five senses

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FEEL SENSORS

• Humans can detect change in temperature relative
  to the environment
• A human or a sensor needs to be "calibrated."
  There are differences between people and between
  cultures in the way the human "sensors" are
  "calibrated." For example, an Eskimo might call a
  room "too hot" that a person from New York calls
  "just right."
• Sensors relating to - pressure, temperature and
  gravity
• Thermometers, wind speed, motion detectors, etc.
• Magnetic field sensors
• Some birds and fish can sense the earths
  magnetic field, humans seem unable to (we use
  compasses)
• Electric Fields
• Sharks and eels seem to be able to, humans cannot
  (electrometers)

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IMPORTANCE OF SENSORS

• There are inventions or devices that can extend
  the human physical senses of sight, hearing,
  taste, smell, touch (pressure, temperature and
  gravity).
• To appreciate the role of the environmental
  sensors by considering them as an extension of
  human senses. Sensors sense the same phenomena as
  human senses, but
• they are there 24 hours a day
• they are there 365 days a year
• their measurements are more precise (sensitive
  selective)
• their measurements are reproducible

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SENSORS IN EVERYDAY LIFE

• Automobiles
• Cell Phones
• Remote Controls
• Traffic Lights
• Appliances (stove, refrigerator, furnace,
  thermometer)
• Motion Sensors
• Smoke Detectors
• Gas Detectors

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VERNIER LABPRO O2 SENSOR
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VERNIER LABPRO O2 SENSOR

• How it works
• O2 Gas Sensor measures oxygen levels using an
  electrochemical sensor (meaning it detects a
  chemical change by measuring electrical
  properties)
• Chemical reaction generates a current that is
  proportional to the oxygen level ? current is
  measured across a resistance to generate a small
  voltage output ? voltage output is conditioned
  and read by the Vernier interface

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Questions???