1. Stephanie Pitcher
GK-12

2. 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

3. HUMAN SENSES
[Vision, 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.

4. HUMAN VISION
 Human Eye 4,100Å (violet) to 6,600Å (red)
(400-600nm)
http://www.predictive-maintenance.com/electrical.html

5. VISION TESTS

6. “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.

7. 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

8. 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.

9. 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.

10. 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

11. 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 earth’s magnetic field, humans
seem unable to (we use compasses)
 Electric Fields
 Sharks and eels seem to be able to, humans cannot (electrometers)

12. 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

13. SENSORS IN EVERYDAY LIFE
 Automobiles
 Cell Phones
 Remote Controls
 Traffic Lights
 Appliances (stove, refrigerator, furnace,
thermometer)
 Motion Sensors
 Smoke Detectors
 Gas Detectors

14. VERNIER LABPRO O2 SENSOR

15. 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

16. Questions???