This document discusses sensors and how they relate to and extend human senses. It describes how sensors can detect changes in measurements like temperature, pressure, humidity, and other variables that human senses are limited in detecting. Sensors allow detection of phenomena beyond the visible light and audible sound spectra. Sensors provide measurements continuously unlike intermittent human sensing, and often with more precision and reproducibility. Sensors are found in many everyday devices and applications like cars, phones, appliances, and environmental monitoring to extend sensing capabilities.

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???