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

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. -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 O 2 SENSOR

15.  How it works  O 2 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???