2 The Smart “Things” in IoT
57
changes. The system can take automatic action such as regulating the music level
or notifying authorities.
• Pressure Sensor – A typical pressure sensor comprises a pressure-sensitive element to determine the actual pressure applied to the sensor and some components
to convert the sensed pressure into an output signal. Examples of pressuresensitive elements that have been examined in the literature are the metal strain
gauges that are glued together, capacitance variable cavity and diaphragm, and
silicon diaphragm with integrated strain.
• Barometer – Quantifies atmospheric pressure.
• Altimeter – Measures altitude of an object above a certain designated level.
• Acoustic Sound Sensors – Measure and convert the level of sound into a digital
or analog signal, for example, hydrophone, microphone, and geophone.
• Radiation Sensors – Measure radiation in the environment through ionization or
scintillating detection.
• Biosensors – Detect biological components including enzymes, antibodies,
organisms, cells, tissues, and nucleic acid.
• Ohmmeter – Quantifies resistance.
• Voltmeter – Calculates the voltage.
• Galvanometer – Determines current.
• Watt-Hour Meter – Measures electrical energy provided to and consumed by a
business or residence.
• Oxygen Sensor – Calculates the percentage of oxygen present in a liquid or gas.
• Carbon Dioxide Detector – Recognizes the presence of CO2.
• Light Sensor (Photodetector) – Perceives light as well as electromagnetic energy.
• Photocells (Photoresistor) – Resistor affected by ambient light intensity changes.
• Infrared Sensor – Recognizes infrared radiation.
• Seismometer – Measures seismic waves.
• Acoustic Wave Sensor – Calculates wave velocity to recognize chemicals present.
• Air Pollution Sensors – These sensors generally monitor five main air pollutants
including nitrous oxide, ozone, sulfur dioxide, particulates, and carbon monoxide.
• Infrared Sensors – Monitor an object’s movement by generating and receiving
infrared heat waves.
• Moisture and Humidity Sensors (Hygrometer Sensors) – Measure and record air
humidity using electrical capacitance.
• Speed Sensors – Often used to detect vehicle speeds. Examples include laser
surface velocimeter, speedometers, Doppler radar, and wheel speed sensors.
• Accelerometer – Small device that detects static (i.e., gravity) and dynamic
acceleration (i.e., starting/stopping). These sensors are most often used in tilt
sensing (or stop sensing) because they react to gravity and tell you how
something is oriented in relation to the Earth’s surface. For example, Apple’s
iPhone uses an accelerometer to detect if the phone is being held in landscape or
portrait mode. Accelerometers are also capable of sensing motion. For example,
Nintendo’s Wiimote can sense the imitated forehand or backhand tennis racket
motion or the motion of rolling a bowling ball. This device is also able to sense
57
changes. The system can take automatic action such as regulating the music level
or notifying authorities.
• Pressure Sensor – A typical pressure sensor comprises a pressure-sensitive element to determine the actual pressure applied to the sensor and some components
to convert the sensed pressure into an output signal. Examples of pressuresensitive elements that have been examined in the literature are the metal strain
gauges that are glued together, capacitance variable cavity and diaphragm, and
silicon diaphragm with integrated strain.
• Barometer – Quantifies atmospheric pressure.
• Altimeter – Measures altitude of an object above a certain designated level.
• Acoustic Sound Sensors – Measure and convert the level of sound into a digital
or analog signal, for example, hydrophone, microphone, and geophone.
• Radiation Sensors – Measure radiation in the environment through ionization or
scintillating detection.
• Biosensors – Detect biological components including enzymes, antibodies,
organisms, cells, tissues, and nucleic acid.
• Ohmmeter – Quantifies resistance.
• Voltmeter – Calculates the voltage.
• Galvanometer – Determines current.
• Watt-Hour Meter – Measures electrical energy provided to and consumed by a
business or residence.
• Oxygen Sensor – Calculates the percentage of oxygen present in a liquid or gas.
• Carbon Dioxide Detector – Recognizes the presence of CO2.
• Light Sensor (Photodetector) – Perceives light as well as electromagnetic energy.
• Photocells (Photoresistor) – Resistor affected by ambient light intensity changes.
• Infrared Sensor – Recognizes infrared radiation.
• Seismometer – Measures seismic waves.
• Acoustic Wave Sensor – Calculates wave velocity to recognize chemicals present.
• Air Pollution Sensors – These sensors generally monitor five main air pollutants
including nitrous oxide, ozone, sulfur dioxide, particulates, and carbon monoxide.
• Infrared Sensors – Monitor an object’s movement by generating and receiving
infrared heat waves.
• Moisture and Humidity Sensors (Hygrometer Sensors) – Measure and record air
humidity using electrical capacitance.
• Speed Sensors – Often used to detect vehicle speeds. Examples include laser
surface velocimeter, speedometers, Doppler radar, and wheel speed sensors.
• Accelerometer – Small device that detects static (i.e., gravity) and dynamic
acceleration (i.e., starting/stopping). These sensors are most often used in tilt
sensing (or stop sensing) because they react to gravity and tell you how
something is oriented in relation to the Earth’s surface. For example, Apple’s
iPhone uses an accelerometer to detect if the phone is being held in landscape or
portrait mode. Accelerometers are also capable of sensing motion. For example,
Nintendo’s Wiimote can sense the imitated forehand or backhand tennis racket
motion or the motion of rolling a bowling ball. This device is also able to sense