certificates. PKI works as an arrangement that combines public keys with particular user iden-
tities with the help of a certificate authority.
A Certificate Authority works as a company or a trusted third-party organizer that is respon-
sible for issuing digital certificates utilized in creating public-private key pairs and digital signa-
tures. The work of a Certificate Authority is to ensure that the individual unique certificate is the
same as he or she claims it to be. This means that the Certificate Authority has contact with a
financial organization like a credit card company, which is responsible for providing accurate
information to confirm the claimed identity of an individual. Certificate Authorities stand as the
most important component in electronic commerce and data security. They eectively guarantee
that the two parties exchanging information to each other are actually who they claim to be.
An X.509 certificate consists of information related to the identity to which a certificate
has been issued. This eectively establishes a foundation of trust that is based on cryptographic
verification. This certificate is also often referred to as SSL (Secure Socket Layer). However, this
term is not valid as X509 certificates are just individual part of SSL.
The information that is included in an X.509 certificate:
1. Version: This version applies to the certificate (This tells us what data the certificate
must consist of).
2. Serial number: This serial number will distinguish it from the other certificates.
3. Algorithm information: The algorithm information is utilized by the issuer to sign the
certificate.
4. Issuer distinguished name: The name of the entity which is responsible for issuing the
certificate is also important.
5. The validity period of the certificate: This will include the start/end date and time.
6. Subject distinguished name: This will include the name of the identity to which the cer-
tificate is issued.
7. Subject public key information: The public key information is related to identity.
SENSORS
Internet of Things platforms operate and provide several data and intelligence features with
the help of sensors. Sensors collect data, forward it ahead, and share it with other IoT modules.
Following are some of the sensor types that are used in IoT.
Temperature Sensors
A temperature sensor is a device that is used to determine the exact amount of heat energy in
order to detect physical temperature changes from a source and converts that data for a user or
a device.
Before the emergence of IoT, temperature sensors were used in refrigerators, air conditioners,
and other home appliances. With the advent of IoT, they are used in agriculture, health, and man-
ufacturing industry. Among the sub-categories of temperature sensors, some are the following.
• Thermistor,
• Resistor temperature detectors,
• IC, and
• Infrared sensors.
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Proximity Sensor
A proximity sensor is used to detect an object’s absence or presence. This information is
then converted into a signal and forwarded to a user. In IoT, these sensors are widely utilized in
the retail domain. When a customer in a retail outlet comes closer to a specific product, then
they can receive special oers and discounts related to that product via the sensor. Following are
some of the types of proximity sensors.
• Capacitive sensors,
• Photoelectric sensors, and
• Ultrasonic sensors.
Pressure Sensor
A pressure sensor is used to detect pressure so it can be converted into an electrical signal. Many
devices depend on liquid or other pressure forms. With the use of a pressure sensor, an IoT
application can assess devices that are propelled by pressure. Whenever any change is discov-
ered that is dierent from the standard range, it alerts the relevant authorities about any possible
issue. These sensors are deployed mainly in manufacturing. In addition, they are also utilized to
maintain water and heating systems to identify fluctuations in pressure.
Water Quality Sensor
A water quality sensor is a device that is used to identify the quality of water and monitors ion
in water distribution systems. Some of the water sensors are the following.
• Total organic carbon sensor: It is used to determine the water’s organic element.
• Chlorine residual sensor: It is used to determine any possible chlorine residual in the
water. Due to this reason, it is largely used for disinfectants.
• Turbidity sensor: It is used to determine water’s suspended solids. Mostly, it is used for
stream and river gauging.
• pH sensor: To find the pH level in the dissolved water, the pH sensor is used to determine
its acidity or alkalinity.
Quick Challenge
Come up with a project that can be implemented in a rural area to improve drinking water
quality? All these sensors data should go to the central management console so the quality
can be tracked. Also, this data can be used in detailed analysis for various policies making
process?
Quick Challenge
Describe a project where you can utilize a pressure sensor and make sure you explain the
benefits of using it?
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Chemical Sensor
In IoT, chemical sensors are used in various industries. The objective of a chemical sensor is to
check for liquid changes or to discover chemical changes. These sensors are often used in urban
areas to find chemical changes in order to improve the health of residents.
Chemical sensors are used in the controlling and monitoring of the industrial environment
and detecting harmful chemicals and radioactive materials in laboratories and pharmaceutical
companies. Interestingly, they are also used in space stations where they provide assistance in
the recycling processes.
Gas Sensor
Gas sensors bear similarity to the chemical sensors. They dier in their purpose where they are
used to identify changes in the quality of air and verify the presence of dierent gases. These
sensors are used to detect combustible and toxic gas, assess gas levels in coal mines to identify
hazardous gases, and maintain air quality through monitoring. Some of the gas sensor types
are the following.
• Breathalyzer,
• Catalytic bead sensor,
• Air pollution sensor,
• Oxygen sensor,
• Ozone monitor,
• Gas detector,
• Air pollution sensor, and
• Carbon monoxide detector.
Smoke Sensor
A smoke sensor is used to detect smoke levels in the atmosphere. While these sensors
have been extensively used in different applications, in IoT, they have been integrated
with home automation systems and industrial setups where they alert users about any
issue instantly.
Smoke sensors are used in HVAC, manufacturing, and buildings for gas and fire detection.
As a result, they help to save lives for those professionals who work in dangerous workplaces.
Smoke sensors discover gases, flame, or smoke by two methods.
1. Optical smoke sensor: This type of smoke sensor operates on the basis of the light
scattering principle.
2. Ionization smoke sensor: This type of smoke sensor operates on the basis of the light
ionization.
IR Sensors
An IR (infrared) sensor is used to detect dierent properties of a surrounding. This is done by
detecting or emitting infrared radiation. Moreover, this sensor can also assess the emitted heat
from other objects. IR sensors are utilized in dierent types of IoT applications. One of their
uses is in the healthcare industry where they help with blood pressure and blood flow monitor-
ing. They are also used in home automation systems as remote controls. Moreover, Infrared
vision helps to view heat leaks in electronic appliances.
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Level Sensors
Level sensors are used to assess the amount or level of liquids, fluids, and similar elements, which
flow in a closed or open system. They are used in the following:
• To measure the levels of fuel.
• In businesses where there is heavy use of liquid materials. For instance, it is used in the
alcohol, juice, and the recycling industry.
• They are also used for tsunami warnings, medical equipment, hydraulic reservoirs, water
reservoirs, compressors, and sea level monitoring.
To measure levels, there are two sensor types:
• Point level sensors: It is used to determine a specific level to alert users instantly through
a trigger or alarm.
• Continuous level sensor: It is used to check dry material or liquid levels in a defined
range and “continuously” show outputs for the specified levels.
Image Sensors
An image sensor is used for the conversion of optical images into electronic signals to store or
display files in an electronic format. They are often used in medical imaging, digital cameras,
thermal imaging devices, sonar, radar, night vision equipment, IRIS, and biometric services.
Some of their use cases are the following.
• They are used in the car industry to identify obstacles, signs, and similar objects to assist
drivers on the road. Therefore, they carry huge importance in IoT due to their contribu-
tion toward driverless cars.
• Modern IoT security systems use these sensors to capture a criminal’s details.
• For retail businesses, they gather customer data such as gender, age, and race so business
owners can use it to improve their products and services.
Quick Challenge
List 5 different real-life implementations of IR sensors.
Can you use image sensors to improve quality of service in a Hospital environment?
Explain how.
Flash Question
Motion Detection Sensors
A motion detector is used to determine any physical motion of an object or human being. This
is why they are heavily used in IoT security systems to protect homes and oces. Some of their
applications are the following:
• They are used in intrusion detection systems.
• They are used by businesses for detection in sensitive spaces that must be kept secure
from unauthorized or malicious individuals.
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• Since these sensors can decode several movements, therefore they are used by busi-
nesses for improving customer service. For example, customers can make hand gestures
to signal a message or action.
Accelerometer Sensors
An accelerometer sensor is used to determine measurable or physical acceleration that is sensed
by an object because of inertial forces. It is then used to change mechanical motion into an elec-
trical output. They are used for the following applications:
• In smartphones, they are used for tilting, acceleration, and vibration detection.
• They are used to monitor the driving fleet.
• They are used in security systems; if an object is touched by a third party, then they for-
ward a warning through the IoT system.
Gyroscope Sensors
A gyroscope sensor is used to determine the angular velocity or rate. They are used in game con-
trollers, camera devices, car navigation systems, robotics controls, vehicle control, consumer
electronics, and other domains.
A gyroscope sensor can dier on the basis of the output type, sensing range, power, and most
importantly their working mechanism. Optical, MEMS, vibrating structure, and rotary are some of
the gyroscope types. Usually, these sensors are integrated with accelerometer sensors. This combi-
nation is popular because it allows IoT devices to provide more detailed data to the system.
Optical Sensors
An optical sensor is a sensor that determines the amounts of light rays, which are then converted
into an electrical signal. This signal is readable by user from an electronic device. They are used
to detect electromagnetic energy from light and electricity.
They are used in energy, aerospace, environment monitoring, and other industries. It
has helped oil and pharmaceutical companies to detect changes in the environment and keep
employers safe. Some of their applications are digital optical switches, ambient light detection,
and optical fiber communication.
ENDPOINTS
Endpoints are one of the important elements in IoT. Following is an Endpoint model that defines
various variants.
Endpoint Model
Earlier, the endpoint model was considered as a combination of several dierent technologies
with physical world interactions that were linked with a web server for assistance and provision
Quick Challenge
Think of ten different projects where motion detection sensors will be useful.
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