IoT Sensors and Protocols

Class Rules

• Arrive on time for class
• Pay attention to the instructions and explanations provided
• Engage in discussions with classmates when there is an activity
• Communicate respectfully and professionally in your language
• Keep cell phones silent during class

Sensors and Protocols

• The diagram presented illustrates the various layers and components involved in sensors and protocols within a system
• The layers include the business layer, application layer, middleware layer, network layer, and perception layer
• Each layer has a specific function and associated technologies that facilitate the overall operation of the system

Lecture Topics

• Overview of IoT sensors
• Examination of different types of IoT sensors and how they are used
• Overview of communications and protocols for sensors (MQTT, CoAP, Bluetooth, etc.)
• Examining methods for processing and analyzing sensor data
• Identifying the challenges that IoT sensors face in terms of security
• Case studies and hands-on demonstrations

What are Sensors?

• Play a crucial role as the link between the digital and physical environments
• Defined as devices that can detect and respond to changes in their surroundings, converting physical, biological, or chemical characteristics into electrical signals
• Processed by an IoT and allow it to respond or take action

Differences between a Sensor and a Transducer

• The terms transducer and sensor are often interchangeable but have subtle differences
• A transducer generally refers to any device that converts any form of energy into another
• For example, a loudspeaker converts electrical energy into sound energy
• Sensors are a specific type of transducer that responds to a certain stimulus and outputs an optical or electrical signal read by a device
• While all sensors are transducers, not all transducers are sensors
• A sensor is specialized to detect stimuli and produce signals, while a transducer is a more general term for energy conversion

Analog vs Digital Sensors

• Analog sensors output a continuous signal proportional to the measured quantity
• Digital sensors provide a discrete output representing the measured quantity in digital form

Sensors and Actuators

• Sensors and actuators are referred to collectively as transducers because they both function to convert signals or power from one energy domain to another
• A sensor recognizes occurrences in its environment and generates an electrical signal
• Actuators perform actions based on received signals
• Sensors gather data as input devices, while actuators act as output devices based on readings
• Automation, robotics, and IoT applications rely on both sensors and actuators

Sensor and Actuators

• Sensors are able to measure physical properties, while actuators are able to convert electrical signals into physical actions
• Collect data from the environment, whereas actuators perform the actions given by these signals
• Sensor output is in form of digital or analog signals, meanwhile actuators have mechanical movement as output
• Temperature, motion, and light sensors are examples, where actuators include motors, relays, solenoids, LEDs, etc
• Power consumption is usually low for sensors, yet can be high for actuators, determined by the action performed
• Sensors are used in industrial sensing, weather monitoring, and health tracking, actuators are used in automation, robotics, and smart home devices,
• Sensors capture data that flows from an environment into a system, meanwhile, actuators send signals out of a system to affect the surrounding environment

Types of Sensors in IoT

• IoT systems utilize various types of sensors to gather real-time environmental data
• These sensors are classified based on the specific types of data they measure

Temperature Sensors

• Measure changes in temperature
• Examples, DHT11, DHT22, LM35, Thermocouples
• Used in weather monitoring, HVAC systems, and industrial temperature control

Light Sensors

• Light intensity is measured
• LDR (Light Dependent Resistor), Photodiodes
• Used in mobile screen adjustments, street lighting, and solar tracking systems

Humidity Sensors

• Measure moisture levels in the air
• HIH-4000, DHT22, DHT11
• Used in homes/offices climate control, smart agriculture and industrial processes involving drying

Motion Sensors

• Detect the movement of objects or people
• Microwave Sensors, PIR (Passive Infrared), Ultrasonic
• Used in security systems and smart appliances with touchless features

Pressure Sensors

• They measure changes to pressure in air, liquids and water
• MPX5010, BMP180
• Used in industrial fluid control and tire pressure monitoring (automobiles)

Gas Sensors

• Detect harmful gases in the environment
• MQ-7, MQ-2, and CO2 Sensors
• Used for detecting gas leaks, air quality monitoring and offer industrial safety

Sound Sensors

• Detect sound waves and convert them to electrical signals
• Sound Level Sensors, MEMS Microphones
• Used in surveillance based security, voice recognition in smart assistants, and noise pollution monitoring

pH Sensors

• Determine liquid acidity or alkalinity
• Analog pH Sensor, pH Meter
• Applied in soil analysis for smart farming and general water quality monitoring

Accelerometers & Gyroscopes

• Allows measurement of tilt, orientation, and motion
• ADXL345, MPU6050
• Applied in counting steps with fitness trackers and general smartphone screen rotation

How Does a Sensor Work?

• Sensors work by taking an input and producing a related output
• The receptor senses the input in forms such as temperature, light, or motion
• Input is converted through transduction to an energy whether thermal or electrical
• The transduced signal is then amplified and processed through digital conversion and filtering
• The conditioned signal is converted for it to be human readable, such as voltage, current, or code
• Certain sensors use feedback loops so they can improve accuracy and environmental compensation
• Inputs are detected and transduced into output signals which quantify amount or change

Sensor Parts

• Sensors have three parts;
• A sensing element to detect physical and chemical quantities
• Transducer is used to convert the parameter into an electrical signal
• A computer or device to read and interpret the converted signal

Sensor's Performance Characteristic

• Sensitivity determines the lowest amount of desired substance concentration
• Sensitivity is the Output Signal/Input Signal
• In thermocouples, Sensitivity is change in voltage over change in temperature in Celsius
• Resolution refers to the minimum magnitude of measure to the smallest part that can be determined
• Accuracy is the amount of uncertainty, which directly influences quality
• Linearity is equal to the max deviation from Best Fit Line over Full Scale

Sensor's Performance Characteristic (cont)

• Limit of detection (LOD) is the lowest amount of substance distinguished by the sensor
• Capability of sensor to identify a given substance
• Response time is the particular wait until concentration limit where warning signal occurs
• Response Time= Time to reach 63.2% of the final value = Time Constant (t) for 1st order system
• Repeatability = Maximum Deviation between Repeated Output Measurements at Constant Input
• Recovery time: Time period is the time it takes to recover after detecting process for sensing material

Sensor's Performance Characteristic (Accuracy vs Precision)

• Accuracy is the closeness to the true value
• Precision is how close multiple measurements are to one another

Sensor's Performance Characteristic (Linearity)

• The maximum deviation between measured values on the ideal response curve

Example Light Sensor Specs

• Photoresistors have high variance within their specs, photo diodes, and transistors can be made to a high degree of accuracy

How a Light Sensor Works

• Light sensor detects intensity of light in the environment and inputs the electrical signal
• This process adjusts screen brightness, activates alarms, or turns on street lights automatically
• Ambient light is detected using photoresistors, phototransistors, or photodiodes
• Light intensity is converted to a current or voltage electrical signal
• Signal is micro-controller analyzed, such as ESP32 or Arduino
• Data can increase/decrease screen brightness, adjust camera exposure for phone photos or turn on/off lights

How a Light Sensor Works (cont)

• The resistance changes to the light intensity using a LDR (Light Dependent Resistor)
• Light is converted to an electrical current
• Automation systems used transistor that are more sensitive than diodes

How a Light Sensor Works (IoT Applications)

• Applications of light sensors in IoT:
  • Home automation and smart street lighting systems
  • Smart phone and laptop Automatic brightness adjustment
  • Solar Panel adjusting systems
  • Motion activated light Security systems

Example Light Circuits

• Circuits help to demonstrate the possible applications with light sensors

Case Study: Introduction (Smart Irrigation System)

• The study examines the proper sensor selection process to improve crop yield and efficiency

Case Study: Problems (Smart Irrigation System)

• Inefficient irrigation systems lead to overwatering or underwatering, requiring real-time environmental monitoring to determine water usage

Case Study: Sensors (Smart Irrigation System)

• Smart irrigation criteria can be achieved by using the following sensors:
  • Must provide the correct soil and weather conditions
  • Have the lowest power as possible and wireless capabilities
  • Durable material withstanding conditions like heat and rain
  • A cost effective solution

Case Study: Selected

• Selected sensors include capacitance soil moisture sensor (measures moisture), DHT22 temperature & humidity (monitors environmental conditions), BH1750 light (detects sunlight for plant growth), FC-37 rain (determines irrigation levels), analog pH (checks soil acidity)

Case Study: In Practice (Smart Irrigation System)

• Automated system controls irrigation valves based on localized data as the data is deployed to areas in the field
• Farmers can access real time insights through a web application to improve water usage

Case Study 2: Introduction (Healthcare Monitoring System)

• With the rising demand for remote healthcare, sensor selection in this system is critical
• The process monitors patient data by sensing vital signs and is intended to improve general care

Case Study 2: Problems (Healthcare Monitoring System)

• Monitoring conditions is critical, but human error makes the process difficult, therefore smart systems require continuous and non invasive monitoring

Case Study 2: Criteria (Healthcare Monitoring System)

• To design an effective system, the following are considered

  • Sensor must give precise measurements in real time
  • Sensors should be comfortable for long term use while low power
  • Can use Bluetooth, Wi-Fi or cellular for data transferring
  • Is cost effective for all uses

Case Study 2: Selected Sensors (Healthcare Monitoring System)

• Chosen sensors must have the following:
  • Photoplethysmography (PPG), which measures heart rate by blood flow
  • Heart Rate sensor, which monitors blood rates
  • Monitor O2 saturation, and tracks body temperature
  • Module measuring heart activity for cardiac monitoring
  • Gyroscope detecting motion and falls

How Sensors work in IoT

• Sensors allow for the ability to measure parameter changes such as humidity, temperature or motion, then convert data as electrical signal
• The signals send data to communicate through Bluetooth, Wi-Fi
• The IoT system then analyzes date and performs actions from alerts to adjusting

Protocols

• Communications processes which transmit data for efficient exchange

Sensor Communication & Protocols (MQTT, CoAP,

Bluetooth, etc.)

• Communication protocols are needed to transmit data from platforms such as the cloud or edge
• Protocols also allow for essential efficient and secure data exchange

Types of IoT Communication Protocols

• IoT Protocols can be categorized as follows:
  • Range Protocol: Bluetooth, Zigbee or Wi-fi
  • Long: LoRaWAN, NB-IoT, or LTE

Short Range A: Bluetooth & Bluetooth Low Energy (BLE)

• The short range wireless is used to exchange data between devices
• In widely used methods the transmission power can be limited to only 2.5 milliwatts
• These can be found in smart home devices such as speakers or smart watches

Short Range B: Zigbee

• Wireless IOT Protocol with light bulbs/sockets
• Distribute data by passing through intermediate devices to reach more distant ones
• Secured by 128-bit symmetric encryption keys
• Smart lighting systems and thermostats in homes are now being automated because of them

Short Range: C) Wi-Fi

• Computers, smart phones and facilities must connect wirelessly to communicate within a specific region
• Requires more power, though can support large amounts of transferred data
• Found in appliances as well as automation with industry

Long Range: LoRaWAN (Long Range Wide Area Network)

• Top powered networking protocol that uses low radio modulation techniques
• Works in remote locations with minimal infrastructure
• Used for pollution monitoring, smart agriculture and pipeline monitoring

Long Range, B: NB-IoT (Narrowband IoT)

• Radio standard for connecting devices which uses low energy consumption over long distances
• Can penetrate walls within buildings as well as underground structures
• Used for remote monitoring and waste management

Long Range, C: LTE-M (Long Term Evolution for machines)

• Evolution that maintains balances power and efficiency

Constraints on Communication Protocols

• Protocols must be judged on efficiency, bandwidth, latency, or speed

Communication Protocol A: MQTT (Message Queuing Telemetry Transport)

• Lightweight network protocol is used to send data

• Efficient for low bandwidth unreliable IOT

  • Publishes data from temperature sensors and runs messages with subscribers

• Uses smart home Iot or industrial monitoring

Communication Protocol B: COAP (Constrained Application Protocol)

• Lightweight protocol is similar to HTTP designs but optimized for low power IoT devices
• Very efficient, with its use applied in agriculture, lighting, and meter sensors

Communications Protocol C: HTTP/HTTPS

• Allows cloud - based appliances
  • Effective for web analytics though with higher power consumption
  • used with web dashes and storage

Choosing the Right Protocol

• Bluetooth (BLE) is best to used for wearables and smart home
• Zigbee is best in home automation and industrial
• Wi-Fi is best used for smart cameras
• LoRaWan is best for smart agriculture
• NB-IoT is best used as asset tracking
• MQTT IoT message
• CoAP is best a for IOT device

Choosing The Right Protocol (Cont)

• Battery benefits include BLE, ZigBee or NB
• Data Volume or WiFi
  • MQTT and COAp for low bandwidth or WiFi use

Security Challenges in IoT Sensors

• Data breaches occur with risks on security

  • Device Hijacking and Firmware Vulnerabilities occur

Challenges in Managing IoT Sensors

• Energy usage as well as data usage
• Data needs a solid internet connection

Security Challenges in IoT Sensors

• Authentication and Firewall required
• Regular software updates as well as network security measures
• Edge computing needed to process local data to prevent attacks

Case Study (Precision Agriculture)

• An IOT smart agriculture deploys sensors as smart farming which monitors moisture, temperature, and humidity

Case Study: IoT (Precision Agriculture Protocols)

• Best choices include LoRA for long range and low power
• Cellular networks insure coverage

Case Study: Step 3 (Precision Agriculture Protocols)

• Best decision is to use reliable networks which use low amount power and connect on long distances

Case Study ( Smart Home IoT System )

• Automatic controls which connect to the clouds and hubs on smart phones

Key Requirements (Smart Home IoT Systems)

• Must use secure and short range IOT which works with reliable networks