1 Introduction

The concept of "smart cities" has lately gained popularity as urban areas all over the world strive to improve the quality of life for their residents by utilizing technology and information. This innovative approach uses cutting-edge technology and innovative methods to optimize several elements of urban living, including transportation, energy use, healthcare, trash management, and more. These cutting-edge urban settings are built around sensors and actuators, which seamlessly integrate technology to gather data and respond to the changing demands of the city. Sensors are essential to the creation of smart cities because they gather information from various infrastructure systems and the outside environment. By measuring a wide range of parameters, such as temperature, air quality, traffic flow, and energy usage, these devices gather an abundance of real-time data [1]. Thanks to this continual monitoring and data collection, cities are better able to comprehend how they are running, spot trends, and make justifiable decisions to boost productivity, long-term viability, and general livability. The actuators work in conjunction with the sensors as the moving components that respond to the data acquired. These technologies assist smart city architectures in adapting and enhancing their operational capabilities by making it simpler to complete specific tasks based on the data obtained [1]. A city's successful functioning depends on several mechanisms that actuators can regulate, such as garbage collection management, building system energy efficiency optimization, traffic light control, and signal control. The goal of this in-depth review paper is to emphasize the crucial role that sensors and actuators play in transforming urban landscapes. This paper aims to highlight the importance of these technologies in the development of smart cities by examining their applications, difficulties, and potential solutions. Successful implementation and real-world case studies will be discussed to demonstrate the tangible advantages of sensor and actuator convergence across various urban domains. The various kinds and technologies of sensors and actuators used in smart cities will be covered in more detail in the sections that follow, with an emphasis on how each one is used specifically and how it improves urban living. This paper will go through crucial data integration and analytics topics, addressing the difficulties of using these tools in big cities. Understanding current trends and foreseeing future improvements in sensor along with actuator technology becomes crucial as the drive towards innovation for smart cities grows. This review will examine current developments, such as the incorporation of machine learning and artificial understanding into computing systems, while also discussing privacy issues and ethical concerns with the enormous volumes of data collected. This review article's ultimate goal is to give researchers, decision-makers, and urban planners a thorough grasp of the enormous possibilities available in the field of actuators and sensors.

2 Related works

Klein & Kaefer [2] Present a business perspective on industrial infrastructure and solutions, focusing on smart cities and energy efficiency in information centers, highlighting the importance of autonomous computing principles in addressing widespread computing devices. Balakrishna [3] Examines the Smart-city architecture from the standpoint of Mobile Technology, along with the related invited talk, the conceptual framework offered, and the standout features of future directions for this field of study's unanswered questions. Obinikpo & Kantarci [4] look at deep learning techniques that help improve forecasting and making decisions in intelligent healthcare facilities using sensed data. Based on the numerous sensor types and data gathered, they also evaluate and classify alternative methodologies. Additionally, they comprehensively evaluate the unsolved issues and research challenges in each category. Jiang & Pozza [5] A study on three single-occupancy residences demonstrates the use of Hidden Markov Models for sensor-based activity identification, the study demonstrates the consistency between self-reported behaviors and sensor-generated data, using features from mean-shift segments and point change analysis. Riouali et al., [6] Present a wireless network-based system for managing traffic on roads, focusing on analytical analysis using a new batch Petri net modification, and discussing its functionality and distribution architecture. Park et al., [7] aim to explore the role of ICT in citizen participation in smart sustainable cities. Through critical content analysis and literature review, the research focused on the relationship between digital citizen participation (DCP) and sustainability. The findings highlighted ICT's crucial contribution to environmental sustainability and the development of smart cities beyond human capabilities. Table 1 displays the related works.

Table 1 Comprehensive analysis of previous research contributions
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3 Sensors, actuators, and their role in IoT network connections

  • Sensors: Sensors and transducers are real mechanical devices that convert one kind of electricity into another. Sensors turn an actual thing into an electrical current to carry out the specified activity. In outdoor lighting, the system's sensors, for instance, can measure the brightness of the light by converting it into an electrical signal. These sensors can be used by the IoT network for many different purposes. As these get to understand the characteristics of a physical object, the outcome of their observations is converted into blockage, capacitance, impedance, etc.

  • Actuators: To continue the discussion of sensors, actuators work in contrast to what sensors do. Electrical impulses are transformed into visible phenomena or actions by them. When a sensor measures a light's brightness and converts that measurement into an electrical signal, an actuator responds by what is wanted in the lighting example. This will cause the light intensity to change to conform to the predetermined criteria. In an Internet of Things network, we may use actuators to oversee and regulate our equipment based on the data that the sensors transmit.

  • IoT network connections between actuators and sensors: IoT-based Sensors and actuators play a major role in connected technologies. Actuators and sensors assist organizations in improving efficiency, accuracy, and intelligence, particularly as IoT and Network of Things (IoT) technology gain popularity. IoT software solutions are used to connect the sensors and actuators. IoT sensors are used to document and maintain track of both operations and equipment by capturing data and information. As a result, this can acquire data regarding a device's functionality, evaluate the outcomes, and offer recommendations. On the other hand, the use of actuators enables the automation of industrial processes while reducing the demand for human work. These two components work together to develop effective IoT solutions. Robots that work to paint cars or assemble pharmaceuticals employ the information and motions generated by actuators and sensors used in manufacturing. Numerous sensors and actuators are used to carry out the specified functions. Learn more about them right away [10].

3.1 Understanding different types of sensors for IoT applications

Sensors are devices that monitor and detect physical attributes or environmental changes and convert them into measurable messages or data that may be comprehended, presented, or processed more thoroughly. These are critical components in numerous industries, including research, technological advancement, and daily living, because they provide essential details for control, observation, and decision-making. Figure 1 highlights the various applications and functionalities of several sensors, including environmental, biometric, and motion sensors.

Fig. 1
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Types of sensors

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Sensors can measure a wide range of chemical and physical quantities, including:

  • Temperature: The temperature sensor measures the temperature of an area, such as a device or room, and can be used to reduce ambient temperature, automating the process accordingly.

  • Moisture: Moisture sensors monitor humidity in various settings like agriculture, food production, research, and environmental protection, using psychrometers or internal hair pressure wetness components.

  • Lighting: Smartphones use light sensors and electrical actuators to track and adjust lighting conditions, often used in automated lighting controls in modern homes.

  • Motion: Motion sensors in the Internet of Things (IoT) alert personnel to unacceptable conduct through changes in weight or temperature, using radar detectors, infrared, or ultrasonic waves.

  • Noise: Noise sensors measure noise levels in specific areas, such as towns, homes, and cars, and are used in IoT to design safe environments and notify appropriate parties when noise levels exceed predetermined limits.

  • Proximity: Motion detectors and proximity sensors use infrared and electromagnetic radiation to record nearby activities, alerting people about potential dangers in various venues like automobiles, garages, stores, stadiums, and airports.

  • Level: Level sensors monitor substance quantities and levels, with optimal use in manufacturing, waste management, and water treatment sectors, ranging from semi-solid liquids to granular solids.

  • Accelerometers: Accelerometers are IoT sensors used to measure object acceleration, detect changes in gravity, and detect theft in smart pedometers, driving fleets, and stationary items.

  • Gas: Gas sensors track air quality changes by identifying hazardous gases in specific areas. Typically used by mineral extraction, natural gas, oil, and energy companies, they also measure CO2, particulate matter, and carbon monoxide levels [11].

  • Optical: Optical sensors are increasingly used in driverless cars to detect environmental signals, identify roadside items, transmit information to the central processing unit, and potentially order behavior changes.

  • Gyroscope: Gyroscope sensors are used in stability control and navigation systems for automobiles to calculate the speed of an object in motion, using interchangeable terms for velocity.

  • Chemical: Gas and chemical sensors are crucial in industrial IoT systems for predicting and detecting various chemical types, ensuring environmental and worker safety.

A sensor's sensitivity, drift, linear manner, conclusion, radio spectrum, precision, and accuracy determine what it can measure and record. These features allow IoT sensors [12] to deliver accurate data.

3.2 Factors influencing the service life of precision gauges and sensors

The service life of a gauge or sensor [13] is an important consideration in numerous industries where measurement precision is essential. These devices serve as the systems' eyes and ears, gathering and sending crucial information for a range of tasks, from manufacturing machinery to environmental control systems. The lifespan of a sensor is not a common statistic because of the wide range of factors that jointly influence it. The type of sensor employed, the environmental conditions it must endure, and the quality of its construction all play a significant role in determining how long a sensor can consistently function. The dynamic environment of sensor service life is further enhanced by ongoing maintenance practices, adherence to manufacturer instructions, and the inescapable progress of technology. Regardless of their operational contexts, industries must strike a compromise between integrating cutting-edge technology and ensuring the ongoing dependability of these sensors. A gauge's or sensor's service life might change significantly based on several variables. These variables include the kind of sensor, the environment it functions in, the standard of its construction, and the level of maintenance given to it. Here are some general concepts for maintaining in consideration:

  • Type of sensor: Different types of sensors have varying life spans. Solid-state sensors, for instance, might be more durable over time than sensors with mechanical parts that have moving elements [14].

  • Environmental factors: The operating environment of the sensor has a significant impact. The sensor's longevity may be altered by factors like extremes of temperature, humidity, contact with corrosive agents, and other pressures from the environment.

  • Construction quality: Sensors come in varied levels of quality, and those manufactured with higher engineering as well as materials are likely to endure longer.

  • Maintenance: Regular maintenance, precise measurement, and careful handling can extend the life of a sensor. This requires keeping the sensor away from potentially damaging situations and sticking to the manufacturer's directions for calibration intervals.

  • Technology advances: As the sensor industry evolves, earlier sensors might become obsolete. Upgrading to new sensor models with improved features and dependability can be necessary.

  • Use: The lifespan of the sensor may be affected by its specific application. In particular, sensors used in harsh industrial applications might not last as long as those used in settings with fewer demands.

  • Manufacturer standards: For details on the anticipated service life of a certain sensor, it is critical to refer to the manufacturer's standards and guidelines. Manufacturers frequently offer suggestions for maintenance and operating circumstances.

3.3 Understanding different types of actuators for IoT applications

Actuators are instruments or processes that convert control or input signals to actual motion, force, or other desired actions [14]. It serves as sensors' structural counterparts and are vital for managing and controlling multiple processes, machines, and systems. Actuators are employed in a wide range of applications, from automated production to consumer electronics. Figure 2 shows a wide variety of actuators, each designed for a particular application in turning energy into mechanical motion, including electric motors, hydraulic as well as pneumatic equipment actuators, solenoids, piezoelectric along shape memory alloy actuators.

Fig. 2
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Types of actuators

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3.3.1 Hydraulic

To carry out mechanical actions and activities, these actuators use hydraulic power. These actuators are often driven by a cylinder or fluid-powered motor. The engineered motion is transformed into oscillatory, simple, or rotary motion by the specifications and guidelines [15].

3.3.2 Pneumatic

Rotary or linear motions can be produced by pneumatic actuators. These are propelled by a state of vacuum or highly pressurized air to produce the necessary velocity. Pneumatic actuators are inexpensive and need less maintenance when compared with other types of actuators.

3.3.3 Electrical

Using motors, these gadgets transform electrical power into mechanical motion. These electric actuators are powered by electricity and offer precise control. In industrial contexts, these actuators are frequently employed to automate mechanical tasks.

3.3.4 Thermal

To provide linear motion, the thermal actuator contains heat-sensitive material. Because they are commonly referred to as thermal actuators, it is assumed that they are employed in response to temperature variations. Valve shutting and latching or switch actuation are the most typical usage scenarios.

3.3.5 Magnetic

These types of actuators convert electromagnetic energy into mechanical output and operate in a linear or rotational direction. In the automotive and aerospace industries, magnetic actuators are frequently used to deliver continuous mechanical action [15].

Since IoT is forming the fresh face of the business, sensors, and actuators are used to give the required basis for building a strong industry. These are essential to almost every industrial process, helping companies automate processes to streamline work and boost productivity.

3.4 Secure big data exchange for actuators

A network of interconnected devices, or actuators, has been developed as a result of the Internet of Things (IoT) expansion, and in the rapidly evolving technological environment, these actuators are producing tremendous volumes of data [16]. Although this data influx presents opportunities for increased effectiveness and decision-making, it also presents challenges, particularly in terms of data management as well as sharing. Two critical concerns in this field data security and attribution require sophisticated solutions to ensure the ethical and secure handling of information [17]. Figure 3 outlines the key challenges in big data sharing.

Fig. 3
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Key challenges in big data sharing

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3.4.1 Challenges in big data sharing

  1. (a)

    Security concerns: Actuators are essential in many applications, including industrial automation and smart cities. Sharing data across these actuators, meanwhile, poses security issues. Protection of sensitive data's availability, confidentiality, and integrity becomes crucial [18].

  2. (b)

    Interoperability issues: Actuators frequently are produced by several companies and may use various connection protocols. The effectiveness of collaborative systems is hampered by the difficulty of establishing smooth interoperability for data sharing.

  3. (c)

    Data volume and speed: Traditional systems for managing data may become unmanageable due to the sheer volume and speed of data created by actuators. Making timely decisions requires efficient management of real-time data streams.

3.4.2 Data management concerns

  1. (a)

    Attribution and accountability: To guarantee accountability for the use of the data and to explicitly identify the data's owner. Inaccurate attribution could lead to moral and legal problems.

  2. (b)

    Data quality and beatification: Actuator raw data may be inconsistent or incomplete. Techniques for quality of data verification and "beatification" (raising the accuracy and usefulness of data) must be used to gain pertinent insights.

  3. (c)

    Regulatory compliance: The implementation of privacy regulations like GDPR makes managing data much more challenging. To safeguard user confidentiality and prevent legal repercussions, actuators must follow these standards. Figure 4 highlights the essential data management concerns.

Fig. 4
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Essential data management concerns

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3.4.3 Solutions

  1. (a)

    Using blockchain to securely share data: Blockchain technology offers a decentralized, tamper-proof ledger for transactions, which can increase security. This ensures the accuracy and traceability of shared data.

  2. (b)

    Standardization of protocols: Industry-standard communication protocols can be developed and used to alleviate interoperability issues, enabling actuators from different vendors to communicate with one another without any issues.

  3. (c)

    Data beatification using machine learning: Algorithms for artificial intelligence can aid in improving the quality of the data by autonomously cleaning, validating, and augmenting raw data.

  4. (d)

    Ethical AI methods: Artificial intelligence algorithms [18] and systems that take ethical considerations into account enable responsible data utilization, reduce the likelihood of unexpected results, and address problems with data attribution. To effectively share and manage massive data across actuators in the IoT and linked device era, a comprehensive strategy is required. Stakeholders can create a future in which data-driven technologies positively impact a variety of industries while preserving privacy and assuring accountability by resolving security, interoperability, the issue of attribution, and ethical issues. To overcome these challenges and realize all that is possible of big data in the field of actuators, collaboration among industry executives, decision-makers, and technologists is essential. Figure 5 outlines strategic data management options for actuator systems that meet security, interoperability, data quality, and ethical concerns. These options include blockchain, standardized protocols, machine learning, and ethical AI.

Fig. 5
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Strategic solutions for data management in actuator systems

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4 Smart city legal foundations and frameworks

The design and administration of smart cities necessitate a combination of policies, rules, and legislation to ensure sustainable development, efficient resource utilization, and improved quality of life for people [19]. The components listed below make up the strategy and legal groundwork for smart cities. Legal foundations and strategic frameworks are shown in Fig. 6 as being essential for the establishment of a comprehensive smart city.

Fig. 6
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Legal foundations and strategic frameworks for holistic smart city development

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4.1 Infrastructure and technology

The creation of a robust technical foundation capable of seamlessly integrating various smart solutions is a key strategy in the field of technology and infrastructure for smart cities [20]. This comprises the development of networked systems that, via creative applications, improve urban living. Important regulatory frameworks, such as Data Protection as well as Privacy Laws, which are intended to impose strict laws governing the collection, storage, and utilization of personal data, serve to support this strategy. These rules act as a barrier, protecting people's right to privacy in the era of widespread digital transformation. Cybersecurity laws must be implemented to ensure legal safeguards for the infrastructure of smart cities against online dangers.

4.2 Connectivity

Building explosive dependable networks, including 5G and fiber-optic infrastructures, is a critical goal in the endeavors to increase connectivity for smart cities to enable the efficient operation of smart systems and gadgets. Internet Access Laws are an essential piece of legislation that supports this strategy. By putting into place rules and policies that support policies promoting widespread access to fast internet, these laws help close the digital divide. These legal frameworks play a crucial role in encouraging inclusion and fair opportunities for all persons within the framework of smart cities by providing balanced access to Internet services.

4.3 Energy management

Technology that uses little energy Adoption and support of renewable energy sources are crucial tactics for encouraging the use of sustainable energy in smart cities. To power urban infrastructure, this entails prioritizing the development and application of energy-saving technology. This approach is accompanied by significant legal constraints. Building designs and appliance designs must abide by strict energy efficiency standards, which can only be achieved with the help of energy efficiency standards. Additionally, the Renewable Energy Mandates outline specific objectives for the inclusion of renewable energy in the city's energy portfolio, contributing to the reduction of carbon footprints and fostering a more ecologically conscious urban environment. The combination of these strategies and policies helps to advance sustainable and responsible energy practices in smart cities.

4.4 Urban mobility

The strategic focus for improving urban mobility is the creation of intelligent transportation networks that ease traffic, enhance public transit, and encourage sustainable modes of transportation. To improve general transportation efficiency, this includes using cutting-edge technologies. Regulations called "Transportation Management Regulations" (TMRs) are essential legal measures that use cutting-edge technologies for traffic control and enforce the law [21]. Additionally, incentives are put in place to encourage the use of public transportation, shared rides, and electric vehicles. By embracing both legislative considerations and technical advancements, this all-encompassing strategy encourages a more efficient and ecologically friendly urban transportation sector.

4.5 Environmental sustainability

Smart city strategies that integrate choices for waste management, pollution avoidance, and the creation of green spaces promote environmental sustainability [22]. This plan aims to lessen the detrimental effects of urban living on the environment while improving urban living standards. This approach is supported by the enforcement of Waste Management Rules and Regulations, which establish legislation for proper waste disposal and recycling practices. Green building regulations are another tool used to monitor and promote the construction of ecologically friendly structures. Together, these initiatives contribute to the development of a city that is more sustainable and environmentally conscious.

4.6 Citizen engagement

Smart city projects place a high priority on citizen engagement, with a strategy that promotes active participation when making decisions using digital platforms and feedback mechanisms. Important legal structures assist in implementing this plan. Open Data Policies provide regulations that make non-sensitive government data available to the general public, promoting transparency and cooperation [23]. In addition, Public Consultation Mandates implement rules requiring public input for large development projects, ensuring that residents play a key part in determining the future of their communities. The creation of smart cities benefits from the mutually beneficial connection between strategy and law by promoting inclusion and democratic government.

4.7 Data governance

The growth of smart cities, which places a significant emphasis on good data governance, requires the development of a cohesive framework to manage the large amounts of data created by intelligent city technology. This method is supported by particular legal limitations [15]. Laws governing data ownership specify the guidelines that distinctly define who is the rightful owner of data generated by people and machines, establishing rights and obligations. The safe and lawful flow of personal information across international borders is another issue that is addressed by cross-border data flow regulations. This strategy and legal framework enable responsible data management, privacy protection, and the promotion of an environment for responsible utilization of data within the smart city ecosystem.

4.8 Affordability and inclusivity

Prioritizing affordability as well as inclusivity, the strategic goal is to ensure that initiatives related to smart cities are accessible to all segments of the population. To firmly establish this dedication, Digital Inclusion Regulations are enforced, establishing regulations that work diligently to eliminate disparities in access to technology. Table 2 offers a quick reference for comprehending the crucial components in increasing urban intelligence by providing a succinct summary of the development of smart city strategies and related regulatory frameworks.

Table 2 Smart city development strategies and regulatory framework
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5 Essential steps and key elements for creating a smart city

A smart city is a metropolitan area that makes use of cutting-edge data and technology to improve livability, encourage sustainability, and more effectively manage resources and assets. Smart cities use a variety of techniques, including the Internet of Things (IoT), artificial intelligence (AI), and big data analytics, to gather and analyze data in real-time from many sources, including sensors, cameras, and mobile devices. Next, city operations are optimized, services are enhanced, and the public's involvement is increased by using this data [24].

Smart cities are important and necessary since they make use of technology and information to address urban difficulties, enhance sustainability, boost productivity, and enhance citizen enjoyment of life. Smart cities encourage economic growth by fostering innovation and technology, luring new enterprises and investments, and encouraging entrepreneurship. Smart city decision-making involves citizens, which encourages openness and democratic engagement. By better using resources and promoting a more habitable and environmentally friendly atmosphere for future generations, metropolitan places could potentially have a smaller negative influence on the environment. Figure 7 depicts key components for developing a smart city.

Fig. 7
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Key elements for smart city

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5.1 Smart infrastructure

A "smart city" is envisioned as a location where innovation and technology come together to build a livable and effective urban environment. Creating an advanced infrastructure that acts as the backbone of a smart city is one of the key elements in its construction. Smart infrastructure is needed to increase the effectiveness, security, and sustainability of current infrastructure [25]. Figure 7 illustrates the five keys for building smart cities.

Examples of intelligent infrastructure include:

  • Intelligent solar benches: Equipped with solar panels, intelligent solar benches use the energy of the sun to create electricity. After that, the energy may be used to run portable devices or lighting systems. These benches enhance the sitting experience for the general public while also contributing to a sustainability strategy. These benches have Wi-Fi, which has a significant impact on the development of an intelligent town [25].

  • Solar tiles: These cutting-edge tiles run on solar energy and pressure-sensing technologies that react to individuals walking over them by turning on the LEDs incorporated into the floors and triggering several floor-based activities. These tiles provide renewable energy that can be utilized immediately or put into a storage container for later use. All across the world, solar tiles are deployed in busy areas of smart communities. These emerald-colored, highly collaborative tiles would be a terrific addition to the infrastructures of smart cities. To interact with their audience, offer an unforgettable experience, and lessen their carbon footprint, businesses throughout Australia use ecologically friendly technologies for brand stimulation [26].

5.2 Open data and connectivity

To create a smart city, connectivity, and accessible data are essential. By enabling people, companies, and governments to create new services and enhance current ones, open data promotes openness, collaboration, and innovation. On the other hand, connectivity enables systems to talk to one another and share information, allowing smart city technologies to operate as a whole. Increased transparency and accountability, better decision-making, and enhanced efficacy and efficiency are just a few advantages of open data. Technologies for smart cities must be fully integrated for them to function together [27]. By allowing various technologies to communicate with one another, cities may improve their transit systems, increase public safety, and consume less energy. On a platform for open data developed by the Finnish city of Helsinki, more than 3,000 datasets are now freely accessible. These data sets contain data on public transit, air quality, energy use, etc. The city has also set up interconnection to allow communication among its several city technologies. A mobile application that provides real-time information about public transport schedules and availability: this interconnection technology helps the city's efforts to reduce energy use and carbon emissions by facilitating the exchange of energy information between various systems and devices [27].

5.3 Citizen engagement and smart governance

Smart governance and community interaction are essential for a successful smart city. The phrase "smart governance" describes the application of technology to improve governmental operations and decision-making. At the same time, citizen participation makes sure that locals are involved in the development and implementation of smart city programs. Smart management and citizen participation are essential to ensure that smart city programs are tailored to the requirements and tastes of local communities as they help to build trust and confidence among people. By involving citizens in decision-making and providing them with access to resources and information, cities may create more sustainable and inclusive smart cities that are beneficial to every member of society [28].

An example of clever management and public involvement in action is the "Madrid Participatory Budgeting" program in Madrid, Spain. By putting forward and voting on projects for neighborhood communities, citizens can engage in the allocation of the city's resources through the program. Officials from the city will evaluate each project proposal's cost and viability after receiving it from the public online. The ideas that are in line with the requirements are put to a vote by members of the public, and the winning ideas are then put into action. With the aid of this plan, the city's decision-making procedures will be more participatory, and money will support initiatives that residents will value [28].

5.4 Mobility and transportation

A smart city must have seamless transport and mobility. They use technology to promote sustainability and lower carbon emissions to increase mobility, reduce traffic, and increase transportation efficiency. Intelligent systems traffic management systems, which use data and statistical analysis to enhance traffic flow, knowledgeable storage systems, which use sensors and data to help motorists find available parking spaces, and autonomous vehicles are just a few examples of smart mobility and transport solutions. Mobility and transport must be seamless in a smart city. They employ technology to improve mobility, lessen congestion, and boost transportation effectiveness by promoting sustainability and minimizing carbon emissions. Intelligent storage systems that use sensors and data to help drivers find free parking spots, traffic management systems that use information and statistical analysis to improve traffic flow, and self-driving automobiles are merely a few instances of smart accessibility and transport solutions [29].

5.5 Sustainability and an intelligent environment

The promotion of sustainability is a crucial component of a smart city. A sustainable environment makes use of data and technology to promote eco-friendly behavior, reduce negative environmental effects, and keep cities livable and appealing to locals [30].

Examples of smart environmental and sustainability initiatives include energy-efficient structures that use sensors and computerization to optimize the consumption of energy, waste disposal structures that use sensors and data to maximize collection and reduce waste, and green public spaces that encourage biodiversity and provide recreational opportunities for residents. Many smart city programs in Australia could be used as illustrations of clever environmental and sustainability initiatives. The goal of this project is to create a city that is more environmentally friendly through the use of intelligent technologies in areas like waste management, electricity, and transportation. There have been notable projects completed in major Australian cities like Adelaide, Perth, Brisbane, Darwin, and others.

6 Empowering smart cities through advanced sensor technology

The employment of various types of sensors, data-gathering devices, and sophisticated technologies to obtain immediate data from urban surroundings is referred to as sensor technology for smart cities [31]. The goal is to increase municipal environmental sustainability efficiency, as well as the standard of life through decisions based on information and the application of intelligent technologies. Sensor technology is an essential component of the smart city's Internet of Things (or IoT) infrastructure, facilitating data collection, manufacturing, and interpretation for better urban management and oversight. Key sensor technologies necessary for the creation of a smart city are illustrated in Fig. 8.

Fig. 8
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Sensor technologies for smart city

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6.1 Environmental monitoring

Because they enable the real-time monitoring and analysis of several environmental parameters, environmental sensors are essential for smart cities. In addition to the amount of noise, humidity, temperature, air quality, and pollutants from the atmosphere, these sensors may also monitor a wide range of other parameters. Environmental sensor data provides invaluable insights into the state of the overall urban environment, supporting municipal politicians and planners in making astute decisions to improve air quality, lower contaminants, and provide better living situations for citizens [32]. Due to the ongoing collection of environmental data, smart cities may be able to apply dynamic solutions, such as altering traffic patterns or rerouting vehicles during periods of high pollution, activating air purification devices in public areas, or alerting residents to potential health risks. By integrating monitors that monitor surroundings into urban infrastructure, communities may proactively tackle environmental concerns and work towards resiliency and sustainable growth.

6.2 Traffic and transportation sensors

To improve urban mobility and reduce traffic congestion, transportation and tracking equipment are required. One can employ sensors such as cameras, radar detectors, and electrostatic or capacitive loop detectors, to name a few. Traffic and transportation sensors allow the deployment of adaptive traffic control systems in smart cities by capturing current data on automobile flow, acceleration, and occupancy. Smart cities can forecast traffic trends, identify congested locations, and dynamically change traffic signal timings to improve traffic flow by utilizing modern data analysis and machine learning algorithms. By using the information received by these devices to produce dynamic digital signage that directs drivers to available parking spots and less congested routes, it is possible to further cut down on traveling time and the resulting environmental impact [32].

6.3 Sensors that regulate electricity and energy

To improve energy conservation and efficiency in smart cities, power, and energy management sensors are essential. These sensors keep track of the quantity of energy used by various infrastructure components, such as structures, lights, and other machinery. They offer current information on patterns in energy use, spikes in consumer demand, and waste of energy. Smart cities can put in place demand response systems that change energy use during peak hours, reducing pressure on the power grid, by integrating power as well as energy monitoring sensors with actuator technology [33]. These sensors are also used by smart grids to control electricity transmission efficiently, integrating sources of renewable energy and improving energy utilization based on demand.

6.4 Sensors for good health

By using health and wellness sensors, urban environments can be made more welcoming and inclusive. The temperature, the condition of the air, and several additional environmental variables that have an impact on public health can be monitored using these sensors in workplaces and public spaces. They can occasionally pick up excessive amounts of pollutants, infections, or sensitivities that could be dangerous for persons who have become vulnerable. In smart cities and neighborhoods, medical and fitness equipment that permits immediate tracking of individuals' health and fitness is also becoming more common. These wearables can monitor symptoms, exercise routines, and sleep habits, giving users useful information they may use to decide what is best for their health.

6.5 Sensors for waste management

Waste management sensors can greatly improve the efficiency of trash collection and recycling procedures. These sensors are frequently discovered in trash cans to check fill levels. Waste management systems can optimize garbage transportation routes, ensuring that collection vehicles only run when necessary, and reducing fuel consumption and emissions by collecting data on the capacity of dumpsters for disposal in real-time.

7 Enabling smart cities with advanced actuator technology

Actuator equipment for intelligent houses refers to the application of numerous techniques and procedures that enable remote or independent management of the physical structures and products within a home. The aforementioned actuators are an essential component of the worldwide Internet of Things (IoT) infrastructures in smart homes, allowing people to connect with and regulate their environment via digital user interfaces, sensors that are and automated platforms [34]. Actuators are devices in automated houses that can do a range of things that will enhance your living environment, consumption of energy, and security. The numerous actuator technologies highlighted in Fig. 9 give an overview of the many mechanisms and developments used in various applications.

Fig. 9
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Actuators technology for smart city

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The following are major aspects and examples of actuator technologies used in smart home.

7.1 Overview of smart city actuators

As the dynamic elements that react to sensor input, actuators are crucial to the foundation of smart cities. These tools are essential for converting the understanding acquired from sensor-derived data into activities that improve urban systems and urban life. Smart cities' numerous systems are managed, controlled, and regulated by actuators, allowing them to react fast to shifting circumstances and demands.

7.2 Actuators for regulating transportation and traffic

Because they increase mobility and reduce traffic in urban areas, actuators are crucial to the transportation and congestion management industries. Traffic lights and signaling systems are examples of actuators that regulate traffic and pedestrian movement at crossings [35]. Modern actuator-based traffic management systems can increase traffic efficiency and reduce delays by dynamically altering signal timings with real-time traffic data. Intelligent parking systems also use actuators to direct drivers to available parking spaces. By using detectors that detect when a parking spot is used, these devices facilitate parking and lessen traffic congestion. Actuators then transmit this information to vehicles through signs or mobile applications.

7.3 Actuators for energy-saving and energy-optimization

Actuators play a significant role in energy management and conservation in smart cities. Building automation systems employ actuators to control HVAC, lighting, and lighting systems to optimize energy efficiency and reduce consumption. Using real-time information from external sensors, these actuators may adjust both light and temperature levels based on the owner, the time of day, and the weather outside, creating a cozy but energy-conscious indoor atmosphere. Actuators are additionally utilized in demand response programs, which enable utilities to balance their supply and demand of power by remotely controlling certain appliances and equipment during peak usage periods. By lowering energy usage during times of high demand, these actuator-driven demanding management techniques reduce the need for additional power generation [36].

7.4 Infrastructure management and maintenance actuators

Smart cities use actuators to enhance infrastructure management and upkeep. For instance, sophisticated waste disposal systems use actuators to deliver optimized garbage pickup schedules based on fill-level data from smart trash cans. By only deploying garbage pickup vehicles when receptacles are practically full, cities may reduce the number of unnecessary trips, operational expenses, and environmental effects. Actuators are also utilized in intelligent water management systems to control water flow and pressure inside distribution systems. By controlling water pressure depending on current demand and leak detection information, these actuators help reduce water losses, improve system performance, and provide a steady supply of water to homes [37].

8 Integration of sensors and actuators in smart cities

Sensor and actuator technological integration in smart cities refers to the seamless coordination and incorporation of sensing-based data collection and actuator-driven functions inside urban environments. This integration is a vital component of building efficient, ecologically friendly, and flexible metropolitan structures that utilize real-time information as well as automated processes to improve many aspects of city life. Through the combination of sensors and actuators, smart cities can gain insights, make informed decisions, and implement automated procedures to optimize resource utilization, improve services, and address urban concerns [38]. A Smart City's operation and effectiveness depend on the seamless combination of sensors and actuators, as shown in Fig. 10.

Fig. 10
figure 10

Integration of sensors and actuators for smart city

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The following are important benefits of adding actuators and sensing capabilities into smart cities:

8.1 Networks for communications and data collection

For actuators and gadgets that seem to be successfully integrated into smart cities, robust data transmission and collection networks are required. Effective ways for collecting, transferring, and processing the massive amounts of data generated by the sensors positioned across metropolitan areas are needed. To do this, cities build Internet of Things (IoT) systems that link actuators, sensors, and other devices and data centers or cloud-based platforms. Wireless communication technologies like Bluetooth, Wi-Fi, Zigbee, and the LoRaWAN are just a few instances of how these make it easier to send data between devices and centralized data repositories. These networks ensure continuous information accessibility and enable prompt responses to dynamic changes in the urban environment [38].

8.2 Analytical techniques and decision-making

Smart cities use sophisticated data analysis as well as machine learning techniques to derive useful insights from sensor data. Urban planners and data scientists examine the gathered data to find trends, patterns, and anomalies. To optimize urban operations and services, these insights fuel data-driven decision-making processes. For instance, traffic sensor data can be used for data analytics to forecast periods of peak congestion, which in turn helps actuator-controlled traffic management tactics. Similar to this, building energy consumption data can be processed to spot energy-saving potential and start actuator-based energy management processes [39].

8.3 Problems with integration and solutions

Even if there may be benefits, adding actuators and sensors to smart cities comes with its own set of challenges. An important problem is presented by the sheer amount and complexity of data generated by the massive number of networked devices. Scalable, reliable cloud-based solutions are needed for the storage and processing of data because of the volume of data. The safety and confidentiality of data produced by sensors must also be preserved. Smart cities must use strong data encryption, access controls, and authentication methods to safeguard critical information and prevent unauthorized access.

Another issue is interoperability because different actuators and sensor components may use multiple communication standards or protocols. Smart cities embrace open protocols and interoperability frameworks to address this, facilitating the collaboration and seamless integration of various systems and devices. Additionally, before adopting large-scale smart city initiatives, cities must carefully assess the return-on-investment return and long-term advantages as the integration of actuators and sensors may need major financial inputs. Collaboration amongst many stakeholders, including local authorities, technology suppliers, investigators, and citizens, is essential to overcoming these obstacles. Smart cities can develop creative ways to improve the incorporation of sensors and actuators by encouraging interdisciplinary collaborations and knowledge exchange, which will ultimately result in improved efficiency and environmentally friendly urban settings.

8.4 Prospects and developments for the future

Smart cities' utilization of sensors as well as actuators will undoubtedly alter as technology advances. An intriguing prospect is the fusion of artificial intelligence (AI) and machine learning techniques with sensor and actuator systems. Artificial intelligence-enabled solutions can dynamically adapt to changing urban conditions and considerably enhance municipal operations [40].

By processing data closer to the source (i.e., sensors and actuators) rather than relying solely on centralized data centers, edge computing has the potential to reduce latency and enhance actual time adaptability in applications for smart cities. Additionally, as the Internet of Things (IoT) ecosystem matures, the range and capabilities of sensors and actuators will continue to expand. Miniaturization and advancements in sensor technology will enable the deployment of more discrete and versatile sensors.

Additionally, the advancement of 5G as well as beyond 5G (B5G) communication networks promises to give higher bandwidth and exceptionally low latency, thereby facilitating the speedier and more dependable flow of information between sensors and actuators. To encourage equitable and ecological urban growth, it is critical to address new concerns as smart cities emerge and seize opportunities. By using cutting-edge technologies and fostering collaboration, smart cities may maximize the advantages of sensing and actuation interaction to create more efficient, livable, and adaptive urban environments.

9 A case study: smart traffic management system in Bengaluru, India

9.1 Introduction

Bengaluru, India, frequently referred to as the "Silicon Valley of India," struggled with transit problems and increasing traffic congestion as a result of growing urbanization. As a result, using an integrated system of sensors, data analysis, and actuators, local authorities started a transformative traffic control initiative. To address these issues and improve urban mobility, the city authorities started a creative traffic management effort [41].

  • Sensor deployment: Bangalore has strategically positioned a vast system of traffic sensors at key intersections, thoroughfares, and transportation hubs. To gather real-time data on traffic flow, vehicle speed, and occupancy, the sensor array includes induction loop detectors, radar networks, and cameras.

  • Sensor technology integration: A thorough sensor array was created at important crossroads, thoroughfares, and transportation hubs using strategically placed traffic sensors, such as induction loop sensors, radar networks, and cameras. Real-time data on traffic flow, speed of vehicles, and occupancy might be collected thanks to this deployment.

  • IoT integration and data analysis: Real-time data from the sensor's array was effortlessly transferred to a central data repository using a cutting-edge IoT network. The massive dataset was processed and interpreted using contemporary statistical examination and artificial intelligence techniques, which allowed us to identify crowded locations and predict traffic patterns while taking into account environmental aspects like weather. Tables 3 and 4 present a representative sample of the information acquired by Bangalore's intelligent traffic management system. It gives the date and time as well as information about the volume of traffic, the mean velocity, and the level of connectedness at different periods of the day.

  • Integration of data and analysis: Via a cutting-edge IoT network, real-time data from the traffic sensors was acquired and transferred to a central data repository. The vast amount of traffic data was processed and examined using modern statistical analysis and artificial intelligence methods. The algorithm was able to predict traffic patterns, identify congested regions, and assess the effects of many external factors, such as weather conditions or special occasions.

  • Implementing actuators and managing dynamic traffic signals: Actuators were introduced into the traffic signal management devices at key intersections to dynamically change the durations of the traffic signals based on the data analysis. The actuator-controlled traffic signals minimized driver wait times and optimized them for heavily used routes by adjusting their green timings to the flow of traffic in real time. Additionally, the system incorporated dynamic message signs and mobile applications that provided real-time traffic updates and advised detours to help drivers steer clear of crowded areas [42]. Actuators were added to traffic signal management platforms, enabling them to dynamically alter signal durations by data analysis carried out in real-time. Effective traffic flow was achieved as a result of the responsive control that decreased driver wait times and enhanced the timing of green lights. Mobile applications and dynamic message signs both offered real-time information and suggestions for detours to help drivers navigate more effectively. Tables 3 and 4 provides a concise overview of statistics about traffic management measures in the city by compiling important information from Bengaluru's Smart Traffic Management System.

Table 3 Information from the smart traffic management system in Bengaluru
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Table 4 Outcomes of Bengaluru's smart traffic management system interventions
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This table displays the results of the interventions done as part of Bengaluru's intelligent traffic governance system. It shows the length of each aid, how it affected the quantity of congestion, the % reduction in time required to travel, and how it affected the air quality. Through Tables 3 and 4, the data and results are specific to Bengaluru's smart traffic management method by switching the location of the municipality in the data tables to Bengaluru.

9.2 Results and benefits

Bengaluru's urban transport substantially improved after the implementation of the automated traffic management system, and passengers as well as the city's overall transport infrastructure benefited in a variety of ways:

  1. 1.

    Reduction in congestion: The immediate time route recommendations and dynamic traffic signal timings greatly reduced traffic during peak hours, resulting in a better traffic flow and quicker travel times for motorists on Bengaluru's crowded roadways.

  2. 2.

    Improved quality: Reduced stop-and-go traffic and unnecessary idling in areas with heavy traffic helped to improve air quality and reduce emissions.

  3. 3.

    Improved safety: The system's capacity to anticipate traffic patterns and spot potentially dangerous spots allowed for preventive safety measures and accident-avoiding techniques, improving commuter and pedestrian traffic safety.

  4. 4.

    Resource efficiency: Because of the improved traffic flow, vehicles used less fuel and cost less to operate, which improved resource efficiency all around and reduced operating costs for drivers.

  5. 5.

    Citizen engagement: Mobile applications that provided real-time traffic updates improved public involvement and gave Bengaluru commuters the power to make knowledgeable travel decisions, minimizing irritation during everyday travel.

9.3 Conclusion of the case study

Bengaluru's successful implementation of an intelligent traffic management system serves as an example of how sensors and actuator interaction may alter urban transportation. Real-time data and variable actuator control allowed the city to drastically enhance traffic flow, reduce congestion, and boost overall mobility. This case study serves as an example of how sensor-driven, data-driven, and actuator-enabled systems may effectively handle complex urban challenges, particularly in crowded cities like Bengaluru while creating more practical and comfortable urban settings.

10 Emerging trends and future prospects

10.1 Development of new sensor technologies

Rapid advancements in sensor technology present fascinating opportunities for smart cities. Major developments in the creation of sensors include shrinking in size, improving data accuracy, and using less energy. Less obtrusive and more aesthetically pleasing sensors are those that are more quietly incorporated into urban infrastructures.

Additionally, advances in sensor calibration and data processing techniques improve data accuracy, enabling more precise and reliable readings. This ensures that significant resource management and urban planning choices can depend on sensor data.

Energy efficiency must be carefully considered when implementing smart cities. Low-power gadgets and energy-harvesting sensors are becoming more common, which reduces the demand for traditional sources of energy and lengthens the lifespan of sensor deployments. Energy-saving sensors can help sustain smart city initiatives by lowering energy consumption and environmental effects.

10.2 Innovative actuator technologies

Actuator technologies are also evolving to meet the demands of smart cities. More efficient and responsive actuators allow for real-time adjustments and seamless sensor data integration. Urban infrastructure can be controlled more precisely by modern controllers with better precision and faster response times, which improves operational efficiency and resource utilization. Several actuators can now operate more seamlessly and in unison across various urban systems thanks to developments in actuator control and automation methods. The total reactivity and flexibility of smart metropolitan infrastructures can be improved through integrated control systems, which can dynamically alter actuators according to real-time data from sensors.

10.3 Integrating artificial intelligence and machine learning

The combination of artificial intelligence (AI) and machine learning (ML) is a breakthrough trend in the context of smart cities. AI-powered analytics can glean valuable information from the massive volumes of data generated by sensors, empowering cities to make fast decisions based on accurate information. To allocate resources proactively and perform predictive maintenance on urban infrastructures, artificial intelligence algorithms can recognize trends and patterns in data. For instance, ML models can predict the breakdown of utility equipment, enabling preventative maintenance to stop service outages [23].

10.4 Smart cities' resilience and sustainability

The development of smart cities is increasingly taking sustainability and resilience into account. To achieve these objectives, sensor and actuator technologies are essential since they maximize resource utilization, cut down on waste, and improve urban flexibility. Sustainable urban planning includes establishing energy-efficient structures, implementing eco-friendly transportation systems, and creating sensor-based green spaces. Cities can monitor and manage their water, sewage, and electricity systems in actual time with the help of artificial actuators and sensors, encouraging sustainable practices and minimizing their adverse environmental consequences.

10.5 Privacy concerns and moral issues

As the use of sensor data increases in smart cities, ethical and privacy concerns take the central stage. Cities must place a high priority on privacy, security, and openness to ensure that citizen data is protected from misuse or unauthorized access. Transparent data collection rules and clear permission procedures are essential for building community trust and promoting residents' involvement in smart city initiatives. Cities must actively address two ethical issues: the use of citizen data for surveillance and the potential for prejudice in AI systems. By establishing solid governance frameworks and incorporating stakeholders in decision-making procedures, smart cities may be able to strike a balance between harnessing data for innovation and protecting citizen rights.

11 Conclusion

This review explores advancements in sensors and actuator technologies for smart cities, highlighting the importance of precision and longevity in infrastructure. The dynamic role of actuators in real-time adjustments facilitates responsive urban management. Data security within these systems is crucial, and robust information-sharing mechanisms are needed. The case study on Bengaluru's Smart Traffic Management System demonstrates how the fusion of actuator technology and sensor arrays can enhance urban transportation and sustainability efforts. Prospects include blockchain technology and AI-driven urban management. The objective of this review is to provide a comprehensive analysis of recent developments in sensors and actuators for smart cities, with a particular emphasis on their implications for urban planning, data security, legal issues, and the potential for transformative innovation in urban management.