Using STEM to Educate Engineers about Sustainability: A Case Study in Mechatronics Teaching and Building a Mobile Robot Using Upcycled and Recycled Materials

Abstract

Background: Sustainable design means to base design on any systems and methods that can fulfill any of the sustainability goals: reducing waste, recycling plastics, upcycle materials, etc., and having less of an impact on the environment. Therefore, a challenge arises: how to design products based on sustainable design. This research presents a case study, about how students in a university’s design department, used sustainability practices in their projects, to adopt sustainability as a major aspect during the design process of a product. Methods: The researchers used STEM methodologies to educate and guide the students to adopt recycling and upcycling practices to design and develop an educational mobile robot for Educational Robotics and Mechatronics applications. Results: Students were encouraged to develop their problem-solving approaches when developing their designed robots, for a mechatronics project given to them. In this way, the researchers fostered the active and motivated participation of students; an increased interest was found related to several factors, including challenge, competition, group participation, and more. Conclusions: This research aimed to evidence the use of upcycled and recycled materials in product development to fulfill some of the sustainability goals. The research’s results were very promising and has sparked an ongoing research.

1. Introduction

Sustainability means using resources in a way that does not harm the planet and it has become a key element in every industry. The UN Commission on Environment and Development provided the report “Our Common Future” in 1983 [1]. The report included a definition of sustainable development as development that “meets the needs of the present without compromising the ability of future generations to meet their own needs”.

Sustainability is considered to have three dimensions: environmental, social, and economic [2]. The environmental dimension of sustainability is usually emphasized. It focuses on global problems, including pollution, species extinction and biodiversity loss, climate change, deforestation, and loss of ecosystem services. Human activity is harming the planet, jeopardizing the future of humanity on it. Sustainability means using resources in a way that does not harm the planet, so that humankind may live well on it for a long time. The concept of sustainability indicates the wise use of natural resources catering to the needs of the planet’s population, helping economies grow, and meeting human development goals. It also indicates the protection and conservation of natural resources, enabling nature to provide the resources and ecosystem services that sustain life, making them available for all the generations to come. Sustainability, as a key element to every industry, can guide decisions and actions for development at the global, national, and individual levels aiming to meet goals for development. That is considered sustainable development. According to UNESCO, “Sustainability is often thought of as a long-term goal, while sustainable development refers to the many processes and pathways to achieve it” [3]. The UN adopted 17 Sustainable Development Goals (SDGs) in 2015. These are objectives that form a plan of sustainable development on a global level [4,5].

Sustainable design or “Design for Sustainability” means to base a design on any system and method that can fulfill the sustainability goals. The term “sustainable design” has been used in many disciplines, as well as in product design. Sustainable design integrates an environmentally friendly approach that considers nature’s resources to be a part of the design. Principles such as reducing waste, recycling plastics, upcycling materials, energy-saving, etc., allow for human activities to have less of an impact on the environment and help us address the challenge of designing products based on sustainable design. In such a way products are recyclable, compostable, or reusable [6]. Sustainable design creates solutions through reasonable consumption of the planet’s resources so that societies can live well and in harmony with the environment today and can safeguard their future. The concept of ‘Design for Sustainability’ (D4S) indicates that environmental, social, and economic concerns should be considered throughout the design process and the resulting product [6]. The conscientious effort to embed sustainability into curricula is defined as Education for Sustainable Development (ESD). ESD is defined by UNESCO (2021) as: “the process of equipping students with the knowledge and understanding, skills and attributes needed to work and live in a way that safeguards environmental, social and economic wellbeing, in the present and for future generations” [3,7]. The numerous definitions of ESD, outline the relationship between the environment, society, economy, and education to support the development of knowledge, skills, attributes, and values [8]. There is evidence of a growing trend in higher education institutions globally to embed ESD in curricula, providing mindful, transformative education that gives students a strong sense of agency and hope for a better future [9].

2. Background

Worldwide, there is a rising number of efforts in academia to embed sustainability into curricula, so that students are provided with the necessary knowledge, skills, and attributes to act in their professional and private lives, in a way that protects the environment and enables well-being [9]. Within the work presented, we have investigated cases of embedding sustainability principles into higher education at the teaching and learning level. There are many cases of sustainability embedded into curricula and these include various subjects that are taught, i.e., basic science [10], business curricula [11], or engineering [12]. However, there are very few cases of sustainability embedded into mobile robotics courses at the higher education level. STEM and Educational Robotics are very popular in K-12 education, but there are limited works published regarding the sustainability and development of educational mobile robots in higher education. Nevertheless, among the limited works published, it is concluded that STEM projects based on educational robots, following education on sustainability approaches, would improve student’s skills and increase their motivation [13,14]. We should point out that Bernardine Dias et al., in their work examine the potential intersections of robotics and its component technologies with education and sustainable development, and Sathiya et al., in their work, focus on the green design and development of mobile robots [15].

2.1. Engineering Education

Education in industrial design and production is one of the primary pillars of economic development [16]. The students of the industrial design and production engineering university departments are trained to find solutions to issues related to industry and beyond. Through their education, they learn how to study a problem, analyze it, and propose and design feasible, applicable, and acceptable solutions [17]. For this purpose, many didactic approaches have been utilized including problem-oriented and problem-based learning, and recently STEM and Educational Robotics have become the new modern trends of teaching and learning, gaining popularity over the last few years due to their proven learning value even in the higher education [18,19]. STEM methods support students at all education levels to develop cognitive skills in critical thinking and problem-solving [20,21]. Nowadays it is crucial to embed sustainability and the Sustainable Design Goals (SDGs) into education in order to cultivate an innate sustainability mind-set and relevant competencies in students.

2.2. STEM

In the 1990s, the National Science Foundation (NSF) first introduced the SMET as a precursor to today’s STEM acronym, to describe learning and teaching in the fields of Science, Technology, Engineering, and Mathematics [22,23]. In the literature there are many different definitions of STEM; however, STEM is related to teaching and learning methods that integrate the content and skills of the terms that compose it [24,25]. STEM can be integrated into education via two different approaches:

• The content integration approach, which focuses on consolidating content areas into a single teaching activity to highlight “big ideas” from multiple content areas, and
• The contextual integration approach which focuses on content from a single scientific field, while also using frameworks from other disciplines in order to make the topic more relevant [26,27].

2.3. Educational Robotics

Educational Robotics is one such well-known STEM integration that is commonly used within and outside schools. It refers to technology platforms (e.g., robots and robot kits), educational resources (and programs), and learning theories. It has gained popularity over the last years due to the students’ involvement in undertaking challenges and learning outputs through the process of exploration, discovery, and invention using real problems and situations [25]. Both STEM and Educational Robotics share many of the same benefits [28,29,30,31,32,33,34,35,36,37]:

• They increase students’ motivation and curiosity.
• They encourage students to express new ideas, think differently, and problem solve.
• They encourage teamwork, cooperation, and socialization.
• They improve the learning experience and the students’ concentration.
• They develop students’ soft skills, such as teamwork, critical-thinking, creativity, problem-solving, and cognitive–social skills.
• They provide practical experiences with many scientific subjects, making them fun and attractive and retaining the students’ curiosity and attention.
• Eliminate stereotypes about gender roles, and bridge ethnic and gender differences.

2.4. Educational Robots for Educational Robotics and STEM

To date, robots and, specifically educational robots are increasing in popularity in education. Their playful nature, together with their STEM integration into educational activities, transforms them into interesting learning tools. Although Educational Robotics can be “unplugged”, meaning that educational activities can be implemented without the necessity of educational robots, in most cases, an appropriate educational device (robot, robot kit) must be used for Educational Robotics. Today, a wide variety of such educational devices can be found in the retail market, distinguished into two basic categories: (i) programmable robots (e.g., Thymio, mBot, Edison, Ozobot, etc.), and (ii) robotics kits (e.g., Lego^®, Robotis, Makeblock, VEX, etc.). While these options meet the educational needs of K-12 students, in tertiary education, custom robots are usually used due to their advanced specifications, different teaching goals, and increased variety of possibilities in the context of the robot’s hardware and software [38]. Consequently, custom robots were introduced, into many university engineering courses as teaching and experimental tools for learning disciplines.

Custom robots are robots that are designed and built according to the needs that they are called upon to fulfill, bypassing the main limitations of commercial robots and robotic kits, such as the following [39]:

• Expensive—not affordable—robot cost;
• Limitations concerning expandability (not so many sensors, actuators available to add, absence of specialized sensors to use, etc.);
• Some of them use close-source robot architecture placing constraints on the further development of software/hardware by its community;
• Limitations concerning the robot’s shell and shape customization;
• Limitations concerning the robot’s accompanied software e.g., absence of different languages programming, or cooperation with specialized computer programs/software;
• Robots demand specialized hardware e.g., modern PCs, latest versions of operating systems, and sometimes Internet connection for programming.

While the didactic approaches of STEM and Educational Robotics are widely used in higher education and gaining popularity, it is most likely that they are “hidden” in the teaching context of a course such as in Mechatronics, Robotics, Automatic Control Systems, etc.

2.5. Mechatronics

Mechatronics is defined as the intersection of mechanics, electronics, computers, and control [18,40]. Mechatronics is a new and growing field that combines different types of engineering practices to create robots and systems that can think and act on their own. It involves technical and non-technical skills like building and designing robots (mechanical engineering), designing and implementing circuits (electrical and electronic engineering), and using computer programs (computer software engineering) to make robots do what we want them to do [19]. Like STEM, the application of Mechatronics in education has been developed in many forms and contexts [18,41]. For instance, Alptekin et al. [42], and Amerongen et al. [43] pointed out the “integration” aspect of Mechatronics, and that should be a key teaching objective for any engineering curriculum. Furthermore, multiple studies [44,45,46,47,48,49] have already documented Mechatronics’ value in the interdisciplinary context of an engineering curriculum. As in STEM education, the didactic methods that are most suitable for Mechatronics education focus on the use of project-oriented and project-based learning [50,51,52,53,54,55,56]. This gives Mechatronics (similar to STEM) considerable appeal as a general-purpose educational tool for imparting general skills and competencies.

2.6. Mechatronics Course at University of West Attica

The Industrial Design and Production Engineering Department (IDPE) delivers an Industrial Design and Production Engineering degree after ten semesters of taught courses [17]. The subject of the department is the design of modern systems and services, creatively combining knowledge and methodologies from a broad spectrum of sciences, using new technologies for the design and production of innovative products, with the ultimate goal of increasing productivity and production and maintaining environmental sustainability [16]. In this way, its graduates must be capable of creatively using new technologies, science, and art to design solutions in the form of easy-to-use and functional products, processes, and systems in all productive sectors [16].

IDPE’s curriculum incorporates a Mechatronics course taught in the 7th semester. As noted above, Mechatronics is the intersection of multiple engineering disciplines, most of which are covered in specialized courses. Ιn the case of IDPE, the following courses are offered: Automatic Control Systems, Data Collection and Analysis, Robotics, Electronics, System and Signal Analysis, Microcontroller-Based System Design, and more [57]. However, none of these courses deals with an authentic, real-life problem, developing the problem-solving and team-working soft skills of the students, and nor do they introduce the aspect of the different technologies’ integration for designing integrated systems and devices. In this context, the team who is responsible for the delivery of the Mechatronics modules examined these requirements considering the literature and developed the Mechatronics courses based on STEM education principles and using Educational Robotics methodologies and practices.

2.7. The Teaching Model for the Mechatronics Curriculum

In this direction, existing STEM and Mechatronics teaching models were used from the literature, resulting in the following adapted proposed model that best served the purposes of the Mechatronics course in the IDPE and met the following conditions [42,45,58]:

• The model must be adapted to the requirements of the IDPE curriculum.
• It has to be in line with other didactic models reported and used in the literature.
• It has to adopt a participatory way of teaching Mechatronics, where students have to develop their problem-solving approaches to the Mechatronics challenge given to them.
• It has to improve the students’ soft skills, including complex problem-solving skills, critical thinking, creativity, teamwork, coordination with others and management, judgment and decision-making, communication, etc.
• It has to foster active and motivated student participation.

The proposed theoretical model represents these factors and it comprises four stages. It was based on the literature [59,60,61,62], it is a modified model of Chatzopoulos’ framework [27], and it utilizes the Computational Thinking Skills Model in synergy with the Teacher Guidance Protocol [63]. The model’s four stages (Figure 1) are as follows [18]:

• Challenge. A complex problem is presented to the students with a specific goal to accomplish. While the project’s goal seems to be feasible, it is not so easy to achieve.
• Explore. The students must develop a problem-solving approach by decomposing and simplifying the problem into smaller manageable parts to find a solution. These parts are equally outsourced to the other members of the team. In this way, the team members can easily understand the parts and tasks that need to be done.
• Exchange. At this stage, the students communicate their knowledge and exchange views and solutions with fellow students, teaching staff, and peers. Also, the students manage the teamwork between them and with partners.
• Generalize. The students recognize task parts that are known and frequently lead to easier use (e.g., designing algorithms). Therefore, they use general pieces of learning as reusable parts of their tasks.

Figure 1. The model’s four stages of the “students’ loop”.

Figure 1. The model’s four stages of the “students’ loop”.

This model uses a circular process (called students’ loop), where the knowledge students gained from the last (Generalize) stage, can be useful to review and modify the problem under a new scope, feeding a new cycle (loop) of the model’s stages. This may be useful in the case where the completion of a full four-step student loop leads to the student being able to cope better with another project (Mechatronics assignment). In this way, the Generalize stage of the first loop feeds the Challenge stage of the second loop, and so on. In addition, this model specifies one more loop: the educator’s loop (Figure 2).

The educator’s loop is an outer loop that nests the student loop. It has the following four stages [18]:

• Review didactic goals,
• Introduce new means,
• Receive student’s feedback,
• Appraise results.

It was based on Atmatzidou’s Teacher Guidance Protocol [27,63], and used to develop students’ problem-solving and metacognitive skills.

3. Research Materials and Methods

3.1. Research’s Gap

This study focuses on sustainable design, and in particular on how students can be trained to adopt a friendly culture for sustainability for their future employment as engineers. While sustainable design, has been used in many disciplines [12,14,64,65], and there is an effort to be embed it into curricula [7,66,67] e.g., Education for Sustainable Development, there is a limited number of works in the literature on how to embed it—based on specific guidelines—into engineering courses, such as Mechatronics, Robotics, Control Theory, etc., as well as in product design. In the literature [68,69,70] the most common guidelines and principles regarding sustainable design are mostly related to the design of sustainable buildings, but there is very little work in the literature—as far as we have looked —on the above. Therefore, a research gap is revealed and a question arises: how can we train engineering students to adopt sustainable design practices (principles) when they are asked to design innovative products?

3.2. Research’s Question

Based on the above clarifications, this research investigated whether the contribution of sustainable design principles to STEM-based education and Educational Robotics can educate university students –and consequently tomorrow’s engineers—to adopt a friendly attitude toward and develop a culture around sustainability through the curriculum of a Mechatronics course. Below, a pilot case study and its early qualitative findings are presented, based on the educational practice at the IDPE of the University of West Attica (UoWA).

3.3. Objective and Significance

Education in industrial design and production is one of the primary pillars of economic development. The students of relevant engineering university departments are trained to find solutions to issues related to industry and beyond [16]. Through their education, they learn how to study a problem, analyze it, and propose and design feasible and applicable, and acceptable solutions [16,17,57]. This research presents the results of a pilot case study, about how university students—who that will be the future engineers—of an industrial design and production engineering department, applied some of the principles of sustainable design to the design and development of a mobile educational robot for use in Educational Robotics and Mechatronics applications.

Caring about the future is essential. We need to promote prosperity while protecting the planet. So, it is crucial to adopt strategies that build economic growth while tackling climate change and protecting the environment. This research is particularly important because, if we train future engineers in sustainability practices, can they design the innovations in the modern world that are needed to sustain life on theplanet and safeguard the future.

3.4. Methodology

The research was conducted at the IDPE of the UoWA in the context of the Mechatronics course and it lasted for one semester. The research’s methodology was based on a literature’s STEM education model from the literature [27]. A total of 54 students attending the IDPE department participated, divided into teams of 3 people in a total of 18 teams.

Role play (see Section 3.8.2) was used in each team, and each student took on a role. The distinct roles proposed were the role of (a) the hardware developer (maker), who was responsible for the robot’s hardware; (b) the software developer (programmer), who was responsible for the programming of the robot; and (c) the system engineer (CTO), who was responsible for the sustainable design of the whole project. These roles were discrete and chosen by each student at the outset depending on their experience; however, they could be changed along the way (role rotation). Teaching staff following the STEM education model (see Section 3.8.3) were involved more in supporting the process and less in transferring knowledge; therefore, the approach was not teacher-centered, and, thus, it was more supportive. Educational Robotics was used to refresh/repeat knowledge that students had been taught in the past, in the subjects of electronic/embedded/control systems, microcontrollers, programming, etc. As a vehicle for the lectures / experiential workshops of educational robotics, the educational robot Mechatron developed by the laboratory was used, and, through it, the students gained experience both from its design and construction, as well as from programming it.

As far as sustainable design is concerned, no clear guidelines were given as it was the responsibility of each team to investigate what sustainability and sustainable design means, and to find principles of sustainable design, to adopt for use in their designs. In this way, the students researched, explored, and discovered the meaning of these terms through direct expreince. The first task of the teams was the selection of sustainable design principles and after one week, they presented the results of their research to the class in a plenary session, where the students gathered and exchanged views on their findings. The faculty’s contribution in this particular case was to present a list of some initial guidelines/principles of sustainable design, which the students then used in their groups as a guide to see if they had applied any of the stages and principles of sustainable design to their projects. Through this process, the student teams explored sustainability and sustainable design in an experiential way, and tried to apply it to the design of their own product and specifically to the specifications of the project they had undertaken. Each project had its own Mechatronic scenario the steps of which are listed above (see Section 2.7), however, all projects required the implementation of a mobile robot equivalent to the Mechatron.

3.5. Schedule

The research’s schedule is presented below in Figure 3. The duration of the research was 13 weeks, and it was distributed over time, as follows:

• 1st Week. Course presentation and teams’ management. First, the students were informed about the organization and conduct of the course on Mechatronics. The teaching staff presented the teams’ concept, and the course’s assignments—projects. Students formulated the student teams (3 students per team), and they chose a distinct role (see Section 3.8.2). Every team was given a project to fulfil, and they were given guidelines to research about sustainability, and sustainable design.
• 2nd Week. Teamwork and class plenary. Student teams had one week to research about what is sustainability and sustainable design, and to find rubrics or lists (related to engineering) about how to design, based on the principles of sustainable design. They presented their findings to the class in a plenary session. Accordingly, the teaching staff presented their own ideas on the principles of sustainable design and after a thorough discussion with the students, the final list was formed which was used in the evaluation of the team projects.
• 3rd to 5th Week. Workshops and Educational Robotics activities. During these weeks the teaching staff introduced and presented the educational robot Mechatron with the aim on the one hand, for students to gain experience and remember the knowledge learned, and, on the other hand, to be used as a source of inspiration for their own team projects. In addition, the teaching staff delivered Educational Robotics workshops related to electronic/embedded/control systems, microcontrollers, and programming.
• 6th to 12th Week. Teamwork. Student teams had 6 weeks to design and develop their educational robot to fulfill their projects requirements according to sustainable design principles.
• 13th Week. Teamwork presentation. Student teams presented their project. The teaching staff evaluated them based on in-depth observations of the artifacts delivered by the student teams, analysis of the accompanying text of the project, observations of the student teams during their working (recording their interest, teamwork, collaboration, dedication, and time spent), and the score (score 0–30) of the formed sustainable design principles’ list. A full discussion and feedback with the teams followed.

Figure 3. The block diagram of the research’s schedule.

Figure 3. The block diagram of the research’s schedule.

3.6. Participants

The participants of this study were 54 students in the 7th semester, attending the Mechatronics course at the IDPE at the UoWA. During this research, no written or online questionnaires were given, so we did not record any demographics at that time, as this was the first, pilot qualitative study. All students attending the course were included in the research, as they were obliged to fulfill the assigned Mechatronics team project.

3.7. Type of Study

This study is the first, pilot case study, and—in terms of the type of data, it consists of qualitative research. Based on its results, a future quantitative research study is planned to follow.

3.8. Methods and Materials

The following supportive teaching techniques methods (Scenario, Role Play, Teacher and Guidance Protocol) and materials (Mechatron and Sustainable Design Checklist) were used to support the STEM education model [27] and evaluate the overall process.

3.8.1. The Scenario

The scenario, collaborative scenario, or script is a teaching contract between educators and students on how to work together. It describes students’ collaboration in roles, tasks, deliverables, work phases, etc. [27,71].

3.8.2. Role Play

Another collaborative scenario is the role play, which describes the students’ roles within the team or group [27,72]. The Mechatronics course was designed as a series of increasing-complexity problems (assignments), which can be performed with the same equipment: an educational mobile robot (see Section 3.8.4) designed and built by the Laboratory of Industrial Systems and Mechatronics Applications (ISMA) of UoWA [73]. Note: From this point of view, the delivered Mechatronics course followed the Educational Robotics methodologies.

An educational robot consists of two main parts: its hardware and software [74], The hardware includes all the mechanical parts of the robot, its electronics, its shell (shape), and what other materials it has, while the software refers to the program (or code) that is responsible for the smooth operation of the robot’s hardware [37]. Correspondingly, the two main roles of maker and programmer were assigned to the members of the team. Makers were responsible for the robot’s hardware and programmers for the software. Furthermore, another member had the role of CTO, who was responsible for the technological needs of the project, oversaw the members of the team to reach the projects goals, and was responsible for aligning the project with the given sustainable design principles. Each team member knew his/her responsibilities; thus, the roles were clearly defined. However, they could be changed along the way (role rotation).

3.8.3. Teacher Guidance Protocol

The Teacher Guidance Protocol was based on Atmatzidou’s research [27,63], and was used to develop students’ problem-solving and metacognitive skills. In this protocol, the educators (IDPE’s teaching staff) have the role of consultant and facilitator and they provide support in the form of feedback, hints, and prompts. Thus, students need to externalize their thinking and their reflections, on how to apply their strategies to solve the problem. Moreover, this proposed teaching model utilizes additional supportive teaching techniques that from the literature [27,71,72], such as the scenario and the role play.

3.8.4. Mechatron, the Mobile Educational Robot for Mechatronics Education

The Mechatron is a mobile educational robot that was designed and built by the ISMA lab and continues to evolve. The Mechatron’s specifications and its development process have been reported in previous research [19,58]. It has been steadily evolving for the past 23 years. The left image in Figure 4 depicts Mechatron I (1st version), and on the right, Mechatron II (2nd version) is depicted. The first-generation Mechatron’s design was based on recycled and upcycled materials and parts to promote sustainability. It was built using hard disk platters disassembled from obsolete computers. It is still used as an inspiration for the students.

The robot Mechatron, includes a differential wheel drive, a breadboard (solder-less board for assembling electronic circuitry), a power supply, and a microcontroller (computer-on-a-chip) for its programming. It was designed and built to fulfill the Mechatronics course’s needs, advancing toward a variety of specs and to other commercial robots and robotic kits [37]:

• It is a low-cost, affordable, and modular robot that can be expanded into three dimensions.
• It can be built with common electronic parts that can be found in abundance on the retail market.
• Mechatron III–The third generation uses the cheap, open-source, well-known Arduino Uno board as its main microcontroller [19]. Optionally, it can be equipped with another microcontroller if there is a need for it. Newer Mechatron versions use advanced AI microcontrollers (e.g., Arduino Nano 33 BLE Sense) and/or a Single Board Computer (SBC) such as Raspberry Pi to support advanced Artificial Intelligence (AI), Machine Language (ML), and many other types of software (apps, libraries, and tools) running on an open-source operating system (Linux).
• It uses an open-source high-level C/C++ programming language for its programming. Furthermore, other Mechatron versions can be programmed with Visual Basic, and Python (which supports TinyML and Tensorflow).
• It can be connected to a variety of sensors and actuators. An embedded 6-channel A/D converter can be used for analog sensors and it is equipped with PWM, I2C, UART, and other peripherals.
• Finally, the Mechatron’s shape and shell can be freely customized.

The Mechatron’s design consciously consisted of low-cost, though modern and up-to-date technology. Its designs (blueprints and schematics) are open-source designs, so students can copy them and use them as inspiration for their robot projects. Over the years, the platform has proved to be a valuable source of learning, both for the students and for the teaching staff [75].

3.8.5. Design for Sustainability—A Sustainable Design Checklist

The concept of sustainable design requires that the design process and product creation consider not only environmental concerns but also social and economic concerns [6]. However, in the case of the project assignment within the Mechatronics course, no clear guidelines were given to the students, as it was their responsibility—according to the STEM model—to investigate about sustainability and sustainable design, and to find rubrics, lists, or principles of sustainable design (related to engineering), to adopt for their designs. In this way, the students researched, explored, and discovered the meaning of these terms and proposed their version for a sustainable design principles checklist.

So, after a week, the students presented their proposed sustainable design checklist (based on their findings, such as [69,70,76,77,78,79]) during the plenary sessions of the class, and a full discussion occurred, which resulted in the compilation of the following sustainable design checklist (

Table 1. The sustainable design checklist.

No.	Requirement	Points
	Energy Efficiency
1	Incorporate energy efficient electronic parts and techniques (e.g., LEDs for lighting, Pulse Width Modulation for motor control, etc.).	1
2	Incorporate renewable energy power sources into the project such as solar panels.	1
3	Use of materials sourced locally, where possible, to reduce travel.	1
4	Use of rechargeable batteries.	1
5	Use of higher-energy-density batteries, e.g., Li-ion, Li-Po, etc.	1
6	Reduce/minimize energy consumption during operation and in stand-by mode.	1
7	Choose appropriate components to reduce energy consumption, and materials to reduce the overall project’s mass.	1
8	Minimize and optimize software code to eliminate energy consumption.	1
9	Use of advanced, energy-efficient, new-technology microcontrollers.	1
	Waste Management
10	Use of renewable materials e.g., bamboo, cork, paper, cardboard, etc., or certified sustainably materials.	1
11	Use low-maintenance and/or durable materials that require very little energy to maintain over their life.	1
12	Use of standard size materials to minimize on site cutting and waste.	1
13	Arrange pieces when cutting materials in sheets, bars or rods in a way that they will eliminate material waste.	1
14	Use of batteries that do not contain toxic metals (e.g., mercury, cadmium, lead, cobalt, nickel, and manganese), such as NiMH.	1
15	Use of batteries with an increased cycle life e.g., Li-ion.	1
16	Use of a lead-free solder when soldering.	1
17	Use of breadboard instead of a PCB, where applicable in order to avoid the soldering of the electronic parts.	1
	Recycle
18	Use of materials containing recycled content e.g., PLA, PET, PET-G, etc.	1
19	Use of 3D-printing facility to make 3D parts from recycled filament.	1
20	Use of recycled materials e.g., recycled paper, recycled cardboard, etc.	1
	Upcycle
21	Use of upcycled cables for the project’s wiring.	1
22	Upcycle materials or reuse everyday devices and appliances e.g., materials and parts from toys, disused and/or obsolete devices, etc.	1
23	Upcycle electronic parts from disused and/or obsolete devices.	1
24	Upcycle batteries from disused and/or obsolete devices.	1
	Economic
25	Use of materials sourced locally where possible to reduce travel.	1
26	Reuse of parts and components coming from disused devices or older projects.	1
27	Minimal use of new materials.	1
28	Minimal use of overall materials.	1
29	Use of rechargeable batteries instead of single-use.	1
30	Use of batteries with an increased life-cycle e.g., Li-ion.	1

).

Each one of the above sustainable design requirements added a point to the overall score of the team’s project; thus, the maximum grade was 30. Of course, the above checklist does not fully comply with all of the 17 sustainable development goals, and their 169 targets and indicators of the United Nations [5], but it mainly focuses to the 12th goal, which is to “Ensure sustainable consumption and production patterns” [80]. This goal tries to achieve the sustainable management, and the efficient use of natural resources; the management of chemicals and all wastes throughout their life cycle, and the reduce waste generation through prevention, reduction, recycling, and reuse, -to name a few [80].

So, in the case of the project assignment within the Mechatronics course, we focused mainly on the environmental aspect and encouraged the student teams to build their project based on the principles of sustainable design. We especially, guided them on how to integrate sustainable recycled materials and/or upcycled (reuse) everyday materials into their artifacts. For this reason, two different approaches were used: (i) recycle and use sustainable materials, and (ii) upcycle/reuse existing materials and everyday devices and appliances. As for the first approach, sustainable materials such as wood, bamboo, cork, paper, cardboard, foam materials (e.g., Styrofoam), PLA, PET-G, and other recyclable 3D printer filaments, hot glue, etc. were suggested. Regarding the second approach, it was proposed to reuse disused appliances as they are or to disassemble them into useful materials and parts. Examples include the following:

• Cardboard, paper, plastics, cork, wood, metal, foam materials, etc. from products packaging;
• Various plastics from household products, lids, glasses, bottles, and straws, as well as disused cables (copper);
• Disused devices and power supplies;
• Obsolete devices e.g., mobile phones, audio systems, VCRs, TVs, modems, routers, children’s toys, etc., as well as other obsolete materials, and electronic parts;
• Obsolete computers, laptops, tablets, and smartphones, and obsolete electronic components and parts, such as hard drives, floppy disks, CD-ROMs (magnetic plates, motors), power supplies, LEDs, fans, cables, plugs, cases, etc.

In all cases, the implementation of low-cost solutions with easily found materials was recommended.

3.9. Data Collection

The research was carried out in accordance with ethical principles which ensure and define the ethical rules by which the research was conducted and completed. The data collection of this pilot research was limited to qualitative data (such as students’ observation, artifacts, notes, checklist and document analysis [81]), and the only quantitative data involved, were the scoring of the teams’ deliverable project according to the above sustainable design checklist (see Section 3.8.5). Klein notes observation as a research method that is suitable for both classroom and sample research scenarios [81]; thus, it was selected.

3.10. Data Analysis

The researchers and the laboratory’s teaching staff -who have many years of experience in the design and development of such systems- carried out the analysis of the qualitative data. Our data were based on in-depth observations of the artifacts delivered by the student teams; an analysis of the accompanying text of the project; and observations of the student teams, including recording their interest, teamwork, collaboration, and dedication shown, as well as the time they spent on the project. Additionally, we used the scoring sustainable design checklist to evaluate each team’s project related to sustainable design. We did not conducted a thematic analysis, which is usually used in qualitative research, since this was a pilot study, and we did not have any survey data.

3.11. Limitations

This research faces multiple limitations such as the following:

• It is the first pilot case study, and, therefore we cannot extrapolate/generalize its results to the general population.
• The data collected were mostly qualitative (rather than quantitative) and one axis of the analysis was based on the subjective observations of the teaching staff.
• Sustainability is considered to have three dimensions, namely environmental, social, and economic [82]. Although, an ambitious attempt was made to compile a checklist of sustainable design elements of all three dimensions, for sustainable design focused on industrial, design, production, and engineers, with specific criteria and scores, our study was based more on the environmental dimension of the sustainability. Regarding the UN’s 17 sustainable development goals [5], in our case, we focused on the 12th goal “Ensure sustainable consumption and production patterns” [80]. Regarding the 4th and 5th goals, “gender equality” in terms of numbers could not be achieved since in IDPE department much more males than females are enrolled, creating technical problems in terms of gender participation in the working student teams.
• We did not use a STEM evaluation rubric -based on the literature [83]- to evaluate how do this STEM-based course reflects the principles of the theoretical framework, as it was the first pilot study, and we collected mostly qualitative data.
• The literature searches have practical limitations in exploring all the literature sources in all the relevant databases.

4. The Mechatronics Course Implementation

The Mechatronics curriculum content was organized into two correlated parts: the lectures and the coursework (project). The lectures were focused on presenting several selected topics, including the following:

• The Mechatronic system: structure, information flows, role of interfaces.
• The actuator subsystem and interfacing: motors, e/m actuators.
• The sensor subsystem and interfacing: binary and analog.
• Microcontroller circuits: analog–digital conversion, hysteresis loop, filtering.
• Communication sub-system: serial, Serial Peripheral Interface (SPI), Inter-Integrated Circuit (I2C).
• Microcontroller programming and operating system features.
• Real-time programming: processing multiplexing, interrupts.
• Examples and applications.

The delivered lectures were focused on general engineering and several selected topics relevant to the specific coursework assigned to students. The coursework was a Mechatronics project assigned to student teams at the beginning of the semester. The coursework combined physical computing and Mechatronics to build hands-on autonomous mobile robots for educational and everyday applications. To achieve this, the team who was responsible for the delivery of the Mechatronics modules provided the following organizational support:

• Facilitated the organization of student teams of 3 people and provided support by being available during normal course hours and during several special “events”, like test runs.
• Helped the teams’ organization by breaking down their project into milestones and deliverables, scheduling and planning for the development of the solution, performing diagnoses and finding expert assistance, preparing reports and presentations, etc.
• Motivated, guided, coordinated, and supported the learning process for students to acquire skills and enrich their technical knowledge.

As proof of this, the team delivered auxiliary workshops focused on students’ projects. A typical workshop consisted of three phases: introductory, training, and practice. Workshops were hands-on Educational Robotics labs based on the ISMA lab’s developed robot named “Mechatron” (see Section 3.8.4). In the introductory phase, the necessary background theory was taught and explained. In the training phase, a typical practical example was based on theory was presented. In this phase, the robot Mechatron was involved in a physical computing example or Educational Robotics activity. In the practice phase, students took action, used the lab’s robots, assembled their electronic circuits, wrote and uploaded their software, and tested the result. In this way, they built their knowledge and gained confidence and experience to accomplish their assigned projects using Educational Robotics methodologies and practices. Furthermore, students were additionally supported by peer facilitators, such as students who had completed the Mechatronics course, and wanted to share their knowledge and experience with individual people or teams. This direction was facilitated by the “open philosophy” of the lab, which allowed students who are not enrolled in the course, to enter the laboratory area. Last but not least, both students and peer facilitators were strongly encouraged to provide feedback to the didactic team (see Figure 2: The educators loop), to evaluate learning outcomes, and didactic results, address students’ difficulties, and develop the projects for the next semester.

The Assigned Mechatronics Projects

During the semester the students formed teams of three people to complete a Mechatronics project assigned to them. The theme of the project was not random but was chosen to involve the students in “authentic learning”. The term “authentic learning” is used to describe educational approaches that encourage the students to learn through collaborative projects, that address “real” problems that are relevant to their everyday lives [84]. Almost all the assigned projects required an educational robot to fulfill. The students had two options: (i) to build their robot from scratch, based on the Mechatronics courses experience gained; or (ii) to borrow the ISMA lab’s robot (see Section 3.8.4) and customize it according to their needs. Some examples of Mechatronics projects that were assigned are as follows:

• Locate and Carry. In this project, the robot had to find (locate) several objects that were scattered in an arena and carry them in a pre-specified position in the minimum time.
• The Fire Brigade. In this project, the robot had to find and distinguish a fire source (e.g., a tea candle) located in an arena, and put out the fire within a specified amount of time.
• Hunter and Hunted. In this project, the students chose a role (hunter or hunted) and built the corresponding robot; for example, the hunter had to locate and capture the hunted robot in the minimum time.
• The Carriage. In this project, the robot pushed a carriage and had to deliver its content to a specific position within an arena within a specified amount of time.
• The Parking. In this project, the robot moved along the pavemen, found a parking space (able to fit), and automatically parked itself.

The assigned projects were suitably designed to achieve good STEM practices. Students were encouraged to develop their problem-solving approaches based on their experience. The didactic team was responsible for the Mechatronics course and facilitates the student teams, encouraging them to follow the engineering design process to accomplish their projects [27]. This process included the following phases that can guide the teams toward a solution:

• Define the problem. Describe the problem in detail, and break it down into smaller parts easier that are easier to understand and solve.
• Plan the solution. Think, make a detailed plan (with clearly defined steps that need to be done), and apply different solutions to the problem.
• Try. Build the necessary hardware, and write the accompanying software (program).
• Modify. Evaluate your solution, and if it meets the success criteria, keep it. If it is not, modify it and go through the above steps one more time.
• Communicate. Communicate your solution, keeping the right level of detail and editing out the unnecessary parts.

5. Results

In this study, we examined whether the contribution of STEM and Educational Robotics can encourage university students–and, consequently, tomorrow’s engineers–to adopt sustainable design in their robotic project designs, through the curriculum of a Mechatronics course. Based on the STEM education model [27], the teaching staff adopted a supportive and distinctive role to leave room for a participatory form of teaching, and inquiry learning, and guided the students in the following areas:

• To research, explore, and discover the meaning of sustainability, and sustainable design;
• To search the literature and find rubrics, lists, or principles of sustainable design, to adopt to their designs;
• To evaluate them and propose a suitable version of them for a sustainable design principles checklist;
• To adopt a more a sustainable policy and use recycled and upcycled materials, during the development of their artifacts.

Furthermore, the students were encouraged to develop their problem-solving approaches while designing their robots, thus engaging them in inquiry learning [83]; and the researchers fostered the students’ active and motivated participation.

The research’s results were based on in-depth observations by the teaching staff, along with the score of each team’s project based on the sustainable design checklist (see Section 3.8.5). The results of the team assignments are shown in

Table 2. The score of the teams based on the sustainable design checklist.

Req. No.	Team Number
	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18
1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1
2	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
3	1	1	1	1	1	1	0	0	0	1	0	0	0	0	1	0	0	0
4	1	0	0	0	1	0	0	1	1	0	0	1	1	0	1	1	0	0
5	1	0	0	0	0	0	0	0	0	0	0	1	1	0	0	0	0	0
6	0	0	0	0	0	0	0	0	0	0	0	0	1	0	0	0	0	0
7	1	1	1	1	0	0	0	0	1	1	1	1	1	1	1	0	1	1
8	1	1	1	0	0	0	0	0	0	0	0	0	1	0	0	0	0	0
9	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1
10	1	0	0	0	1	1	1	0	1	0	0	0	0	0	0	0	0	0
11	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1
12	1	1	0	0	0	0	0	0	0	1	1	0	1	1	0	0	1	1
13	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
14	1	0	0	0	1	0	0	1	1	0	0	1	1	0	1	1	0	0
15	0	0	0	0	0	0	0	0	0	0	0	1	1	0	0	0	0	0
16	0	0	0	1	0	1	1	0	1	1	1	1	1	0	0	0	0	0
17	0	1	1	1	1	1	0	1	1	0	0	1	1	1	0	0	1	1
18	0	0	0	0	0	0	0	0	0	0	1	1	1	0	0	0	0	0
19	0	0	0	0	0	0	0	0	0	0	1	1	1	0	0	0	0	0
20	0	0	0	0	1	1	1	1	1	1	0	0	0	1	1	0	1	1
21	1	1	1	1	1	0	1	1	1	1	0	1	0	1	1	1	1	1
22	0	0	0	0	0	0	0	1	0	0	0	0	0	0	1	1	0	0
23	0	0	0	0	0	0	1	1	1	0	0	0	0	1	1	1	1	1
24	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
25	0	0	0	0	1	1	1	1	1	1	0	0	0	1	0	1	1	1
26	1	1	1	1	1	1	1	1	1	1	0	0	0	1	1	1	1	1
27	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
28	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
29	1	0	0	0	1	0	0	1	1	0	0	1	1	0	1	1	0	0
30	1	0	0	0	0	0	0	0	0	0	0	1	1	0	0	0	0	0
Team’s Score	15	10	9	9	13	10	10	13	15	11	8	15	17	11	13	11	11	11

. It is evident, that most of the assignments managed to incorporate several of the principles of sustainable design, directly demonstrating the understanding and adoption of the principles by the students themselves. However, this score can be interpreted mostly as proof that the student teams tried to achieve the above criteria one by one, no matter how difficult it was, since there are principles on the checklist that work in competition with the others. For example, Requirement 5 (Use of higher-energy density batteries e.g., Li-ion, Li-Po, etc.), is competitive with requirement 14 (Use of batteries that do not contain toxic metals e.g., mercury, cadmium, lead, cobalt, nickel, and manganese, such as NiMH), since it is well known that NiMH batteries have less energy density from Li-ion, or Li-Po batteries.

In addition to the observations of the teaching staff, the following were recorded. Τhe artifacts delivered by the student teams were really interesting; several of them were beautifully designed, and, in almost all cases, at the core of their design, they were based on the principles of sustainable design. Two different approaches were used:

• Recycle and use sustainable materials;
• Upcycle/reuse existing materials and everyday devices and appliances.

As for the first approach, students used sustainable materials in their projects such as wood, bamboo, cork, paper, cardboard, Printed Circuit Board (PCB), insulation tape, PLA, PET-G, and other recyclable 3D printer filaments, hot glue, foam materials, etc. Regarding the second approach, it was proposed to reuse everyday appliances as it is or to disassemble them into useful materials and parts. Examples include the following:

• Cardboard, paper, plastics, cork, wood, metal, foam materials, etc., from products’ packaging;
• Various plastics from household products, lids, glasses, bottles, straws, disused cables (copper);
• Parts from disused devices and power supplies;
• Parts from obsolete devices e.g., mobile phones, audio systems, VCRs, TVs, modems, routers, children’s toys, materials, and electronic parts;
• Parts from obsolete computers, laptops, tablets, and smartphones, and electronic components and parts such as hard drives, floppy disks, CD-ROMs (magnetic plates, and motors), power supplies, LEDs, fans, etc.

However, in many cases, students combined both approaches and presented robotic projects that used recycled and sustainable materials, and upcycled and reused materials and appliances. The credentials of sustainable design are captured in Figure 5, where, some representative students’ robots that were built using recycled, sustainable materials, upcycle, and reused materials and devices are presented.

Last but not least, in relation to the teaching model that had been followed in the previous semesters, and was based entirely on the teacher-centered approach (i.e., typical university lectures), the following observations were recorded:

• Students demonstrated increased attention and participation in relation to lectures.
• They demonstrated more interest and spent much more time on their tasks.
• They worked as a team and cooperatively, took on roles that they carried out.
• They communicated with the other teams, exchanged knowledge and experiences towards achieving their goal.
• They showed interest in the problem given to them, possibly because it was authentic and related to real problems in everyday life.
• They engaged in the task while appearing to enjoy it, possibly due to the playful nature of the educational robots.
• Interacted more with the teaching staff, asked targeted questions, and spent multiple hours in the lab.
• However, there was no lack of problems such as:
• Communication problems related to roles and leadership.
• Leadership and decision-making problems.
• Various conflicts.
• Different commitment and dedication to the goal; within the teams, some members worked harder than the others.

6. Discussion

This study aimed to examine whether the contribution of STEM-based education and Educational Robotics can educate university students to adopt a friendly attitude toward and built a culture around sustainable design, through the curriculum of a Mechatronics course.

For the purpose of this study, a research methodology based on the literature’s STEM education model [23] was used. A total of 54 students divided into a total of 18 teams participated in and accomplished a Mechatronics team project; the design of it was based on a sustainable design checklist that was formulated by the students themselves. During the research, the students had to explore and understand, in depth the concepts of sustainability and sustainable design in order to propose a sustainable design checklist to evaluate their projects. At the same time, in order to support their work, they attended Educational Robotics workshops covering the topics of the Mechatronics course. Through this experiential process of inquiry learning, the students were able to learn about sustainable design on the one hand and to consolidate and utilize their knowledge in the Mechatronics course on the other hand; their artifacts were the proof.

The results showed that almost all students managed to incorporate several of the principles of sustainable design into their projects, as is clearly stated in Table 2. Furthermore, the teaching staff who had a more supportive, and less teacher-centric approach that following the STEM education model, interpreted its observations and other qualitative data as follows. Student teams’ artifacts were based on the principles of sustainable design. They mostly used recycled and sustainable materials and/or upcycled and reused existing materials. Morever, in relation to the teacher-centered model that had was followed in the previous semesters, the teaching staff recorded the positive impact that the STEM teaching model had on the students (increased interest, attention, participation, communication, teamwork, exchange of knowledge, etc.), as recorded elsewhere in the literature [28,29,30,31,32,33,34,35,36,37].

Limitations are still evident since it was the first pilot case study, and many things can be improved in future research, such as the use of more quantitative data, the composition of a new checklist of sustainable design that fulfills more sustainable goals, and the use of a STEM evaluation rubric -based on the literature [85]- for evaluation.

7. Conclusions and Future Work

This research evidences the use of sustainable design—in this case, by university students—in the design and building of an educational robot in the context of a Mechatronics curriculum. While there is an increased interest in embedding sustainability into curricula [9], there are only a few—and, therefore, not enough—works in the literature on higher-education case studies [86], especially using a STEM and Educational Robotics approach [64]. There are cases of sustainability embedded into engineering curricula [87,88] or cases of sustainability embedded into curricula related to environmental studies [12], and although there are many works in the literature [85,89,90,91,92,93,94,95,96] on the use of recycled and upcycled materials in STEM and Educational Robotics activities in K-12 education, the activites that they cover are not performed within a sustainability framework. STEM and Educational Robotics are very popular in K-12 education, but there are limited works published regarding the sustainability and development of educational mobile robots in higher education. Therefore, from this perspective this research is original.

This research’s results were very promising; students showed an increased interest in the Mechatronics curriculum, and they based the robot that they built on the principles of sustainable design. Likewise, students joined competitions and challenges, group participation, and team collaboration, proving that STEM-based education and Educational Robotics work constructively towards the pedagogical process. Based on the teaching team’s records and notes, we can see that the students showed an increased engagement in robot construction and took sustainable design principles seriously when integrating them into their design, proving the positive impact of the above teaching model methodology.

Based on the above clarifications, this research testifies that the contribution of STEM-based education and Educational Robotics can educate university students to adopt a friendly attitude toward and culture around sustainability, and it could be the spark for ongoing research.

The next step for this research should be a new study that incorporates a new, more complete sustainable design checklist (a good starting point could be the Nickels et al. work [97]), the use of a STEM evaluation rubric [83], and more quantitative data for better comparison and evaluation. Additionally, the proposed Mechatronics curriculum has already been evaluated in the past [18,98], so a new and thorough evaluation must be performed of the robot acceptance and the sustainability design by the IDPE’s students themselves. A suitable evaluation framework could be (a) the updated DeLone and McLean success model (U-IS success) [99]; (b) the Dynamic Model of Educational Effectiveness (DMEE) [98]; or (c) the Technology Acceptance Model (TAM), which predicts and explains the factors that lead to the use of an information system (in our case, the robot) [38,39,74].