Challenge Statement

Traditional biomedical engineering education, which excludes specialized design courses, often happens in a classroom or laboratory, with a focus on knowledge acquisition.18 This knowledge is less frequently applied to a practical application in an authentic working environment, where fundamental concepts and governing equations are applied to a specific application that is then built, assembled, and tested by a student-led team with varying backgrounds. To overcome this limitation and ensure that students garner adaptive expertise and are equipped for practical, generalized application of knowledge, they must be educated in experiential team-based exercises to solve multi-faceted problems.2,3,4,5,6,7,8,9 This type of environment allows students to gain a better understanding of their own potential contributions, their team members’ expertise and how to ensure successful outcomes.

MIT’s Medical Device Design course is comprised of in-class didactics, individual laboratory assignments, and a semester-long team project, which approximates a real-world, team-based design and prototyping challenge (course overview in Supplementary Fig. 1).5,6,7,8,9,10,11,12,13,14 Central to this experience is the identification of tangible unmet biomedical needs, in areas including physiology or pathophysiology diagnostics, therapeutic interventions, and biomedical research, which necessitate the design, fabrication and testing of mechanical and electrical device prototypes (ex., a tool to better visualize the cervix; a portable drug storage device for perishable pharmaceuticals). Students tackling these design problems represent a broad set of undergraduate and graduate students (third year undergraduates through PhD candidates), from diverse education backgrounds (multiple majors), with different levels of training and expertise (including professional joint MBA-Engineering program majors).5,6,7,8,9,10,11,12,13,14

To introduce these diverse students to new disciplines at a professional level, we challenged ourselves to design, pilot and evaluate a new structured experiential learning lab that would encompass the broad, multi-disciplinary set of skills required for medical device design, including mechanical engineering, electrical engineering, biological science, and software, as specified by ABET’s (Accreditation Board for Engineering & Technology’s) biomedical curriculum guidelines.1 While our semester-long team project already aligns with many of the best practices in biomedical education, with regards to authentic, contextual, teamwork, and co-participatory and problem-based learning, we identified the need for a structured hands-on in-class lab that would capture these aspects, be intellectually engaging for our diverse student cohort, and serve as a team-building precursor to their more involved semester-long projects.9,10,11,12,13,14,15,16,17,18,19,20,21,22,23 More simply, we aimed to foster the sort of technical literacy (and joy!) that comes from developing the hands-on mechanical and electrical engineering tinkering skills, which are important for today’s budding engineers.7,10 Finally, we aimed to create an affordable, approachable, and adaptable exercise, suitable for sharing with other biomedical engineering instructors. While the pre-laboratory assignment was graded, the in-class exercise, designed as a skills- and cohort-building exercise, was ungraded – the focus of both the teaching and student teams was on the doing and successful completion of the exercise.

Novel Initiative

Conceptualization, Analysis, and Building of a Syringe Pump

We selected a syringe pump as the base of this experiential learning exercise due to its prevalence in the clinical setting, exemplification of core mechatronics concepts – including hardware design, circuitry, and software control – and suitability for a team exercise. The complete initiative included a pre-laboratory assignment, the structured experiential learning exercise, and a post-laboratory survey. We positioned this lab to occur at the end of the first half of the semester, right before teams were fully dug into their semester-long projects (Fig. 1). Both this experiential learning exercise, and the semester-long project-based learning experience around the design of medical devices, represent a unique aspect of this course that offers students the opportunity for hands-on learning with projects that are motivated by real-world clinical challenges provided by clinical sponsors.

Figure 1
figure 1

Semester timeline, flowchart of experiential learning exercise, student teams building and testing, and complete list of semester-long projects.

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The experiential learning lab was prefaced by a an in-class lecture wherein we presented syringe pumps, their basic screw-driven operation, and critical safety considerations around their operation. We specifically discussed the importance of correct dosing, the history of failures, and the human factors requirements. The pre-laboratory assignment then emphasized the importance of a deterministic design process that begins with analysis,11 ,introducing the calculation of dosing volumes, according to drug pharmacokinetics and patient-specific dosing (nominally to sedate one of the course instructors), along with the mechatronic underpinnings of stepper motor control and basic motor selection. Students were individually asked to make decisions on motor sizing, step resolution, and cost benefit analysis, and calculate the ratio of output fluid volume to commanded stepper motor steps. Together, this taught them basic clinical, mechanical, and electrical engineering decision-making and analytical skills.

During the in-person experiential learning exercise, completed within a single 90-minute class period, we met in the electronics lab and each team (the same groupings as for the semester-long project) was assigned a bench. Then they worked together to program, assemble, and test a custom-designed syringe pump, shown in Fig. 2. Alternative syringe pump designs are available for additional inspiration as part of an emerging ecosystem of DIY open hardware, with the caveat that we emphasize the safety considerations around syringe pumps.4,6,22 Tasks were split between hardware assembly, electronic assembly, and software programming, with teams responsible for assembling the mechanical and electrical components of the pump and programming a basic infuse/withdraw pump function.

Figure 2
figure 2

Overview of syringe pump assembly. (a) Mechanical components and sub-assembly. (b) Electrical circuit diagram and breadboard assembly. (c) Assembled syringe pump and breadboard. (d) Activity workflow with each step and dedicated and/or recommended time allocation.

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Teams were provided with kits that included the following hardware (detailed in the appended Bill of Materials): a laser cut (Universal Laser Systems, pls6.75) acrylic frame and syringe holder and the necessary hardware to assemble it; hex keys, a set of rails and bearings; an Arduino nano; a stepper motor driver; an OLED (organic light-emitting diode) display; a breadboard with associated jumper wires; and buttons and a potentiometer for setting dose volume and extrusion time. While most electrical hardware was sourced from Amazon and the acrylic stock and mechanical components from McMaster-Carr, all are available from a wide range of vendors. The laser cut frame and simple hardware, as opposed to precision components, offered opportunities for students to learn about rapid prototyping with (and designing for) non-ideal components, and incorporating design elements, such as flexures, to accommodate inconsistent or irregular parts. Mechanical redesign was not a component of this activity; however, future courses could explore the opportunity to empower student teams to come up with their own mechanical design.

We met the goal of an affordable exercise with a cost of ~$70/kit and a design that can be produced in moderate scale (up to 50 kits), with access to a laser cutter, and assembled by students with hand tools. Furthermore, the final syringe pump can be easily disassembled, and all kit components can be reused.

The Arduino IDE (integrated development environment) platform was selected, because of its general familiarity to the students, simplified syntax and user-friendly USB programming procedure.3 Teams were also provided with commented skeleton code that included instructions for modification in the Arduino IDE. Due to our desire to complete the experience within a single 90-minute class period, students were only responsible for modifying a limited portion of the code to reduce the likelihood for potentially frustrating compilation errors that might distract from the overall learning objectives. An OLED screen was included to display user input and to help with debugging.

Following successful pump assembly and programming, teams were asked to dispense a specified volume of water over a set time, for example 10 mL over a minute, into a plastic cup. They measured time with a stopwatch and weighed the cups with a tared weighing scale (able to measure in grams or smaller increments) and discussed their overall accuracy.

The full assignment description, which includes Part 1: Pre-Lab & Solutions, Part 2: In-Class Experience, the complete Bill of Materials, a GitLab link to relevant code and DXF files for laser cutting, and the Post-Lab Survey, is provided as Supplementary Materials.

Outcome and Reflection

We prefaced this lab by telling students that it was a new, experimental assignment and that we would be soliciting their candid feedback on to help improve it for future cohorts. To that end, we administered an ungraded 15-min (time-limited) post-lab survey, which is included in the Supplementary Materials, to evaluate students’ pre-existing experience with mechanical, electrical, and programming concepts, assess their learning experience, and solicit open feedback.

Demographics and Experience

Twenty-eight out of the fifty-one (54.9%) enrolled students graciously responded to the survey. A summary of the respondents’ demographics and prior familiarity with syringe pumps is provided in Table 1. We had a 1.7 ratio of graduate student respondents to undergraduates and the same ratio of women to men – this was on par with the overall course demographics. Syringe pumps were new to over two thirds of the students. There was wide variability in students’ prior experience with the core mechatronics concepts, as shown in Fig. 3, with most reporting moderate experience. Across the three mechatronic categories, after normalizing for student count, given in Table 1, graduate students were slightly more likely to identify as experts than undergraduates.

Figure 3
figure 3

Student’s self-reported prior experience with core mechatronics concepts.

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Table 1 Respondent student’s demographics and prior familiarity with syringe pumps.
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Learning Evaluation

The next set of questions employed a 5-point Likert scale, with eight questions specific to the lab experience and student responses shown Fig. 4.26 We considered responses of Agree or Strongly Agree to be positive and anything less to be negative, including “Neither agree nor disagree,” and reported these percentages after each question on the plot. Sub-questions 2 – 4 also provided the option to indicate “did not participate,” abbreviated as “DNP,” and these were excluded from calculating the negative and positive responses. The final three questions in the survey, not plotted, asked students to self-report the time spent on the pre-lab assignment (to the nearest 30 min), whether the lab would be better split over two class periods (yes, maybe, no) and, lastly, “How could this lab be improved, for next year and if we share it with others?”.

Figure 4
figure 4

Evaluation of learning experience for eight metrics with a 5-point Likert scale.

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Starting by looking at the broadest learning goals, the majority of respondents indicated that the lab successfully connected to medical devices’ requirements and served as a team-building experience, with 79% and 86% positive responses, respectively. Half the students also indicated that they gained an understanding of steppers and mechatronic systems. The responses to Sub-questions 1 – 4 had a more normal distribution, with at least half the students reporting a positive experience with the mechanical and electrical components, but a negative experience with the pre-lab and software component. Excluding one student who spent >3 hours, the average time to complete the pre-lab assignment was 1.5 hours. Three quarters responded that “yes” the lab should be split over two periods, with the remainder indicating “maybe.” The open feedback, which was provided by half of the respondents, was detailed and valuable.

Discussion and Open Feedback

We looked first at the numbers and then the open feedback for explanatory insights. While we revealed the material in a stepwise manner – from the brief in-class lecture introduction, to the pre-lab analysis, to the full writeup during the in-class experiential learning exercise – students indicated a strong preference to receive all the material in advance, so that they could better prepare and review aspects of interest. The pre-lab was, unfortunately, a source of student frustration, with few accurately calculating commanded motor “steps” from required dispensed fluid volume. Typifying the feedback, one student recommended “Consider redoing the pre-lab quiz to be more instructional, so people are prepared for building and feel like they are learning vs. being tested on prior knowledge.” In tandem, we were asked for an applied lecture focused specifically on how stepper motors work, breadboarding circuits, and the motor control and display code. The mostly pre-built code, comprised of stepper, interface and display, with values that needed to be modified, proved hard to understand and debug, and students wanted more time and explanations to work through understanding and debugging the code blocks. While students broke up the lab based on their skill sets, as evidenced in sub-questions 2 – 4, many commented that they wanted the opportunity to hone skills with which they were less comfortable.

The single build and test session was repeatedly described as “rushed.” Students recommend that we “perform building the electrical circuit, mechanical pump, and code in one class period or prior to the class” and then “spend the second half giving every team a chance to test it out, and finally a debrief/wrap-up before letting everyone go.” One student went further with, “While I'm not usually a proponent of more assignments, I really think that a post-lab (even as a group) would be helpful in solidifying the connection between the different systems.” We are very grateful for the students’ candid feedback, which clearly highlights the importance of including students as active participants in curriculum co-design.12

Conclusions

By incorporating both mechanical and electrical engineering principals with a software layer, united through a clinically relevant medical device, this pilot hands-on activity provides a strong biomedical learning opportunity that encourages learners to integrate multiple subsystems into a single system – to think about the system “as a whole” – and parallels the nature of modern medical devices. Successful completion of the initiative required contribution from all team members, both encouraging team growth, and replicating the experience of working on a diverse design or clinical team.

The implementation of this novel pedagogical initiative promotes adaptive expertise as students apply the analysis from the pre-lab to the hands-on experiential lab component.2 Presenting the theory of the dosing, syringe pump, and motor calculations in this context, and subsequently building the device promotes the ability to apply this knowledge, and generalize theoretical concepts and governing equations to diverse problems in the future.] This student-centered instruction is of utmost importance in biomedical engineering education to enable students to apply their innovative thinking to new contexts, encouraging inductive learning.8 As students embark on professional careers in biomedical industry and academia, these skills will equip them to integrate multiple perspectives and fundamental theory to solve healthcare problems. In the future, this activity could incorporate mechanical prototyping, in which students make their own designs, followed by testing and debugging, in which students benchmark their designs against previously calibrated systems. Future analysis of intra-team dynamics (ex., whether level of experience influenced who took on different roles) would also be insightful.

Direct observations and our post-lab survey identified key opportunities to better tailor this assignment to our cohort. Students specifically suggested expansion into a multi-class exercise, with stepwise pre-learning, increased sub-system depth, enhanced opportunities for all students to gain comfort with material that is new to them, and a post-lab group reflection to solidify learning. Future work will also evaluate the impact of this activity on outcomes of the semester-long project through objective evaluation of final grades and subjective online student evaluations. We share this lab and experience freely with other biomedical educators and look forward to hearing of their modifications and improvements.