Electrochemical Sensor Project

Design a Sensor: An Electrochemistry Inquiry-Based Project

Instructor Notes

Purpose:

Often times, students struggle with grasping the concept of electrochemical cells and their applications. This active learning module aims to familiarize both introductory chemistry students and those enrolled in upper level chemistry courses with real-world applications of electrochemistry through electrochemical sensors. The goal of this project is to spark curiosity, inspire awareness, and facilitate inquiries into markets that utilize electrochemical concepts in their operations.

Textbooks tend to focus on electrochemical cells in the context of batteries, namely because they are a convenient real-world example of their application. Advanced chemistry courses, like analytical chemistry, are much the same, with labs that focus on voltammetry and electrochemistry in static conditions. This project allows students to explore concepts within the context of chemical and biochemical sensors. In this module, students were required to (1) identify a problem that could be mitigated through the use of chemical/biochemical sensors, (2) design a sensor and explain its implementation while integrating an electrochemical (or analogous) reaction, (3) estimate the costs of producing their sensors, and (4) “pitch” their problem and corresponding sensor to the class. Since the nature of the module was conducive to independent learning, students were given free-reign on the specifics of their projects/chemical reactions, and were encouraged to be creative.

Implementation:

Students were assigned this project at the beginning of the electrochemistry lectures in General Chemistry II. Students were required to read the background materials on sensors (attached to this packet). The concepts presented in the ‘Sensors background’ document were also referenced throughout the electrochemistry lectures. This module was implemented in a large lecture with roughly one-hundred-and-sixty students. Electrochemistry lectures were covered throughout the 3 week duration of this project.

Due to the nature of large lectures, students were required to form groups of four to six individuals to facilitate presentations, and presentations were limited to a maximum of three minutes. Groups chose a team name and signed up on a Google Form in an organized fashion.   In smaller settings, students may work in smaller groups or work independently. In addition to efficiency, group work facilitates the exchange of ideas among students. Students had opportunities to consult with any number of resources, including the use of office hours (especially to ensure the accuracy of their chemical reactions), before and after class, use peer-student instructors, and graduate teaching assistance. This project would be much easier to implement in small lecture or lab courses in terms of logistics. However, with planning and use of google forms, the implementation in large lecture was relatively simple. The Google forms that have been used to facilitate simpler implementation are attached for reference.

Modifications for upper level chemistry courses may ask students to identify which electrochemical technique would be best utilized for their sensor,  calibration methods, and current to concentration conversions. There are a vast number of permutations that could be achieved through modifications to this project. 

Grading:

This module may be used as an extra credit assignment or may be counted for a portion of students’ overall grades depending on the class. In this case, the project was assigned as extra credit. The instructor and students both filled out an evaluation form (sent via email to students as a Google form) at the time of the presentation; there are seven categories, and each category may receive a minimum score of 1 and maximum score of 5. A sample google form is attached to this packet. Score analysis was simplified through excel.

Final grades were determined by correlating the instructor’s evaluation to the students evaluation via a linear regression. In our case, students received ten points if their total score reached a minimum of 80. Students scoring below an 80 received a fraction of the score, scaled to ten points. Alternatively, instructors may choose to set the grade as a weighted sum of student evaluations and instructor evaluations. For instance, if student evaluations were worth 50% of the grade, then grades would be calculated as: (0.5*average peer score) + (0.5* instructor evaluation), and scaled to a total of ten points.

Learning Outcomes:

Although the module was only assigned as extra credit, students went above and beyond the outlined requirements. Students read peer reviewed literature to formulate their problem and their proposed sensor, in addition to researching different chemical reactions beyond the scope of the textbook lectures. They researched and inquired about multiple reference electrodes, in addition to specifying how different electrodes could be used to optimize their sensor design. Many students used 3D printing software to create their designs, and some students even printed physical versions of their designs to supplement their presentation. Moreover, students showed comradery and team work throughout the course of this module.

Giving students free-reign over the project allowed them to present creative solutions to different, niche sets of problems. In our case, students were not aware of the grade breakdown; in order to prevent students from being disincentivized from putting forth substitive effort, it is recommended that the grade calculation (especially if weighted between instructors and average peer evaluation) not be made public.

A STRIP survey was utilized to gauge student participation and time investment. Survey results indicate student felt the project was valuable to their leaning and gave overwhelmingly positive feedback. Attached to this packed is the STRIP survey that was utilized in our class.

Contributors and Attributions

• Asmira Alagic ([e-mail]) and Tara Tabibi, Saint Louis University
• Sourced from the Analytical Sciences Digital Library