2024 AIChE Annual Meeting

(253e) Low-Cost Hands-on Micro Spectroscopy Experimental Module for Chemical Engineering Education

Authors

Thiessen, D. B., Washington State University
Dutta, P., Washington State University
Adesope, O., Washington State University
Van Wie, B., Washington State University
The focus of the project is to teach prospective engineers about microfluidics and microtechnology. We wish to do so interactively to visualize the topic being studied for students, providing a complete model of the phenomena to address common misconceptions. Microfluidics was the topic chosen to be addressed by this project due to its importance, complexity, and relative obscurity in the current paradigm of engineering education. Microfluidics is de ned as the fluid behavior associated with the processing of micro-scale quantities of fluids and is thus a vital topic for those in the field of biochemical engineering and analytic science. Microfluidics has radically impacted chemical and biological analyses, allowing for improved understanding of cellular biology, point-of-care medical diagnoses, and of course fluid mechanics, while allowing for the production of economic and disposable micro-devices due to the advancement in soft lithography techniques. However, despite the topic’s relevance to many engineering disciplines, including microfluidics in a traditional engineering academic track has proven difficult, as it is multidisciplinary in nature, deriving concepts from physics, material science, chemistry, and biology.

There is currently a serious gap in engineering curricula involving microfluidics, so in the long term we intend to promote a new educational pedagogy to be adopted by the larger community to address this gap. In the short term, we attempt in this project to address this shortcoming through the development of low-cost desktop learning modules for classroom and laboratory usage. Educational materials will be provided with these modules, and the effectiveness of these new pedagogical implementations will be assessed through a careful examination of student comprehension of the material provided.

The first module under development to meet this end is a micro-scale glucose assay analyzer, which relies on microfluidic principles and a common biomedical topic, glucose, to cover several scientific topics at once: reaction kinetics, absorption spectroscopy, and Beer’s Law.

Glucose is commonly measured as a blood chemistry because it is a key indicator for many medical conditions, such as diabetes. The concentration of glucose in blood is commonly measured via a multi-stage reaction in which glucose is first oxidized to produce peroxide, which is then detected by reacting with 4-amino antipyrine in the presence of a different enzyme, peroxidase, which in turn yields a final product, quinonimine, a red dye with a characteristic wavelength of light it absorbs. Under optimal circumstances, the concentration of glucose in the solution can be correlated to the amount of light allowed to pass through based on Beer’s Law, as it will be proportional to the amount of peroxide produced, which is in turn proportional to the amount of quinonimine present in the sample after the reaction. While common in the biomedical sector, use of this reaction allows instructors to cover enzyme-mediated reaction

kinetics, stoichiometry, and basic spectroscopy, making it ideal for an educational setting.

The experimental set up is simple. Students will inject sample and reagent into respective legs of a Y-shaped chip held in the vertical position, with an on-off valve at the intersection of the Y. From there, the sample will be mixed through a serpentine micro-channel static mixer as flow is induced by gravity, resulting in shades of red depending on the concentration of glucose in the sample (faint pink for low concentration, deep red for high). From there, the sample will pass into a reservoir with two sides. One side is covered with a polarized film, intended to allow only a narrow bandwidth of green light to pass through. This side of the reservoir is backlit, allowing green light to pass through the sample, which is then absorbed by the red dye present in the sample. From there, the green light that manages to pass through to the other side of the reservoir will be measured using a smartphone camera, and with Beer’s law, students can determine the concentration of glucose in the sample based on the measured intensity and a calibration curve. Students will be guided through the experimental proofs by using accompanying worksheets. Comprehension of related concepts will be tested where the reaction kinetics and scientific principles will be tied in with the course. This experiment will work well within biomedical and reaction engineering courses.

The Prototype for dissemination is still in the conceptual phase and is currently in development. Since prototyping moved passed the proof-of-concept version, different manufacturing methods are being considered for the optimal route for mass production, e.g., traditional 3D printing, resin printing, laser cutting, etc. At present the concept is to form the module as a three-piece design composed of acrylic for transparency, with the micro-channels machined into the center before being fused to front and back panels using a UV cured epoxy. The module would be gravity fed, with holes drilled through the front and back panels at the bottom of the module, just above the reservoir, to provide an outlet for air and for easy washing after experimentation. This proposed version of the design minimizes the number of components per kit in favor of a single pass, gravity fed, set-up with the only electronic components being the student’s cellphone and a light source for back lighting. The hope is this will limit manufacturing and maintenance costs, so that the bulk of expenses can be received for experimental materials, such as the glucose and enzyme solutions.