(364e) Creation of Low-Cost Spectrophotometers for Use By Students

Spectrophotometers are standard equipment in chemical engineering laboratories and industrial processes. They may be used to track reactions which change solution color over time, and determine kinetic parameters or properties of cellular growth. Commercial spectrophotometers are very expensive, often costing thousands of dollars, making them prohibitively costly for use by all students in a large classroom setting.

We have developed several teaching modules around inexpensive spectrophotometers built by students, which we have used in classrooms of approximately 100 students. In our fall introduction to chemical engineering course, our freshmen students are given a package containing a few materials, including an LED and photoresistor, totaling less than a dollar, and instructed to build a photometer using also an Arduino Uno board. The rest of their spectrophotometer can be created with any materials they desire, often consisting of scraps and garbage. In the spring semesterâ??s freshman design laboratory, students work in groups of three and redesign their apparatus with materials and tools provided in the lab; here they make a more robust product that they will use throughout the semester. These spectrophotometers, depending on the studentâ??s design, may rival even commercial products in their signal to noise ratio and range of sensitivity.

We have also created many of these inexpensive spectrophotometers for use throughout our lab for various purposes. Additionally, we have used them in our K-12 outreach efforts as portions of high school introduction to engineering projects, during engineering summer camps, and in the Science Olympiad.