The Physics and Astronomy Department at Pomona has extraordinary access to research equipment and facilities, and we encourage our students to undertake research. Below are recent projects that students completed via Pomona's Summer Undergraduate Research Program.
Harvesting Energy from Human Motion Using Piezoelectric Materials
Natal Negusu ’22; Advisor: Gordon Stecklein
Piezoelectric materials generate electricity when subject to mechanical stress or strain due to the creation of a potential difference. In this research project, we investigate the practicality of a wearable energy harvester that would make use of a piezoelectric material. The piezoelectric material used for the research was a PZT (lead zirconate titanate) bender. Our objective was to establish the parameters of the intrinsic material and use this information to develop a wearable piezoelectric generator. The wearable device would include an SD card data logger to provide feedback and record the electricity produced. Through various lab and field tests used to quantify the efficiency of the device, we were able to determine that the power output is improved by increasing the free end length of the bender. Power output is further maximized by adding proof masses to the end of the bender. This is due to the resulting decrease in the resonance frequency of the bender. For proof masses beyond 7 grams, we observe a decline in efficiency that we attribute to increased mechanical damping. Our wearable generator produces up to 2.5 mW of power with a capacity factor of 14%.
Thin Film Measurement and Deposition
Haidee Clauer ’22; Advisor: Gordon Stecklein
Applications of alumina thin films range from transistor encapsulation and biochemical research to coatings that improve the shelf-life of commercial goods. While alumina can be grown through several techniques, atomic layer deposition allows for precise control of atom-level thickness. In this project we designed a simplified system for carrying out this growth technique at a tenth of the cost of a commercial version. To measure the thickness of oxide films similar to those grown by our proposed deposition system, we employed two optical techniques, reflectance and ellipsometry. We built optical models to calculate the thickness based on our measurements, ultimately verifying the consistency of reflectance and ellipsometry for films up to 3000 Angstroms thick. Through ellipsometry, we measured films as thin as 17 Angstroms with uncertainties as low as 3 Angstroms.
Sphagnum Moss Spore Dispersal Mechanism
Guido Dominguez ’22; Advisor: Dwight Whitaker
Sphagnum moss disperses its spores using a vortex ring generated by a pressurized capsule that ruptures on a warm sunny day. This mechanism of spore dispersal enables Sphagnum to carry its spores beyond the turbulent boundary layer where it grows so that they can be carried indefinitely by wind currents, which would not be possible if the tiny spores were launched ballistically. Here we present a finite element analysis of the explosive spore discharge from Sphagnum capsules using ANSYS Fluent. By matching the trajectories of vortex rings in our models to high speed videos of capsule explosions we can determine the initial pressure of the capsule. Moreover by analyzing the flow of vorticity out of the capsule we can determine if the vortex rings produced by Sphagnum are optimal as is seen for the vortex rings produced by animals.
Fabrication and Characterization of Screen-printed Perovskite Solar Cells
Phuong Nguyen ’22; Advisor: David Tanenbaum
Perovskite solar cells (PSCs) are an alternative to mainstream silicon solar technologies due to cost-efficient materials, competitive power conversion, and ease of fabrication. We fabricate PSCs by screen printing inks of Titania, Zirconia, and Carbon and infiltrating them with a Perovskite precursor, then record IV curves and spatial current maps.
Supported by Pomona College grants from the Hirsch and Sontag families.
The Physics Education Workspace Prototype
Kenneth Ochieng ’22; Advisor: Thomas Moore
Research on learning trends and styles in physics education is limited by the lack of efficient methods to strategically collect information about how students think when solving problems. The Physics Education Workspace would be a computer application that allows students to work on physics problems, and in the process, collect and provide a transcript of a student’s thinking processes and problem-solving techniques. The transcript generated will provide information valuable to physics instructors, physics education researchers, and physics textbook authors. Specifically, the PEWP seeks to address the shortcomings of the recorded interview technique, which is the most common method that education researchers use to collect data about student thinking. The workspace, unlike the time-intensive analysis of a recorded interview, can provide large volumes of data from many subjects simultaneously and economically.
Our immediate goal for the workspace is to build it up into a usable application that will enable students to solve a very limited set of introductory physics problems (for now) and submit their solutions through the application. The workspace will provide essential drawing tools for students, as well as tools for manipulating equations based on physics principles. In addition, it will also provide links to equations when using unknown quantities and will complete the math involved in solving equations with variables.