Pollen + Lasers: Tweezing Pollen to learn about its Optical Properties

Pollen and other organic aerosols influence how light interacts with the atmosphere, shaping our understanding of climate science. Furthermore, the wide range of optical measurements that can be made on pollen makes it an ideal candidate for a group-sourced research project. Optical tweezers are an effective tool for measuring these properties. An optical tweezer uses a focused laser within a microscope objective to manipulate tiny particles. Commercial setups are often unattainable to smaller institutions that are a good fit for a group-sourced project. Our team has developed a low-cost optical tweezing setup based on a 3D-printed OpenFlexure microscope design, a Helium-Neon laser, and several affordable optics. With this inexpensive setup, we strive to create a reproducible measurement that these institutions can replicate to contribute to the greater scientific community. We will do this by suspending pollen in water and measuring our trap stiffness —the degree to which a particle is held in the trap —which is proportional to its refractive index. To accomplish this, we need to determine how to trap pollen particles and accurately measure their trap stiffness effectively. Our long-term goal is to create a database of these measurements to improve climate studies and provide opportunities for group-based research projects for underfunded institutions with young researchers.