ChE MS Thesis Defense: Julie Penn

Name: Julie Penn

Title: Development, Optimization, and Evaluation of SWIR Emitting QD Imaging Tools

Date: 07/24/2025

Time: 10:00:00 AM

Committee Members:
Prof. Allison Dennis (Advisor)
Prof. Bryan James
Prof. Ryan Koppes
Prof. Bryan Spring

Location: Shillman Hall 315

Abstract:
Shelf-stable fluorescent imaging references are commercially available. However, they are only available in the visible range (380-700 nm) and the near infrared I range (NIR I, 700-900 nm). These references are not available within the shortwave infrared range (SWIR, 1000-1700 nm). SWIR emitting semiconductor quantum dots (QDs) have a tunable emission spectrum and are used in a range of SWIR imaging applications. In addition to their adjustable spectrum, QDs, particularly lead sulfide/cadmium sulfide (PbS/CdS) core/shell QDs, are incredibly photostable. This quality makes them optimal fluorophores for SWIR fluorescent imaging references. When the PbS/CdS QDs are embedded in epoxy, the QDs are contained in a permanent, shelf stable, oxygen-free environment. Thus, a SWIR fluorescent imaging sample is created. By changing the form factor of these objects, researchers can investigate SWIR imaging at depth, multiplexed imaging for spectral demixing using a baseline fluorescence intensity measurement. The performance of each tool was evaluated based on the photostability, the florescence intensity at depth, and the emission spectrum of the QDs contained within each type of florescence imaging tool.

Julie Penn is currently a 2nd year master’s student studying chemical engineering at Northeastern University. She is studying under the guidance of Dr. Allison Dennis, and her thesis is on Development, Optimization, and Evaluation of SWIR Emitting QD Imaging Tools. Outside of the laboratory, Julie is a proud and active member of the Boston section of Society of Women Engineers. In 2019 Julie graduated from Wentworth Institute of Technology with a degree in mechanical Engineering with a concentration in chemistry and began working at 908 Devices, a mass spectrometry manufacturer based in Boston, MA. As a member of the Customer Experience Team, Julie supported the R&D, manufacturing, quality, and sales departments, but most importantly the customers by repairing internal and customer-returned mass spectrometers, answering technical support phone calls, and traveling around the world to train users on their equipment. She was awarded the 2022 Customer Service Person of the Year for her outstanding support of the 908 Devices sales team. Upon the completion of her degree, Julie is looking to rejoin the workforce as a materials engineer. She is very excited to start this next journey of her career.