Event
Ph.D. Research Proposal: Leon Stevenson
Thursday, April 23, 2026
1:30 p.m.
AVW 2328
ANNOUNCEMENT: Ph.D. Research Proposal Exam
Name: Leon Stevenson
Committee:
Dr. Kevin M. Daniels (Chair)
Dr. Timothy Horiuchi
Dr. Sahil Shah
Date/time: April 23, 2026 - 1:30 PM - 3:30 PM
Location: AVW 2328
Title: Quasi-Freestanding Epitaxial Bilayer Graphene Enhanced Detection of Chemical and Biological Agents
Abstract:
Emerging infectious diseases, engineered biological agents, and chemical warfare exposures continue to challenge existing diagnostic paradigms, which rely heavily on prior knowledge of specific molecular targets. Gold-standard techniques such as polymerase chain reaction (PCR) and enzyme-linked immunosorbent assays (ELISA) provide high analytical specificity but require centralized laboratory infrastructure, predefined primers or antibodies, and multi-step workflows, limiting their utility for rapid, field-deployable threat detection.
This proposal advances a graphene-based biosensing platform for ultrasensitive detection of small-molecule analytes through antibody-functionalized quasi-freestanding epitaxial graphene (QEG) sensors. Preliminary results demonstrate a strong electrical response to penicillin G across an ultra-wide concentration range, with detectable signals observed down to the attogram regime. As with previously demonstrated sensors for SARS-CoV-2 and influenza, functionalization of the graphene surface significantly enhances the electrical response, with a clear distinction between target and control analytes. Notably, the novel sensing mechanism, polarization-induced strain, and the sensor's structure reject nonspecific binding while amplifying the transduction of target analytes.
Building on this foundation, the proposed research will integrate molecularly imprinted polymers (MIPs) with the QEG platform to enhance stability and enable class-selective recognition of analytes. Unlike antibodies, MIPs provide robust, shelf-stable synthetic recognition elements capable of targeting shared structural features across analyte families, thereby supporting more generalized and agnostic detection strategies.
This work aims to transition from target-specific sensing toward effect-based detection architectures that capture molecular and physiological perturbations. Leveraging polarization-induced strain and incorporating complementary electrochemical readouts, including impedance, redox activity, and oxidative stress indicators, the proposed platform seeks to detect downstream system-level responses associated with biological infection or chemical exposure. Collectively, this work will establish a scalable and robust framework for agnostic graphene-based biosensing platforms, progressing from target-specific detection to class-selective and ultimately effect-based sensing for real-time chemical and biological threat monitoring.
