University of Illinois Urbana-Champaign

Photonic resonator absorption microscopy for dynamic point of care biosensing

Liu, Weinan

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https://hdl.handle.net/2142/130098

Description

Title
Photonic resonator absorption microscopy for dynamic point of care biosensing
Author(s)
Liu, Weinan
Issue Date
2025-07-18
Director of Research (if dissertation) or Advisor (if thesis)
Cunningham, Brian T.
Doctoral Committee Chair(s)
Cunningham, Brian T.
Committee Member(s)
  • Do, Minh N.
  • Gruev, Viktor
  • Zhao, Yang
Department of Study
Electrical & Computer Eng
Discipline
Electrical & Computer Engr
Degree Granting Institution
University of Illinois Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • Digital-Resolution Biosensing
  • Photonic Crystal
  • Point-of-Care
  • Microscopy
  • Metasurface
  • Computational Imaging
  • Biomedical Detection
Abstract
This dissertation introduces Photonic Resonator Absorption Microscopy (PRAM), a label-free, digital-resolution biosensing platform designed for highly sensitive and accessible point-of-care diagnostics. By coupling photonic crystal (PC) surfaces with gold nanoparticle (AuNP) tags, PRAM enables attomolar detection of biomolecules without enzymatic amplification or complex workflows. To advance PRAM for real-world applications, several innovations are presented. A portable, automated PRAM system (ap-PRAM) integrates motorized autofocus, large field-of-view (FOV) tiling, and a differential dynamic detection algorithm to enable real-time, single-particle kinetic analysis of binding and unbinding events. These capabilities are demonstrated in both sandwich immunoassays for viral antibodies (HIV, HCV) and a target recycling amplification assay for miRNA, achieving detection limits as low as 1 aM. In parallel, a miniaturized PRAM system (PRAM Mini) is developed, featuring compact optics, smartphone integration, and digital image processing for decentralized or resource-limited settings. To further enhance signal spatial uniformity and polarization independence, a two-dimensional PC substrate is designed and fabricated, improving signal consistency across the sensor surface. Together, these developments establish PRAM as a versatile and scalable platform with broad potential for clinical diagnostics, liquid biopsy, and dynamic biosensing in both laboratory and point-of-care environments.
Graduation Semester
2025-08
Type of Resource
Thesis
Handle URL
https://hdl.handle.net/2142/130098
Copyright and License Information
Copyright 2025 Weinan Liu

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Graduate Theses and Dissertations at Illinois