Oral Presentation Royal Australian Chemical Institute National Congress 2026

Polymer Coated Microcantilever Resonators for Low Dose X Ray Detection and Biological Sample Monitoring (136380)

Samali Liyanaarachchi 1 , See Yoong Wong 2 , Roshantha W Perera 1 , Aafreen Ansari 3 , Muamer Dervisevic 4 5 , Nicolas H. Voelcker 3 4 5 , Victor J. Cadarso 1 5
  1. Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC, Australia
  2. Centre for Materials and Surface Science, La Trobe University, Melbourne, VIC, Australia
  3. Department of Materials Science & Engineering, Monash University, Clayton, VIC, Australia
  4. Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
  5. Melbourne Centre for Nanofabrication, Victorian Node of the Australian National Fabrication Facility, Clayton, VIC, Australia

Ionizing radiation, particularly X-rays, can induce molecular degradation that alters chemical structure, weakens material properties, and compromises the integrity of sensitive biological specimens and devices.1 As radiation use expands across research, clinical, industrial, and security environments, including airport baggage and cargo screening, the likelihood of unintended low-dose exposure to stored biological samples is increasing.2 Conventional dosimeters are often bulky and unsuitable for monitoring small specimen volumes, highlighting the need for compact, highly sensitive alternatives.

This study presents polymer coated microcantilever resonators as a passive platform for ultra-sensitive detection of low-dose X-ray exposure, aimed at safeguarding biological samples during storage and transport. Silicon microcantilever arrays were spray-coated with ~3 μm polymethyl methacrylate (PMMA) films and exposed to doses ranging from 0–20 Gy. Resonance frequency shifts were quantified using Laser Doppler Vibrometry (LDV) as a function of absorbed dose. Scanning electron microscopy confirmed that spray coated PMMA provided the uniform thickness required for reliable sensing. The cantilevers exhibited a linear frequency–dose response with a sensitivity of 120 ± 11 Hz/Gy and a detection limit of 21 ± 9 mGy. Resonance frequency analysis indicated nanogram scale mass loss consistent with radiation induced polymer degradation.

Complementary characterization using AFM, FTIR, XPS, and ToF-SIMS revealed dose-dependent surface roughening (Ra = 2.11 ± 0.74 nm at 15 Gy), a reduction in elastic modulus (~1 GPa), and chemical changes indicative of chain scission and oxidative degradation, including diminished C–H, C=O, and C–O–C functionalities and a lower C:O ratio.

Biological validation with L929 fibroblast cells exposed to comparable doses showed dose  and dose-rate dependent declines in viability, confirming the biological relevance of low-dose exposure. Overall, this work demonstrates a compact, passive sensing platform for real-time, in-situ X-ray monitoring, offering a promising next-generation solution to support biosample protection during cryogenic storage and transport.

  1. Carante, M. P., Ramos, R. L., & Ballarini, F. (2023). Radiation damage in biomolecules and cells 2.0. International Journal of Molecular Sciences, 24(4), 3238.
  2. Gloor, K. T., Winget, D., & Swanson, W. F. (2006). Conservation science in a terrorist age: the impact of airport security screening on the viability and DNA integrity of frozen felid spermatozoa. Journal of zoo and wildlife medicine, 37(3), 327-335.