Melanoma incidence continues to rise in Canada, and early diagnosis is critical to improving survival rates. Current diagnostic approaches rely on visual examination followed by biopsies—procedures that are invasive and sometimes unnecessary.
By enabling rapid, direct, and non-invasive assessment of suspicious skin lesions, this technology could reduce unnecessary biopsies, improve early diagnostic accuracy, and support clinical decision-making.
“Our goal is to provide a minimally invasive tool to detect very small, but still aggressive melanomas," said Liang, the study's senior author, who specializes in ultrafast imaging and biophotonics at INRS.
"Because of their small size, (the melanomas) are usually excluded from clinical visual inspection, which leaves the threat unwatched. We want to detect them, so that intervention can be made as soon as possible,”
"Even though this study was conducted in mice, this animal model replicates the genetic changes observed in human melanomas and could therefore potentially benefit patients," added Meloche, a researcher at UdeM's Institute for Research in Immunology and Cancer and co-principal author of the study.
The approach also redefines the role of temperature in cancer detection. While tumours are known to generate more heat due to their higher metabolic activity, this signal has traditionally been too imprecise to use as a diagnostic marker. SMEAR-ULM changes that by turning subtle thermal variations into a highly sensitive and measurable signal.
A temporary “tattoo”
At the core of the system is a patch of painless microneedles that deposits specialized nanoparticles just beneath the skin. These nanoparticles form a temporary “intelligent tattoo” that behaves like an array of microscopic thermometers.
When illuminated with near-infrared light, the nanoparticles emit visible light. Crucially, the lifetime of this light emission—how long it lasts—depends directly on local temperature. Because cancer cells consume more oxygen and nutrients than healthy cells, they produce additional heat, which can be detected through this optical signal.
Using an ultrafast imaging system, SMEAR-ULM captures all this information in a single high-speed snapshot, generating a detailed thermal map with submillimeter spatial resolution and sub-degree temperature sensitivity.
“We capture all the necessary information for an instantaneous temperature map in a single shot, which makes the method fast and robust to continuously monitor abnormal thermal responses in small melanomas—even within complex in vivo conditions,” said INRS graduate student Yingming Lai, the study's first author.