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.
Conversely, conventional thermal imaging methods rely on infrared technologies that suffer from limited spatial resolution and high noise levels.
As a result, they usually only detect tumours larger than 5 millimeters—lesions already visible to the naked eye.
This breakthrough effectively transforms skin temperature into a precise diagnostic biomarker for early-stage melanoma, the researchers say.
SMEAR-ULM, a new high-tech system, may detect skin cancers at their earliest stages by measuring tiny temperature variations at the surface of the skin, according to research in mice out of the Université de Montréal, and scientists at Université du Québec’s Institut national de la recherche scientifique (INRS).
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, the research team reports in Nature Sensors.
“Our goal is to provide a minimally invasive tool to detect very small, but still aggressive melanomas,” say Jinyang Liang, the study’s senior author, who specializes in ultrafast imaging and biophotonics at INRS, in a news release. “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,” adds Sylvain Meloche, a researcher at Université de Montréal’s Institute for Research in Immunology and Cancer and co-corresponding 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.
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,” says first author Yingming Lai, an INRS postdoctoral fellow who completed their PhD in Energy and Materials Sciences at INRS.
With this approach, the researchers successfully detected micro‑melanomas as early as four days old—a stage at which they are typically far too small to be identified by conventional imaging techniques.
Conversely, conventional thermal imaging methods rely on infrared technologies that suffer from limited spatial resolution and high noise levels. As a result, they usually only detect tumours larger than 5 millimeters—lesions already visible to the naked eye.
As well, existing microneedle-based sensing approaches require repeated measurements, limiting their use in living subjects.
The SMEAR-ULM technology overcomes these limitations by combining microneedle encoding, rare-earth-doped nanoparticles, and ultrafast optical imaging into a system capable of real-time, single-shot thermal mapping in vivo.
This breakthrough effectively transforms skin temperature into a precise diagnostic biomarker for early-stage melanoma, the researchers say.
