A tiny patch that acts like an “intelligent tattoo” could spot melanoma before it can even be seen.
Scientists in Canada say the minimally invasive technology worked in preclinical studies in mice and could change how very small malignant skin tumors are detected. The system, called SMEAR-ULM, measures tiny temperature changes at the skin’s surface to identify skin cancers at very early stages.
The study was published in Nature Sensors and was carried out by scientists from the University of Montreal and the University of Quebec’s National Institute for Scientific Research, or INRS.
Research leader Jinyang Liang, of INRS, said the work could have a “significant” impact on skin cancer detection.
Melanoma cases are rising. In 2022, more than 20,000 people in the UK were diagnosed with melanoma, the most serious form of skin cancer, according to Cancer Research UK. That figure is expected to rise to more than 26,000 a year by 2040.
Study senior author Liang said early diagnosis is “critical” to improving survival rates. He said current diagnostic methods rely on visual examination followed by biopsies, which are invasive and sometimes unnecessary.
He said: “Our goal is to provide a minimally invasive tool to detect very small, but still aggressive melanomas.
“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.”
Co-corresponding author Sylvain Meloche, from the University of Montreal, said: “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.”
The researchers said the system changes how temperature can be used in cancer detection. Tumors are known to generate more heat because of higher metabolic activity, but that signal has traditionally been too imprecise to use as a diagnostic marker.
Liang said: “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 the information in a single high-speed snapshot and produces a thermal map with sub-millimeter spatial resolution and sub-degree temperature sensitivity.
Study first author Yingming Lai, of INRS, said: “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.”
The team said it detected micro-melanomas as early as four days old, when they are usually too small to be identified by conventional imaging techniques.
The researchers said conventional thermal imaging methods rely on infrared technology with limited spatial resolution and high noise levels. They said those methods usually only detect tumors larger than five millimeters, lesions already visible to the naked eye.
They also said current microneedle-based sensing methods require repeated measurements, which limits their use in living subjects.
Liang said: “This breakthrough effectively transforms skin temperature from a secondary indicator into a precise diagnostic biomarker for early-stage melanoma.”
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