Modified window-tint meter measures leaf moisture for wildfire risk
King's College London researchers adapted a low-cost handheld device, normally used to check car window tint, to gauge leaf water content in seconds. The roughly £140 instrument performed close to lab methods across six plant species, accounting for at least 81% of variation in leaf moisture. It could help monitor fuel dryness for wildfire prevention and guide irrigation, which consumes about 70% of global freshwater.
Researchers at King's College London repurposed a commercial device designed to test vehicle window tint, swapping its emitters for two LEDs: one wavelength absorbed strongly by water, another nearly unaffected. Comparing transmission at those wavelengths lets leaf water signal be separated from tissue structure. The team modeled 1,000 synthetic leaves, then tracked six species—wheat, rapeseed, beech, birch, hazel and sycamore—as they dried at Rothamsted Experimental Farm between April and June 2026.
The modified unit costs roughly £140 and approached laboratory performance, explaining at least 81% of moisture variation. It needs species-specific calibration and is less reliable for very dry leaves. The work appeared amid the UK's worst wildfire year on record.
If validated more widely, low-cost leaf-moisture sensing may help farmers schedule irrigation more precisely and give fire agencies another tool for tracking vegetation dryness. That could matter in regions facing wildfire risk or water scarcity. Researchers and educators might also benefit from affordable instruments, though species calibration and limits on very dry leaves may constrain routine use.