To enable the development of wearable devices that possess advanced ultraviolet (UV) detection functions, scientists have created a new type of light sensor that is both flexible and highly sensitive. A wearable device, such as a T-shirt or watch that monitors the actual personal UV exposure throughout the day, would be a useful and more accurate guide for people seeking to avoid sun damage.
The flexible UV light sensors were 25 times more responsive, and 330 times more sensitive, than existing sensors, exceeding the performance level required for optoelectronic applications. The team created their flexible UV light sensors on a semiconductor wafer 8 in. in diameter, using free-standing single-crystalline layers of GaN and aluminum gallium nitride (AlGaN), arranged using membranes that consist of two different thin semiconductor layers (heterostructure membranes).
Under a range of external strains (compressive, flat, and tensile), the sensors recorded a responsivity level of between 529–1340 A/W (unit used to measure the ability of a device to transfer an optical signal to an electrical signal), which is about 100 times higher than existing UV sensors. This responsivity remained stable after 100 cycles of repetitive bending, demonstrating its potential to be integrated into wearables.
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