The team, from Queensland University of Technology, Brisbane, Australia several separate academic establishments in Saudi Arabia, made use of a smartphone application used for the commercial calibration of radiation detectors and applied it to the output of a CMOS image sensor with black tape used to block visible light.
The image sensors are also sensitive to X-ray and gamma radiation and beta particles with high energy, but not to alpha particles.
The team reported their results in Nature Scientific Reports and showed that smartphone CMOS image sensors are sensitive to radiation doses as low as 10microgray/hour, with a linear dose response and an angular dependence.
To test the image sensors on the iPhone 6s smartphone was irradiated with a calibrated Caesium-137 radioactive source, calibrated concrete pads with various known concentrations of radioactive elements, and direct Sunlight.
The researchers report that the RadioactivityCounter application is limited in that it requires 4 to 10 mins to offer a stable measurement. The precision of the measurement is also affected by heat and a smartphone’s battery level. They conclude that although the smartphone is not as accurate as a conventional detector, it is suitable to detect radiation before the radiation reaches hazardous levels. It can also be used for personal dose assessments and as an alarm for the presence of high radiation levels.
The team added that image sensors in commercially available cameras need to be evaluated before being used as radiation alarms and further research should be carried out to characterize radiation-induced pixel intensity on a smartphone’s CMOS sensor while distinguishing it from thermal noise.
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