Landmark test results suggest a promising class of sensors can be used in high-radiation environments and to advance important medical, industrial, and research applications.

A NIST prototype photonic thermometer. (Credit: J.L. Lee/ NIST)

The test results indicate that the sensors could be customized for measuring radiation dose in both industrial applications and clinical radiotherapy. Specifically, the results suggest the sensors could be used to track levels of ionizing radiation (with energy high enough to alter the structure of atoms) used in medical device sterilization. The sensors also have potential applications in medical imaging and therapy.

The researchers found that oxide-coated silicon photonic devices can withstand radiation exposure up to 1 million gray.

To determine the effects of radiation, the researchers exposed two kinds of silicon photonic sensors to hours of gamma radiation from cobalt-60, a radioactive isotope. In both types of sensors, small variations in their physical properties change the wavelength of the light that travels through them. By measuring those changes, the devices can be used as highly sensitive thermometers or strain gauges. This remains true in extreme environments like space flight or nuclear reactors, only if they continue to function properly under exposure to ionizing radiation.

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