Potential of smartwatch touchscreen glass for electron paramagnetic resonance dosimetry in radiological emergencies

In radiological emergencies, retrospective dosimetry is essential for estimating absorbed radiation doses when conventional dosimetric data are unavailable. Various human-derived tissues and surrounding materials have been used for dose assessment using electron paramagnetic resonance (EPR) techniques. However, because the retrospective dosimetric materials have inherent limitations, dose assessment should reasonably be determined through the combined application of various retrospective dosimetry methods. With the increasing use of smartwatches for health monitoring and fashion, touchscreen glass on smartwatches has a potential as a material for retrospective dosimetry.

The radiological characteristics of smartwatch touchscreen glass (STG) were evaluated for its potential role in public health emergency preparedness during radiological incidents. STGs samples extracted from several smartwatch models were evaluated for their radiological characteristics, including background signal, mechanically induced signal, light-induced signals, radiation-induced signal (RIS), time stability of RIS, dose-response relationship, ultraviolet (UV) effects on RIS, thermal and pretreatment effects on RIS, and the minimum detectable dose.

Among the tested samples, STG-4, derived from the Mi Band series produced by Xiaomi, demonstrated the most suitable performance in various radiological characteristics. Based on the radiological characteristics, a preliminary STG-EPR dosimetry protocol was established, and a blind test was performed using E_n score analysis under laboratory conditions. The E_n scores, calculated from the evaluated and reference doses, were within ±1, satisfying the acceptance criterion specified by ISO 13528.

STG-4 was confirmed as a potential material for application in EPR dosimetry through the blind test, demonstrating the feasibility of achieving rapid and reliable dose assessment using STG. Because the UV effects on RIS and the material composition of the STGs vary by manufacturer and smartwatch version, further research is recommended to optimize their use in radiation emergency response and public health protection.