Accurate and low-cost wearable or portable monitors for personal solar ultraviolet (UV) exposure are of interest to reduce the risk of adverse UV effects such as eye diseases, sunburn and skin cancer. Here, a novel sensor involving the racemization of a chiral dopant within a nematic liquid crystalline matrix is described, and the suitability of these sensors to act as personal UV dosimeters is explored. It was shown that these sensors respond to UV light with a significant change in the position of the reflection band of the chiral nematic liquid crystal. The sensitivity of these sensors is shown to be 0.23 nm/mJcm À 2 . This corresponds to a change of 80 nm over a dose equivalent to two hours of solar exposure.