A sensor for detecting a temperature distribution imparted on a substrate in an environment is disclosed. The sensor includes a sensor substrate with one or more temperature sensing elements formed on the sensor substrate. In embodiments, a temperature sensing element includes at least one cavity with a thermally expandable material disposed within the cavity and a channel extending from the cavity with a slug disposed within the channel. In embodiments, the cavity has a fixed volume and is enclosed by a cover layer disposed or formed over the cavity. The thermally expandable material is configured to extend from the cavity into the channel to actuate the slug from a first position within the channel to at least a second position within the channel, where the position of the slug is indicative of a temperature of a respective portion of the sensor substrate.