Thermal sensor array device, method of measuring a temperature gradient and method of measuring a temperature

A thermal sensor element device comprising:

• a substrate having a cavity formed therein;
• and
• an infrared absorbing membrane suspended over the cavity from a first beam and a second beam, the first beam being thermally coupled at one end thereof to the substrate at a first substrate cold junction and the second beam being thermally coupled at one end thereof to the substrate at a second substrate cold junction;
• and
• a plurality of thermocouples disposed over the first and second beams and the infrared absorbing membrane;
• wherein
• the plurality of thermocouples is arranged on the first and second beams and the infrared absorbing membrane as a first thermopile and a second thermopile;
• the first and second thermopiles are arranged on the infrared absorbing membrane to measure, when in use, a sum of first temperature differentials and second temperature differentials, the first temperature differentials being between the first substrate cold junction and a hot junction on the infrared absorbing membrane, and the second temperature differentials being between the second substrate cold junction and the hot junction on the infrared absorbing membrane;
• and
• the first thermopile is configured to connect selectively to the second thermopile in series and anti-series.