We observed that each heavy metal showed a significantly large rise in temperature (3-4 °C), indicating that the sensor was quite efficient to detect heavy metal contamination. However, we also noticed that some heavy metals showed different responses than others. For example, mercury showed a very large rise in temperature (4.5 °C), probably because of its high binding affinity with protease enzyme. Mercury is known to deactivate biomolecules by binding to thiol groups. Other metals may have deactivated the enzyme by any of the following methods: