Before revision: History An example is the pH-sensitive LAPS that uses LEDs in combination with (semi-conducting) silicon and pH-sensitive Ta2O5 ( |SiO<sub>2| ; |Si<sub>3N<sub>4| ) insulator.
After revision: History An example is the pH-sensitive LAPS that uses LEDs in combination with (semi-conducting) silicon and pH-sensitive Ta2O5 ( |SiO<sub>2| ;SiO2Si3N4 |Si<sub>3N<sub>4| ) insulator.