D. O. Sensor

During the interaction between dissolved oxygen in water and fluorescent substances, both the fluorescence intensity decreases and the fluorescence lifetime shortens. This fluorescence quenching can be described by the Stern–Volmer equation:

Where:

• I0I_0 — Fluorescence intensity in the absence of oxygen
• II — Fluorescence intensity in the presence of oxygen
• τ0 au_0 — Fluorescence lifetime in the absence of oxygen
• τ au — Fluorescence lifetime in the presence of oxygen
• [O2][O_2] — Oxygen concentration
• KK — Stern–Volmer constant