Stable Miniature Oxygen-pH-Temperature Sensor

A new miniature, low-power, and stable oxygen-pH-temperature sensor is proposed. It can measure both the atmospheric oxygen and dissolved oxygen over the pressure ranges of interest for plant-growth systems and bioreactors. The sensor measures the phosphorescence decay time from a doped-silica material. Unlike total phosphoresence intensity, phosphorescent decay time is a property of a molecule that should remain highly stable over time, eliminating the need for re-calibrations.) Because phosphorescence occurs on a much slower time scale than fluorescence, this sensor is simpler, smaller, and more accurate than a fluorescence-based sensor. We have also found methods for measuring pH and temperature from the same sensor making this a versatile instrument suitable for plant and animal studies including extremophile research on earth and particularly in space.