Hach has released the newest model of its LDO® Probe which says "no" to calibration, membrane replacement, and drift while maintaining reliability and durability. The probe uses a luminescent sensor to measure the concentration of dissolved oxygen in a solution. Molecules within the senor are excited by a blue LED and the oxygen in a sample causes them to relax. The higher the concentration of O2 in a sample, the faster the luminescent molecules will return to their normal state. The sensor also takes into account the temperature of a sample, which has significant bearing on an accurate DO measurement.