Text by Jill Heinerth
Ask a rebreather diver what drives their rebreather and they will undoubtedly tell you, the oxygen sensors. These annually disposable devices are critical to creating a safe breathing loop and yet when not functioning properly can reduce a $10,000 investment in life support to a useless hulk of unusable equipment. Oxygen sensors are a crucial component, informing the rebreather control systems about the partial pressure of oxygen within the exhaling loop-the-loop. They apprise the electronics package when solenoid should fire and send more life dedicating oxygen into a diveras breathing loop-the-loop and alert the computer system when too much oxygen could cause a toxicity seizure that might result in drowning.
Oxygen sensors are galvanic fuel cells that were originally devised for applications within the medical and automotive industry. Inside these relatively inexpensive devices, a chemical reaction is produced when the potassium hydroxide in the cell comes into contact with oxygen. This creates an electric current between a lead anode and gold-plated cathode through a loading resistance. The current rendered is proportional to the concentration( partial pressure) of oxygen present on the cellas membrane.
The problem with using galvanic oxygen sensors within diving applications is that we treat them to very harsh conditions. They get exposed to great scopes in temperature, mechanical shock from transportation and they slowly degrade in such a way that causes them fail from the top down in a instead unpredictable way. Worse yet, we calibrate oxygen sensors in pure oxygen at ambient pressure and then asking questions offer reliable data at partial pressures up to 1.6 and beyond while get wet inside a diveras CCR. The distrust in electro-galvanic sensors is so great, that we set three or more in a rebreather so that voting logic can help to validate their readings or inform the diver when an abort is necessary.
After 5 years of extensive R& D testing and design iterations, Poseidon Diving Systems AB of Sweden announced a revolution to the diving industry. They released the first solid state oxygen sensor at the TekDiveUSA Show in Miami in late April. This long-awaited breakthrough will certainly change the diving industry by dramatically increasing the safety of rebreathers. This factory-calibrated sensor provides an accurate and highly reliable digital output, meaning that it can be permanently installed in a rebreather. There will be no need for user calibration. They will not expire and will provide a dependable read under the unique conditions of the diving environment.
The solid state sensor employs special luminescent dyes, which are excited with red light. This oxygen dependent incandescence is detected in the range of near infrared light( NIR ). Optical filters read the colour pigments on the membrane and with the help of a temperature sensor, reliably translate that datum into a read on the diveras handset. Compared to todayas galvanic oxygen sensors, these new solid state sensors depict unsurpassed shelf life, operational life day and calibration stability. aThe diving community has waited for many years for a sensor like this and the Solid State Sensor is considered as one of the’ holy grails’ of diving, a tells Jonas Brandt CEO, Poseidon Diving Systems AB.
Poseidon paired their proclamation with the release of their new M28 computer. This wrist-mounted platform offers a robust new graphical interface that feels like the cockpit of an airplane, but more importantly provides the diver with a style to view maps, surface GPS tracking and photos through its 32 GB memory. Coupled with the new solid state sensor, it can be attached to the breathing loop-the-loop of many rebreathers and provide reliable oxygen readout. Both technologies will be integrated into Poseidonas current and future life support systems, but the good news is that it appears that the M28 will be available in June 2016 with the sensors following afterward in the year.
For more information visit Poseidon .