The need for increased sensor reliability

Biofouling is one of the main causes of deterioration and inconsistency in the data collected from oceanographic sensors. The degree of biofouling varies widely between monitoring sites depending on climate, season and the site specific characteristics. The operation and maintenance cost of oceanographic sensors is a crucial element of their life-cycle, and the expense of antifouling technologies can often be higher than the purchase cost of the sensor. However, effective antifouling technology is worthwhile investment since it facilitates the good performance of the sensor.

At present antifouling measures are applied continuously (e.g. copper screens, biocide impregnated coatings, etc.) or on a predefined time-basis (e.g. wipers, local chlorinations etc.), without monitoring the necessity or efficacy of the applied treatment. As yet, only the observation of drift in data indicates the necessity of cleaning the sensor since none have a solution to monitor biological growth on the sensor housing or transduction surface.

There is a need for an integrated solution which will guarantee the performance and the reliability of oceanographic sensors during long-term deployments, and reduce their maintenance costs. Current techniques to protect sensors from biofouling have high energy demand and often involve complex mechanical design (e.g. wipers, biocide flush). This creates problems for many in situ monitoring configurations (e.g. non-cabled seafloor observatories, autonomous coastal monitoring, autonomous vehicles etc.). These constraints are overcome by self biocide schemes, such as copper screens, but these have limited success and can bias the measurements.

NeXOS will adopt an innovative approach to the biofouling problem. A new technology applied to the transducing interface will drastically reduce maintenance costs and guarantee improved sensor performance. NEXOS sensor systems will fulfil the harsh operational requirements of the different application areas. Finally, with the introduction of defined test and validation strategies in NeXOS, the users are provided the means to check the performance of the sensor system independently of the manufacturer.