New non-external field inductive conductivity sensor (NXIC) for long term deployments in biologically active regions

FSI a leader in innovative inductive (noncontacting type) conductivity sensors has been developing a sensor for enhanced long-term deployments in biologically active ocean regions. Long-term deployment of conductivity sensors in such areas normally results in poor conductivity data due to volumetric changes in cell geometry from biological fouling. Traditional inductive sensors allow antifoulants to coat the entire sensor; this technique is highly successful when using newly developed materials, which have high mechanical stability. Alternately, some success has been achieved using internal field electrode sensors with the ends protected using anti-foulant impregnated tubes. These conductivity sensors have had limited success due to the basic instability of the sensor to fouling, biological or mineral, of the electrodes. This problem is further hampered by the very small internal geometry, which has enhanced sensitivity to fouling with combined poor natural flushing characteristics. However, in some applications, pumps have been applied to correct sensor aspiration. Pumps dramatically increase the power requirements, complexity, and cost of the system. FSI has developed a new inductive conductivity sensor with no external electrical/magnetic field-the Non-External Field Inductive Conductivity Sensor (NXIC). The NXIC sensor allows for the use of end tube leaching protection without the disadvantages of a conductivity sensor that does not flush freely or has an unstable calibration due to degradation of electrodes from fouling. The NXIC sensor has been fully developed and is now undergoing extensive laboratory and field-testing.