Online Conductivity (Salinity), Temperature and Depth Sensor

Mini CTD salinity sensor for connection to embedded systems. Wide salinity range.

Conductivity (CTD) sensor connection port for subsea device integration. For both short or long-term oceanographic surveys.

Key features

  • Smallest online conductivity sensor on the market
  • Real time data or data retrieval after surveying
  • Fully submersible rugged design
  • Wide salinity range, low to high conductivity
  • Pressure sensors from shallow to deep ocean
  • Description

    Smallest CTD on the market

    The small and handy CTD online is a modified version of the popular DST CTD standalone data logger. The sensor probe is only 22.4 mm in diameter and 92 mm in length and a subsea cable connects to the connector end. The small measuring device is also available as a CT online if depth measurements are not required.


    The online CTD sensor is used for hydrographic and oceaonographic studies:

    • Survey missions where it is a part of autonomous underwater vehicles (AUV), either streaming data in real-time or for later data retrieval when AUV is surfaced.  
    • Long term stationary monitoring underwater where it is connected to a data logging system.
    • For using the CTD without wired connection, as a self-contained logger, click here.
    • A CT online version is also available.

    Fully submersible rugged design

    The housing is ruggedly designed for durability, strong breakage resistance and high pressure survival. The CTD online has a robust plastic molding around the ceramic sensor housing and the housing has a threaded steel connector on the end. The subsea cable comes with a matching subsea connector for a quick and easy connection to the CTD. 

    Wide salinity range, low to high conductivity

    The CTD online can capture conductivity from 3 to 68 mS/cm. Low conductivity range, 0.1-6 mS/cm, is also available, ideal for measuring in brackish water.

    Depth sensors from shallow to deep ocean

    Customers choose between depth calibration ranges up to 100 m, 500 m, 1200 m or 2400 m. The shallower the range the better the depth resolution and accuracy.

    Originally designed for NASA

    The online CTD was initially designed for use on NASA‘s micro-sub deployed in waters deep under the Antarctic glacier, exploring lifeforms deep under the glacier. Star-Oddi's CTD logger was chosen by NASA because of its small size and reliability.