Deep Sea Sensor Basics and Types

This article covers the fundamentals of deep-sea sensors, explores various types, and discusses their applications.

What are Deep Sea Sensors (Ocean Sensors)?

Introduction: Recent advancements in micro-electronics, sensors, and automated/remote-controlled computing systems, such as ROVs and AUVs, have propelled significant progress in deep-sea research and development.

• ROV: Remotely Operated Vehicle
• AUV: Autonomous Underwater Vehicle

These underwater robots and drones are equipped with intelligent sensors to measure parameters like temperature, pressure, dissolved oxygen levels, pH levels, and ocean depth. Image sensors capture visuals of underwater objects and sea creatures.

Deep Sea Sensor Types and Ocean Instruments

A wide array of sensors and instruments are deployed in the ocean for diverse measurements, serving various applications in civil, military, communications, seismic, and energy sectors. They are also crucial for ocean researchers and industries involved in offshore exploration and ocean resource utilization. Examples include:

• Acoustic Doppler Current Profiler
• Flow Meter
• Pressure and Tilt Meter
• Conductivity-Temperature-Depth Meter (CTD)
• Dissolved Oxygen Sensor
• Digital Still Camera
• High Definition Video Camera
• Hydrophone
• Mass Spectrometer
• Optical Attenuation Sensor
• pH and Carbon Dioxide Sensor
• Pressure Sensor
• Remote Access Fluid and DNA Sampler
• Resistivity Probe
• Seismometer
• SONAR
• Thermistor Array and Turbulent Flow Current Meter

DO (Dissolved Oxygen) Sensor

• A dissolved oxygen (DO) meter assesses water quality.
• It measures the amount of dissolved oxygen in a liquid.
• DO sensors are used in oceans up to a depth of 6000 meters.
• It consists of a pre-amplifier covered by a titanium housing.
• It interfaces with CTD probe systems.

Pressure Sensor

• Seismic activity underwater is monitored using pressure sensors placed on the seafloor at various locations.
• These sensors are often made of piezoelectric quartz crystals, which generate an electric charge when subjected to pressure, allowing them to measure the water pressure above.
• Pressure sensors are prone to drift and may lose accuracy over time.

pH Sensor

• Ion-sensitive FET-based pH sensors can be directly immersed in seawater for ocean pH measurement.
• They provide good accuracy in pH measurement.

SONAR

• SONAR stands for Sound Navigation and Ranging.
• Submarines heavily rely on SONAR for underwater communication.
• Multi-beam sonar has wide applications in the ocean.

Imaging Sensor

• Underwater photogrammetry in the deep sea differs significantly from that on land or in space. Therefore, specially designed high-resolution cameras housing imaging sensors are required. Most operate up to 6000 meters from the seafloor.
• Common challenges include rough conditions, high pressures, absence of natural light, and refractions. Imaging sensors are designed to function effectively under these conditions in the deep sea.