A manufacturer of specialized subsea camera systems for the aquaculture industry required a highly compact and reliable pressure sensor to provide accurate depth data. The primary challenges included ensuring long-term material compatibility with seawater, fitting the sensor within a very small existing housing, and achieving direct digital communication with their onboard electronics. A custom-engineered OEM sensor provided the ideal solution.
- Application: Depth measurement for underwater cameras in marine aquaculture.
- Challenge: Seawater corrosion and extreme space constraints.
- Interface: Direct I2C digital output to a PIC microcontroller.
- Solution: A custom OEM sensor with an Acetyl housing and ceramic diaphragm.
A development engineer for a company specializing in marine technology for the aquaculture industry was tasked with sourcing a pressure sensor to integrate into their subsea camera systems. The sensor’s primary function was to provide an accurate depth measurement, allowing operators to know the precise position of the camera equipment within fish farm pens, which typically have depths of around 15 metres and a maximum of 30 metres. The project presented several significant technical challenges that required a highly specialized and customized sensor solution.
The most critical requirement was material compatibility. The sensor would be used in seawater, a highly corrosive environment. To ensure long-term reliability and prevent galvanic corrosion, the customer was adamant about avoiding any metallic components on the wetted parts of the sensor. The sensor’s main body would be protected inside the camera’s waterproof enclosure, but the pressure port itself would be directly exposed to the saltwater. Another major constraint was the extremely limited space within the camera housing. The existing design could only accommodate a sensor with a maximum total length of 43.5mm, including its process connection thread. Finally, for seamless integration with the camera’s existing electronics, the sensor needed to provide a direct I2C digital output signal for communication with an onboard PIC microcontroller, which would simplify the design by removing the need for additional signal conditioning or analogue-to-digital converter components.
The proposed solution was a custom-designed SCPT series OEM pressure sensor, engineered specifically to meet every one of the customer’s demanding requirements. To address the material challenge, the sensor was constructed with an Acetyl (Delrin) housing and a ceramic alumina (Al₂O₃) sensing diaphragm. This all-non-metallic construction of wetted parts provides exceptional resistance to seawater corrosion, ensuring stable and reliable operation over a long service life. The use of a ceramic diaphragm is particularly advantageous in marine applications due to its chemical inertness and high abrasion resistance.
The sensor’s physical design was tailored for miniaturization. With a total length well within the 43.5mm maximum, the compact body allowed it to be installed easily into the customer’s existing camera housing without modification. The sensor was specified with a G1/8 male process connection and a Viton O-ring seal, matching the customer’s mechanical interface. To meet the electrical integration needs, the sensor was built to provide a direct I2C digital output, compatible with a 3.3V or 5V supply, allowing the development engineer to connect it directly to their PIC microcontroller. The electrical termination consisted of potted flying leads, providing a robust, moisture-proof seal at the back of the sensor while offering the flexibility needed to attach their internal Molex connector within the camera housing. The selection of a 0 to 6 bar absolute pressure range provided the ideal measurement scale for their 30-metre maximum depth requirement, with the absolute reference ensuring that depth readings would be unaffected by changes in atmospheric pressure.
SCPTd Compact I²C OEM Pressure Sensor
- Part No: SCPTd-IB-X8-DV-6000A-43
- Pressure Range: 0 – 6 Bar Absolute
- Output: i2c
- Supply 3.3 or 5V dc
- Accuracy (NL&H): <±0.25% FS BFSL
- Electrical Connection: 240mm PVC wires, potted backend
- Process Connection: G1/8″ male, 4mm internal port
- Housing material: Acetyl (Delrin)
- Diaphragm Material: Ceramic Al2O3
- Seal Material: Viton