Keller Pressure

Pressure Transducers

For specialised OEM applications, such as tracking the diving depths of marine wildlife or embedding small-scale sensors into environmental seals, standard, bulky industrial transmitters are impractical. Instead, these projects require raw piezoresistive pressure cells. These compact, media-isolated components act as the fundamental building blocks of pressure measurement, delivering a highly linear, unamplified millivolt (mV) output proportional to the applied pressure and supplied current or voltage.

Key Characteristics for OEM & Integration

Raw mV Bridge Output: Utilising a classic Wheatstone bridge configuration configuration, these cells change electrical resistance when mechanical pressure is applied. Because the output signal is unamplified (typically ranging from 0 to 100 mV or 0 to 200 mV depending on excitation voltage), they must be integrated into custom circuitry featuring an instrumentation amplifier and an Analogue-to-Digital Converter (ADC).
Ultra-Compact & Lightweight: Stripped of heavy industrial housings, cable glands, and internal transmitters, raw pressure cells offer the smallest physical footprint possible. This is critical for wildlife tagging (e.g., monitoring seals, penguins, or cetaceans), where minimising drag, weight, and volume is vital for animal welfare and natural behaviour.
Media Isolation: Despite being bare components, high-quality OEM cells feature a thin, flexible stainless steel diaphragm. This diaphragm isolates the delicate silicon sensing element from harsh environments like saltwater, biological fluids, or corrosive chemicals using a tiny volume of silicone or oil fill.

Design Considerations for Custom Circuits

When designing these cells into automated monitoring tags or custom subsea enclosures, your engineering team will need to account for:

Temperature Compensation: Because silicon is highly sensitive to temperature fluctuations, the raw mV output will drift as a sensor is heated or cools down when in use. Integration requires utilising mathematical compensation algorithms in your microcontroller firmware or embedding a secondary temperature-sensing element (like a PT1000 or an internal resistor network) onto the circuit board.
Power Consumption: For remote telemetry and battery-powered applications, power budgets are incredibly tight. Designers can optimise longevity by using pulsed excitation voltage, only powering up the bridge circuit for a fraction of a millisecond to take a reading before dropping it back into a low-power sleep mode.

If in doubt, give us a call, or email, and discuss your applications with one of our experienced sales team,