Pressure is one of the oldest quantities in engineering measurement, and pressure sensors are among the most widely used devices in any vehicle or industrial system. They monitor tyres, fuel lines, hydraulics, intake manifolds and weather. Yet the role of the pressure detection sensor is changing. In electric vehicles, hydrogen systems and energy storage, pressure has become an early-warning signal for events that can threaten lives and assets, as well as a process variable to be controlled.
How a pressure detection sensor works
Most modern pressure sensors use a thin diaphragm that deflects as pressure changes. That deflection is converted into an electrical signal, commonly through piezoresistive elements on a silicon membrane or by measuring changes in capacitance. MEMS (micro-electromechanical systems) manufacturing has made these sensors tiny, low cost and highly repeatable, which is why they now appear everywhere from smartphones to battery packs.
The key design choice is the reference. A gauge sensor measures pressure relative to the surrounding atmosphere. A differential sensor measures the difference between two ports. An absolute sensor measures relative to a sealed vacuum reference, which means its readings are not affected by changes in weather or altitude.
Why absolute pressure matters for detection
When the goal is to detect a sudden event inside an enclosure, stability of the baseline is critical. A gauge sensor’s reference moves with the weather and with altitude, so a vehicle climbing into the hills or a storm front passing a storage site can shift readings in ways that mask or mimic the event of interest. An absolute pressure detection sensor provides a consistent reference, making abrupt changes stand out clearly against slow environmental drift.
This is why Metis Engineering uses absolute pressure sensing across its environmental sensor range, including Cell Guard, H Guard and Air Wise.
From measurement to detection
There is a difference between measuring pressure and detecting an event with pressure. Detection depends on three characteristics: resolution, speed and context.
Resolution defines the smallest change the sensor can see. Cell Guard and Air Wise resolve absolute pressure to 0.0001 bar across a range of 0.3 to 1.2 bar, with accuracy of 0.0005 bar between 0.3 and 1.1 bar. That sensitivity allows subtle changes, such as the gas released by a single venting battery cell in a large enclosure, to be identified.
Speed defines how quickly the sensor reports a change. A pressure channel updating at up to 50 Hz captures fast events rather than averaging them away.
Context is perhaps the most important. A pressure change on its own can have several causes. Combining pressure with other measurements, such as gas concentration, temperature and humidity, allows a control system to tell the difference between a benign fluctuation and a genuine hazard.
Pressure detection in battery safety
In lithium-ion battery packs, a failing cell releases gas through its safety vent, raising pressure inside the enclosure. This often happens before neighbouring cells heat up enough for temperature sensors to react. Cell Guard combines absolute pressure detection with volatile organic compound measurement, so a pressure step accompanied by a VOC spike provides a strong signature of cell venting. In independent testing by Sandia National Laboratories, Cell Guard detected a thermal event in under 60 seconds, while a hydrogen-only competitor took seven minutes longer.
Pressure detection in hydrogen systems
In hydrogen storage and fuel cell systems, pressure data complements direct hydrogen measurement. H Guard measures hydrogen from 0 to 20% by volume together with absolute pressure, air temperature, VOCs, humidity and dew point, with an optional accelerometer. A change in enclosure pressure alongside rising hydrogen concentration helps characterise the size and location of a leak.
Pressure detection in HVAC and cabins
In vehicle HVAC systems, absolute pressure supports altitude compensation and helps identify blocked filters or ducts. Air Wise combines pressure with CO2, VOC and NOx sensing, humidity, dew point and shock measurement, giving climate controllers a complete picture of cabin air.
Placement decides performance
Even a sensitive pressure detection sensor will underperform if it is badly placed. In a battery pack, it should sit near the breather or vent path, where gas released anywhere in the enclosure will pass. In a hydrogen enclosure, hydrogen rises, so gas sensing belongs high in the space, while the pressure channel reads the whole volume wherever it is mounted. In HVAC ducting, the sensor should see representative airflow away from dead zones. Getting placement right at the design stage costs nothing and avoids false alarms and missed events later.
Built for automotive environments
A pressure detection sensor used for safety must be as robust as the systems it protects. Cell Guard has been developed in line with ISO 26262 processes and tested to ISO 7637-2:2011, ISO 16750-2:2012 and ISO 16750-4:2010, and is used by OEMs and Tier 1 suppliers in ASIL B applications. Air Wise has been tested to the same ISO 7637-2 and ISO 16750 standards, and H Guard has been tested to ISO automotive compliance standards.
Integrated from day one
Every Metis sensor communicates over CAN bus with configurable address and baud rate, and is supplied with a DBC file, so pressure data can be decoded by the BMS, vehicle controller or logger immediately. Low power monitoring modes allow continuous detection while systems are idle, with a 500 mA low-side drive output that can trigger a response directly when a threshold is crossed.
A familiar sensor with a new job
The pressure detection sensor is a familiar component, but its job is evolving. In the systems that will define the energy transition, it is becoming a first responder, spotting the earliest physical signs of a fault and passing them to the controllers that can act.
To discuss pressure detection for your application, contact Metis Engineering at info@metisengineering.com.
