How to Ensure 10-Year Stability Through Design, Manufacturing and Calibration
Carbon monoxide (CO) alarms play a crucial role as “safety guardians” in industrial production, smart homes, underground parking lots, hospitals, schools, and other locations. The core component of a CO alarm is the carbon monoxide sensor. Many CO alarms are sold with lifespans from 1 to 10 years, and some even less than a year. The lifespan depends on the carbon monoxide sensor’s life. How to get a long lifespan and a high stability sensor?
This article introduces the CFS carbon monoxide sensor from material selection to manufacture.
CFS is a CO sensor manufacturer with nearly 20 years of experience in the research and development of carbon monoxide, offering multiple product series with lifespans ranging from 5 to 10 years and custom CO sensors.
What Determines CO Sensor Lifespan?
A CO sensor is an electrochemical sensor, similar in characteristics to a fuel cell. When CO gas is present, the CO sensor generates a current output. This output current has an approximately linear relationship with the CO concentration. Under normal circumstances, the sensor’s sensitivity is 1 nA to 2.5 nA/PPM (CO) (sensitivity can be increased through product design). A typical characteristic of lifespan degradation is a decrease in sensitivity. For example, after being installed in a carbon monoxide alarm and calibrated, the sensitivity is 1 nA/PPM CO. After attenuation, it may become 0.5 nA/PPM CO, or even lower. It causes delayed alarms or even no alarm at all because it cannot accurately detect the carbon monoxide concentration in the environment.
How Electrochemical CO Sensors Work？
The working principle of an electrochemical carbon monoxide sensor is illustrated as follows:
You can read more about CO sensor working principles from the following link:
Why CO Sensor Fails Prematurely？
The lifespan decline of electrochemical carbon monoxide sensors mainly stems from the following aspects.
Contamination and Catalyst Deactivation
Contamination can originate from outside sources or the materials themselves. Sulfide-containing gases, ammonia, gasoline, and silicon can cause catalyst failure in the reaction layer or adhere to the catalyst, hindering the catalytic reaction of carbon monoxide and reducing its catalytic capacity. Alternatively, post-reaction chemical substances can block the proton transport channels of the proton exchange membrane, reduce the number of channels and prevent protons from crossing the membrane to their polarity, thus decreasing output sensitivity.
Internal contamination may originate from the materials themselves. If the selected materials contain contaminants, these will slowly leach out over time, poisoning the MEA proton exchange membrane. For example, impure electrolytes containing contaminating ions, or inadequate cleaning of the materials.
PEM Membrane Degradation and Internal Resistance
During manufacturing, a catalyst is coated onto the base membrane. The coating process significantly determines the membrane’s resistance to degradation. An excessively thick coating makes it prone to peeling, while a thin coating affects output sensitivity. Internal resistance also affects lifespan: After prolonged use, the base membrane ages, leading to increased internal resistance.
Additionally, an excessively thick base membrane also results in high internal resistance. The manufacturing process and packaging steps further influence internal resistance. High membrane internal resistance directly hinders proton penetration, resulting in reduced sensitivity and a short lifespan.
Electrolyte Drying and Leakage Risk
For electrochemical carbon monoxide sensors with an electrolyte, the internal electrolyte may leak out due to poor sealing. The membrane becomes dry in the absence of electrolyte wetting, and the ability of the dry membrane to conduct protons will be greatly reduced, resulting in decreased sensitivity.
How to Design a 10-Year CO Sensor
CFS boasts over 20 years of experience in CO sensor R&D and OEM/ODM manufacturing, shipping over 1 million units annually. Design control is primarily implemented through the following three aspects:
1. Selecting a suitable MEA membrane
CFS sensors all use proton exchange membranes from internationally renowned brands, ensuring a membrane lifespan of over 10 years.
2. Product structural design
We use more redundant structural materials in the design stage to reduce contamination of the catalyst by other gases. When some channels are contaminated or blocked, or the catalyst is poisoned and ceases to function, there are still sufficient proton channels or catalysts to participate in the reaction.
We also use dense activated carbon as a filter material at the air inlet to allow carbon monoxide gas to enter freely and absorb other impurities so that they do not enter the interior.
3. Material selection
All materials used in CFS sensors are 100% tested and pollution-free. All materials and the proton exchange membrane are placed in the same sealed container and subjected to 12 months of high temperature and high humidity testing (test conditions: 70 degrees Celsius, 90% humidity). The changes in membrane properties before and after the experiment are compared to ensure that no substances that would pollute the proton exchange membrane are released, even under high temperature and high humidity conditions.
Every CFS sensor undergoes 100% accelerated lifespan degradation aging test during product development, with thorough experimental verification to ensure that each model’s lifespan meets expectations.
Material Selection and Anti-Contamination Strategy
All hardware and rubber materials must undergo at least three cleaning and drying processes. The materials are inspected under a microscope to check for contamination before production after cleaning. We use automotive production lines to assemble CO sensors in a dust-free workshop to ensure a consistent sensor. Operators are required to wear finger cots to prevent secondary contamination. CFS has independently developed various testing equipment. Before sensors leave the factory, 100% of products undergo testing for internal impedance, insulation impedance (low insulation impedance affects circuitry and sensitivity to low concentrations), capacitive reactance (capacitive reactance affects sensor response time), and sensitivity.
Manufacturing Process Control for Long Lifespan
In actual mass production, the core of manufacturing process control for long lifespan lies in the systematic control of “material cleanliness + process consistency + full inspection mechanism”. All critical materials must undergo multiple cleaning and drying processes and be confirmed free of contamination through microscopic inspection before being put into production. The production environment adopts cleanroom management, and key assembly processes are automated to replace manual labor, reducing human error.
At the same time, 100% factory testing is performed on each sensor, including internal impedance, insulation impedance, response time, and sensitivity calibration, to ensure batch consistency. From an engineering perspective, this closed-loop control from materials and processes to testing is the key foundation for achieving stable operation for 5-10 years and meeting the requirements of UL2034 and EN50291.
100% Testing and Calibration System
In the mass production system, the 100% Testing and Calibration System is not only a quality control measure but also the core foundation for ensuring the long-term stability of sensors. Each CO sensor undergoes a full testing process, including sensitivity calibration (nA/ppm linear output), internal impedance and insulation impedance testing, response time, and stability verification under temperature and humidity conditions, and 30/70/150/400 ppm CO gases calibration.
Depending on the product characteristics, anti-interference gas testing, temperature cycling testing, and long-term stability verification are also conducted to ensure that output deviation is within a reasonable range. All test data is recorded and traceable in batches, forming a closed-loop control from design verification to mass production delivery, effectively reducing certification risks and market complaints.
👉 Contact us to get the CO Sensor Stability Checklist
Case Insight: Why Some Sensors Fail Within 1 Year
In some project reviews, the failure of some CO sensors within one year is often not due to a single device, but rather to inadequate design and manufacturing controls. Common causes include:
These factors directly lead to decreased sensitivity and response delay, thus affecting the alarm time curve and failing to meet UL2034 or EN50291 requirements. From an engineering perspective, it is essential to incorporate anti-contamination structures and temperature /humidity adaptation solutions during the design phase, perform multiple cleaning processes and 100% critical parameter testing during the manufacturing phase, and verify lifespan consistency through accelerated aging testing to avoid the risk of early failure.
Why Choose CFS CO Sensors
OEM / ODM Custom CO Sensor Solutions
CFS provides OEM/ODM customized CO sensor solutions, supporting customization of structural dimensions, sensitivity range, interfaces, and lifespan requirements. Through design optimization and production consistency control, we ensure products meet certification requirements such as UL2034 and EN50291, reducing project risks.
FAQ – CO Sensor Lifespan and Stability
Why Trust CFS Engineering Capability
Summary
The lifespan and stability of electrochemical carbon monoxide sensors essentially depend on the systematic control of design, materials, processes, and testing systems. A reliable 10-year lifespan CO sensor needs anti-fouling structural design, PEM membrane quality control, rigorous manufacturing processes, and 100% testing and calibration. All sensors must undergo high-temperature and high-humidity testing, temperature cycling, and long-term aging verification to reduce the risk of early failure.
Customers aren’t looking for “sensor principles,” but rather: “Why can your sensor last 10 years?”
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