Top 3 Gas Sensor Failures and How Solid-State Sensors Fix Them

Gas sensors play a vital role in a wide range of industries and applications, from industrial safety and environmental monitoring to smart buildings and healthcare systems. These devices detect the presence and concentration of specific gases in the environment, offering real-time data crucial for maintaining safety and operational efficiency.

Despite their importance and widespread use, gas sensors can face performance issues or even complete failure under certain environmental conditions. Factors such as high gas concentrations, chemical interactions with soluble gases, or the inability to desorb particular gas molecules from the sensor's catalyst can significantly degrade sensor accuracy or cause permanent damage.

This article delves into three common reasons behind gas sensor malfunction and explores how solid-state polymer electrochemical sensors are designed to overcome these challenges, offering a more robust and reliable sensing solution for demanding environments.

The modern world is increasingly dependent on gas sensors for safety and regulatory compliance. Whether it’s detecting hazardous gases in a chemical plant, monitoring CO₂ levels in office spaces, or ensuring air quality in urban environments, the accurate and continuous performance of gas sensors is non-negotiable. Any failure or degradation in performance can lead to serious consequences, including safety hazards, regulatory violations, and costly downtime.

While manufacturers aim to produce gas sensors that are both precise and durable, the nature of gas detection—particularly in volatile or extreme conditions—poses significant design challenges. Sensors must not only detect minute concentrations of gases but also withstand long-term exposure to fluctuating environments without losing functionality.

Let’s explore the core issues that commonly lead to sensor degradation and how solid-state polymer technology offers promising solutions.

One of the most frequent causes of gas sensor failure is prolonged or sudden exposure to high concentrations of target gases. When gas levels reach into the tens or even hundreds of thousands of parts per million (ppm), this concentration can overwhelm the sensor’s internal components—especially the catalytic electrode.

Traditional electrochemical gas sensors rely on chemical reactions occurring at the catalyst surface, where gas molecules are converted into detectable signals. However, when exposed to extreme concentrations of gases, the current generated by these reactions can surge beyond the designed overload capacity of the sensor. This results in:

Current overload

Thermal damage

Irreversible physical changes to the catalyst

Permanent loss of sensitivity

In severe cases, the catalyst may lose its activity entirely, rendering the sensor incapable of producing accurate readings or becoming completely non-responsive.

Solid-state polymer electrochemical sensors address this challenge with an innovative design. In these sensors, both electrodes are embedded on the same two-dimensional plane and fully encapsulated in solid polymer electrolyte. This configuration helps in two key ways:

Even Current Distribution: The flat layout ensures the current produced during high-concentration exposure is more uniformly distributed, reducing local hotspots and current spikes that typically damage traditional sensors.

Improved Thermal and Chemical Stability: The solid-state design resists heat and chemical changes more effectively, preventing irreversible damage to the catalyst material.

The result is a sensor that can better endure high-concentration gas impacts without compromising long-term performance.

In environments where soluble gases—those that dissolve easily in water or solvents—are present in high concentrations, traditional liquid-state electrochemical sensors can suffer significant performance degradation.

Here’s how the failure mechanism unfolds:

Gas molecules enter the sensor through microchannels designed to allow gas flow.

If the gas concentration is too high and cannot be rapidly processed at the catalyst, excess gas penetrates deeper into the sensor.

These gas molecules reach the lower internal compartments and react with the liquid electrolyte.

Over time, the chemical properties of the electrolyte are altered, impacting the sensor’s ability to catalyze future gas interactions.

Chemical instability of the electrolyte

Reduced signal accuracy

Potential corrosion of internal components

Sensor drift or failure

Solid-state polymer electrochemical sensors are inherently resistant to the effects of soluble gases due to their non-liquid electrolyte structure. The solid polymer electrolyte forms a dense matrix of micropores, which serves two critical purposes:

Prevention of Deep Gas Penetration: The dense pore structure significantly reduces the diffusion rate of gas molecules, ensuring that unreacted gases cannot reach deeper internal components.

Stable Electrolyte Composition: Without a liquid medium to alter, the solid-state electrolyte maintains its chemical integrity even when exposed to high concentrations of soluble gases like ammonia, SO₂, or H₂S.

This robust design allows solid-state sensors to function reliably even in high-humidity or solvent-rich environments, where traditional sensors would typically fail.

Another major factor in gas sensor malfunction is the accumulation of gas molecules that cannot be easily decomposed or desorbed from the catalyst surface. This is particularly problematic with strongly adsorptive gases, such as certain sulfur or chlorine compounds, which exhibit the following behavior:

Gas molecules bind tightly to the surface of the catalyst.

Due to weak catalytic reactivity or incompatible material selection, these molecules fail to break down effectively.

As more molecules adhere over time, the surface becomes saturated.

The catalyst is no longer available for further reactions, leading to catalyst poisoning.

This poisoning effect manifests as:

Declining sensitivity

Inaccurate readings

Eventually complete sensor failure

What makes this scenario particularly concerning is that the adsorbed molecules are often very difficult to remove, especially at room temperature. Without the use of external cleaning mechanisms or thermal regeneration, the sensor may never recover its initial performance level.

Solid-state polymer sensors mitigate this risk by enabling the use of catalyst materials with improved resistance to poisoning and by operating in environments that support easier desorption.

Moreover:

The flat electrode structure allows for more efficient heat dissipation and surface regeneration, which can help in the desorption process.

The use of specialized non-porous or self-cleaning catalyst coatings is easier to implement in solid-state designs.

This results in longer operational lifespans, even when exposed to challenging gases that are known to poison traditional sensors.

Gas sensor failure is not just a minor inconvenience—it can be a significant safety and operational risk in critical infrastructure, industrial operations, and public health applications. Understanding the root causes behind sensor degradation is essential for both designers and end-users who rely on consistent and accurate gas detection.

The three primary causes of failure—overload from high gas concentrations, chemical degradation by soluble gases, and catalyst poisoning from strong adsorptive gases—present substantial challenges to conventional electrochemical sensors.

Solid-state polymer electrochemical sensors represent a major advancement in sensor technology. Their innovative design not only overcomes the limitations of traditional liquid-state sensors but also enhances performance, stability, and reliability under adverse conditions.

By leveraging the benefits of solid-state construction, manufacturers and users can achieve:

Greater sensor longevity

Reduced maintenance and replacement costs

Improved safety and regulatory compliance

Enhanced accuracy and reliability in diverse environments

As demand for smarter and more resilient sensing technologies continues to grow across industries, solid-state polymer electrochemical sensors are poised to become the new standard in gas detection systems.