What is MEMS sensor technology?

First things first: MEMS stands for Microelectromechanical Systems.
You can see why it’s universally shortened.

MEMS flow sensors are intricate, accurate, and low-power little devices that measure air and fluid flow rates within a system. Here at Flusso, we’re focused on airflow sensors, so we’ll be covering that in this blog, exploring their operating principles, their key components, our proprietary T-MEMS technology, and briefly looking at some of the key applications that MEMS sensors can be usefully deployed within.

Why is MEMS technology so useful?

MEMS sensors are designed to measure various metrics, from airflow and air velocity through to acceleration, angle, pressure, magnetism and more. Our MEMS sensing technology is designed to accurately measure the flow and velocity of air in diverse applications, such as automotive equipment,medical devices and HVAC systems. This technology is most frequently deployed at a miniature scale and offers several additional advantages, including low power consumption, high sensitivity, and fast response time.

At their core, MEMS air flow sensors are a combination of mechanical and electrical components that work in tandem to detect changes in air velocity and convert these changes into electrical signals that help systems work more effectively.

Under the hood: what are the key components of MEMS flow sensors?

From a technical and compositional standpoint: MEMS sensors involve the integration of mechanical elements, sensors, actuators, and electronics on a silicon substrate using microfabrication techniques.

• Sensing element: The sensing element — typically a micro-scale structure sensitive to airflow — is the beating heart of the MEMS air flow sensor. Different structure materials include silicon, polymers, or metals. Flusso’s sensors utilise standard CMOS materials that further stand us apart in the market.
• Heating element & temperature sensor: Flusso’s sensors utilise thermal principles, incorporating a heating element that generates heat and temperature sensors that monitors temperature fluctuations as air flows through the sensor. These temperature changes allow the sensor to provide accurate airflow measurements.
• Mechanical element: Heating and temperature sensing elements are embedded within a thin stress-compensated membrane, so to be thermally isolated from the environment. This allows for efficient heat generation for low-power consumption and highly sensitive sensing of flow induced temperature variations.
• Electrical contacts: Electrical contacts interface the heating and temperature sensing elements with external electronics, enabling the measurement of electrical signals in response to airflow. Part and parcel of Flusso’s growing renown in the MEMS flow sensor space is the incomparably compact nature of our components.

MEMS sensing operations; focusing on thermal principles

Now we know the core components, let’s look at how MEMS flow sensors actually function.

Flusso’s market-leading airflow and air velocity sensors hinge on the accuracy of thermal sensing principles. For that reason, we’ll be focusing on those in this blog.

Thermal sensing

As highlighted, in thermal-based MEMS flow sensors, the sensing element contains a heating element (a heated resistor or thermistor) and temperature sensors.

The temperature sensors detect shifts in the temperature profile as air/gas flows through the sensor. In the absence of flow, the temperature sensors positioned around the heating element will display uniform readings. When there is flow, the variation in temperature between the upstream and the downstream sensors provides information about the flow characteristics.

In short: increased airflow leads to more heat dissipation from the heating element, resulting in a change in the temperature difference between the upstream and downstream sensors.

By measuring this temperature change in real-time, the sensor can determine air velocity or airflow and continuously feed the data back to the system, enabling it to optimise or control flow and adapt to changing conditions.

Mass flow: low flow vs. high flow rates

Flusso’s MEMS mass flow sensors precisely measure the rate of mass of air or gas passing through a system per unit of time. This is accomplished by detecting temperature changes as the substance flows through the sensor, enabling accurate monitoring and control of airflow in various applications. As opposed to mass flow, volumetric flow measures the volume of a medium (for Flusso, gas) moving per unit of time, and air velocity measures how fast the air is moving in distance per unit of time.

At low flow rates, the entire gas flow is directed to the MEMS sensing device, operating in a through-flow configuration. For higher flow rates, an application-specific fluidic fixture diverts a portion of the gas flow to a bypass gas stream where the MEMS sensing device is located, preventing saturation of its sensing signal. This configuration is known as a bypass configuration, effectively enlarging the flow range of the thermal flow sensor.

Regardless of the configuration and application requirements, Flusso has the expertise to optimise the design of the fluidic fixture tailored to your specific needs. This ensures that the gas flow conditions meet the sensor in the optimal state, enabling the best possible performance for your unique design.

Flusso’s MEMS-based flow sensors represent a remarkable advancement in airflow sensing technology, offering exceptional accuracy and reliability across a wide range of flow rates, even in the most space-constrained environments. We are excited about the potential of thermal-based MEMS flow sensing to further enhance adaptability to applications across a range of key industries.

An alternative to thermal principles: mechanical principles

Differential pressure sensors can operate on a different principle than thermal sensors, focusing on pressure fluctuations rather than temperature changes. Typically, these sensors consist of two chambers separated by a flexible membrane. As air flows through, it exerts pressure on one side of the membrane, causing deflection and generating electrical signals proportional to airflow pressure.

However, compared to Flusso’s MEMS thermal flow sensors, they come with certain drawbacks. They are more sensitive to environmental changes, making them prone to accuracy issues, particularly in varying temperature and humidity conditions.

They may also face limitations in measurement range and accuracy, especially in extreme flow conditions. Furthermore, the presence of moving parts can lead to mechanical wear and tear over time, potentially reducing overall accuracy and reliability.

Flusso’s sensors: going beyond typical MEMS flow sensing

Our proprietary sensing technology is called T-MEMS because it combines the robustness of purely physical thermal principles (the T stands for Thermal and Tungsten) with the small size and super-scalability of MEMS technologies.

However, we go even further.

Our proprietary MEMS flow sensors offer superior performance with reduced sensitivity to environmental changes, a wider measurement range, higher accuracy, and reduced mechanical wear compared to competitors using mechanical-based sensing technologies, making them the preferred choice for many airflow sensing applications.

Where can MEMS flow sensors be used effectively?

MEMS air flow sensors can be found across a wide array of industries and systems.

The below industry overview blogs give you an indication of where Flusso’s T-MEMS technology is improving product performance and increasing energy efficiency.

• Automotive: Powering a standout passenger experience while minimising environmental impact.
• Medical: Smarter medical equipment to reduce treatment costs and timescales.
• HVAC: Improving efficiency and air quality with a leading sensor technology.
• Semiconductors: Safeguarding the integrity of semiconductor wafers.
• Computing: Optimising AI-enhanced servers and hyperscale data centres.

Of course, the impact of MEMS flow sensors goes beyond the industries outlined above. There are incredible examples of this technology at play in everything from instrumentation apparati to everyday consumer appliances — another indicator of the widespread effectiveness of MEMS technology and thermal sensing principles.

Final thoughts — why Flusso?

MEMS flow sensors are sophisticated devices with ever-evolving component capabilities. They play a crucial role in measuring airflow in diverse applications and industries. Whilst MEMS technology is steadily improving in the market, Flusso has invested considerable resources into developing additional benefits that give you an even greater edge.

Flusso’s flow sensors are not only the smallest in the world, but we deploy thermal-based sensing mechanisms within novel T-MEMS technology, offering outstanding sensitivity and low power consumption within compact devices.

This also means we can move beyond the competition and measure airflow with very high levels of accuracy and reliability. The heating element and temperature sensors are incorporated in a sophisticated, proprietary sensing design that is already helping various industries increase their product performance around the clock.