Airflow Sensors

Airflow Sensors – Evolution, Function, and Applications

Airflow Sensors, or mass flow sensors, have become an integral component in various industries, ensuring the precise measurement of air and gas flow. As technology has advanced, so has the need for more sophisticated and reliable sensors. This article delves into the evolution of mass airflow sensors, their functioning, and their diverse applications.

Airflow Sensors – Key Specs

• Measurement Range: 0…200 sccm to +- 800 SLM
• Sensor Type: MEMS technology
• Material: Silicon chip, SiC coating
• Output Signals: Analog and digital
• Fast Response Time
• Durability: Resistant to shocks, particles, liquids
• Low Power consumption

Evolution of Airflow Sensors

The journey of mass Airflow Sensors has been marked by continuous innovation to meet the demands of modern technologies. Central to this evolution is the MEMS sensor chip, a silicon semiconductor chip. Our supplier, Posifa Technologies, has taken the lead in this domain, developing and patenting their own semiconductor. Manufactured in their Wafer Fab in the USA, this chip has been designed to be more resilient and efficient.

Linear output signals, analog and digital, offer an ideal connection to the electronics for each application. The sensor chip developed and patented by Posifa is very robust against particles, moisture and pressure shock. The flat surface is protected with silicon carbide (SiC). The sensors operate without a cavity under a fragile microbridge. In addition, the PMF86000 and PMF83000 airflow sensors are coated with Parylene.

Functionality of Airflow Sensors

At the heart of the Airflow Sensor is the thermal semiconductor sensor chip. This chip houses a heating element maintained at a constant temperature using electricity. Surrounding this heating element are thermopiles (resistors). In the absence of any airflow, these thermopiles remain at the same temperature and resistance as the heating element.

However, when air flows through the sensor, it sweeps over the semiconductor, causing a change in the temperature distribution across the thermopiles. This results in the cooling of one thermopile and the heating of another. This temperature differential is evaluated using an electrical circuit known as the “Wheatstone bridge”, which then outputs a calibrated signal corresponding to the airflow.

Applications of Airflow Sensors

Airflow sensors find applications wherever there’s a need to measure air and gas flow. They are crucial in:

• Ventilators
• Gas analysis devices
• Air quality “Sampler” measuring devices
• Density testing devices
• Oxygen concentrators

Furthermore, when we talk about “air velocity sensors”, we refer to devices that measure wind or airspeed. These sensors are pivotal in climate and ventilation systems, monitoring airflow in computer and server installations (like cooling fans), and measuring wind speed in aerodynamic test stands.

Posifa Technologies – A Leader in Airflow Sensors

Posifa Technologies, based in Silicon Valley, California, is at the forefront of thermal silicon sensor chip development and manufacturing. The Airflow sensors are produced and calibrated in factories in China and Taiwan. They offer measuring ranges from 0…200 sccm (cm³/min) to +- 800 SLM (standard liters/min.).

Unlike the fragile designs of competitors, which are highly sensitive, Posifa’s design stands out. This makes Posifa sensors significantly more durable than competitor products. We even offer versions directly interchangeable with competitor Honeywell, allowing customers to replace Honeywell sensors with Posifa’s without any adjustments. Notable examples include AWM3300V with PMFc3300V and AWM3100V with PMFc3100V. AWM720 with PMFc720, AWM43300 with PMFc43300.

In addition to standard products, we offer customer-specific calibration and mechanical adaptations. The Posifa R&D team provides extensive support with application-related questions. Call us or use the contact form, BS-rep and Posifa will support your design.

FAQ

Airflow sensors specifically measure the flow rate of air or gases, utilizing MEMS technology and specialized materials like silicon chips with SiC coating. In contrast, other flow sensors might be designed for liquids or have different sensing mechanisms. The unique design of airflow sensors ensures accurate readings in applications like ventilation systems, medical devices, and more.

Regular maintenance of airflow sensors involves cleaning to remove any particulate matter or debris that might affect readings. It’s also essential to periodically calibrate the sensors to ensure they provide accurate measurements consistently. Some advanced airflow sensors come with self-calibration features, but manual checks are always beneficial.

Advanced airflow sensors are equipped with fast response times, allowing them to adapt quickly to changing flow conditions. This rapid adaptability is crucial in dynamic environments where air or gas flow can fluctuate frequently. The sensors’ MEMS technology and sophisticated circuitry enable them to detect and respond to these changes almost instantaneously. Additionally, some sensors come with advanced algorithms that predict and compensate for rapid flow changes, ensuring consistent and accurate readings even in the most volatile conditions.

further information

• air velocity sensor
• pressure switches
• air bubble detectors
• vacuum gauges
• hydrogen sensors