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This is our third air sensor, based on the Swiss SFA30. It has excellent performance, and we are excited to explore this type of sensor!

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SFA-1 News

Title	Date
SCREEK Formaldehyde Sensor SFA-1 YAML Release	Jan 1, 2026 4:49 PM

HA Interface

Sensor Specification

It’s use SFA30

DateSheet

🔧Online Advanced Maintenance Tools

https://tool.screek.io/factory_tool/sfa-1

FAQ

Why is there so little information about SFA‑1?

This is actually the third sensor we completed in July. The process included testing hardware solutions, designing the enclosure, pre‑ordering parts, manufacturing reservations, and testing. Time was really tight, and we haven’t had the chance to think carefully about how to write a proper introduction yet.

What’s special about the SFA‑1?

We’re not formaldehyde enthusiasts, but sensors that can detect formaldehyde are usually very expensive, and most won’t even tell you the model of the sensor inside. Just for the sake of exploring the mysteries of formaldehyde, we feel this sensor is worth it.

We have no intention to compete with any product—DIY sensors are imperfect. But watching them work, running 24/7 with open‑source software, fully localized, and perfectly integrated with Home Assistant, is very satisfying. Adding it to our DIY collection is going to be great.

How many people actually need to measure formaldehyde at home—aside from high‑school biology teachers? (From Ken)

I think most people don’t really need it, just like CO₂ sensors—we rarely reach any critical threshold, and every city has its own overall monitoring systems.

Even so, if someone has a newborn in the family, or brings in new furniture, or just moved into a freshly renovated house, then these new things might release some formaldehyde. Knowing that formaldehyde stays within a safe range and gradually decreases can be quite interesting.

Judging by the marketing material of many commercial sensors, it seems like people are told they need such sensors to protect their long‑term health. We can’t say for sure, but making a cost‑effective DIY sensor for exploration sounds like fun.

Most of the time the readings are in the “good” range, and besides giving peace of mind, that might be the reason why such a sensor could find its place in many homes.

But just like CO₂, in poorly ventilated indoor environments it can accumulate, and if it reaches a critical value, then it’s worth paying attention.

What’s special about the SFA30 sensor used in SFA‑1?

It’s a Swiss‑made sensor (https://sensirion.com/products/catalog/SFA30), and it looks beautifully built. One key feature is its cross‑interference resistance against acetaldehyde.

A major challenge for formaldehyde sensors is eliminating interference from similar gases, and another is ensuring long service life (the datasheet shows patented technology that reduces the internal electrochemical reactions to extend lifespan).

What are your expectations for the SFA‑1 sensor?

We hope to produce as few as possible, considering the high cost—each unit we make makes us nervous, but having it available feels important. People might discover interesting uses for it, and being able to use Home Assistant to study the air around us is exciting—it’s like studying the air we breathe every day and night.

After PM2.5 sensors and CO₂ sensors, we’re happy to add a new member to our air‑sensor lineup. We hope it can provide useful tools for those who are interested in formaldehyde.

What about SFA‑1’s performance and error margins?

Its core is the SFA30, so its specs follow that sensor’s performance. The error margin is ±20 ppb or ±20% of the measured value, whichever is greater.

The sensor itself is very power‑efficient: SFA30’s average current consumption is around 1 mA (not including the ESP32‑C3’s Wi‑Fi transmission). Cross‑sensitivity to acetaldehyde is less than 0.5%.

We’ll add the SFA30 datasheet and related information to the documentation page later.