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Seeing the name SPEC Sensors again brought back old memories

original Engineering

Continuing from the last post

The last post covered how far the idea of correcting cheap air sensors against reference stations has come over the past ten years. The trade publication Asian Environmental Technology that the post drew on also carried another article that caught my eye, about a company called EC-Sense near Munich.

It’s an electrochemical gas sensor that uses a solid polymer electrolyte printed directly onto ceramic instead of a liquid electrolyte, and according to the article the element measures 1cm × 0.8cm × 1mm, smaller than a postage stamp. It costs 5 to 12 euros, and a single machine can produce up to 10 million units a year.

Article introducing EC-Sense (Source: quoted from Asian Environmental Technology, August/September 2026 issue (ILM Media))

Article introducing EC-Sense (Source: quoted from Asian Environmental Technology, August/September 2026 issue (ILM Media))

While looking into this, I came across a name I hadn’t heard in a while: SPEC Sensors.

The discussions in Menlo Park

SPEC Sensors was a US company that made plastic-laminate electrochemical sensors using printing technology. About ten years ago, if you wanted a thin, low-power gas sensor, this was the first name that came up.

As I wrote in the last post, back then I was running an air-quality measurement business in San Francisco, and I met with the SPEC Sensors people around Menlo Park many times to talk things through. In the end I bought several of their sensors and put them into actual devices. Even now, when I open my box of electronics-hobby sensors, several SPEC Sensors products are still sitting in there.

A SPEC Sensors product (a flat PCB) that I used to keep in my sensor box back then

A SPEC Sensors product (a flat PCB) that I used to keep in my sensor box back then

The product line is still around today. Interlink Electronics acquired the company in December 2022, and it now sells sensors at 20×20×3mm, under 50µW power consumption, with elements starting at $20.

SPEC Sensors | Interlink ElectronicsProduct page for SPEC Sensors, maker of printed electrochemical gas sensorsinterlinkelectronics.com

Back then, quite a few people probably thought this would let everything around us start measuring gases. Electrochemical sensors work at room temperature, and the element itself barely draws any power. Make it thin enough and it would even fit in a smartwatch. But ten years on, looking around, hardly anyone is measuring CO on their wrist.

Not even in my own logger

To be honest, that’s true of me too.

I’m currently building a small logger to carry around and record the air around me. Inside it are Bosch’s BMV080 (PM2.5), Sensirion’s SCD41 (CO2), and the BME280 for pressure, temperature and humidity — not a single electrochemical sensor. I didn’t even consciously decide to leave electrochemical sensors out when choosing components.

Around the same time, a Paris company called Plume Labs gained popularity for a “portable air sensor.” Their consumer air pollution sensor “Flow” was a small device that could measure NO2, VOC, PM1, PM2.5 and PM10, and it was reportedly used in 74 countries. Plume Labs entered an exclusive partnership with the weather information company AccuWeather in 2020, and AccuWeather acquired it at the end of 2021. It’s now positioned within the AccuWeather group as a hub for climate and environmental data, its focus shifted from the device itself toward air quality forecasting and data.

AccuWeather Acquires Plume LabsAccuWeather acquires Plume Labs, maker of the portable air sensor “Flow”prnewswire.com

In the direction of wearable measurement, value shifted away from the device and toward the data that came after it.

Why didn’t it become the main act?

The first thing to consider is accuracy. But that doesn’t seem to be it — SPEC tests its sensors at the factory before shipping, the output is linear, and the company markets its sensors as able to withstand ten years of field operation. It’s well past the stage, common with cheap sensors, of “the numbers themselves are questionable.”

Next, price. Starting at $20 is considerably cheaper than conventional liquid-based sensors, but still a bit much to simply drop into a consumer product. EC-Sense’s 5 to 12 euros should matter here, and I think it’s part of the reason. But if price were the whole story, prices should have come down sooner, and it doesn’t feel like the main issue.

What about lifespan and drift? Electrochemical sensors are sensitive to humidity, and the zero point drifts over long use. This is a weakness too, but in a world that assumes calibration anyway, every method has similar headaches, and it’s hard to say electrochemical sensors are uniquely disadvantaged.

Thinking back on why I didn’t choose an electrochemical sensor for my own logger, the answer turned out to be fairly simple: the gas I wanted to measure was different. What matters in the air of a room or during a commute is CO2 as a proxy for ventilation, PM2.5, and at most VOC as a vague indicator of “the air feels off somehow” — and each of these has already been claimed by a different sensing method. Small photoacoustic NDIR sensors have taken CO2, and MEMS metal-oxide sensors have taken VOC, both becoming smaller and cheaper in the past few years. What electrochemical sensors are good at is specific toxic gases like CO, NO2, ozone and hydrogen sulfide, and in daily home life the only one people routinely worry about is CO for smoke detectors.

Before the question of whether it would fit in a smartwatch came the question of whether there was a gas worth measuring on a wrist in the first place.

Seen this way, the subsequent moves make sense. At CES 2025, SPEC announced a CO sensor built into the industry-standard “4-Series” package shape. A company that had come to market on the strength of thinness moved toward a form that could be swapped in for existing products — which suggests customers wanted drop-in replaceability more than something new.

Diapers, restrooms, and insect farms

Meanwhile, the applications listed alongside the EC-Sense article are rather interesting. Early forest-fire detection by attaching sensors to trees to sniff out smoldering fires just starting to catch, clips attached to diapers, a system at restrooms in Indian train stations, airports and gas stations that calls a cleaner when a threshold is exceeded, ammonia monitoring at a French insect farm, and oxygen monitoring on the ISS. In every case a specific gas is fixed in advance, a large number of units need to be deployed, and there isn’t much battery or power budget to spare. Electrochemical elements barely drawing power was always an inherent strength, and it seems fair to read this as: now that the technology has gone solid-state and become smaller and cheaper, that strength has started reaching the places where it actually matters.

Diapers, restrooms and insect farms — those are applications I never would have thought of.

EC SenseEC Sense of Munich, developer of solid-electrolyte electrochemical gas sensorsecsense.com

Ten years inside the sensor box

Looking at the SPEC Sensors products in my sensor box, I’m reminded of the discussions in Menlo Park back then. At the time, I thought that once thin, low-power sensors came along, the range of applications would keep expanding rapidly. Well, that’s an understandable thing to have thought. I’m simply the type of person who gets excited by the mere fact that real-world data keeps accumulating little by little every day (laughs). Even then I had thought about uses like insurance and real estate, but I can’t deny I was somewhat optimistic about applications. In reality, finding the application turned out to be far harder.

Even so, SPEC Sensors has stayed in this category for more than ten years while changing its corporate shape, adding hydrogen and ammonia sensors, releasing pin-compatible packages, and even reaching into food quality monitoring as a new application. EC-Sense, too, founded in 2015, has spent roughly ten years refining a machine that automatically manufactures sensors without liquid, finding one place after another that nobody thought of — diapers, restrooms, space stations.

There are people who, in a category that never became the main act, have kept searching for applications for ten years without giving up. As someone who picked up this sensor during that same era, I have real respect for that persistence.

References

This piece was drafted and directed by Kuzuryu, written by AI.

Originally published in Japanese at https://clazytech.com/2026/09/1837/. Translated with LLM assistance and reviewed before publication.