Real-time CO2 monitoring without batteries or external power | Hacker News Reader

Real-time CO2 monitoring without batteries or external power

news.kaist.ac.kr

132 pointsgnabgib34 comments

> The core of this new system is an "Inertia-driven Triboelectric Nanogenerator (TENG)" that converts vibrations (with amplitudes ranging from 20-4000 ㎛ and frequencies from 0-300 Hz) generated by industrial equipment or pipelines into electricity. This enables periodic CO2 concentration measurements and wireless transmission without the need for batteries.

Ingenious, I love it.

I was thinking would there be a passive chemical alternative, something that changed color according to CO2 level. Kind of: https://en.wikipedia.org/wiki/Bicarbonate_indicator

These generally - as the article indicates - have the issue that they aren't just sensitive to CO2 but virtually anything else.

You could maybe get by with some sort of antibody coagulation stuff like in many rapid test strips, but these are to my knowledge not reversible.

I was hoping it would be a mechanical system that uses no electricity at all

anyone can explain why this is such a big breakthrough?

vibration powered electricity generator is not new, neither is CO2 monitoring. so what's the big deal?

More concerning - can anyone explain why there is such a variation in the results from the DC powered unit vs. the TENG-powered one? The graph at the bottom of the report shows a difference of 30-50ppm between both units when they are sitting side by side on the bench.

I skimmed the original article and it only mentions the graph and says that it's "comparable to DC powered unit". I'm guessing < 100ppm difference is somewhat acceptable?

You might be right - it's just odd that it's always showing "more" rather than similar amounts.

Also, according to Claude[1] a 50ppm difference is equivalent to around 25 years current atmospheric carbon increase.

* Pre-industrial (1700s): ~280 ppm

* 1958 (when systematic measurements began): ~315 ppm

* 2000: ~370 ppm

* 2015: ~400 ppm (milestone crossed)

* Current: ~420-425 ppm

[1] "What is the normal range for background CO2 concentrations in the air?"

It’s crazy to think that many people alive today experienced a 30% increase in ambient atmospheric carbon dioxide concentration within their lifetimes.

You’re missing some deeply important context there, which is that those measurements are for outdoor atmospheric CO2 only.

Average indoor air quality ranges from 400-1000 ppm CO2, with adverse mental effects starting to appear close to 2000 ppm.

In that context, you can see why a 50 ppm difference is marginal. This is why asking an LLM is not generally a great idea for understanding something - you need to follow it up with more research.

> adverse mental effects starting to appear close to 2000 ppm.

cognition is harmed starting at 1000ppm (https://pmc.ncbi.nlm.nih.gov/articles/PMC3548274/)

I'm having a hard time parsing the data in this paper - is it showing that task focus increases at 1000ppm compared to 600ppm CO2 exposure?

Not odd at all that it’s always showing more — sensor error is often biased. This is within the listed range though.

I have to know, what's the the rise of people like you chiming in with AI sourced tidbits? It's like the people with no knowledge on a subject that use google as a quick catch up tool so they can participate in a conversation, but somehow even worse. Are they the same people, but now lazier or just true believers in the non-sense engines?

That's in the normal range of accuracy of modern CO2 sensors, for example SCD40 from Sensirion is described with an accuracy of ±50.0 ppm ±5.0 %m.v.

That’s if the voltage supply was stable and within electrical specs for a sufficient period of time. We can see this is a snippet 2 hours into the discontinous collection.

3.6V is the maximum value that the nrf52832 SoC can handle. I would suspect the VDD is variable.

Actually the real accuracy is much better, especially with optical NDIR sensors.

We do a lot of testing against reference grade sensors and typically see very good performance and reproducibility [1].

[1] https://www.airgradient.com/blog/performance-of-low-cost-co2...

A low powered co2 monitor is likely a big deal. And one that fits to specific power generation systems is even a bigger deal.

The challenge with CO2 monitoring is the sensor, not the electronics. Sensor accurracy and service life are key information.

It is easy to create a low power chemical CO2 sensors with a service life of a few weeks/months. Obviously not pratical for real world applications. So critical data is missing in this press release.

Replacing sensors every few weeks is totally practical for some real-world applications such as life support systems.

The power consumption is the thing, these sensors usually run in the low-digit milliwatt range... and they managed to get it to run on a power generation of 0.5 mW, making the combination of both possible at all.

Tangential/Spoiler: I came to know about Kaist (Korea Advanced Institute of Science & Technology) in the Netflix series Devil's Plan (season 2) which had two of its students as the top three contestants.

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