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Ozirma - near infrared spectrometer

A small infrared spectrometer to help plastic recycling. Dedicated to micro-factories around the world.

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OZIRMA is an open-source, low-cost sensor for identifying different types of plastic (PE, PVC, PET, PS, etc.), the first essential step in recycling.
The aim is to facilitate local, autonomous recycling of plastic waste.

Large industrial recycling centers use infrared spectroscopy to sort plastic waste.
Small plastic-recycling workshops don't have the budget for this type of technology.

OZIRMA finally democratizes access to infrared spectroscopy.

Beyond the engineering challenges (optics, mechanics, electronics) it represents, OZIRMA meets fundamental socio-economic needs:

1/ Frugal design
the component budget is ~300€ (motor, lenses, LEDs, electronics, etc.).

2/ Manufacturing compatible with Fablab technologies
3D printing, laser cutting, digital milling.

3/ Open-source hardware and software
everyone is free to modify, repair, copy and improve.

4/ Open-source databases and analysis algorithms
system durability and guaranteed quality of results.

THE CONTEXT :

Barely 10% of plastic waste is recycled today. Sorting used plastic is the first essential step in recycling.

Industrial recycling centers use a highly efficient sorting method based on infrared spectrometers that are very fast, but very expensive (+€100k).

In recent years, a number of projects have emerged to democratize plastic waste recovery techniques (eg Precious Plastic, Plastic Odyssey, paillettes-plastique).

Small structures that emerged from these trends use qualitative manual methods, which do not enable all types of plastic to be sorted efficiently. A low-cost sensor would enable these structures - as well as small workshops, fablabs and makers - to better sort plastics, and thus recycle more of them.

Although recently, more affordable spectrometers have appeared, such as the Plastri at €25,000, or the Plastell at €3,500; Today, there are no truly low-cost, open-source sensors for sorting plastic on a small scale...

THE TECHNO :

OZIRMA is a small spectrometer that operates in the infrared (900-1700nm). It measures diffuse reflection with a spectral resolution of 15nm. Its light source consists of four infrared LEDs (and a laser, for alignment). Its detector is a photodiode (a single pixel) which scans the spectrum by rotating around the diffraction grating (while compensating for alignment errors).

OZIRMA :

OZIRMA is ultra-low-cost. It requires just €300 of raw materials to be manufactured. The downside of this low cost is speed... OZIRMA is slower than existing solutions. In the context of small recycling workshops, this remains acceptable.

USE : - The plastic sample is placed on OZIRMA. - OZIRMA measures the spectrum of the sample (~30s). - The shape of the spectrum is used to determine the type of plastic, via an algorithm and an open-source database. Eventually, we may also be able to detect other plastic properties such as moisture content or the presence of flame retardants.

What's been done so far

Since 2019, we've been developing OZIRMA on our own time and our own funds. It's a project close to our hearts.

Started a simple idea, it took several modifications and re-designs before OZIRMA v4 (the 4th version) finally worked;
in the sense that it measures spectra similar to those measured on the same samples with a large laboratory spectrometer (thank you, CNRS!).


What's next?

Now that OZIRMA_v4 is up and running, we have a 3-stage plan for building OZIRMA_v5 and validating it in real-life use.

1/ Prototyping OZIRMA_v5 (six months' work for two people)

  • Integrate all bug fixes from v4
  • Reduce size
  • Increase measurement speed (a full scan would now take just 30s)
  • Improve mechanical robustness and user interface for field use.

2/ Pre-series (“beta MVP” in start-up language) of six OZIRMA_v5 machines, four of which will be given to partner recycling workshops for evaluation, including the Precious Plastic community and the Paillettes network!

3/ Feedback after 6 months of use: Measurement of spectra of 1000+ known and unknown plastic samples, accessible in open-data. This will enable us to objectively assess OZIRMA's failure and error rates.

We need your help!

To fund our engineering work on this open-source project, we've decided to use crowdfunding.

1st threshold: 5k€ Mejdi and Vivien will produce engineering drawings, specifications and schematics that will form the basis of OZIRMA_v5's design.

2nd threshold: €30k Mejdi and Vivien go into a technical design tunnel (optics, mechanics, electronics and software) to build/test/test OZIRMA_v5.

mejdi_with_ozi_v4.jpg

JPEG Image - 4.13 MB - 12/11/2024 at 10:19

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Portable Network Graphics (PNG) - 3.77 MB - 12/11/2024 at 10:19

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  • 1 × Illumination unit (custom PCB and 3D printed housing). 30€ including two IR LED at 1200 and 1600nm (~200nm bandwidth) and a 405nm laser-diode.
  • 1 × Scanning spectrometer. 65€ including a flat diffraction grating (photographic slide format, 600 groove/mm), few lenses, a NEMA 17 motor (for horizontal circular scan); as well as a CNC base (aluminium) and pinhole (copper sheet)
  • 1 × Detection unit (custom PCBs and 3D printed housing). 45€ Including NIR Photodiode, 1 GigaOhm transimpedance amplifier, micro stepper motor (for vertical linear scan), 2mm shafts and zero-backlash spring
  • 1 × Control Board. 40€ Including ARM MCU, Low noise power supply (from USB 1A), ADC, PDM controlled sources generation, USB Communication

  • Launching the Crowdfunding !

    Vivien Henry12/11/2024 at 10:16 0 comments

    We need your help!

    To fund our engineering work on this open-source project, we've decided to use crowdfunding.

    1st threshold: 5k€ Mejdi and Vivien will produce engineering drawings, specifications and schematics that will form the basis of OZIRMA_v5's design.

    2nd threshold: €30k Mejdi and Vivien go into a technical design tunnel (optics, mechanics, electronics and software) to build/test/test OZIRMA_v5.

    The link is here !

  • OZIRMA works !

    Vivien Henry12/11/2024 at 10:15 0 comments

    Hi there !

    It's been a long time !

    We got good news; 

    Ozirma finally works ! This summer, we were able to access to spectrometers for

    a) debug and improve the optical path

    b) get real mesures for our samples with a laboratory spectrometer (again, thank you CNRS !)

    So, the proof of concept is FINALLY validated ! Here you can see our measurement and the one from CNRS. We can see features for PVC and PS. Cheers !

  • Q1 2022 - Updates

    mejdi02/22/2022 at 10:51 0 comments

    Vivien and Me had to put the project on pause for few months, but we are back at it since the beginning of the month!

    Heavy modification (some upgrade but also many simplifications) of the optcomecanics and electronics is afoot...

    Plan is to finish designs of "OZIRMA v2" in March and fab+testing in May/June. 1st pilot production (and test IRL by "independant" partners) during the summer....

    Maybe Crowdfunding for this autumn... Anyway release of the sources by the end of the year.

    Stay tuned!!

  • Releasing Ozirma

    Vivien Henry11/07/2021 at 13:49 0 comments

    We are happy to share with you our work !

    But for now, it is still a "lab notebook" !

    Repositories are messy, they need a lot of cleaning !

    We will release everything in time (and with a instruction manual), when the improvements are implemented, and Ozirma is stable and ready for manufacturing  !

  • Last preparation for the 2021 Hackaday price final!

    mejdi11/06/2021 at 23:11 0 comments

    Dead line is tmr 7am Pacific Time. Luckilly it means 4pm French time ^^!

    We have few hours to have a nap and then:

    - Finish to consolidate the documentation of OZIRMA (one zip for PCB, for opto-mechanical, the firmware, the software...)

    - Finish editing the video

    - Finish recording its sounds

    - Have at least 10 entries in our project logs... Just one to go!

  • Pollutech Show

    Vivien Henry11/06/2021 at 22:54 0 comments

    In Lyon, France, 15 of October was the Pollutech show, dedicated to fighting against waste!

    I saw a lot of big actors, and had a lot of discussions about Ozirma !

    It is good to see that we are working in the right direction, and that the spectrometer will be useful around the world !

  • Making a video

    Vivien Henry11/06/2021 at 22:51 0 comments

    Hey ! It's time to rush !

    As a developer, that was my first time shooting a video clip !

    What a day !

    Fortunatly, good friends are helping, they are doing real magic !

    Can't wait to see the result ! (hopefully, before 7th, 16h00 !)

  • Entry to the Hackaday prize 2021

    mejdi11/06/2021 at 19:33 0 comments

    We did rethink and refresh infra-red spectroscopy...

    And OZIRMA is designed to be (re)buildable in any Fablab...

    Why not try our chances to Hackaday prize 2021?

    Reactive Wildcard, a better future! lets go.

  • Octobre 2021

    mejdi11/06/2021 at 19:27 0 comments

    Octobre 2021


    We got some cool "recognizable" spectra for some plastics. But almost no signal for sample that are too or too translucid (especially thin-film)

    While using all the tricks of averaging, denoising and deconvolution we are very close to the limit of detection .

    We still need to increase SNR to detect broader spectral bands on opaque plastics and/or see some signal on dark plastics.

    What would be the cheaper way? a faster ADC (reducing noise by averaging) or switch to a reflection grating (increasing optical signal)?... We may end up trying both ^^

    We also need to modify the geometry of the sample holder to be able to detect thin plastic film (like PET) by retro-diffusion.

  • 1st spectra

    mejdi10/27/2021 at 12:21 0 comments

    September 2021:

    First spectra of PP, PS and PE.

    NB: Spectra are not completely repeatable and the deconvolution sometime diverges. The aquisition need to be done very slowly (high averaging).

    Still some issue with PET, but we have some clues why...

    Next R&D session is schedule for end of November!

View all 13 project logs

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Discussions

Ki Keri wrote 10/15/2023 at 14:49 point

I was thinking of building a similar design as a project sometime soon to compliment my UV/VIS spectroscope and wondered if instead of the photodiode rotating around the diffraction grating it could be feasible to rotate just the diffraction grating slightly at a high gear ratio. Maybe this would skew the optical axis too much?

  Are you sure? yes | no

Ivor Hewitt wrote 08/16/2022 at 11:33 point

Fascinating, would be great to see the circuit designs when ready, I'm struggling to design a TI amp for the NIRS build I'm currently working on.

  Are you sure? yes | no

ameerbasha12 wrote 05/19/2023 at 17:45 point

you finished?

  Are you sure? yes | no

mejdi wrote 11/03/2021 at 20:43 point

Hi 3d6!

Classically plastic are identified/sorted using their reflection spectra in the NIR (1100-1700nm).

Classically using "broadband IR light-source" aka  "incandescent light bulb".

The full spectra is not necessary, though. Some carefully chosen bands (like the one we chose ^^) are enough to see some specific spectral features.

The  spectral bandwidth of the LED we are using is about 200nm @ 20% power  (if you only consider the FWHM, ie 50% power, it is more like 80nm). It is not much, but it is enough to see specific spectral features. The real challenge is to be sensitive enough, as the level of signal reflected are very low.

We can see the feature of some plastics, though not all YET ( it depends also on the plastic darkness and  thickness). Soon... ^^

NB: SInce 2018 it is easier to find NIR LED with wavelength from 1000 to 1700nm.

We are using the MARKTECH ones that come in  1206 packages.

See all NIR LED of marktech here:

https://marktechopto.com/marktech-emitters/swir-emitters/

Exemple of the LED we use for the 1100-1300nm band:

https://marktechopto.com/pdf/products/datasheet/MTSM0012-194-IR.pdf

  Are you sure? yes | no

the_3d6 wrote 11/03/2021 at 23:27 point

I hope enough information can be extracted this way. Thanks for LED link, on several occasions we had in mind projects requiring those wavelength and getting proper parts was a big problem, somehow never saw this company!

As for sensitivity - sure, but opa380 combined with a good standalone ADC seems to be good enough here. Btw, are you using proper ADC? If not and you rely on in-built ADC of STM32 - you really should try switching, once you'll try it. you won't ever want to go back :)

  Are you sure? yes | no

mejdi wrote 11/04/2021 at 00:13 point

Glad we can help!

If you use NIR LED maybe you'll also need a NIR Photodiode too...

Check this one out ;)

https://www.digikey.fr/product-detail/fr/advanced-photonix/0090-3111-185/209-0090-3111-185CT-ND

Best bang for your buck in the (new) world of 1206 packaged NIR.

For the sensitivity: ADC is not the big issue (but indeed need to be done properly via dedicated IC ^^). The GigaOhm TIA is the bottleneck (or the optical power, that could be improved); bellow the opa: EMI clip, power supply rejection trace capacitance... it ain't easy to get "good enough"  (ie being only limited by the thermal noise) above 10MegaOhm :p

I wander what Vivien thinks of the OPA380...

  Are you sure? yes | no

Vivien Henry wrote 11/04/2021 at 09:03 point

Did a (very) quick look at the opa380. Not sure that the GBW is high enough.

In term of noise, is a little bit higher that the ones we use.

I should give it a try in sim BTW :)

yes definitly we use a proper ADC :)

Best

  Are you sure? yes | no

the_3d6 wrote 11/04/2021 at 09:58 point

And what opamp and ADC you are using now? Also, is schematics available somewhere?

  Are you sure? yes | no

Vivien Henry wrote 11/05/2021 at 15:10 point

We use the ads868x series for the adc, the first opamp used was a opa2156, and we are investing and testing some others references ! but i'll take a deeper look at the opa380 as soon as possible !

  Are you sure? yes | no

the_3d6 wrote 11/05/2021 at 15:29 point

opa2156 looks good, possibly it's better than opa380 in this role (definitely better by specs but it also depends on how exactly it's used). As for ADC - that one doesn't look optimal here, I can recommend looking either into 16-bit ones with smaller input range (we use mcp391x, at 1 kHz it has 15 noise-free bits for +-19 mV range, with configurable gain it can be set from +-19 to +-600 mV) - or into 24-bit family if you want to keep wide input range, I saw some promising ADS129x parts. Those are sigma-delta ones, but that doesn't look like a problem for this application

  Are you sure? yes | no

mejdi wrote 11/07/2021 at 14:46 point

I like the price of this MCP3910.

reducing range to +/-600mV would work, but not bellow (we are doing fft on large buffer to get the modulation amplitude of each LED).

ADS1291 is a little pricey... And I am not sure more bits is what we need as the thermal noise, in sqrt(k_b x T x 1GOhm) is quite high, even in a 1kHz bandwidth.

More speed (with still low band pass) would allow us to do more averaging and increase SNR. What would you advise as cheap "good" ADC 12bits with higher sampling rate (10MSaps?)  that can easilly be plugged to an MCU (FPGA would be out of price, we think).

  Are you sure? yes | no

the_3d6 wrote 11/08/2021 at 00:43 point

12 bits at 10 Msps is something I haven't ever met - I believe SAR is necessary there, while I mostly search for sigma-delta ones.

If you will decide to use MCP391x - I suggest 3911, then you can use code from our uECG project - I dedicated some time to declare unions with named bitfields, which makes testing different configurations significantly simpler ))

  Are you sure? yes | no

Vivien Henry wrote 11/08/2021 at 09:54 point

The  mcp391x looks nice !

except for the analog range, which is annoying because we need the very high dynamic, i think.
(I like the Oversampling, if i did understand it well, because it does the avering for us at very hiigh speed, and we can keep the data samplerate low, to avoid overstressing the MCU) (maybe i'm mistaken. Need to do more research and calculation ^^)

  Are you sure? yes | no

the_3d6 wrote 11/03/2021 at 18:40 point

Have you compared captured spectra from different materials? Does it have enough sensitivity in the right spectral areas to distinguish between different plastic types? We considered making this kind of device, but from available information it didn't look like plastics can be sorted using easily available LED wavelengths...

  Are you sure? yes | no

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