The open source modular spectrophotometer

Di-Lambda is a fixed-wavelength spectrophotometer designed for colorimetric assays, used in biochemistry or environmental science.


Di-lambda is not just another lab tool: it is a modular spectrophotometer, which can be opened, reassembled and customized. It is a powerful tool for education in chemistry, physics and biology courses. This tool has been the result of a close work with teachers and school for over 4 years.

dilambda logo


Alexey Zaytsev

Hardware design

Hardware documentation

Industrial production

Juanma Garcia
General support

Juanma Garcia

School workshops


Science applications


Sonia Agüera

Workshop documentation

Institutional partners

CRI logo

CRI Paris

Funding for first test production

Hosting and equipment at CRI makerlab

logo tsinghua

Tsinghua graduate school in Shenzhen

Open F.I.E.S.T.A. program

Hosting in Shenzhen in 2016


Académie de Versailles

Science workshop and feedback

Teacher training

ditos logo

Doing It Together Science

EU project H2020. Funding for school workshops using di-lambda


Absorption measuring range 0A - 3A
Light path height 8.5mm
Cuvette shaft 12.5 mm × 12.5 mm
Spectral bandwidth 10nm - 35nm (see list below)
Detector Type Enhanced UV PIN Photodiode
Fixed wavelength (nm)
Power consumption 1W (5v, 200ma)
Power supply Micro-USB (5V DC, 200ma max)
Interfaces Micro-USB (to PC)
Weight w/o accessories
Dimensions (W × D × H)


A spectrophotometer measures the amount of light that passes through the sample at a given wavelength. To produce light at the right wavelength, most spectrophotometers use a mechano-optical system to position a monochromator at the right angle from the light source, and a slit to only select the right wavelength. DIλ is an Open Hardware spectrophotometer, designed to be accurate, easy to modify, and extremely cheap. We achieve this by using LEDs instead of an optical refraction system.

This design choice means that the device is limited to one or a few pre-selected wavelengths, but most biological applications only use a few. It is also possible to select a different wavelength by populating a spare LED board, but since it's so cheap, it might be easier to just buy one for each task. Another disadvantage is large spectral width of LEDs, typically 15-25nm, compared to 1-5 nm for traditional spectrophotometers.

With a few wavelengths, the spectrophotometers allows anyone to make real experiments! You can measure the quantity of glucose in your drink, measure the pH in water, and much more. One of our early versions is still used by a start-up from Paris to quantify grown of the spirulina algae.All this means that DI-lambda is not always able to replace a traditional spectrophotometer, but works great for a majority of biological applications.


This machine is now being produced and sold by Koi Science, based in China. Check for software and contact Koi Science if you are interested in buying one!


The last version (v1.7) of the open hardware spectrophotometer has been used with more than 200 students and teachers including: 
  • SWIS workshop in IES Antonio Domínguez Ortiz in Sevilla, Spain (May 2018). Mentors: Juanma García and Sonia Agüera.
  • Summer school CRI Paris, France (July 2018). Mentor: Juanma García.
  • Science Fair at CRI Paris (September 2018). Mentors: Sonia Agüera, Joanna Zoell, Forum Shah.
  • DITOS Final event at Brussels' Natural history museum (May 2019). Mentor: Juanma García.
  • SWIS workshop in Liceul Tecnologic Pantelimon in Bucharest, Romania (June 2019). Mentors: Juanma García and Sonia Agüera.
  • Sustainability summer school in CRI Paris, France (July 2019). Mentor: Juanma García.
The open hardware spectrophotometer is a flexible platform to approach to different topics (biochemistry, microbiology, environment, electronics, programming, physics...) learning objectives in the workshops. The specific topics we've covered so far are:
1. Scientific instrumentation.
2. Theory of color (complementary colors, light wavelength, photons).
3. Calculation of microbial density by light scattering (optical density).
4. Colorimetry and calibration curve.
5. Calculation of absorbance from light transmittance (Beer-Lambert law).

Student's guide

Click on the link below to start downloading

↓ Student's guides (PDF)

Student guide spectrophotometer 1
Student guide spectrophotometer 2
Student guide spectrophotometer 3


Other open hardware projects

For some time, we put some efforts to design and mass-produce open and low-cost laboratory equipment for schools, laboratories, DIY-Bio community, industry, Citizen Scientists, and everybody else. We try to do this without compromising on performance, by taking unconventional approaches, concentrating on just major use-cases for a given device, and staying true to our goal.

We welcome everybody to participate! All our hardware is open-source, you are free to build, modify and share it. We will also mass-produce the devices to make them available to all users at a low cost.

Criteria for our projects include:

  • We need to be able to lower the price significantly, ideally an order of magnitude or more.
  • We can make it work as well or nearly as well as existing devices, even if for a subset of applications.
  • It's possible to mass-produce the device.

All our hardware projects are documented extensively in our wiki and github repositories. Click here to visit.