iSPEX®: Pioneering smartphone spectropolarimeter for environmental monitoring
From Nature magazine's pioneering air quality citizen science project (2013) to breakthrough water quality validation (2024). Transform your smartphone into a research-grade spectropolarimeter with proven dual capabilities.
Current Status & Availability
Water quality validation complete at Plymouth Marine Lab. We are not currently accepting individual unit orders. With limited production capacity and proven technology, we are prioritizing strategic partnerships and investment opportunities to scale development and production capabilities.
12+ Years of Innovation: From Nature Magazine to Water Quality Breakthrough
2012-2013: iSPEX launched as one of the world's first large-scale citizen science projects, featured in Nature magazine. Backed by a consortium of leading Dutch institutions (Leiden University, KNMI, RIVM, SRON), thousands of citizens measured air quality and aerosol properties across Europe using the original iSPEX smartphone add-on.
2014-2020: Technology refined through multiple iterations. SPEX spectropolarimetry methodology deployed on NASA's PACE satellite mission, validating the core scientific approach.
2024-2025: Major breakthrough – iSPEX2 achieves validated remote reflectance (Rrs) measurements for water quality, matching equipment costing tens of thousands of euros. Plymouth Marine Lab validation confirms research-grade performance.
A proven platform with real IP, institutional partnerships, and over a decade of field validation.
iSPEX partnership formalized
Leiden University, DDQ Pocket Science, and Plymouth Marine Laboratory have signed a Memorandum of Understanding, formalizing each institution's contribution to iSPEX development—from core spectropolarimetry technology (Leiden) and hardware/software integration (DDQ), to rigorous field validation (PML).
Professors Simis and Snik and Norbert Schmidt at the MoU signing.
Validation complete at Plymouth Marine Laboratory
70% of smartphone spectra successfully converted to Rrs, with performance benchmarked against SoRad instrumentation.
✓ Validation complete ✓ Seeking investment for scaled development ✓ Not accepting individual orders
Compatible with recent smartphones, the iSPEX device empowers users to collect and scrutinize data with precision and ease.
Ideal for citizen science initiatives, in-depth environmental studies, and even recreational exploration, iSPEX simplifies the data collection process without compromising on quality. Moreover, our state-of-the-art app and platform enable efficient data analysis and promote seamless sharing of results with relevant parties, enhancing the overall user experience.
Breakthrough: Remote Reflectance (Rrs) Validation
iSPEX2 achieves the holy grail of above-water measurements: accurate remote reflectance (Rrs) comparable to equipment costing tens of thousands of euros. This breakthrough was validated by Dr. Tom Jordan and Prof. Stefan Simis in 2024 during the AMT31 campaign.
Scientific Validation: iSPEX2 Rrs measurements (colored lines) closely match professional HyperSAS equipment (grey lines) across multiple wavelengths. Validated by Dr. Tom Jordan and Prof. Stefan Simis, 2024.
This validation demonstrates that iSPEX2 can deliver professional-grade water quality measurements at a fraction of the cost, making advanced oceanographic research accessible to institutions worldwide.
What is Remote Reflectance (Rrs)?
Remote reflectance (Rrs) is the "gold standard" measurement in water quality science. It tells us exactly how much light bounces off water at different colors (wavelengths), revealing what's in the water - algae, sediment, pollution.
Until now, measuring Rrs required expensive equipment costing tens of thousands of euros, limiting it to well-funded research institutions. iSPEX2 achieves the same accuracy for under €200, democratizing professional water quality monitoring.
Why Rrs matters: It's the same measurement satellites use, so iSPEX data can validate and enhance satellite monitoring of lakes, rivers, and coasts worldwide.
SPEX Technology
iSPEX uses SPEX spectropolarimetry technology, which is also deployed on NASA's PACE satellite mission. This shared methodology makes iSPEX well-suited as a validation instrument for satellite observations.
Spectropolarimetry using the SPEX method is sophisticated technology typically found in research-grade instruments. iSPEX makes this accessible through smartphone integration.
iSPEX® name, logo, and design are registered through the Benelux Patent Office (BOIP). EU registered trademarks.
Dual-Capability Platform: Air Quality & Water Quality
Air Quality & Aerosols
Proven since 2013
- Aerosol optical depth measurements
- Particulate matter characterization
- Atmospheric composition studies
- Large-scale citizen science campaigns
- Satellite validation (PACE mission alignment)
Water Quality & Ocean Color
Validated 2024
- Remote reflectance (Rrs) measurements
- Algae and phytoplankton detection
- Turbidity and sediment monitoring
- Pollution source identification
- Satellite ground-truthing
This dual-capability platform makes iSPEX uniquely versatile – the same instrument validated for both atmospheric and aquatic spectropolarimetry. Whether monitoring air quality in urban environments or water quality in lakes, rivers, and oceans, iSPEX delivers research-grade measurements.
Water Quality Applications
Particles such as algae, minerals and detritus, as well as dissolved substances, colour the water by absorbing and scattering sunlight. By measuring the reflected light, iSPEX can be used to determine colour properties that relate to biogeochemical water quality. Combined with other information from water samples this information can be used to monitor water quality of rivers, lakes, or oceans, and to identify sources of pollution. Spectro(polari)metry is uniquely suitable to combine with satellite observations of water quality and should be considered in cases where additional local-scale water colour information can help monitor and protect the world's water resources.
Introduction Video
Instructional videos
iSPEX Assembly
Positioning the iSPEX unit
Example water measurement protocol (Hydrocolor alike)
Current Research Users
iSPEX2 is currently being used by leading research institutions worldwide:
- Leiden University - Atmospheric and water quality studies
- University of Georgia - Environmental monitoring research
- Plymouth Marine Laboratory - Water quality validation and ocean color studies
- University of Sorbonne (Plankton Planet) - Marine ecosystem monitoring and oceanographic research
- University of Stirling - Environmental sensing research
- University of Maine - Marine ecosystem monitoring
- LandSeaLot Consortium - Ocean color validation studies with multiple research partners
Strategic Partnerships & Investment Opportunities
Proven Technology, Ready to Scale
iSPEX represents a unique opportunity: validated technology with 12+ years of field testing, EU registered trademarks, institutional partnerships (Leiden University, Plymouth Marine Lab), and proven applications in both air and water quality monitoring.
Current Status:
- 30 units available from current production run
- Active demand from research institutions worldwide
- Proven dual-capability platform (air + water)
- Protected intellectual property (EU registered trademark)
- Established scientific partnerships and MOU agreements
We are seeking investment and strategic partnerships to scale production, accelerate software development, and unlock the commercial and scientific potential of this platform. Past experience has shown that product orders alone (100+ units shipped in 2025) do not fund the R&D needed to advance this technology. We need partners who understand that breakthrough environmental monitoring technology requires development capital, not just purchase orders.
If you represent an investment group, environmental organization, or research institution interested in funding the next phase of validated environmental monitoring technology, we welcome serious partnership discussions.
Citizen Science with iSPEX
We have more than ten years experience in citizen science projects. iSPEX 2 is suitable for large scale citizen science campaigns for water quality monitoring, satellite validation, and environmental research.
Frequently Asked Questions
What configurations are offered?
For research applications, we provide comprehensive kits that include:
- A calibrated research-grade smartphone
- Professional grey cards for calibration
- Durable carrying case
- Calibration lamp
- Detailed research methodology manual
- Optional: transmission case (cuvette) for specialized experimental projects
What apps complement the product?
Our research-oriented applications include the 'iSPEX Water' apps for both Android and iOS, specifically designed for advanced calibration and water quality analysis. These apps feature professional-grade tools for spectral analysis, data collection, and research documentation.
Which smartphones can run iSPEX?
Most recent Android and iPhone models are compatible. iOS 13 and up are supported and the Android phones that support Camera2 (Raw imaging).
Who's behind iSPEX?
The current team consists of Norbert Schmidt and Joep van der Heiden (of DDQ Pocket Science), hardware design and early production by Armand Perduijn. We work closely together with Stefan Simis and Tom Jordan from Plymouth Marine Lab, Frans Snik and Olivier Burggraaff from Leiden University. Credit goes to Frans Snik and Jeroen Rietjens from Leiden University and SRON. They are the founding fathers.
Relevant papers and articles
- Standardized spectral and radiometric calibration of consumer cameras. Burggraaff O. et al. Optics Express, Vol 27, Issue 14, 2019.
- A universal smartphone add-on for portable spectroscopy and polarimetry: iSPEX 2. Burggraaff O. et al. Proc. SPIE 11389, Micro- and Nanotechnology Sensors, Systems, and Applications XII, 2020.
iSPEX2 smartphone spectropolarimeter and mounting backplate