Miniaturized sensor system for continuous soil-nutrient monitoring based on integration of a lab-on-a-chip microfluidic cartridge with an optoelectronic detection unit

Project Information

SOILMONITOR

Grant agreement ID: 101097989

DOI

10.3030/101097989

Project closed

EC signature date 26 October 2022

Start date 1 November 2022

End date 31 January 2026

Funded under

• The European Innovation Council (EIC)

Total cost

€ 2 499 716,25

EU contribution

€ 2 499 716,00

Coordinated by

CHRISTIAN-ALBRECHTS-UNIVERSITAET ZU KIEL
Germany

Periodic Reporting for period 2 - SOILMONITOR (Miniaturized sensor system for continuous soil-nutrient monitoring based on integration of a lab-on-a-chip microfluidic cartridge with an optoelectronic detection unit)

Reporting period: 2023-11-01 to 2026-01-31

Summary of the context and overall objectives of the project

The SOILMONITOR project aims to develop an innovative, miniaturized sensor system for time-series, in-situ monitoring of nitrate, phosphate, and ammonium. Based on a microfluidic chip, combined with nutrient-specific assays and photometric detection, the system enables nutrient measurements directly in the soil. Designed as a fully closed-cycle system, SOILMONITOR can operate maintenance-free without releasing any chemicals into the surrounding soil. Nutrient concentration data are transmitted wirelessly via a LoRaWAN network to a user-friendly interface accessible on PCs and mobile devices, enabling real-time data access and analysis.

The overall objective of the project is to provide a direct and dynamic insight into soil nutrient status, supporting data-driven decision-making in agriculture and environmental management. By enabling precise fertilization strategies and continuous soil-quality monitoring, SOILMONITOR contributes to reduced management effort, minimized nutrient leaching, compliance with environmental regulations, and lower greenhouse gas emissions, particularly nitrous oxide (N2O). Ultimately, the project seeks to advance sustainable soil management practices through reliable, long-term, and autonomous nutrient monitoring.

The project is embedded in the broader political and strategic context of increasing regulatory pressure on fertilization practices, groundwater protection, and climate change mitigation. In particular, it addresses key challenges related to nitrate pollution and nutrient losses, which are central to European environmental policies and agricultural regulations. By enabling continuous, site-specific monitoring of soil nutrients, SOILMONITOR supports the transition toward precision agriculture and more sustainable land management.

The results of SOILMONITOR are currently being further developed within the innovate! follow-up project Kiel “Novel Sensor Concepts for Agriculture”, funded by the Joachim Herz Stiftung. This follow-up project focuses on advancing sensor technologies and facilitating their transfer into practical applications, including continued integration of user needs and stakeholder feedback (e.g. farmers, advisors, and institutions) to ensure applicability and acceptance.

The expected impact of the project is substantial, as it enables high-resolution, real-time monitoring of soil nutrients, potentially transforming fertilization management and reducing environmental impacts at scale. To further strengthen the pathway to impact, an application for the EXIST Forschungstransfer is currently being prepared, aiming at the establishment of a spin-off company for technology transfer and commercialization.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The SOILMONITOR project started at TRL 3/4, with the core concept and key components validated only at laboratory proof-of-principle level. The primary objective of the project was therefore to advance the technology toward an integrated, application-oriented system (TRL 5/6). During the first project year, the technological foundations were established. Key components, including soil water extraction, microfluidic handling, photometric nitrate detection, and optoelectronic readout, were individually developed and validated under controlled conditions. In parallel, market needs were assessed and an initial business model and IP strategy were defined.

In the second project year, the focus shifted to system integration and prototyping, resulting in a fully automated SOILMONITOR-N prototype that combines soil-solution extraction, microfluidics, sensing, and electronic control in a single device. The system was produced in multiple prototype units. The nitrate assay was further optimized for speed and robustness, and soil-solution extraction was successfully validated for over 80% of tested agricultural soils. In parallel, concrete agricultural use cases were defined, a detailed business plan was completed, and post-project financing activities were initiated. By the end of the second project year, key functions of the SOILMONITOR system had been validated in a relevant environment, advancing the technology from a conceptual sensor idea to a validated, integrated prototype supported by a clear commercialization strategy and protected intellectual property.

In the third project year, significant technical progress was achieved in improving system performance and reliability. Key challenges such as fluid mixing accuracy and automated soil water extraction were systematically addressed. Mixing accuracy was improved through optimized fluidic control strategies, enabling reliable nutrient quantification in autonomous field deployment. The nitrate assay was further optimized for speed and robustness, while phosphate and ammonium assays were successfully implemented and validated under laboratory conditions, extending the system toward multi-nutrient sensing. In addition, the system architecture was refined to enable robust operation under real-world conditions, including stable data acquisition, wireless data transmission via NB-IoT, and integration into a user-oriented data infrastructure. A dedicated soil-solution extraction unit was developed and filed as a patent.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

1. Economic benefits
The capability to quantify soil nutrients directly within water extracted from the soil and thus available to growing crops is pertinent to determine proper amounts of fertilization. More accurate and efficient fertilization practices can result in cost savings for farmers by allowing them to apply the right amount of nutrients at the right time, reducing waste and overuse of fertilizers. The SOILMONITOR can thus enhance fertilizer efficiency and improve cost-effectiveness for farmers.

2. Impacts on the agricultural industry
SOILMONITOR advances the growing use of data-driven decision-making in agricultural practices. Continuous monitoring over an entire season provides farmers with real-time data to make informed decisions about fertilizer use, planting, and soil management. The project further encourages and facilitates the adoption of sustainable agricultural practices through its aim to provide critical data for nutrient management and crop growth and quality optimization at a low cost and maintenance-free. As a technological innovation, SOILMONITOR has the potential to increase the overall competitiveness and resilience of agriculture and offers the opportunity to set EU and global standards in precision agriculture.

3. Impacts on the soil-remediation industry
With SOILMONITOR we developed an automated lab-on-a-chip system for obtaining time-series data for nutrients in soil solution. This system has the potential to be extended to other ions interesting for soil-remediation purposes after adaptation of the chemical assay. As a technological innovation, SOILMONITOR has the potential to facilitate soil remediation by frequent monitoring.

4. Environmental and societal impacts
SOILMONITOR contributes directly to reducing nutrient leaching into groundwater and surface waters, thereby supporting water protection efforts and compliance with environmental regulations (e.g. nitrate directives). By optimizing fertilization, the system also helps to reduce greenhouse gas emissions, particularly nitrous oxide (N2O), contributing to climate change mitigation. On a broader level, the technology supports more sustainable food production and contributes to global challenges such as food security, in line with the United Nations Sustainable Development Goal 2 (Zero Hunger).

5. Key needs for further uptake and success
To fully realize the impact of the SOILMONITOR technology, several next steps are required:
---Further research and development: Optimization of system robustness, reduction of power consumption, and extension to additional analytes
---Field validation and demonstration: Large-scale, long-term field trials across different soil types and agricultural systems
---Standardization: Aligning with regulatory frameworks for agricultural and environmental monitoring
---Market access and user integration: Close collaboration with farmers, advisors, and institutions to ensure usability, acceptance, and integration into existing workflows