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

The soil of the earth is the basis of our life. Efficient use of soil is needed for feeding the growing population. Contaminated soil needs to be regenerated to protect the quality of drinking water and more generally the ecosystem.

Here, we propose a highly miniaturized sensor system for monitoring nitrate, ammonium, and phosphate based on integration of a lab-on-a-chip microfluidic cartridge with an optoelectronic detection unit.

The optoelectronic detection chip employs the directional organic light emitting diode (OLED) we developed within the ERC PoC project BEAMOLED.

This kind of OLED allows for direct integration of the optoelectronic chip with the microfluidic cartridge providing a new level of miniaturization of the optical readout measurement system.

We propose the use of colorimetric assays based on starting with standard assays and improving performance using nanozyme catalysis. A hydrophilic ceramic as inlet to a microfluidic channel is proposed for intake of soil solution. Reagents as well as the waste are stored in the sensor system.

We target a system size of 3 cm x 3 cm x 5 cm for maintenance-free operation in the soil for a duration of one year for in-situ monitoring of 100 data points per nutrient.

In a soil-science study the soil-solution extraction into the microfluidic will be investigated for soils with a wide range of pore size distributions, bulk densities, pore-space connectivity, and soil water content to validate the extraction approach scientifically.

Pot and field tests in agriculture and soil remediation are planned for validation in application-relevant environments of two potential markets and to develop market readiness. Our aim is to start a spin-off company after completion of this project.

By the parallel development of the technology and business side with an interdisciplinary team from electrical engineering, chemical engineering, soil science, and economics/entrepreneurship an iterative adjustment process is achieved.