Unique expertise to overcome industrial and research challenges

Unique expertise

Shaped by years of experience, unique expertise to meet customers' needs

User-friendly interface

Powerful functionality with friendly interface and accessible data from every device

Powerful Performance

Optimized software and precise calibration that deliver unmatched performance



Success of Smart VFA project

Technology for in-line Volatile Fatty Acids sensor was developed and proved during the Smart VFA project. Wetsus was the project coordinator, while Appsen and Paques were advisors. The project was co-financed by EIT Climat-KIC.


Presentation at MORAMA meeting

Tomorrow Appsen will present at 13 international mining congress in Hermosillo (Mexico) during MORAMA's project meeting. More information you can find in this flyer.


Appsen at BASF Innovation Day

Appsen was invited to BASF Innovation Day organized in Ludwigshafen, Germany. We had an opportunity to present our work, see many inspiring talks and visit the largest BASF’s production site, representing high integration level (verbunden).


New housing on the way!

At last, we received the project of a new housing for the controller. Few of its new features are connection for two sensor probes, data logger and Wi-Fi connectivity. Housing is already in the production phase!


Application of the sensor in biorespiration tests

You can see in the figure above an example of sulfide measurement under high pH (>9) and high salinity (1.5 M Na+) in reactor with sulfideoxidizing biomass in comparison with conventional dissolved oxygen measurement. It can be seen that the sulfide sensor, compared to dissolved oxygen sensor, does not have a lag phase and has a short response time resulting in much more sharp response allowing to distinguish between different oxidation stages.


Appsen joined the Wetsus platform

Today Appsen became a Platform member of Wetsus, European Centre of Excellence for Sustainable Water Technology in Leeuwarden. Appsen will participate in the cooperation within the framework of Wetsus for the next two years.


Sensor for raw material sector

Appsen started work under the grant awarded from the Resourcing water program. The objective is to develop sulfur and metal ions sensor and validate it in lab- and full-scale installations. The main ions of interest are: sulfide, thiosulfate, chromium(III), copper(II), iron(III), and cobalt(II).


Cooperation with Aquacolor Sensors

Appsen and Aquacolor Sensors started a cooperation on development of sulfur and metal ions sensor. Also for this purpose, Aquacolor Sensors acquired a patent from Wetsus that was filed by Appsen’s founder.


Funding package granted!

Resourcing water program launched by WaterCampus Leeuwarden and EIT RawMaterials offers business support to start-ups with innovative ideas on the recovery and recycling of metals and minerals from water streams. Appsen went successfully through all 4 phases of this program and received a funding package for the sensor development for sulfur and metal ions.


Appsen is a startup company owned by Pawel Roman founded in early 2017. The company is a spin-off from Wetsus, European Centre of Excellence for Sustainable Water Technology. Appsen developed the sensor technology for measuring sulfur ions such as sulfide and thiosulfate, and metal ions such as copper(II), iron(III), and cobalt(II) in aqueous samples. Now, the main objective is development of in-line alkalinity sensor.

Dr inż. PawelaRoman

Pawel studied Applied Chemistry at the Gdansk University of Technology in Poland, where he obtained Master of Science degree in engineering. In 2016, Pawel obtained a PhD degree in the field of biological sulfur recovery from sour gas streams at the Sub-department of Environmental Technology, Wageningen University. The offered sensor technology was invented during Pawel’s PhD as a spin-off project enabling analysis of sulfide ions under high pH conditions. Between 2013 and 2017, Pawel Roman issued his research in one book and ten publications in top quality journals in the field of analytical chemistry, sulfur chemistry and biological gas desulfurization.


Sensors and transmitters

Appsen develops prototypes of sensors for other compounds than sulfur and metal ions, specified by a customer and depending on sample matrix. Development of the protype is preceded with a feasibility study. Sensors for sulfur and metal ions, for lab- and full-scale applications, can be purchased from Aquacolor Sensors. For more information do not hesitate to contact us.

1- / 2-channel transmitter

Digital multiparameter transmitter for process monitoring. Main features are:
- one or two sensor probes ports,
- data logger (SD card),
- and Wi-Fi connectivity (webserver).

Signal communication (4-20 mA) can be added to enable process controlling. It is suitable for all applications in in-house areas, for example in laboratories. On special request functionality of transmitter can be changed to meet needs of customer.

Sensor probes are custom made.


Appsen offers consultations in the field of sulfur chemistry, analytical chemistry, and scientific research.


For further information or inquiries please use the following contact details:



0031 (0) 652 380 644


Appsen is registered (no. 68043554) at the Chamber of Commerce in Leeuwarden.