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



Sensors and transmitters

Appsen develops sensor prototypes for other compounds than sulfur and metal ions, "on request" specified by a customer and depending on sample composition. 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.

Nitrate sensor (with TOC & TSS on request)

The nitrate sensor with optional extension to measure Total Organic Carbon (TOC) and Total suspended Solids (TSS). Main features are:
- All-in-one probe,
- Cleaning system,
- Small dimensions: OD=28 mm and length of 220 mm,
- Detection limit at 10 mg(NO3-)/L,
- Multiple communication protocols available.


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


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 2020, Pawel Roman issued his research in one book and 21 publications in top quality journals in the field of analytical chemistry, sulfur chemistry and biological gas desulfurization.


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.