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Design and advances in OhmPi: an open hardware resistivity meter
Rémi Clement1, Arnaud Watlet2,3, Guillaume Blanchy4,5,6
1INRAE - French National Research Institute for Agriculture, Food and Environment, REVERSAAL Research Unit, 5 rue de la Doua, CS 20244, 69625 Villeurbanne Cedex, France.
Hardwarex
|July 23, 2026
Summary
OhmPi v2024 is a cost-effective, open-source resistivity meter for environmental monitoring. This updated system offers improved performance and advanced features for time-lapse electrical resistivity tomography (ERT) at an affordable price.
Area of Science:
- Geophysics
- Environmental Science
Background:
- Time-lapse electrical resistivity tomography (ERT) is crucial for monitoring subsurface hydrologic and biogeochemical processes.
- Commercial ERT equipment is often expensive and lacks flexibility, limiting its widespread adoption.
Purpose of the Study:
- To introduce OhmPi v2024, an upgraded, cost-effective, open-hardware resistivity meter.
- To enhance accessibility and usability for environmental ERT applications.
Main Methods:
- Redesigned architecture with a new multiplexer and upgraded measurement board.
- Complete software redesign featuring a graphical interface for remote control and MQTT protocol for network integration.
- Extensive testing using ground analogue circuits and small-scale field experiments.
Main Results:
- OhmPi v2024 maintains affordability (under €1500 for 16 electrodes) while improving performance and accuracy.
- New software offers enhanced flexibility, remote control, and network integration capabilities.
- Testing confirmed improved sensitivity, stability, and robustness compared to previous versions.
Conclusions:
- OhmPi v2024 provides a reliable, adaptable, and affordable alternative to commercial systems for environmental ERT.
- The open-hardware approach fosters wider accessibility and continued development in geophysical monitoring.
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