OhmPi: an open source resistivimeter for electrical resistivity tomography

Coordinator :

Rémi CLEMENT

Active periode :

Since 2017

Financing

Project-based

Partners :

Université Gustave Eiffel, IGE Grenoble, Umons, ILVO

Summary:

The OhmPi project, initiated in 2017 by INRAE’s REVERSAAL research unit and opened up in 2019 to the University Gustave Eiffel’s GERS Department (Bron campus), is both collaborative and participative; it welcomes the participation of the company Iris Instruments. This project’s objective is to propose a so-called “open-hardware” resistivity meter for unrestricted use by the scientific community. The role of such a device is to effectively meet new challenges and allow for wider access to the underlying method by means of:

• Making an academic tool available for instruction in geophysics
• Offering a flexible tool capable of remote data transmission
• Providing the opportunity to monitor measurement initiation via servo control with an external sensor (e.g. rain gauge, water content probe, flowmeter), yielding a more intelligent measurement
• Satisfying the need to expand characterizations through electrical resistivity tomography in either a static or temporal mode of monitoring, for use in many applications (infiltration, dyke supervision, concrete aging, in-laboratory characterization of pilots, reed filters, etc.).

The eight contributors to the OhmPi project are as follows:

Rémi Clement (INRAE-REVERSAAL): Coordination and development of the electronic component (since 2017)

Yannick Fargier (University Gustave Eiffel): Electronic advances, programming and scientific utilization (since 2018)

Nicolas Forquet (INRAE-REVERSAAL): Programming, Gitlab archival and graphical interface (since 2018)

Vivien Dubois (INRAE-REVERSAAL): Testing and evaluation of new equipment (since 2018)

Hélène Guyard (IGE): Advice and recommendations in electronic design (since 2020).

Olivier Kaufmann (UMons): electronic and programming (since 2021).

Arnaud Watlet (UMons): electronic and programming (since 2021).

Guillaume Blanchy (Université de Liège: electronic and programming (since 2021)).

Version 1.01 of the OhmPi 1 resistivity meter was published in the review HARDWARE X (issue released on January 1, 2020). All associated files are available on https://gitlab.irstea.fr/reversaal/OhmPi and now published and entirely reproducible, based on the description provided in both the article and our online documentation (https://reversaal.gitlab.irstea.page/OhmPi/index.html).

An OhmPi 2 version will be available online very shortly; this updated version will offer:

• Assembly diagrams featuring from 16 to 512 electrodes.
• A much more robust and reliable measurement card, for a wider range of uses; note that this card will be compatible with future IP measurements.
• The system should allow for current injections of up to 1A for 80V.
• A graphical interface will also be displayed.
• The PS measurements will be programmed in the very near future for both OhmPi 1 and 2.

All those interested in joining this project are welcome, whether working toward future OhmPi versions or showcasing the resistivity meter in a research or academic setting. Contact remi.clement@Inrae.fr or yannick.fargier@univ-eiffel.fr.