Scalable Relay Switching Platform for Automated Multi-Point Resistance Measurements

TL;DR

This work addresses the need for flexible, scalable routing of measurement signals for automated DC resistance measurements. It introduces a $4×4$ bistable-relay switching platform driven by a microcontroller, with open hardware design and the ability to cascade into larger matrices. The authors characterize switching dynamics, quantify noise contribution, and validate the approach by reconstructing a cube network's edge conductances from 420 four-terminal measurements using a nodal admittance framework and a regularized fit. The platform enables high-throughput multi-point measurements using a single voltmeter and current source, with broad applicability to materials research and automated laboratory workflows.

Abstract

In both research and industrial settings, it is often necessary to expand the input/output channels of measurement instruments using relay-based multiplexer boards. In research activities in particular, the need for a highly flexible and easily configurable solution frequently leads to the development of customized systems. To address this challenge, we developed a system optimized for automated direct current (DC) measurements. The result is based on a 4x4 switching platform that simplifies measurement procedures that require instrument routing. The platform is based on a custom-designed circuit board controlled by a microcontroller. We selected bistable relays to guarantee contact stability after switching. We finally developed a system architecture that allows for straightforward expansion and scalability by connecting multiple platforms. We share both the hardware design source files and the firmware source code on GitHub with the open-source community. This work presents the design and development of the proposed system, followed by the performance evaluation. Finally, we present a test of our designed system applied to a specific case study: the DC analysis of complex resistive networks through multi-point resistance measurements using only a single voltmeter and current source.

Figures (14)

• Figure 1: Example setup for the van der Pauw method. The voltmeter positive and negative terminals are connected, respectively, to A and B inputs, while the current generator source and sink terminals are, respectively, connected to C and D inputs. Closed connections can be described by a list of pairs composed of a letter(input) and a number(output), i.e. A3 B2 C1 D4.
• Figure 2: Main schematic of the relay board
• Figure 3: Schematic of the sub sheet. The board has been laid out on four instances of the latter. All commercially available models of the HFD2-012-x-L2-x relays with dual coil and 12V voltage are compatible with the board.
• Figure 4: Front view of the assembled Relay Matrix board
• Figure 5: Complete view of the 4 layers