Sensing techniques based on accelerometers for modal parameters identification are among the most studied and applied in Structural Health Monitoring of civil structures. The advent of low-cost MEMS accelerometers and open-source electronic platforms, such as Arduino, have facilitated the design of low-cost systems suitable for modal identification, although there is still a lack of studies regarding practical application and comparison of commercially available low-cost accelerometers under SHM conditions. This work presents an experimental performance evaluation of six low-cost MEMS accelerometers for the identification of natural frequencies and damping ratios of a three-storey frame model and a reinforced concrete slab, as well as their noise characteristics. A low-cost Arduino-based data acquisition system was used. The results showed an overall good performance of the MEMS accelerometers, with identified natural frequencies errors within 1.02% and 7.76% of reference values, for the three-storey frame and concrete slab, respectively, and a noise density as low as 108 g/√Hz.

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Low-cost electronics developed on easy-to-use prototyping platforms, such as Arduino, are becoming increasingly popular in various fields of science. This article presents an open-source and low-cost eight-channel data-logging system for temperature and humidity monitoring based on DHT22 (AM2302) sensors, named HIGROTERM. The system was designed to solve real needs of the Laboratory of Material Testing of the Department of Civil and Environmental Engineering at the University of Brasília. The system design, functionalities, hardware components, source code, bill of materials, assemblage and enclosure are thoroughly described to enable complete reproduction by the interested reader. The terminologies and instructions presented were simplified as much as possible to make it accessible to the greatest extent to researchers from different areas, especially those without electronics background. The data-acquisition system has an estimated total cost of USD 96.00, or USD 136.00 if eight sensor nodes are included, with a considerable margin for cost reduction. The authors expect that the HIGROTERM system may both be a valuable low-cost and customizable tool for the readers, as well a source of innovation and interest in low-cost electronics for real problem-solving in various fields of science.

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