Design and Development of an Open-Source Wireless System for Structural Deformation Measurement with Smartphone Communication

Abstract

Measuring deformation using strain gauges is well-established in literature and industry. Commercially, several systems can acquire strain gauge measurements, yet those that offer wireless data transmission or communication with portable devices such as smartphones are very limited. This work introduces a new portable acquisition device with smartphone communication to acquire deformation data from instrumented structures with strain gauges. The developed device uses accessible, low-cost components such as the microprocessor provided by Espressif Systems, the operational amplifier, and a secure digital card reader. The microprocessor handles the processing and transmission of deformation data to the smartphone via Bluetooth Low Energy, while the data is processed and analyzed through an Android application developed in Kotlin. The system’s measurement and data transfer capabilities were validated through tests on bending and pure torsion setups. In addition, experiments were conducted to verify the similarity between the data collected by the smartphone and the card, and the system’s operating range was also evaluated. This work presents an open-source device that enables smartphone-based acquisition, facilitating and reducing the cost of strain gauge signal acquisition, while also allowing installation on structures in hard-to-reach areas for remote monitoring.