electronics Article Designing a Multiaxial Extensometric Force Platform: A Manufacturing Experience Jorge Rodolfo Beingolea 1, * , Helder Andrade Rodrigues 1 , Milagros Zegarra 2 , Erasmo Sulla-Espinoza 2 , Romildo Torres-Silva 3 and Jorge Rendulich 2   Citation: Beingolea, J.R.; Rodrigues, H.A.; Zegarra, M.; Sulla-Espinoza, E.; Torres-Silva, R.; Rendulich, J. Designing a Multiaxial Extensometric Force Platform: A Manufacturing Experience. Electronics 2021, 10, 1907. https://doi.org/10.3390/ electronics10161907 Academic Editor: Enzo Pasquale Scilingo Received: 16 June 2021 Accepted: 25 July 2021 Published: 9 August 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Department of Electronic Systems Engineering, University of São Paulo, São Paulo 05508-010, Brazil; helder.rodrigues@pad.lsi.usp.br 2 Department of Electronic Engineering, Universidad Nacional de San Agustin de Arequipa, Arequipa 04001, Peru; mzegarra@unsa.edu.pe (M.Z.); esullae@unsa.edu.pe (E.S.-E.); jrendulich@unsa.edu.pe (J.R.) 3 Núcleo de Pesquisas Tecnológicas, Universidade Mogi das Cruzes, Mogi das Cruzes 08780-911, Brazil; rtorres_63@hotmail.com * Correspondence: jorge.beingolea@alumni.usp.br; Tel.: +55-11-30919741 Abstract: Studies that lead to the development of more accessible and low-cost electronic technologies and devices for biomechanical and biomedical analysis applications are becoming increasingly needed. In this work, the development of a multiaxial extensometric force platform will be addressed, aiming to improve the sensitivity and reduce the costs of existing platforms. Additionally, this platform can be used for analysis and characterization of flight time and postural characterization of volleyball athletes. As a result, a functional and easily produced prototype was created, due to the processes used (final cost of the developed platform—USD$100). The interfaces of visualization and analysis of the device functions were designed in LabView. The purpose of the experiments is to perform flight analysis of athletes, and all functions designed for the platform strength and endurance are focused on that same purpose. The prototype’s functions were evaluated by applying loads from 700 to 1000 N (Newtons) and its future integration with other instruments such as the surface electromyography (EMG) and an electrocardiogram (ECG) is expected to form an instrument kit that improves the characterization of studies of balance, strength and muscular endurance. Keywords: force platforms; electronic devices; postural analysis; multiaxial extensometric; biomedi- cal devices 1. Introduction The demand for studies that promote the development of new electronic, biomechani- cal and other devices that will reduce the costs of analysis, treat postural problems and the degradation of muscle power in athletes and in the elderly population is increasing [1–3]. Applying several methods and techniques that include the use of force platforms for conducting postural analysis studies is not new. However, these studies are not focused on the improvement of force platforms, their precision and low cost, but only in their use as a product for sports professionals and physiotherapists. As an example, some studies use force platforms to apply the method of ground reaction forces on each child’s foot. Their objective is to apply a method that decomposes ground reaction forces (GRF) profiles, right and left, in relation to the GRF profile registered on the platform, to identify atypical postures [4]. In the study by P. Kutilek et al. [5], a force platform was used to assess the entire pathological prosthetic gait, which included groups of healthy people with prostheses. In the study that proposes the application of the GRF method by B. Samadi et al. [4] and, when it comes to the reconstruction of the foot-to-ground reaction forces from force platform records, the results suggested the efficient application of this method in the recovery of corrupted data due to incorrect Electronics 2021, 10, 1907. https://doi.org/10.3390/electronics10161907 https://www.mdpi.com/journal/electronics