Artigos - Engenharia de Controle e Automação - Sorocaba

URI Permanente para esta coleçãohttps://hdl.handle.net/11449/220

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Enlightening Load Modeling by Means of Power Factor Decompositions
(2023-05-01) Paredes, Helmo K. Morales ; Arcadepani, Matheus Branco ; Moreira, Alexandre Candido ; Gonçalves, Flávio A. Serrão ; Pinhabel Marafão, Fernando ; Universidade Estadual Paulista (UNESP) ; Universidade Federal de Sergipe (UFS)
Considering the proliferation of power electronics applications and distributed energy resources, modern power grids are facing a significant increase in harmonic currents circulation and supply voltage deterioration, occasionally associated with small frequency variations. In such a context, the understanding of power phenomena in circuits with linear and non-linear loads under non-sinusoidal voltage conditions is nontrivial and still does not allow for an easy interpretation of harmonic sources, harmonic power flow or the identification of the parameters of a proper equivalent circuit. The main challenge is to develop modern theoretical approaches for load characterization, modeling, and parameter estimation so that new techniques can be formulated to provide adequate guiding for the analysis, compensation, revenue metering, accountability and other applications of power systems. Thus, based on the Conservative Power Theory (CPT) and further decomposition of its apparent power and power factor definitions, this paper proposes a novel methodology for estimating equivalent parameters and for proposing proper equivalent circuits capable of representing/modeling the main characteristics of single-phase generic loads (black boxes) and the related power phenomena in terms of passive dipoles (linear loads) or of harmonic voltage/current sources and their intrinsic transimpedances/transadmittances (non-linear loads). Simulation and experimental results were depicted to support and validate the proposed approach, showing that it might be a powerful modeling technique to represent generic loads in a modern power grid scenario, while being used for complex applications such as reactive power compensation or accountability in circuits with nonlinear loads and distorted voltages.
The Effect of PEO Treatment in a Ta-Rich Electrolyte on the Surface and Corrosion Properties of Low-Carbon Steel for Potential Use as a Biomedical Material
(2023-03-01) Marcuz, Nádia ; Ribeiro, Rafael Parra ; Rangel, Elidiane Cipriano ; da Cruz, Nilson Cristino ; Correa, Diego Rafael Nespeque ; Wilson Roberto Ribeiro de Camargo ; Universidade Estadual Paulista (UNESP)
Fe-based materials have extensive applications in the building and automobile industries due to their excellent mechanical properties and low cost. However, their biomedical employment is restricted by the corrosion propensity when in contact with bodily fluids. In this study, single-step Plasma Electrolytic Oxidation, PEO, treatment in Ta-rich electrolyte was used, for the first time, to improve the corrosion resistance of low-carbon steel SAE 1020 for possible use as device implants. The effect of the applied voltage on the chemical and phase composition, topography, wettability, roughness, and corrosion properties were addressed. The results indicated that the Fe-based oxide coatings had a rough and hydrophilic surface, increasing the Ta content with the applied potential. The phase composition of the coatings was mainly composed of hematite (Fe2O3), with the Fourier-transform Infrared Spectroscopy, FTIR, spectrums indicating the presence of some absorbed water and organic molecules. The corrosion resistance of the PEO-treated samples was better than the substrate against saline solution (0.9% NaCl) due to the Fe2O3 growth decorated with Ta particles, especially the sample treated at 200 V. The results state that Ta-enriched Fe-based oxide coatings could significantly improve the applicability of low-carbon steel SAE 1020 as a low-cost biomaterial, particularly for medical devices.
Antimicrobial behavior of titanium coating with chlorhexidine-doped thin film exposed to a biofilm supplemented with nicotine
(2023-01-01) Matos, Adaias Oliveira ; Rangel, Elidiane Cipriano ; Barão, Valentim Adelino Ricardo ; Gregory, Richard Lee ; University of Detroit Mercy ; Universidade Estadual de Campinas (UNICAMP) ; Indiana University School of Dentistry ; Universidade Estadual Paulista (UNESP)
Because nicotine upregulates the growth of most oral bacteria, this in vitro study investigated the antimicrobial effect of chlorhexidine-doped thin film on commercially pure titanium against Fusobacterium nucleatum (F. nucleatum) biofilm supplemented with different concentrations of nicotine (0, 1, and 2 mg/mL). Biofilms were formed on a chlorhexidine-doped thin film on commercially-pure-titanium discs and compared to the control groups. Biofilm viability, total biofilm growth using a spectrophotometer, extracellular polysaccharide content, and pH variations were assessed as dependent variables. Data were submitted to ANOVA and Tukey honest significant difference tests (α=0.05). F. nucleatum biofilm growth was inhibited when exposed to chlorhexidine-doped thin film (p<0.05). Biofilm supplemented with nicotine did not impact the synthesis of EPS on the same type of treatment (p>0.05). The pH values were significantly increased with the increase of nicotine concentration (p<0.05). Chlorhexidine-doped thin film was effective in reducing F. nucleatum biofilm supplemented with nicotine.
A Tribological Investigation of the Titanium Oxide and Calcium Phosphate Coating Electrochemical Deposited on Titanium
(2023-02-01) Santos, Adriana ; Teixeira, Jean ; Fonzar, Carlos ; Rangel, Elidiane ; Cruz, Nilson ; Lisboa-Filho, Paulo Noronha ; Universidade Estadual Paulista (UNESP)
Titanium (Ti) and its alloys are widely used in biomedical applications due to their excellent mechanical properties and biocompatibility. However, they are a concern due to the possibility of cytotoxic effects coming from the degradation products. This degradation occurs by the combined action of corrosion and mechanical wear of these materials, which are released in the biological environment by the biomaterial implanted. The present article aims to investigate a new route to improve electrochemical and tribological performance with surface modification. Regarding the deposition of a protective layer on the surface, it consists of titanium oxide (TiO2) and calcium phosphate (CaP). Both coatings were performed by chronoamperometric methods with titanium oxidation at 1 V and calcium phosphate reduction at −1.5 V. The corrosion and tribocorrosion tests demonstrated the effective combination of TiO2 and CaP layer to protect the Ti substrate. Furthermore, this coating combination reduced corrosion degradation and mechanical wear in PBS, simulating a physiological environment. Additionally, it was observed that this combination of coating decreased the dissipated energy, and consequently, the wear decreased during sliding tests. All these findings indicate the protective behavior of the TiO2 and CaP layer during the tribocorrosion tests.
UTBB FD-SOI MOSFET with SELBOX in DTMOS configuration
(2022-12-31) Da Silva, Jeveson Cardoso ; Martins, Everson ; Junior, Nilton Graziono ; De Andrade, Maria Glória Caño ; Universidade Estadual Paulista (UNESP) ; Universidade Federal de Goiás (UFG)
For the first time, Ultra-Thin Body and Buried Oxide Fully Depleted Silicon-On-Insulator (UTBB FDSOI) n-channel with Dynamic Threshold MOS configuration (DTMOS) using the SELBOX (Selective Buried OXide) sub-strate was analyzed. The drain and substrate current, transcon-ductance (gm) and Subthreshold Slope (SS) ware compared in the DTMOS mode and the standard biasing configuration for different gap width (WGAP) of SELBOX. Additionally, the out-put conductance and the transconductance gain also studied through numerical simulations. The results indicate that the SELBOX structure in DTMOS mode is competitive candidates for analog applications.
A Novel Methodology to Estimate Probability Density Function of Voltage Sag Duration and Failure Rates on Power Distribution Systems
(2023-01-01) Cebrian, Juan C. ; Giacomini, Jairo ; Carneiro, Carlos A. ; Silva, Gabriela B. ; Morales-Paredes, Helmo K. ; Universidade Estadual Paulista (UNESP)
Voltage sags and power interruptions are important power quality problems that affect sensitive customers, mainly because they cause annual massive economical losses to the industrial sector as a result of unexpected production process disruptions. In this sense, to propose corrective and preventive measures and improve the power quality of the distribution systems, stochastic methodologies have been proposed in the literature to estimate annual voltage sags and power interruptions. However, these methodologies, generally, use typical cumulative distribution functions of voltage sag duration (PSgD), which may not reflect the real estate of the network under study. To solve this constraint, this paper proposes a novel methodology to estimate a proper PSgD considering information of the distribution network (i.e., topology and coordination schemes of the protection system) and the stochastic behaviors of short-circuits that can affect the distribution system. Moreover, the proposed methodology allows estimating permanent failure rates and average repair time considering known or expected values of reliability indicators. The results show that this proposed methodology is capable to adapt from an initial PSgD curve to another one with fidelity, in order to achieve real values of expected annual power interruptions.
Sensors Applied to Bearing Fault Detection in Three-Phase Induction Motors†
(2021-01-01) Lucas, Guilherme Beraldi ; de Castro, Bruno Albuquerque ; Serni, Paulo José Amaral ; Riehl, Rudolf Ribeiro ; Andreoli, André Luiz ; Universidade Estadual Paulista (UNESP)
Three-Phase Induction Motors (TIMs) are widely applied in industries. Therefore, there is a need to reduce operational and maintenance costs since their stoppages can impair production lines and lead to financial losses. Among all the TIM components, bearings are crucial in the machine operation once they couple rotor to the motor frame. Furthermore, they are constantly subjected to friction and mechanical wearing. Consequently, they represent around 41% of the motor fault, according to IEEE. In this context, several studies have sought to develop monitoring systems based on different types of sensors. Therefore, considering the high demand, this article aims to present the state of the art of the past five years concerning the sensing techniques based on current, vibration, and infra-red analysis, which are characterized as promising tools to perform bearing fault detection. The current and vibration analysis are powerful tools to assess damages in the inner race, outer race, cages, and rolling elements of the bearings. These sensing techniques use current sensors like hall effect-based, Rogowski coils, and current transformers, or vibration sensors such as accelerometers. The effectiveness of these techniques is due to the previously developed models, which relate the current and vibration frequencies to the origin of the fault. Therefore, this article also presents the bearing fault mathematical modeling for these techniques. The infra-red technique is based on heat emission, and several image processing techniques were developed to optimize bearing fault detection, which is presented in this review. Finally, this work is a contribution to pushing the frontiers of the bearing fault diagnosis area.
Towards technical and economic feasibility of power quality compensators
(2023-03-01) Conrado, Bruna R.P. ; de Souza, Wesley A. ; Liberado, Eduardo V. ; Paredes, Helmo K.M. ; Brandao, Danilo I. ; Moreira, Alexandre C. ; Universidade Federal de Minas Gerais (UFMG) ; Federal University of Technology - Parana ; Universidade Estadual Paulista (UNESP)
In industrial grids, equipment lifetime is reduced, and power losses are increased due to typical issues caused by low power quality indices, such as insulation failure, overheating, mechanical oscillation, audible noise, high currents in the neutral conductor, harmonic resonance, and malfunctioning of power electronics converters and protections. These drawbacks can be mitigated by adopting power quality enhancement technologies known as compensators, such as passive power filters, static reactive compensators, and active power filters. However, the most appropriate compensation system must assure power quality indices within limits established by standards, which characterize its technical feasibility and is economically feasible. Therefore, this paper proposes a method to perform a feasibility analysis of power quality improvement projects considering both technical and economic aspects. The effectiveness of the proposed method has been verified by different case studies assessing real industrial operating conditions. The results show that the proposed methodology is robust and can select the best compensation solution under different grid conditions.
Hybrid Integrator Topology with Digital Input Control and Analog Signal Processing
(2022-01-01) Fernandes, Felipe Olivera ; Martins, Everson ; De Andrade, Maria Gloria Cano ; Universidade Estadual Paulista (UNESP)
In this paper, an Analog-Digital integrator topology with selecting the input by gain control and analog processing, for use in general-purpose computers is intended. The integration function, control and of inputs variables condition were performed through development of analog-digital integrator circuits. The results showed that the topology is flexible in real-Time simulation and has good integration results in the tested conditions. The gain control architecture is a new way to control the input and the flexibility of the integrator.
A Non-cooperative Game-theoretic Distributed Control Approach for Power Quality Compensators
(2022-01-01) Burgos-Mellado, Claudio ; Bucarey, Victor ; Morales-Paredes, Helmo K. ; Muñoz-Carpintero, Diego ; Universidad de o'Higgins ; Universidade Estadual Paulista (UNESP)
This paper demonstrates that the Game Theory (GT) can be an effective tool for implementing a distributed control scheme for coordinating the compensation efforts of power quality compensators (PQCs) feeding a common unbalanced load. A non-cooperative game is formulated where each PQCs minimises its own interests, defined as the power losses that incur each PQC in carrying unbalanced power from its connection point in the system to the point of common coupling (PCC). By doing this, the whole system will move until it reaches a global equilibrium (the so-called Nash equilibrium). The power losses are calculated based on the conservative power theory (CPT), allowing the implementation of the proposal in the natural abc reference frame. A comparison (via simulations) between the proposed non-cooperative distributed scheme and a cooperative distributed approach based on the consensus theory shows that the proposed non-cooperative game compensates the PCC with fewer overall losses than the consensus-based cooperative approach, improving the efficiency of the whole compensation system.
Temperature Dependence of AlGaN/GaN High Electron Mobility Transistors on 200 mm Si wafers
(2022-01-01) Junior, Braz Baptista ; De Andrade, Maria Gloria Cano ; De Oliveira Bergamim, Luis Felipe ; Nogueira, Carlos Roberto ; Abud, Renan Baptista ; Simoen, Eddy ; Universidade Estadual Paulista (UNESP) ; Belgium Also Imec
In this paper, the temperature dependence of AlGaN/GaN High Electron Mobility Transistors (HEMTs) on silicon substrates is studied experimentally. Drain current (ID), transconductance (gm), threshold voltage (VT) and drain-induced barrier lowering (DIBL) were analyzed in the temperature range from -35°C to 200°C. In addition, gate current (IG) and subthreshold slope (SS) were also analyzed in order to understand the physical mechanisms involved. The results indicate that gate current increases with increasing temperature. Also, as the gate current (IG) increases, the drain current (ID) decreases. The characteristics of AlGaN/GaN HEMTs on silicon substrates indicate that they may be a promising candidate for analog and radio frequency (RF) applications.
Consensus-Based Single-Phase Control of Three-Phase Inverter for Current Sharing in Three-Phase Four-Wire Isolated AC Microgrids
(2022-01-01) Rodrigues, Diego T. ; Paredes, Helmo K. Morales ; Burgos, Claudio ; Lima, Rogerio Lucio ; Bonaldo, Jakson P. ; Universidade Estadual Paulista (UNESP) ; Institute of Engineering Sciences ; Federal University of Mato Grosso-UFMT
This work proposes a novel secondary control system based on the Consensus algorithm to balance the RMS current between the distributed generation (DG) phases in an isolated four-wire Microgrid (MG) containing unbalanced and non-linear loads. The control strategy proposes using a droop control per phase to regulate the voltage magnitude, whereas the harmonic current sharing is performed using the virtual impedance concept. Additionally, the proposed control scheme guarantees voltage regulation, causing the MG to operate at its nominal voltage value. In addition to sharing the RMS value of the current, the consensus algorithm also provides the equal sharing of the RMS value of the harmonic current between each phase of the DGs that comprise the MG and also ensures that the harmonic distortion of the voltage in the PCC of each DG remains within limits defined by the standards and recommendations. Simulation results demonstrate the functioning and effectiveness of the proposed control strategy.
Plasma surface treatment of transparent commercial polymers to improve their wettability, gas barrier, and optical transmittance in the visible range
(2022-10-01) Sant’Ana, Péricles Lopes ; Bortoleto, José Roberto R. ; Durrant, Steven F. ; Ribeiro, Rafael Parra ; Universidade Estadual Paulista (UNESP)
The objective of this work was to study the modification of the structural, chemical, and optical properties of the surface of certain commercial polymers through the use of Plasma Immersion and Plasma Immersion Ion Implantation techniques. The polymers investigated were blue polyvinyl chloride, polyethylene terephthalate, and low density polyethylene. As the fluorination of a surface tends to increase its hydrophobic character, sulfur hexafluoride plasmas were used as a fluorine source. Treatments with nitrogen plasmas were also investigated. Graphical abstract: An investigation at Nanoscale of a solid using Microscopy and spectroscopy methods are the key to the Nanoscience today, and the characterized materials may find several applications.
A Non-cooperative Game-theoretic Distributed Control Approach for Power Quality Compensators
(Ieee, 2022-01-01) Burgos-Mellado, Claudio ; Bucarey, Victor ; Morales-Paredes, Helmo K. ; Munoz-Carpintero, Diego ; IEEE ; Univ OHiggins ; Universidade Estadual Paulista (UNESP)
This paper demonstrates that the Game Theory (GT) can be an effective tool for implementing a distributed control scheme for coordinating the compensation efforts of power quality compensators (PQCs) feeding a common unbalanced load. A non-cooperative game is formulated where each PQCs minimises its own interests, defined as the power losses that incur each PQC in carrying unbalanced power from its connection point in the system to the point of common coupling (PCC). By doing this, the whole system will move until it reaches a global equilibrium (the so-called Nash equilibrium). The power losses are calculated based on the conservative power theory (CPT), allowing the implementation of the proposal in the natural abc reference frame. A comparison (via simulations) between the proposed noncooperative distributed scheme and a cooperative distributed approach based on the consensus theory shows that the proposed non-cooperative game compensates the PCC with fewer overall losses than the consensus-based cooperative approach, improving the efficiency of the whole compensation system.
Consensus-Based Distributed Control for Improving the Sharing of Unbalanced Currents in Three-phase Three-wire Isolated Microgrids
(Ieee, 2021-01-01) Burgos-Mellado, Claudio ; Donoso, Felipe ; Llanos, Jacqueline ; Martinez-Gomez, Manuel ; Morales-Paredes, Helmo K. ; Torres, Miguel ; IEEE ; Univ OHiggins ; Univ Chile ; Univ Fuerzas Armadas ESPE ; Universidade Estadual Paulista (UNESP)
This paper proposes a secondary distributed control strategy to achieve the sharing of unbalanced currents between 3-leg power converters, operating under droop control, in a three-phase three-wire isolated Microgrid (MG). To this end, a modified Q - E droop controller is used, where new control actions are defined to achieve the unbalanced currents sharing amongst the converters. These control actions are generated, in the secondary control level, by a consensus-based algorithm, where the consensus variables correspond to the single-phase reactive powers of the converters. This paper shows that sharing negative sequence current components amongst the power converters can be managed by achieving a consensus (per phase) of single-phase reactive powers. Extensive simulations demonstrate the excellent performance of the proposed controller.
An evolutionary algorithm for quadcopter trajectory optimization in aerial challenges
(Ieee, 2020-01-01) Alves, Adson Nogueira ; Ferreira, Murillo Augusto S. ; Colombini, Esther Luna ; Simoes, Alexandre da Silva ; Goncalves, LMG ; Drews, PLJ ; DaSilva, BMF ; DosSantos, D. H. ; DeMelo, JCP ; Curvelo, CDF ; Fabro, J. A. ; Universidade Estadual Paulista (UNESP) ; Universidade Estadual de Campinas (UNICAMP)
Machine learning methods have been widely employed in robotics over the years, and recent developments in machine learning have completely re-shaped problem-solving in the area. Indeed, if we consider multi-objective planning, these models' optimization and learning capabilities can derive more robust strategies. Inspired by the species natural selection mechanism, Evolutionary Algorithms (EA) are among the best known computational approaches available for this purpose. In this scenario, this work proposed an EA model developed to find the best travel trajectory for a quadcopter in the Desafio Petrobras challenge. In the challenge, a set of landing platforms that the robot has to visit are displaced in the 3D-space. To find the best trajectory possible, we optimize an EA over a low-level control that can take the quadcopter from point A to B. We vary our fitness function to support more complex decisions. The software-in-the-loop technique was applied for a simulated quadrotor in the Coppelia simulated environment. The proposed approach has shown the capability to generate short trajectories while considering variables like UAV dynamics and energy consumption.
Structural characterization of polymeric nanofibers of polyvinylidene fluoride (PVDF)
(Associação Brasileira de Polímeros, 2023-05-29) Silva, José Augusto Souza Gomes Da ; Silva, Walace Rodrigues Da ; Silva, Ana Neilde Rodrigues Da ; Künzel, Roseli ; Bortoleto, José Roberto Ribeiro ; Melo, Emanuel Benedito De ; Ulsen, Carina ; Trindade, Neilo Marcos ; Instituto Federal de Educação, Ciência e Tecnologia ; Universidade Estadual Paulista (UNESP) ; Faculdade de Tecnologia do Estado de São Paulo ; Universidade Federal de São Paulo ; Universidade de São Paul ; Universidade de São Paulo (USP)
Polyvinylidene fluoride (PVDF) is a polymer material that exhibits piezoelectricity, which is the ability of certain materials to generate an electric charge in response to applied mechanical stress. Electrospun nanofibers were prepared from a solution with 1800 mg PVDF (18 wt.%) powder dissolved in 7.5 ml of dimethylformamide (DMF) and 2.5 ml acetone. The experimental setup used in the electrostatic deposition process was developed in our laboratory. Atomic Force Microscopy (AFM) showed that the fibers vary from 100 nm to 200 nm. Scanning Electron Microscopy (SEM) measurements showed distributed and well-formed nanofibers, but with few incidences of beads. The Energy Dispersive Spectroscopy (EDX) results showed that all points of the formed nanofibers have very similar chemical compositions, based on carbon and fluorine. Raman and Fourier Transform Infrared (FTIR) Spectroscopic analysis revealed the characteristic bands related to β-phase in the sample, which is responsible for the piezoelectricity of PVDF.
Development of non-equiatomic Bio-HEAs based on TiZrNbTa-(Mo and Mn)
(2022-08-01) Torrento, Jhuliene Elen ; Sousa, Tiago Dos Santos Pereira De ; Cristino Da Cruz, Nilson ; Santos De Almeida, Gerson ; Zambuzzi, Willian Fernando ; Grandini, Carlos Roberto ; Nespeque Correa, Diego Rafael ; Universidade Estadual Paulista (UNESP) ; Brazilian Branch ; Institute of Education Science and Technology
This study produced non-equiatomic TiNbZrTaMn and TiNbZrTaMo high entropy alloy (HEAs) by argon arc-melting and heat-treated for microstructural homogenization. The phase composition, microstructure, and selected mechanical properties were measured and compared with theoretical predictions. Additionally, electrochemical and cytotoxicity tests evaluated their potential applicability for use as biomaterials. X-ray diffraction measurements patterns showed a single BCC phase for the TiNbZrTaMn and a secondary HCP phase for the TiNbZrTaMo sample. The microstructural analysis revealed the formation of irregular grain boundaries and some lamellae formation, with chemical segregation of the alloying elements at the sub-micro-scale. The samples exhibited elastic modulus (80-110 GPa) closer to CP-Ti grade 2 (100 GPa) and higher Vickers microhardness (450-550 HV) than Ti-6Al-4V alloy (400 HV). The electrochemical and biological tests indicated a superior corrosion resistance against 0.9% NaCl solution compared with commercial metallic biomaterials, with proper cell adhesion and viability of pre-osteoblastic cells and hydrophilic behavior. Altogether, the data indicate that TiNbZrTaMn depicts better applicability potential for being used as a biomaterial in biomedical applications than some commercial materials (SS 316L, CP-Ti grade 2, and Ti-6Al-4V), mainly considering load-bearing orthopedical implants.
Towards Dynamic Quadruped Locomotion: Development of a CPG-driven Foot Trajectory Generator
(2022-01-01) De Paula, Daniel Teixeira ; Paciencia Godoy, Eduardo ; Becerra-Vargas, Mauricio ; Universidade Estadual Paulista (UNESP)
Legged locomotion has been a widespread daily activity of animals for millions of years, and many of its subtleties are founded on imposed conditions for survival. Agile movement in environments built for human locomotion could be achieved by extracting and implementing key aspects of legged locomotion in artificial creations. This work proposes a novel high-level control system module for dynamic quadruped robot locomotion, integrating the rhythmic developing capabilities of CPGs with foot trajectory generation based on Bézier curves. The proposed system utilizes CPG output signals as driving parameters for a foot trajectory generator based on Bézier curves and is built using a Matlab/Simulink simulated environment, with tests being carried out to validate its quadruped locomotion aptitude with regards to limit-cycle convergence and establishment of synchronized and stable phase shifts corresponding to desired gaits. The results point toward a sound performance of the proposed strategies, showing great promise regarding its locomotion capabilities. Lastly, additions to enhance the system's effectiveness and enable its use in a complete locomotion control system are suggested to be further explored in future works.
A tattoo-inspired electrosynthesized polypyrrole film: crossing the line toward a highly adherent film for biomedical implant applications
(2022-12-01) Borges, M. H.R. ; Nagay, B. E. ; Costa, R. C. ; Sacramento, C. M. ; Ruiz, K. G. ; Landers, R. ; van den Beucken, J. J.J.P. ; Fortulan, C. A. ; Rangel, E. C. ; da Cruz, N. C. ; Barão, V. A.R. ; Universidade Estadual de Campinas (UNICAMP) ; Radboud University Medical Center ; Universidade de São Paulo (USP) ; Universidade Estadual Paulista (UNESP)
Polypyrrole (PPy) films have demonstrated promising application for implants due to their unique topographical and electronic properties. However, the limited PPy adhesiveness to metallic surfaces remains a challenge. Consequently, we propose a two-step technique for the surface modification of titanium (Ti) via a plasma electrolytic oxidation (PEO) step to serve as mechanical interlocking for the subsequent deposition of a highly adherent PPy film (PEO + PPy). Ti discs with machined and PEO-modified surfaces were used as controls. For the experimental groups, PPy film was deposited onto such surfaces by electrodeposition. Then, the role of machined and PEO surfaces in the synthesis, conductivity, microstructure, mechanical, electrochemical, microbiological, and biological properties of the PPy film was investigated. The results showed that a highly adherent “tattoo-inspired” PPy thin film was successfully achieved when the Ti surface was pretreated via PEO. PEO + PPy enhanced Ti mechanical and tribological properties by inducing a lower friction coefficient and wear loss due to the cushion effect of PPy film, besides promoting higher corrosion resistance. The “cauliflower-like” morphology of the PPy favored protein adsorption, calcium phosphate growth and demonstrated cell biocompatibility. The association between PEO and PPy film can be considered bioactive and is promising for the triggering of superior long-term stability of biomedical implants.

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