Modeling and inverse feedforward control for conducting polymer actuators with hysteresis

Conducting polymer actuators are biocompatible with a small footprint, and operate in air or liquid media under low actuation voltages. This makes them excellent actuators for macro- and micro-manipulation devices, however, their positioning ability or accuracy is adversely affected by their hysteresis non-linearity under open-loop control strategies. In this paper, we establish a hysteresis model for conducting polymer actuators, based on a rate-independent hysteresis model known as the Duhem model. The hysteresis model is experimentally identified and integrated with the linear dynamics of the actuator. This combined model is inverted to control the displacement of the tri-layer actuators considered in this study, without using any external feedback. The inversion requires an inverse hysteresis model which was experimentally identified using an inverse neural network model. Experimental results show that the position tracking errors are reduced by more than 50% when the hysteresis inverse model is incorporated into an inversion-based feedforward controller, indicating the potential of the proposed method in enabling wider use of such smart actuators

Conducting polymer microactuators operating in air

We report for the first time on microsized conducting polymer actuators, which operate in air and in liquids. These actuators are potentially useful for a wide range of applications from biotechnology to microrobots. Furthermore, the actuators are fabricated using an excimer laser ablation technique, which does not require clean-room facilities and can provide high throughput production. Preliminary characterization results presented show that the tip displacement of the microactuators is linearly proportional to the magnitude of the input voltage

Electronically integrated microcatheters based on self-assembling polymer films

Existing electronically integrated catheters rely on the manual assembly of separate components to integrate sensing and actuation capabilities. This strongly impedes their miniaturization and further integration. Here, we report an electronically integrated self-assembled microcatheter. Electronic components for sensing and actuation are embedded into the catheter wall through the self-assembly of photolithographically processed polymer thin films. With a diameter of only about 0.1 mm, the catheter integrates actuated digits for manipulation and a magnetic sensor for navigation and is capable of targeted delivery of liquids. Fundamental functionalities are demonstrated and evaluated with artificial model environments and ex vivo tissue. Using the integrated magnetic sensor, we develop a strategy for the magnetic tracking of medical tools that facilitates basic navigation with a high resolution below 0.1 mm. These highly flexible and microsized integrated catheters might expand the boundary of minimally invasive surgery and lead to new biomedical applications. Copyright © 2021 The Authors, some rights reserved

Conducting polymer actuators: from basic concepts to proprioceptive systems

[SPA] Esta tesis doctoral se presenta bajo la modalidad de compendio de publicaciones. Es apoyado por 12 documentos, de los 27 en coautoría del candidato y publicados en diferentes revistas durante el desarrollo de esta tesis. Todos los documentos están indexados en el Journal Citation Reports (ISI-JCR). Los elementos seleccionados alcanzan 45 puntos de acuerdo con los reglamentos de la UPCT (Artículo 33 del Reglamento de estudios oficiales de máster y doctorado de la Universidad Politécnica de Cartagena, aprobado por el Consejo de Gobierno el 13 de abril de 2011 y modificado en Consejo de Gobierno el 11 de julio de 2012.), requiriendo un mínimo de 12 puntos para permitir la presentación de la tesis a través de un conjunto de publicaciones. Siguiendo esas regulaciones, esta tesis incluye: los objetivos de la tesis, el estado del arte, un resumen extendido para cada artículo (incluido el procedimiento experimental y los principales logros), una copia de cada trabajo seleccionado y las conclusiones generales.[ENG] This thesis is presented through a set of publications. Designers and engineers have been dreaming for decades of motors sensing, by themselves, working and surrounding conditions, as biological muscles do originating proprioception. Here bilayer full polymeric artificial muscles were checked up to very high cathodic potential limits (-2.5 V) in aqueous solution by cyclic voltammetry. The electrochemical driven exchange of ions from the conducting polymer film, and the concomitant Faradaic bending movement of the muscle, takes place in the full studied potential range. The presence of trapped counterion after deep reduction was corroborated by EDX determinations giving quite high electronic conductivity to the device. The large bending movement was used as a tool to quantify the amount of water exchanged per reaction unit (exchanged electron or ion). The potential evolutions of self-supported films of conducting polymers or conducting polymers (polypyrrole, polyaniline) coating different microfibers, during its oxidation/reduction senses working mechanical, thermal, chemical or electrical variables. The evolution of the muscle potential from electrochemical artificial muscles based on electroactive materials such as intrinsically conducting polymers and driven by constant currents senses, while working, any variation of the mechanical (trailed mass, obstacles, pressure, strain or stress), thermal or chemical conditions of work. One physically uniform artificial muscle includes one electrochemical motor and several sensors working simultaneously under the same driving reaction. Actuating (current and charge) and sensing (potential and energy) magnitudes are present, simultaneously, in the only two connecting wires and can be read by the computer at any time. From basic polymeric, mechanical and electrochemical principles a physicochemical equation describing artificial proprioception has been developed. It includes and describes, simultaneously, the evolution of the muscle potential during actuation as a function of the motor characteristics (rate and sense of the movement, relative position, and required energy) and the working variables (temperature, electrolyte concentration, mechanical conditions and driving current). By changing working conditions experimental results overlap theoretical predictions. The ensemble computer-generator-muscle theoretical equation constitutes and describes artificial mechanical, thermal and chemical proprioception of the system. Proprioceptive tools and most intelligent zoomorphic or anthropomorphic soft robots can be envisaged.Esta tesis doctoral se presenta bajo la modalidad de compendio de publicaciones. Está formada por un total de doce artículos: 1. Toribio F. Otero, Jose G. Martinez and Joaquin Arias-Pardilla. Biomimetic electrochemistry from conducting polymers. A review. Artificial muscles, smart membranes, smart drug delivery and computer/ neuron interfaces Electrochimica Acta, year 2012, volume 84, pages 112-128. (ISI-JCR IF: 4.086, Q1 in Electrochemistry). 2. Toribio F. Otero and Jose G. Martinez. Artificial Muscles: A Tool To Quantify Exchanged Solvent During Biomimetic Reactions Chemistry of Materials, year 2012, volume 24, pages 4093-4099. (IF=8.535, Q1 in ‘Materials science, Multidisciplinary’ and ‘Chemistry, Physical’). 3. Toribio F. Otero and Jose G. Martinez. Ionic exchanges, structural movements and driven reactions in conducting polymers from bending artificial muscles Sensors and Actuators B: Chemical, year 2014, volume 199, pages 27-30. (IF=3.840, Q1 in ‘Instruments & instrumentation’, ‘Chemistry, analytical’ and ‘Electrochemistry’). 4. Toribio F. Otero and Jose G. Martinez. Structural Electrochemistry: Conductivities and Ionic Content from Rising Reduced Polypyrrole Films Advanced Functional Materials, year 2014, volume 24, pages 1259-1264. (IF=10.439, Q1 in ‘Materials science, multidisciplinary’, ‘Nanoscience & nanotechnology’, ‘Physics, applied’, ‘Chemistry, multidisciplinary’, ‘Chemistry, physical’ and ‘Physics, condensed matter’). 5. Jose G. Martinez, Toribio F. Otero and Edwin W. H. Jager. Effect of the Electrolyte Concentration and Substrate on Conducting Polymer Actuators Langmuir, year 2014, volume 30, pages 3894-3904. (IF=4.384, Q1 in ‘Materials science, multidisciplinary’, ‘Chemistry, multidisciplinary’ and ‘Chemistry, physical’). 6. Toribio F. Otero, Juan J. Sanchez and Jose G. Martinez. Biomimetic Dual Sensing-Actuators Based on Conducting Polymers. Galvanostatic Theoretical Model for Actuators Sensing Temperature The Journal of Physical Chemistry B, year 2012, volume 116, pages 5279-5290. (IF=3.377, Q2 in ‘Chemistry, physical’). 7. Jose G. Martinez and Toribio F. Otero. Biomimetic Dual Sensing-Actuators: Theoretical Description. Sensing Electrolyte Concentration and Driving Current The Journal of Physical Chemistry B, year 2012, volume 116, pages 9223-9230. (IF=3.377, Q2 in ‘Chemistry, physical’). 8. Jose G. Martinez and Toribio F. Otero. Mechanical awareness from sensing artificial muscles: Experiments and modeling Sensors and Actuators B: Chemical, year 2014, volume 195, pages 365-372. (IF=3.840, Q1 in ‘Instruments & instrumentation’, ‘Chemistry, analytical’, and ‘Electrochemistry’). 9. Jose G. Martinez and Toribio F. Otero. Structural Electrochemistry. Chronopotentiometric Responses From Rising Compacted Polypyrrole Electrodes: Experiments and Model RSC Advances, year 2014, volume 4, pages 29139-29145. (IF=3.708, Q1 in ‘Chemistry, multidisciplinary’). 10. Toribio F. Otero and Jose G. Martinez. Physical and chemical awareness from sensing polymeric artificial muscles. Experiments and modeling Progress in Polymer Science, year 2014, DOI: 10.1016/ j.progpolymsci.2014.09.002. (IF=26.854, Q1 in ‘Polymer science’). 11. Yahya A. Ismail, Jose G. Martinez and Toribio F. Otero. Polyurethane microfibrous mat template polypyrrole: Preparation and biomimetic reactive sensing capabilities Journal of Electroanalytical Chemistry, year 2014, volume 719, pages 47-53. (IF=2.871, Q2 in ‘Chemistry, analytical’ and ‘Electrochemistry’). 12. Yahya A. Ismail, Jose G. Martinez and Toribio F. Otero. Fibroin/Polyaniline microfibrous mat. Preparation and electrochemical characterization as reactive sensor Electrochimica Acta, year 2014, volume 123, pages 501-510. (IF: 4.086, Q1 in ‘Electrochemistry’).Universidad Politécnica de CartagenaPrograma de doctorado de Electroquímica. Ciencia y Tecnologí

AN ION SELECTIVE MICROGRIPPER SENSOR DEVICE

This thesis presents the design, fabrication, characterisation and testing of a chemically modified electrothermally actuated microgripper. The chemical modification involves the integration of a potentiometric ion selective electrode (ISE) onto a bare electrode fabricated within the tip of the microgripper. This microgripper sensor device is intended for use in the application of detecting, in real time, the movement of key ions that are involved in intercellular communication from a mechanically stressed cell. An optimised fabrication route for the specifically designed microgrippers, which have tip dimensions of 10 – 60 µm, is described in detail. The fabrication route delivers a high yield (95%) of operational unmodified devices. An 1800 ± 20 µm2 bare gold electrode that is fabricated at the tip of the microgripper is modified into an all solid state ISE that uses PEDOT as the ion-to-electron solid contact. Suitable ionophores that selectively detect K+, Na+ and Ca2+ are used to fabricate potassium, sodium and calcium ion selective microgripper sensor devices. The quality control and testing characteristics that follow the guidelines defined by IUPAC are performed to ascertain the sensitivity, selectivity and stability of the microgripper sensor devices. Good selectivity is achieved, with limits of detection of 2.4 x 10-4 M, 1.8 x 10-4 M and 2.0 x 10-5 M for the K+, Na+ and Ca2+ devices respectively. Proof of concept experiments of the real life testing of the K+ ISE device used to mechanically stress mouse oocytes gave preliminary measurements that indicate that stress signalling occurs via a switch on mechanism, and that there is a small increase in K+ concentration as applied stress increases. Due to the high systematic error within the calibration process the magnitude of this concentration increase is unknown. The Na+ and Ca2+ ISE devices suffer from interference and sensitivity restrictions respectively so a signal response vs. applied cell stress relationship of these ions is currently unobtainable

Modeling, identification, and application of multilayer polypyrrole conducting polymer actuators

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references.Experiments were performed using commercially available, self-contained, multilayer polypyrrole (PPy) actuators to develop low-order lumped parameter models of actuator electrical, mechanical, and electromechanical behavior. Experimental data were processed using system identification techniques. Both grey box and black box models were identified. The grey box model consisted of a first order electrical network that was linearly and algebraically coupled to a second order viscoelastic model. The black box model incorporated a third order Box-Jenkins structure and achieved model to data residues comparable to the grey box model. When utilizing validation data, the grey box model showed very good performance for loads in the range of 0.5 to 3 N. Overall, the results of system identification experiments suggested that low order, lumped parameter models were adequate to describe the gross behavior of multilayer actuators. An online identification scheme was developed for monitoring polymer electrical impedance and thereby monitoring the degradation state of an actuator. This identification was performed successfully using recursive least squares and least squares for a discrete impedance model.(cont.) Experimental validation data, spanning more than 5 hours of continuous operation, were collected and analyzed. A final contribution of this research was the application PPy linear actuators to a custom-designed humanoid foot. Four linear conducting polymer actuators were used to obtain multifunctional behavior of the overall foot. Jacobian analysis of stiffness and damping was performed for the design. Simulations illustrated that PPy actuators through the use of appropriate electrical excitation can modulate their stiffness characteristics as a function of time to match a desired force versus length relationship.by Thomas W. Secord.S.M

Tailoring bombyx mori silk as multifuctional material for advanced applications.

288 p.Materials support human development. Among the available materials, polymers are nowadays essential and practically omnipresent because of their unrivalled properties. Unfortunately, polymers are synthesized from oil, and they tend to accumulate in nature, which represents a serious environmental impact.To minimize these damages, materials science suggests replacing synthetic polymers with bio-based materials. To promote the use of these more sustainable materials, the objective of the work has been to demonstrate the real applicability of bio-based materials, and more specifically Silk Fibroin (SF), a protein obtained from Bombyx mori (silkworm) cocoons. This protein displays unique physical-chemical properties that make it an interesting substrate for the development of new materials with advanced properties.Two main fields of application have been selected in this work for SF: i) electronics (active composites for sensors and actuators) and ii) porous structures for biomedicine, energy, and environment.For electronics, SF has been combined with i) carbon nanotubes (CNT) to obtain force sensors with piezoresistive responses (PR) of ~ 4 MPa-1 at pressures of 0.11 MPa; ii) with silver nanowires (SNW) to obtain PR of 26 GPa-1 when the pressure is between 0.2 and 0.4 MPa. Also, SF/SNW nanocomposites show optical transparency at SNW loads above 3%; iii) with cobalt ferrite nanoparticles (CFO) to obtain magnetic actuators with a magnetization value of ~ 10 emu·g¿1 and coercivity of almost 4 kOe, (20 wt. % CFO); and iv) with ionic liquids (IL) to obtain bending actuators with bending responses of ~ 0.5 by applying low voltages (3-5 V).SF has been processed also for the development of porous structures by i) electrospinning, to obtain scaffolds that when are combined with CFO particles, stimulate the bone cells development; ii) by salt leaching; to obtain Li-ion battery separators that lead to battery performance of 89,3 y 131,3 mAh·g¿1, for 2C and C/8 cycles respectively and iii) by gas foaming, gelation and freeze-drying, to obtain samples with porosity values above 94% and aqueous Cr adsorption capacities up to 3 mg/g.Bc Materials: Basque Center for materials applications & nanostructure

Tailoring bombyx mori silk as multifuctional material for advanced applications.

288 p.Materials support human development. Among the available materials, polymers are nowadays essential and practically omnipresent because of their unrivalled properties. Unfortunately, polymers are synthesized from oil, and they tend to accumulate in nature, which represents a serious environmental impact.To minimize these damages, materials science suggests replacing synthetic polymers with bio-based materials. To promote the use of these more sustainable materials, the objective of the work has been to demonstrate the real applicability of bio-based materials, and more specifically Silk Fibroin (SF), a protein obtained from Bombyx mori (silkworm) cocoons. This protein displays unique physical-chemical properties that make it an interesting substrate for the development of new materials with advanced properties.Two main fields of application have been selected in this work for SF: i) electronics (active composites for sensors and actuators) and ii) porous structures for biomedicine, energy, and environment.For electronics, SF has been combined with i) carbon nanotubes (CNT) to obtain force sensors with piezoresistive responses (PR) of ~ 4 MPa-1 at pressures of 0.11 MPa; ii) with silver nanowires (SNW) to obtain PR of 26 GPa-1 when the pressure is between 0.2 and 0.4 MPa. Also, SF/SNW nanocomposites show optical transparency at SNW loads above 3%; iii) with cobalt ferrite nanoparticles (CFO) to obtain magnetic actuators with a magnetization value of ~ 10 emu·g¿1 and coercivity of almost 4 kOe, (20 wt. % CFO); and iv) with ionic liquids (IL) to obtain bending actuators with bending responses of ~ 0.5 by applying low voltages (3-5 V).SF has been processed also for the development of porous structures by i) electrospinning, to obtain scaffolds that when are combined with CFO particles, stimulate the bone cells development; ii) by salt leaching; to obtain Li-ion battery separators that lead to battery performance of 89,3 y 131,3 mAh·g¿1, for 2C and C/8 cycles respectively and iii) by gas foaming, gelation and freeze-drying, to obtain samples with porosity values above 94% and aqueous Cr adsorption capacities up to 3 mg/g.Bc Materials: Basque Center for materials applications & nanostructure