Response Characterization of Electroactive Polymers as Mechanical Sensors (original) (raw)
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An investigation into behaviour of electroactive polymers as mechanical sensors
IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM, 2007
We present our experimental investigation into 'mechanochemoelectrical' behavior of tri-layer polypyrrole (PPy) -type conducting polymer sensors. One end of the polymer strip is clamped and the other-free end-is excited through a mechanical lever system, which provides sinusoidal displacement inputs. The voltage generated and current passing between the two outer PPy layers as a result of the displacement input is measured to model the output/input behaviour of the sensors through their experimental current/displacement and voltage/displacement frequency responses. We specifically targeted the low frequency behaviour of the sensor as it is a relatively slow system. Experimental transfer function models are generated for three sensors with the dimensions of (7.5mm×1mm×0.17 mm), (10mm×1mm×0.17 mm), and (12.5 mm×1mm×0.17 mm). These models are for use in understanding the dynamic behaviour and sensing ability of the polymers as mechanical sensors. The effect of the active sensor length on the voltage and current outputs are investigated that the shorter is the sensor length, the higher are the voltage output and the current passed. Also, their current and voltage responses under an impulse stimulus (i.e. displacement) are experimentally measured to show their dynamic sensing response.
Sensor response of polypyrrole trilayer benders as a function of geometry
Proceedings of SPIE - The International Society for Optical Engineering, 2008
Trilayer polypyrrole benders are capable of generating voltages and currents when applied with an external force or displacement, demonstrating potential as mechanical sensors. Previous work has identified the effects of dopant and electrolyte on the sensor output, and a 'deformation induced ion flux' model was proposed. The current work aims to identify the change in sensor response with input amplitude and bender geometry as a function of frequency. The current and charge output from the trilayer benders were found to increase proportionally with input displacement and bender strain for multiple input frequencies, indicating linearity. Sensitivities of the current and charge output have also been calculated in response to strain, and are found to increase as the volume of the conducting polymer is increased. Some guidelines for sensor geometry are then suggested, using the identified sensitivities as a guide.
Conducting polymers as simultaneous sensor-actuators
SPIE Newsroom, 2010
Environmental and electrical variables, as temperature, electrolyte concentration or driving current, influence oxidation and reduction oxidation rates of free-standing polypyrrole/DBSA/ClO 4 films. Under flow of a constant current for a constant time, decreasing electrical energies are consumed to oxidize or to reduce the film under increasing temperatures or rising electrolyte concentrations. By consuming the same charge under flow of rising constant currents, the consumed electrical energy increases. As conclusion the consumed electrical energy by flow of constant charges during oxidation, or reduction, of the film is a sensor of the electrochemical cell temperature, the electrolyte concentration or the flowing current. Those sensing capabilities seem to be a general property of the electrochemistry of conducting polymers. Any electrochemical based device, as actuators, polymeric batteries, smart membranes, smart drug delivery devices and others, are expected to sense environmental conditions while working. The sensing abilities of a complex actuator constituted by four polypyrrole films, two acting as electrodes (anodes or cathodes) and the other two as counter electrodes (cathodes or anodes, respectively) are presented. Experimental results are equivalent to sensing charge/discharge processes in all polymeric batteries.
Effect of the Dopant Nature on the Response of Sensor Arrays Based on Polypyrrole
Theoretical and Experimental Chemistry, 2005
The effect of the nature of the dopant on the response of a sensor array based on films of polypyrrole under the influence of the vapor of various organic solvents was studied. It was found the electric conductivity of the polymer can both increase and decrease during the action of analytes on electropolymerized films of polypyrrole. It is suggested that the main factors determining the response of polypyrrole are the morphology of the films and the type of charge carriers in the polymer, which depend on the nature of the dopant anion, and also the polarity and nucleophilicity/electrophilicity of the analyte. The responses of polypyrrole and polyaniline are compared, and the effect of the nature of the conducting polymer on them is analyzed.
Conducting polymers are simultaneous sensing actuators
Conducting polymers are soft, wet and reactive gels capable of mimicking biological functions. They are the electrochemomechanical actuators having the ability to sense the surrounding variables simultaneously. The sensing and actuating signals are sent/received back through the same two connecting wires in these materials. The sensing ability is a general property of all conducting polymers arises from the unique electrochemical reaction taking place in them. This sensing ability is verified for two different conducting polymers here – for an electrochemically generated polypyrrole triple layer bending actuator exchanging cations and for a chemically generated polytoluidine linear actuator exchanging anions. The configuration of the polypyrrole actuator device corresponds to polypyrrole-dodecyl benzene sulfonate (pPy-DBS) film/tape/ pPy-DBS film in which the film on one side of the triple layer is acted as anode and the film on the other side acted as cathode simultaneously, and the films interchanged their role when move in the opposite direction. The polytoluidine linear actuator was fabricated using a hydrgel microfiber through in situ chemical polymerization. The sensing characteristics of these two actuators were studied as a function of their working conditions: applied current, electrolyte concentration and temperature in aqueous electrolytes. The chronopotentiometric responses were studied by applying square electrical currents for a specified time. For the pPy actuator it was set to produce angular movement of ± 45º by the free end of the actuator, consuming constant charges of 60 mC. In both the actuators the evolution of the muscle potential along the electrical current cycle was found to be a function of chemical and physical variables acting on the polymer reaction rates: electrolyte concentration, temperature or driving electrical current. The muscle potential evolved decreases with increasing electrolyte concentrations, increasing temperatures or decreasing driving electrical currents. The electrical energy consumed during reaction was a linear function of the working temperature or of the driving electrical current and a double logarithmic function of the electrolyte concentration. Thus, the conducting polymer based actuators exchanging cations or anions during electrical current flow is a sensor of the working physical and chemical conditions which is a general property of all conducting polymers.
Advances in sensors based on conducting polymers
Journal of Scientific & Industrial Research, 2006
Conducting polymers with a blend of interesting optical and mechanical properties can be used in situations where inorganic materials are not suitable. Synthetic capabilities as well as fabrication techniques have been developed to such an extent that molecular electronic devices based on conducting polymers can be designed, marking evolution of a sophisticated technology in the field of microelectronics. These electro-active conducting polymers cover a broad spectrum of applications from solid-state technology to biotechnology and sensor technology. Present paper addresses the various issues on sensors for chemical and biochemical species.
Electrochemical sensors based on conducting polymer—polypyrrole
Electrochimica Acta, 2006
Conducting polymers can be exploited as an excellent tool for the preparation of nanocomposites with nano-scaled biomolecules. Polypyrrole(Ppy) is one of the most extensively used conducting polymers in design of bioanalytical sensors. In this review article significant attention ispaid to immobilization of biologically active molecules within Ppy during electrochemical deposition of this polymer. Such unique properties ofthis polymer as prevention of some undesirable electrochemical interactions and facilitation of electron transfer from some redox enzymes are discussed. Recent advances in application of polypyrrole in immunosensors and DNA sensors are presented. Some new electrochemical targetDNA and target protein detection methods based on changes of semiconducting properties of electrochemically generated Ppy doped by affinityagents are introduced. Recent progress and problems in development of molecularly imprinted polypyrrole are considered. A. Ramanavicius, A. Ramanaviciene, A. Malinauskas, Electrochemical sensors based on conducting polymerpolypyrrole (Review) Electrochimica Acta 2006, 51, 6025-6037. A. Ramanavicius, A. Ramanaviciene, A. Malinauskas, Electrochemical sensors based on conducting polymerpolypyrrole (Review) Electrochimica Acta 2006, 51, 6025-6037.
Polymers
In films of conducting polymers, the electrochemical reaction(s) drive the simultaneous variation of different material properties (reaction multifunctionality). Here, we present a parallel study of actuation-sensing-energy storage triple functionality of polypyrrole (PPy) blends with dodecylbenzenesulfonate (DBS-), PPy/DBS, without and with inclusion of polyethyleneoxide, PPy-PEO/DBS. The characterization of the response of both materials in aqueous solutions of four different salts indicated that all of the actuating, sensing and charge storage responses were, independent of the electrolyte, present for both materials, but stronger for the PPy-PEO/DBS films: 1.4× higher strains, 1.3× higher specific charge densities, 2.5× higher specific capacitances and increased ion-sensitivity towards the studied counterions. For both materials, the reaction energy, the material potential and the strain variations adapt to and sense the electrical and chemical (exchanged cation) conditions. The...
Polymers
Conducting polymers have been widely used in electrochemical sensors as receptors of the sensing signal’s analytes and transducers. Polypyrrole (PPy) conducting polymers are highlighted due to their good electrical conductive properties, ease in preparation, and flexibility of surface characteristics. The objective of this review paper is to discuss the theoretical background of the two main types of electrochemical detection: impedimetric and voltammetric analysis. It also reviews the application and results obtained from these two electrochemical detections when utilizing PPy as a based sensing material in electrochemical sensor. Finally, related aspects in electrochemical sensor construction using PPy will also be discussed. It is anticipated that this review will provide researchers, especially those without an electrochemical analysis background, with an easy-to-understand summary of the concepts and technologies used in electrochemical sensor research, particularly those inter...
Electrochemical sensors based on conducting polymer -polypyrrole (Review)
Electrochimica Acta, 2005
Conducting polymers can be exploited as an excellent tool for the preparation of nanocomposites with nano-scaled biomolecules. Polypyrrole(Ppy) is one of the most extensively used conducting polymers in design of bioanalytical sensors. In this review article significant attention ispaid to immobilization of biologically active molecules within Ppy during electrochemical deposition of this polymer. Such unique properties ofthis polymer as prevention of some undesirable electrochemical interactions and facilitation of electron transfer from some redox enzymes are discussed. Recent advances in application of polypyrrole in immunosensors and DNA sensors are presented. Some new electrochemical targetDNA and target protein detection methods based on changes of semiconducting properties of electrochemically generated Ppy doped by affinityagents are introduced. Recent progress and problems in development of molecularly imprinted polypyrrole are considered.