Larger Tip Displacement Research Articles

Ultrahigh Electrobending Deformation in Lead-Free Piezoelectric Ceramics via Defect Concentration Gradient Design.

Recent breakthroughs in defect-engineered lead-free piezoelectric ceramics have reported remarkable electrostrain values, surpassing the limit of lattice distortion. This has aroused wide concern on bending deformation and the associated underlying mechanism. Herein, via designing lead-free piezoelectric ceramics with varying volatilization characteristics, it is uncovered that the ultrahigh electrobending deformation is primarily attributed to a large strain gradient induced by unevenly distributed defect dipoles. In 0.5 mm thick Sr/Sn co-doped potassium sodium niobate ceramics featuring volatile K/Na elements, the inherent bipolar electrostrain value can reach 0.3% at 20kV cm-1 due to the existence of defect dipoles, while the gradient distribution of defect dipole generates significant bending displacement, amplifying apparent electrostrain value to 1.1%. Notably, nonvolatile Ba0.99TiO2.99 ceramic with homogeneous defect dipole distribution does not present electrobending. Of particular interest is that the electrobending phenomenon can be observed through introducing a defect dipole gradient into barium titanate ceramic. A monolayer ceramic with defect dipole gradient can generate large tip displacement (±1.5mm) in cantilever structure, demonstrating its promising potential in precise positioning. This study delves into the underlying mechanism driving electrobending deformation and its impact on the apparent electrostrain measurement in defect-engineered piezoelectric ceramics, providing fresh perspectives for the development of piezoelectric bending actuators.

Polyisobutylene Encapsulated PEDOT: Pss Electrode Honeycomb Skeleton Electrolyte for Moisture Resistant Electro‐Ionic Soft Artificial Muscles

AbstractAdvances in electro‐ionic soft actuators hold significant potential as next‐generation bioelectronic interfaces due to mechanical compliance and operation in agreement with soft biological tissues and low voltages. However, current devices call for encapsulation strategies to accommodate high mechanical demands and long‐term stability in environmental changes. In this study, a durability of polyvinylidene‐fluoride‐co‐hexafluoropropylene (PVDF‐co‐HFP) honeycomb skeleton electrolyte encapsulated with a biocompatible polyisobutylene (PIB) thin film is being investigated. A low water vapor transmission rate (0.61 g m−2 day−1) and elastic modulus (10 kPa) are measured from a 7.5 µm‐thick thin‐modified PIB‐encapsulation layer. The PIB‐encapsulated soft actuator maintains 68% of its mechanical durability after 40 000 cycles of zero‐to‐tension fatigue loading at room temperature. A cantilever actuation test of the PIB‐encapsulated 3mm‐wide 30mm‐long actuator film shows a large tip displacement (15.90 mm) at a low voltage (±1.5 V) under 0.1 Hz, 37 °C, 50% relative humidity (RH). Most importantly, while the unencapsulated actuator immediately degrades in a few cycles at 37 °C, 50%RH, and 0.1% applied strain, PIB‐encapsulated soft actuator performs up to 6500 dynamic actuation cycles without any functionality degradation. Exceptional durability against mechanical fatigue and stability at elevated temperature and humidity meet the prerequisite for future soft biomedical robots that enable long‐lasting safe operations.

Highly electro-responsive ionic soft actuator based on graphene nanoplatelets-mediated functional carboxylated cellulose nanofibers

Electro-responsive ionic soft actuators have attracted increasing interest owing to the promising applications for soft robots, biomimetic robots, active medical devices, flexible electronics, and wearable devices. However, existing ionic actuators still need a technology breakthrough for larger bending strain, faster response, and excellent actuation durability. Herein, we report a novel highly electro-responsive ionic actuator based on functional carboxylated cellulose nanofibers (CCNF) by doping with ionic liquid (IL) and graphene nanoplatelets (GN). The proposed CCNF-IL-GN actuator demonstrated a large tip displacement of 15.71 mm (peak-to-peak) at 2.0 V with 0.1 Hz, faster rise time (2.9s), broad frequency bandwidth (0.1–3.0 Hz), markedly reduced phase delay, and long actuation durability (98.6% retention for 3 h) without actuation response distortion, all of which were due to the fast-easy ion migration and massive charge transport ability of the designed ionically crosslinked electrolyte membrane, resulting from the strong ionic interactions and crosslinking of CCNF nanofibers with IL and GN. Furthermore, we investigated the actuator's bionic applications such as the bionic flower, bionic finger, and bionic window. These results elucidate the great potential of the designed CCNF-IL-GN actuators for bionic robots, soft robots, wearable electronics, and biomedical active devices.

Micro-structured porous electrolytes for highly responsive ionic soft actuators

Electro-active ionic polymer actuators are an attractive type of soft actuators that bend due to the ion migration in the polymer electrolyte membrane under the electrical field. However, further explorations are required to enhance their performance, which, in turn, demands for strong and flexible polymer electrolytes with continuous conducting phases, facilitating ion movement. Here, we report a facile methodology to generate continuous ion-conducting channels in polymer electrolytes using two-phase evaporation technique. Immersing the corresponding porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) membrane into an ionic liquid converted it into an electrolyte membrane with continuous conducting phases. In such electrolyte membrane, while the PVDF-co-HFP skeletal frame provided high mechanical strength and flexibility, the continuous conducting phases facilitated the ion movement. This enhanced actuation performance. The prepared actuator showed 1.5 times higher performance in comparison with those made of conventional PVDF-co-HFP electrolyte membranes. The as-prepared actuator exhibited a large tip displacement of 25 mm at low voltage of 0.5 V and 0.1 Hz, fast rise time of 2.5 s without back relaxation, good stability with retrieving of 95% of the original performance after 20,000 actuation cycles. This high performance actuator could potentially be used in future technologies such as soft robotics and healthcare devices.

High‐Performance Ionic‐Polymer–Metal Composite: Toward Large‐Deformation Fast‐Response Artificial Muscles

AbstractAs promising candidates in the field of artificial muscles, ionic‐polymer–metal composites (IPMCs) still cannot simultaneously provide large deformations and fast responses, which has limited their practical applications. In this study, to overcome this issue, a Nafion‐based IPMC with high‐quality metal electrodes is fabricated via novel isopropanol‐assisted electroless plating. The IPMC exhibits a large tip displacement (35.3 mm, 102.3°) under a low direct‐current driving voltage and ultrafast response (>10 Hz) under an alternating‐current (AC) voltage. Furthermore, the simultaneous integration of a large deformation and fast response can be achieved by the IPMC under a high‐frequency (19 Hz) AC voltage, where the largest bending amplitude is 5.9 mm and the highest bending speed reaches 224.2 mm s−1 (596.2° s−1). Additionally, the lightweight IPMC exhibits a decent load capacity and can lift objects 20 times heavier. The outstanding performances of the Nafion IPMC are demonstrated by mimicking biological motions such as petal opening/closing, tendril coiling/uncoiling, and high‐frequency wing flapping. This study paves the way for the fabrication of lightweight actuators with simultaneous large displacements and fast responses for promising applications in biomedical devices and bioinspired robotics.

Design process and simulation testing of a shape memory alloy actuated robotic microgripper

Microgrippers are commonly used for micromanipulation of micro-objects with dimensions from 1 to 100 µm and attain features of reliable accuracy, low cost, wide jaw aperture and variable applied force. This paper studies the design process, simulation, and testing of a microgripper which can manipulate and assemble a platinum resistance temperature probe, made from a 25 µm diameter platinum wire, a 20 mm diameter tinned copper wire, and a printed circuit board type connector. Various microgripper structures and actuator types were researched and reviewed to determine the most suitable design for the required micromanipulation task. Operation tests using SolidWorks and ANSYS software were conducted to test a parallelogram structure with flexible single-notch hinges. The best suited material was found to be Aluminium alloy 7075-T6 as it was capable of producing a large jaw tip displacement of 0.7 mm without exceeding its tensile yield strength limit. A shape memory alloy was chosen as a choice of actuator to close the microgripper jaws. To ensure a repeatably accurate datum point, the final microgripper consisted of a fixed arm and a flexible arm. An optimisation process using ANSYS studied the hinge thickness and radius dimensions of the microgripper which improved its deflection whilst reducing the experienced stress.

Optimum Operating Conditions for PZT Actuators for Vibrotactile Wearables

Recently, vibrotactile wearables have received much attention in fields such as medicine, psychology, athletics and video gaming. The electrical components presently used to generate vibration are rigid; hence, the design and creation of ergonomical wearables are limited. Significant advances in piezoelectric components have led to the production of flexible actuators such as piezoceramic lead zirconate titanate (PZT) film. To verify the functionality of PZT actuators for use in vibrotactile wearables, the factors influencing the electromechanical conversion were analysed and tested. This was achieved through theoretical and experimental analyses of a monomorph clamped-free structure for the PZT actuator. The research performed for this article is a three-step process. First, a theoretical analysis presents the equations governing the actuator. In addition, the eigenfrequency of the film was analysed preceding the experimental section. For this stage, by applying an electric voltage and varying the stimulating electrical characteristics (i.e., voltage, electrical waveform and frequency), the optimum operating conditions for a PZT film were determined. The tip displacement was measured referring to the mechanical energy converted from electrical energy. From the results obtained, an equation for the mechanical behaviour of PZT films as actuators was deduced. It was observed that the square waveform generated larger tip displacements. In conjunction with large voltage inputs at the predetermined eigenfrequency, the optimum operating conditions for the actuator were achieved. To conclude, PZT films can be adapted to assist designers in creating comfortable vibrotactile wearables.

Direct measurement of nanomechanical actuation across phase transition in VO2 crystals

We employ in situ nanoindentation method to measure spontaneous strain during thermally induced structural phase transition in VO2 crystals. Large tip displacement of ~520nm is observed normal to (011) facet of VO2 crystals during phase transition. The captured actuation signals in the form of tip displacement from VO2 indicate 0.53% of spontaneous strain normal to (011) facet during phase transition. Spontaneous strain across phase transition is found to be reversible over thermal cycles with different heating rates. The investigated aspects demonstrate the application of nanoindentation in quantifying actuation of VO2 micro crystals towards highly efficient thermal actuators.

Linear Versus Nonlinear Response of a Cantilevered Beam Under Harmonic Base Excitation: Theory and Experiment

A computational and experimental study of a uniform cantilever beam with a tip mass under base excitation was performed. The beam was excited at various levels of base displacement to provoke tip displacements greater than 15% of the beam length. Damping and yield stress of the beam were both considered. It was found that a large tip displacement causes nonlinear inertial (NLI) and structural (NLS) effects to arise. Each of the structural and inertial nonlinearities has an opposite effect on the resulting resonance frequency, which are nearly mutually canceling. The result was that resonant frequency calculated using the full nonlinear (FNL) model was essentially equal to the value calculated by linear (LIN) theory, and the tip displacement amplitude varied only modestly from the LIN value. It was also observed that the damping in this system is likely nonlinear, and depends on tip displacement amplitude. A theoretical model for fluid damping is suggested. Initial investigation shows encouraging agreement between the theoretical fluid damping and the measured values.

High Speed Imaging of Cavitation around Dental Ultrasonic Scaler Tips.

Cavitation occurs around dental ultrasonic scalers, which are used clinically for removing dental biofilm and calculus. However it is not known if this contributes to the cleaning process. Characterisation of the cavitation around ultrasonic scalers will assist in assessing its contribution and in developing new clinical devices for removing biofilm with cavitation. The aim is to use high speed camera imaging to quantify cavitation patterns around an ultrasonic scaler. A Satelec ultrasonic scaler operating at 29 kHz with three different shaped tips has been studied at medium and high operating power using high speed imaging at 15,000, 90,000 and 250,000 frames per second. The tip displacement has been recorded using scanning laser vibrometry. Cavitation occurs at the free end of the tip and increases with power while the area and width of the cavitation cloud varies for different shaped tips. The cavitation starts at the antinodes, with little or no cavitation at the node. High speed image sequences combined with scanning laser vibrometry show individual microbubbles imploding and bubble clouds lifting and moving away from the ultrasonic scaler tip, with larger tip displacement causing more cavitation.

Novel electroactive PVA-TOCN actuator that is extremely sensitive to low electrical inputs

A novel electroactive biopolymer actuator was developed based on a cross-linked ionic networking membrane of TEMPO-oxidized bacterial cellulose nanofibers (TOCNs) and polyvinyl alcohol (PVA). Ionic liquids were added to develop an air-working artificial muscle and to enhance the performance of the PVA-TOCN actuator. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) conducting layers were deposited on the top and bottom surfaces of the PVA-TOCN membrane via a simple dipping and drying method. The electroactive PVA-TOCN actuator under both step and harmonic electrical inputs shows much larger tip displacements and faster bending deformation than the pure TOCN actuator. The cross-linking reaction between PVA and TOCN was observed in the Fourier transform–near-infrared (FT-IR) spectrum of the PVA-TOCN networking membrane. Scanning electron microscopy (SEM), x-ray diffusion (XRD), thermogravimetric analysis (TGA) and tensile and ion conductivity testing results for the PVA-TOCN membrane were compared with those of pristine TOCN. Most important, the PVA-TOCN actuator shows much larger bending deformation under even extremely low input voltages, and this could be attributed to the cross-linking mechanism and the greater flexibility resulting from the synergistic effects between PVA and TOCN.

Electro-active hybrid actuators based on freeze-dried bacterial cellulose and PEDOT:PSS

We report a high-performance electro-active hybrid actuator based on freeze-dried bacterial cellulose and conducting polymer electrodes. The freeze-dried bacterial cellulose, which has a sponge form, can absorb a much greater amount of ionic liquid, which is a prerequisite for dry-type and high-performance electro-active polymers. In addition, the poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) conducting layers are deposited on the top and bottom surfaces of the freeze-dried bacterial cellulose using a simple dipping and drying method. The results show that the freeze-dried bacterial cellulose actuator with conducting polymer electrodes has a much larger tip displacement under electrical stimuli than pure bacterial cellulose actuators with metallic electrodes. The large bending displacement of the freeze-dried bacterial cellulose actuator under low input voltage is due to the synergistic effects of the ion migration of the dissociated ionic liquids inside the bacterial cellulose and the electrochemical doping processes of the PEDOT:PSS electrode layers.

A Monolithic Compliant Piezoelectric-Driven Microgripper: Design, Modeling, and Testing

In this paper, we report on the design, modeling, and experimental testing of a piezoelectric-driven microgripper making use of both an integrated gripping force sensor and an integrated tip displacement sensor. In the developed microgripper, a stack piezoelectric ceramic actuator is used to simultaneously obtain the tip displacement and the gripping force. A novel monolithic compliant mechanism is proposed to act as the microdisplacement transmission mechanism to obtain the large tip displacement and to provide the possibility of integrating both the gripping force sensor and the tip displacement sensor into the microgripper. The relationship between the gripping force, tip displacement, input force, and input displacement of the piezoelectric-driven microgripper and the dynamic model are established using the pseudorigid-body-model method. The characteristics of the developed microgripper are tested and the case of gripping an optical fiber is presented. The experimental results indicate that: 1) the theoretical model for the developed microgripper matched well with the measured results; 2) the integrated gripping force sensor and tip displacement sensor could accurately measure the gripping force and tip displacement; 3) the developed microgripper could achieve a displacement magnification of 16.0 × with respect to the stack piezoelectric ceramic actuator to realize the large tip displacement with high resolution but is also able to possess the parallel movement of its gripping jaws and the constant displacement magnification.

Nonlinear dynamics of curved IPMC actuators undergoing electrically driven large deformations

The nonlinear dynamics of curved ionic polymer–metal composite (IPMC) actuators having large tip displacement and periodical jumping locomotion was investigated experimentally. Through snap-through phenomena, the actuator generates much larger tip displacement and shows abrupt jumps in the transitions of upswings and downswings with low input energy. Two curved IPMC cantilever actuators having two different constant curvatures of 0.01 mm−1 and 0.02 mm−1 were fabricated through thermal treatment from flat IPMCs, simultaneously with no residual stress. As-fabricated IPMC actuators were tested to evaluate the effect of initial curvature under static and dynamic electrical excitations. Unlike the case of the flat IPMC actuator, asymmetric characteristics in step and harmonic responses were investigated in the curved IPMC actuators. Also, at relatively higher input voltage, snap-through phenomena were observed with much larger transverse displacements and periodical abrupt jumps of the instant speed. This revealed jumping movements between the multiple equilibrium points. The results show that optimum curvatures for better bending performance of curved cantilever IPMCs exist and that this snap-through mechanism could be applied to IPMC actuators by considering their soft and flexible properties and the geometric structures.

High actuation response of PVDF/PVP/PSSA based ionic polymer metal composites actuator

For the biomedical application of IPMC actuator, IPMC should generate fast and large tip displacement at low direct current (DC) and alternating current (AC) voltages of 1–2 V. In this paper, the tip displacement of polyvinylidene fluoride (PVDF)/polyvinyl pyrrolidone (PVP)/polystyrene sulfonic acid (PSSA) based ionic polymer metal composites (IPMCs) actuators were tested at DC and AC voltages of 1–2 V, and the results were compared with that of the Nafion based IPMC actuator. Research on the PVDF/PVP/PSSA ionic membrane identified two novel compositions of PVDF/PVP/PSSA of blend ratios of 25/15/60 and 30/15/55 for the IPMC actuator which gave higher ion exchange capacity (IEC) and higher water uptake (WUP) than that of the Nafion membrane and proton conductivity nearly equal to that of the Nafion membrane. In an ionic membrane, PVDF is the hydrophobic polymer, PVP the basic, water-soluble polymer, and PSSA the strong, water-soluble polyelectrolyte, which provides the free charge carrier. A high-performance ionic polymer actuator should have large IEC, large WUP and large proton conductivity. At DC and AC voltages of 1–2 V, the PVDF/PVP/PSSA based actuator showed larger actuation with quick response time than those of the Nafion based IPMC actuator. The capacitance and imaginary part of impedance of all IPMCs were calculated at AC voltages of 1–2 V and the actuation performances of IPMCs were also tested and compared.

Electrospun Fullerenol-Cellulose Biocompatible Actuators

Though there are many stimuli-responsive polymer actuators based on synthetic polymers, electroactive natural biopolymer actuators are very rare. We developed an electrospun fullernol-cellulose biocompatible actuator with much lower power consumption and larger electromechanical displacement in comparison with a pure cellulose acetate actuator. Morphology of the electrospun membranes resembles the nanoporous structure of extracellular matrix in natural muscles. Presence of minute concentrations of fullerenol leads to sharp increase in the degree of crystallinity and substantial increase in tensile strength of membranes. Chemical interactions between cellulose acetate and fullerenols are confirmed by three shifts in carboxylate, carboxy, and carbonyl linkages from the Fourier-transform infrared spectrometry. Much larger tip displacement, nearly 3-fold even at 0.5 wt % fullerenol content, was observed with much lower power consumption under both alternating and direct current conditions.

1552 IN-VITRO ASSESSMENT OF TIP DYNAMICS IN A NEW PORTABLE BALLISTIC LITHOTRIPTER

You have accessJournal of UrologyStone Disease: New Technology/SWL, Ureteroscopic or Percutaneous Stone Removal1 Apr 20111552 IN-VITRO ASSESSMENT OF TIP DYNAMICS IN A NEW PORTABLE BALLISTIC LITHOTRIPTER Agnes J. Wang, Gavin McAlister, Jamie Gabriel, W. Neal Simmons, Michael E. Lipkin, Michael N. Ferrandino, Glenn M. Preminger, and Pei Zhong Agnes J. WangAgnes J. Wang Durham, NC More articles by this author , Gavin McAlisterGavin McAlister Durham, NC More articles by this author , Jamie GabrielJamie Gabriel Durham, NC More articles by this author , W. Neal SimmonsW. Neal Simmons Durham, NC More articles by this author , Michael E. LipkinMichael E. Lipkin Durham, NC More articles by this author , Michael N. FerrandinoMichael N. Ferrandino Durham, NC More articles by this author , Glenn M. PremingerGlenn M. Preminger Durham, NC More articles by this author , and Pei ZhongPei Zhong Durham, NC More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.1560AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Intracorporeal lithotriptor technology is moving towards devices that do not need a separate unit as an energy source. The benefits are in cost reduction as well as the portability and the “wireless” nature of the device. One such pneumatic device, the LMA Stonebreaker™, is powered by sterile CO2 cartridges. A new device under development is a battery-operated electrokinetic ballistic lithotripter in which probe velocity and displacement can be modified to suit clinical applications by changing the hardness of the probe guide. An in vitro model was designed to compare the tip speed and displacement characteristics of this new electrokinetic ballistic device. METHODS To determine tip velocity and displacement, the probe tip was aligned to partially occlude an expanded laser beam that was aimed at a high bandwidth photo detector. Displacement and velocity were measured for 1mm (ureteroscopic) and 2mm (percutaneous) probes with both hard and soft probe guides. The probe position was correlated with the voltage measurement from the photo detector. A digital oscilloscope was used to capture the time/displacement characteristics of the probe tip. Twenty-five displacement profiles were measured for each probe and support combination. Means and standard deviations were computed for all groups. RESULTS The tip displacement was significantly increased when a soft probe guide was used. The mean probe tip displacement increased 37% (0.31 ± 0.04mm increase) and 52% (0.42 ± 0.10mm increase) for ureteroscopic and percutaneous probes, respectively. Soft probes guides also increased the mean tip velocity by 15% (0.9 ± 0.2 m/s increase) and 14% (0.5 ± 0.2 m/s increase) for ureteroscopic and percutaneous probes, respectively. CONCLUSIONS The elasticity of the probe guide has a large impact on tip velocity and displacement characteristics of electrokinetic ballistic lithotrites. The ability to change tip dynamics may provide optimum performance over a wide range of stone types. High velocity and smaller displacement tip characteristics are suited for hard stones such as calcium oxalate monohydrate while lower velocity and larger tip displacement may be more useful on softer stones. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e623 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information Agnes J. Wang Durham, NC More articles by this author Gavin McAlister Durham, NC More articles by this author Jamie Gabriel Durham, NC More articles by this author W. Neal Simmons Durham, NC More articles by this author Michael E. Lipkin Durham, NC More articles by this author Michael N. Ferrandino Durham, NC More articles by this author Glenn M. Preminger Durham, NC More articles by this author Pei Zhong Durham, NC More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Fabrication of lead zirconium titanium and silica composite films on copper/polyimideflexible substrates

This paper uses the sol–gel technique to deposit lead zirconium titanium (PZT)and silica composite film onto a copper (Cu)/polyimide (PI) flexible structure at150 °C. First,the PZT nanoparticles (NPs) were dispersed in a silica sol. Silica sols with different concentrationsof PZT particles were spin coated on Cu/PI substrates. Finally, the substrates were sintered at150 °C to form PZT–silica composite films. The thickness of the PZT–silica composite film was7 µm with three coatings. The PZT–silica composite films show a random orientation andpolycrystalline phase in XRD. The fabricated PZT–silica composite films were thenimplemented into flexible actuator and flexible sensor applications and were designed in theform of a cantilever beam. For the actuator application, the flexible actuators werelighter than silicon-based actuators and had lower resonance frequencies thansilicon-based actuators. The flexible actuators also had a larger tip displacement (400 µm) than silicon-basedactuators (14.04 µm) when both of the films were driven by 10 V at the first resonance frequency. For the sensorapplication, the flexible sensor was excited at the first resonance mode to generate themaximum vibration amplitude. The applied strain and induced charges were compared. Inour results, the sensor output was 428 mV, when the size of the electrodes was10 mm × 10 mm at 42 Hz.

T1601-1-4 非鉛系KNN圧電薄膜を用いたカンチレバー型アクチュエータの作製([T1601-1]マイクロナノメカトロニクス(1))

We propose a new micro-fabrication process of piezoelectric MEMS actuators composed of lead-free KNbO_3-NaNbO_3 (KNN) thin films. The micro-cantilevers were fabricated on silicon on insulator(SOI) substrates, and successively the KNN thin films were directly deposited on them by rf-sputtering. Thus, piezoelectric unimorph micro-cantilevers of lead-free KNN films could be prepared without microfabrication of the KNN films. The dielectric properties of KNN thin films on micro-cantilevers were as good as those on the substrate. When we applied voltage of 20V, we could obtain relatively large tip displacement of up to 5.8μm and the average piezoelectric constant d_<31> was calculated to be -47.4pm/V. This fabrication process is useful for various applications of MEMS devices with new functional materials such as lead-free piezoelectric KNN films.

Novel biomimetic actuator based on SPEEK and PVDF

In this study, a novel electro-active polymer based on a blended polymer membrane of sulfonated poly(ether ether ketone) (i.e., SPEEK) and poly(vinylidene fluoride) (i.e., PVDF) is newly developed for the realization of a cost-effective and high-performing polymer actuator with controllable stiffness and ionic networking. The chemical, mechanical, and electrical properties of the SPEEK/PVDF membrane are compared with those of the pure SPEEK membrane. The step and harmonic responses of the SPEEK/PVDF actuator show much larger tip displacements without the straightening-back phenomenon in comparison with the SPEEK actuator. Also, the blocking force of the SPEEK/PVDF actuator is greater than that of the SPEEK actuator. The excellent electromechanical responses of the SPEEK/PVDF are due to the tailored stiffness and nano-channels of the ionic networking membrane. Present results show that SPEEK and SPEEK/PVDF ionic polymer membranes can be successfully used to fabricate electro-active polymer.