Showing papers on "Bimorph published in 2008"

Piezoelectric multifrequency energy converter for power harvesting in autonomous microsystems

Abstract: A multifrequency mechanoelectrical piezoelectric converter intended for powering autonomous sensors from background vibrations is presented. The converter is composed of multiple bimorph cantilevers with different natural frequencies, whose rectified outputs are fed to a single storage capacitor. The structure of the converter, description of the operation, and measurement data on the performances are reported. Experimental results show the possibility of using the converter with input vibrations across a wideband frequency spectrum, improving the effectiveness of the overall energy conversion over the case of a single converter. The converter was used to supply power to a battery-less sensor module that intermittently reads the signal from a passive sensor and sends the measurement information via RF transmission, in this way forming an autonomous sensor system with improved measure-and-transmit rate.

A large vertical displacement electrothermal bimorph microactuator with very small lateral shift

Abstract: This paper reports a novel electrothermal actuator design that can generate large vertical displacements with almost no lateral shift. The lateral-shift-free (LSF) piston motion is achieved by using a unique three-bimorph actuation mechanism. Both micromirrors and microlens holders based on this new actuator design have been fabricated using a combined surface- and bulk-micromachining process. A 0.62 mm vertical displacement is measured at only 5.3 V for a fabricated 0.8 mm by 0.8 mm micromirror, and both the lateral shift (10 μm) and tilting angle (0.7°) are very small in that full vertical displacement range. The measured resonant frequency of the vertical motion mode is about 0.5 KHz. The thermal response time is about 25 ms.

Actuating Single Wall Carbon Nanotube-Polymer Composites: Intrinsic Unimorphs**

Abstract: Electromechanical coupling effects in polymers have been routinely employed to create an array of sensors and actuators. The most dominant coupling effects originate from piezoelectric, electrostrictive, and electrostatic (also known as the Maxwell effect) mechanisms. To generate high displacements, electrostrictive and Maxwell effects are typically exploited because the strain in such polymers is a quadratic function of the applied electric field, whereas it is linear for piezoelectrics. However, the high compliance of most electrostrictive and electrostatic polymers limits their durability and output force and reduces their applicability. Owing to their low dielectric constants relative to ceramics, polymers typically require large applied electric fields to actuate. For strain amplification, several actuator concepts have been demonstrated including multilayer and bender designs. Most commercial actuators integrate design concepts, including unimorph, bimorph, and multimorph. These designs require extra processing steps and introduce extraneous layers such as adhesives and inactive, so-called ‘‘dummy’’, layers to convert longitudinal to bending strain. The incorporation of these adhesive and inactive layers reduces the magnitude of the actuation of a given actuation system significantly and often causes delamination. Furthermore, mismatches in the thermal expansion coefficients and mechanical properties among the adhesive, inactive, and active layers can cause additional adverse effects on the actuation performance. Here we introduce a novel electroactive single-walled carbon nanotube (SWNT)–polymer composite, an intrinsic unimorph, which can actuate to a large strain (2.6%) at relatively low driving voltages (<1 MV m ) while maintaining

Piezoelectric Energy Harvesting: A Green and Clean Alternative for Sustained Power Production.

Abstract: Providing efficient and clean power is a challenge for devices that range from the micro to macro in scale. Although there has been significant progress in the development of micro-, meso-, and macro-scale power supplies and technologies, realization of many devices is limited by the inability of power supplies to scale with the diminishing sizes of CMOS-based technology. Here, the authors provide an overview of piezoelectric energy harvesting technology along with a discussion of proof of concept devices, relevant governing equations, and figures of merit. They present two case studies: (a) energy capture from the operation of a novel shear and elastic modulus indentation device subjected to applied voltage and (b) energy capture from vibrating commercial bimorph piezoelectric structures mounted on household appliances. Lastly, areas of development needed for realization of commercial energy harvesting devices are suggested.

An Electrothermomechanical Lumped Element Model of an Electrothermal Bimorph Actuator

Abstract: This paper reports a simple electrothermomechanical lumped element model (ETM-LEM) that describes the behavior of an electrothermal bimorph actuator. The ETM-LEM is developed by integrating an electrothermal LEM of a heater with a thermomechanical LEM of a bimorph actuator. This new LEM uses only one power source in both the electrical and thermal domains. The LEM provides a simple and accurate way of relating the output mechanical response of a bimorph actuator to the electrical inputs. The model shows that the tip angular rotation of the bimorph actuator is linearly proportional to its average temperature change. The LEM predicts a linear relationship between both the average temperature change and bimorph tip angular rotation versus voltage when operated above a certain voltage. The LEM is used to predict the rotation angle of a fabricated electrothermal bimorph micromirror in response to the electrical inputs and produces results that agree with finite element model simulations and experimental data within 15% for all measured parameters.

Scanning proximal probes for parallel imaging and lithography

Abstract: Scanning proximity probes are uniquely powerful tools for analysis, manipulation, and bottom-up synthesis. A massively parallel cantilever-probe platform is demonstrated. 128 self-sensing and self-actuated proximal probes are discussed. Readout based on piezoresistive sensors and bending control based on bimorph dc/ac actuations are described in detail.

Piezoelectric energy harvesting from macro-fiber composites with an application to morphing-wing aircrafts

Abstract: The use of piezoelectric materials for low-power generation has been investigated by several researchers over the last decade. Typically, unimorph and bimorph cantilevers with conventionally poled monolithic piezoceramics have been implemented for this purpose. The experimental and modeling efforts in the literature are mostly limited to these monolithic configurations. However, there are several excitation conditions and operation environments where the monolithic piezoceramic configurations cannot be used due to their extremely brittle nature. The macro-fiber composite (MFC) piezoceramic configuration overcomes this issue owing to its flexible and robust nature. This paper investigates the MFC configuration for piezoelectric energy harvesting and presents a distributed-parameter electromechanical model. MFC unimorph configuration is modeled based on the Euler-Bernoulli beam theory and it is assumed to be excited by the translation of its base in the transverse direction with superimposed small rotation. A resistive load is considered in the electrical circuit for simplicity. After deriving the governing differential equations, closed-form solutions for the coupled vibration response and the voltage response are obtained for harmonic base excitations. Model predictions are first verified for an MFC unimorph with a brass substrate and then validations are given for MFC unimorphs with various substrate materials and thicknesses. For the same type of MFC with three different substrate materials (brass, aluminum and stainless steel), it is shown that the maximum peak power at resonance excitation is obtained for the aluminum substrate. Experimental results for different substrates are predicted successfully by using the coupled analytical model proposed here. Finally, results from the preliminary wind tunnel experiments are presented for piezoelectric energy harvesting from a flow-excited morphing airfoil with MFCs.

Thermal noise cancellation in symmetric magnetoelectric bimorph laminates

Abstract: We have found a symmetric Terfenol-D/Pb(Zr,Ti)03 (PZT) bimorph magnetoelectric (ME) laminate, which operates in a bending mode under an unsymmetrical (U-shaped) magnetic bias. It has a giant ME voltage coefficient of about 70V∕cmOe at resonance. Unlike other symmetric ME laminate structures, the symmetric bimorph structure has the capability to reject thermal noise from a magnetic signal, due to its back-to-back structure. The mechanism for the thermal noise cancellation capability is that the laminate operates in a bending mode (out charges of reverse sign), whereas the thermal noise is contained in a longitudinal mode (out charges have the same sign, allowing cancellation by differential detection).

Optimization of clamped circular piezoelectric composite actuators

Abstract: This paper addresses the design of clamped circular piezoceramic composite unimorph and bimorph configurations, specifically the conflicting requirements of maximum volume displacement for a prescribed bandwidth. An optimization problem is formulated that implements analytical solutions for unimorph and bimorph configurations using laminated plate theory, including the use of oppositely polarized piezoceramic patches. A range of actuator geometric parameters are studied, and bounds for volume displacement and natural frequency of optimal designs are determined and presented via design curves. In the selected design space, Pareto optimization results for unimorph and bimorph configurations show that optimal volume displacement is related to the bandwidth by a universal power law such that the product of the square of the natural frequency and the displaced volume, a “gain-bandwidth” product, is a constant. Characteristic trends are also described that are independent of the actuator radius for the Pareto optimal piezoceramic patch thickness and radius versus normalized bandwidth. The results are relevant, for example, in the design of zero-net mass-flux or synthetic jet actuators used in flow control applications.

Piezoelectric energy harvester having planform-tapered interdigitated beams

Abstract: Embodiments of energy harvesters have a plurality of piezoelectric planform-tapered, interdigitated cantilevered beams anchored to a common frame. The plurality of beams can be arranged as two or more sets of beams with each set sharing a common sense mass affixed to their free ends. Each set thus defined being capable of motion independent of any other set of beams. Each beam can comprise a unimorph or bimorph piezoelectric configuration bonded to a conductive or non-conductive supporting layer and provided with electrical contacts to the active piezoelectric elements for collecting strain induced charge (i.e. energy). The beams are planform tapered along the entirety or a portion of their length thereby increasing the effective stress level and power output of each piezoelectric element, and are interdigitated by sets to increase the power output per unit volume of a harvester thus produced.

Adjusting the resonant frequency of a PVDF bimorph power harvester through a corrugation-shaped harvesting structure

Abstract: We propose a corrugated polyvinylidene fluoride (PVDF) bimorph power harvester with the harvesting structure fixed at the two edges in the corrugation direction and free at the other edges. The resonant frequency of a corrugated PVDF bimorph is readily adjusted through changing either its geometrical configuration or the span length, which can keep the harvester operating at the optimal state in environments with different ambient vibrations. The governing equations of a PVDF bimorph with a corrugation shape, are derived from the transfer-matrix technique. Statistical results show that the adaptability of a harvester to the operating environment can be improved greatly by designing the harvesting structure with adjustable resonant frequency.

Fast bender actuators for fish-like aquatic robots

Abstract: Small, highly-mobile "swimming" robots are desired for underwater monitoring operations, including pollution detection, video mapping and other tasks. Actuator materials of all types are of interest for any application where space is limited. This constraint certainly applies to the small-scale swimming robot, where multiple small actuators are needed for forward/backward propulsion, steering and diving/surfacing. A number of previous studies have demonstrated propulsion of floating objects using IPMC type polymer actuators [1-3] or piezoceramic actuators [4, 5]. Here, we show how propulsion is also possible using a multi-layer polypyrrole bimorph actuator. The actuator is based on our previously published work showing very fast resonance actuation in polypyrrole bending-type actuators [6]. The bending actuator is a tri-layer structure, in which the gold-PVDF (porous poly(vinylidene fluoride) membrane) substrate was coated on both sides with polypyrrole layers to form an electrochemical cell. Polypyrrole films on gold coated PVDF were grown galvanostatically at a current density of 0.10 mA/cm2 for 12 hours from propylene carbonate (PC) solution containing 0.1 M Li+TFSI-, 0.1 M pyrrole and 1% (w/w) water. The polypyrrole deposited PVDF was thoroughly rinsed with acetone and stored in 0.1 M Li+TFSI- / PC solution. The edges of the bulk film were trimmed off and the bending actuators were prepared as rectangular strips typically 2mm wide and 25 mm long. These actuators gave fast operation in air (to 90 Hz), and were utilised as active flexural joints on the tail fin of a fishshaped floating "boat". The actuators were attached to a simple truncated shaped fin and the deflection angle was analysed in both air and liquid for excitation with +/- 1V square wave at a range of frequencies. The mechanical resonance of the fin was seen to be 4.5 Hz in air and 0.45 Hz in PC, which gave deflection angles of approximately 60° and 55° respectively. The boat contained a battery, receiver unit and electronic circuit attached to the actuator fin assembly. Thus, the boat could be operated by remote control, and by varying the frequency and duty cycle applied to the actuator, the speed and direction of the boat could be controlled. The boat had a turning circle as small as 15 cm in radius and a maximum speed of 2m/min when operating with a tail frequency of approximately 0.7 Hz. The efficiency of the flapping tail fin was analysed and it was seen that operation at this frequency corresponded with a Strouhal number in the optimal range.

Development of adjustable grazing incidence optics for Generation-X

Abstract: For X-ray astronomy, 0.1 arc-second imaging resolution will result in a significant advance in our understanding of the Universe. Similarly, the advent of low cost high performance X-ray mirrors will also increase the likelihood of more X-ray telescopes being funded and built. We discuss the development plans of two different types of adjustable grazing incidence optics: one being a tenth arc-second resolution bimorph mirror approach also suitable for extremely large collecting areas, and the second being a few arc-second radially adjustable mirror approach more suitable for modest sized telescopes. Bimorph mirrors will be developed using thin (0.1 - 0.4 mm) thermally formed glass or electroplated metal mirror segments with thin film piezo-electric actuators deposited directly on the mirror back surface. Mirror figure will be adjusted on-orbit. Radially adjustable mirrors will employ discreet radially electrostrictive actuators for mirror alignment and low spatial error frequency figure correction during assembly and alignment. In this paper we report on. In this paper we describe mirror design and our development plans for both mirror concepts.

A large-displacement 65Pb(Mg1/3Nb2/3)O3–35PbTiO3/Pt bimorph actuator prepared by screen printing

Abstract: In this paper we present a novel approach to preparing large-displacement 65Pb(Mg1/3Nb2/3)O3–35PbTiO3/Pt (65/35 PMN–PT/Pt) bimorph actuators. These “substrate-free”, bending-type actuators were prepared by screen-printing the 65/35 PMN–PT and Pt thick-film pastes as the electrodes on alumina substrates. After this screen printing and the subsequent firing the 65/35 PMN–PT/Pt composites were peeled off from the substrates. Displacements of nearly 100 μm at 18 V were achieved for actuators with dimensions of 1.8 cm × 2.5 mm × 50 μm for the 65/35 PMN–PT layer. The normalized displacement (the displacement per unit length) was 40 μm/cm at 18 V. The experimental results together with a computation procedure were used to obtain the material parameters for a finite-element analysis of the 65/35 PMN–PT/Pt bimorph actuators.

An improved small-deflection electromechanical model for piezoelectric bending beam actuators and energy harvesters

Abstract: The analytical model presented in this paper describes the energy conversion mechanism of a piezoelectric beam (bimorph) under small-deflection static and vibrating conditions. The model provides an improved approach to design and analyze the performance of piezoelectric actuators and energy harvesters (sensors). Conventional models assume a linear voltage distribution over the piezoelectric beam thickness, which is shown here to be invalid. The proposed modeling method improves accuracy by using a quadratic voltage distribution. The equivalent capacitance of a beam shows a 40% discrepancy between a conventional model and the proposed model for PZT5A material. This inaccuracy level is not negligible, especially when the design of micro-power electrical energy harvesting is concerned. The method solves simultaneously the solid mechanics and Maxwell's equations with the constitutive equations for piezoelectric materials. The paper also proposes a phasor-based procedure for measuring the damping of a piezoelectric beam. An experimental setup is developed to verify the validity of the model. The experimental results confirm the accuracy of the improved model and also reveal limitations in using models for small deflections.

Electrothermal actuation studies on silicon carbide resonators

Abstract: The electromechanical behavior of SiC clamped-clamped beam (bridge) resonators with u-shaped aluminium (Al) electrodes on top has been studied as a function of electrode length, width, and spacing Negative and positive deflections have been observed, indicating a complex interplay exhibited by the combined single material and bimorph characteristics of the resonator structures It has been found that, both experimentally and theoretically, devices with electrodes applied on the root of the beam have similar or higher displacement amplitudes compared to devices with electrodes covering the half or the entire beam Moreover, the displacement and vibration amplitudes can be maximized by increasing the electrode width and/or decreasing the spacing

Experimental design and analysis for piezoelectric circular actuators in flow control applications

Abstract: Flow control can lead to saving millions of dollars in fuel costs each year by making an aircraft more efficient. Synthetic jets, a device for active flow control, operate by introducing small amounts of energy locally to achieve non-local changes in the flow field with large performance gains. These devices consist of a cavity with an oscillating diaphragm that divides it into active and passive sides. The active side has a small opening where a jet is formed, while the passive side does not directly participate in the fluidic jet. Over the years, research has shown that synthetic jet behavior is dependent on the active diaphragm and the cavity design; hence, the focus of this work. The performance of the synthetic jet is studied under various factors related to the diaphragm and the cavity geometry. Three diaphragms, manufactured from piezoelectric composites, were selected for this study: Bimorph, Thunder? and Lipca. The overall factors considered are the driving signals, voltage, frequency, cavity height, orifice size, and passive cavity pressure. Using the average maximum jet velocity as the response variable, these factors are individually studied for each actuator, and statistical analysis tools are used to select the relevant factors in the response variable. The factors are divided into two experimental fractional factorial design matrices, with five and four factors, respectively. Both experiments are chosen to be of resolution V, where main factors are confounded with three-factor interactions. In the first experimental design, the results show that frequency is not a significant factor, while waveform is significant for all the actuators. In addition, the magnitude of the regression coefficients suggests that a model that includes the diaphragm as a factor may be possible. These results are valid within the ranges tested, that is low frequencies and sawtooth and sine waveform as driving signals. In the second experimental design, cavity dimensions are kept constant and four factors including back pressure are considered. In this case, each diaphragm produces different results with only one diaphragm, Thunder, showing a definite relationship between the studied factors. The other two diaphragms do not show conclusive results, indicating that there may be other factors that need to be considered when pressure is a concern. In summary, independently of the diaphragm utilized in a synthetic jet actuator, applied waveform is an important factor when maximizing peak jet velocity. In addition, frequency is found not to be significant in all cases within the limits of the study. This indicates that the diaphragm and the driving signal should be included in any optimization design of a piezoelectric synthetic jet actuator.

Development and optimization of microcantilever based IR imaging arrays

Abstract: Multispectral Imaging has recently made considerable improvements to the sensitivity, uniformity and dynamic range of infrared FPAs based on capacitively read, bimorph microcantilever sensor technology. The company is presently prototyping 160x120 imaging arrays with 50 µm pitch pixels and is actively pursuing the development of next generation 25 µm pitch pixel arrays. Measured peak NETD values for recently fabricated 50 µm pitch focal plane arrays are in the 40-50mK range, with individual pixels in the 10-15mK range. The modeled and measured tradeoffs discussed in this paper lead to a possible 2-3 times further improvement in average NETD. A number of factors influence the performance of these devices which includes the optimization of sometimes competing design requirements. For example, the tuning and optimization of the infrared optical resonant cavity structure while maximizing the change in sensor capacitance during IR irradiance. Similarly there are tradeoffs between structural rigidity, which increases the structure resonant frequency improving noise immunity, and thermal response times. These tradeoffs are discussed with reference to real world sensor structures. Results from detailed thermo-electromechanical-optical modeling of the operation of the 25 µm pitch pixels will be discussed in reference to the design and fabrication of 25 µm pitch test pixels. The most recent infrared sensitivity and other performance measurements from the development of the company’s first commercial 160 x 120 pixel imaging array product will also be presented. Key Words: Infrared, thermal, bimorph, sensor , imager, MEMS, surface micromachining

Magneto-Electro-Elastic Bimorph Analysis by the Boundary Element Method

Abstract: The influence of the magnetic configuration on the behavior of magneto-electro-elastic bimorph beams is analyzed by using a boundary element approach. The problem is formulated by using the generalized displacements and generalized tractions. The boundary integral equation formulation is obtained by extending the reciprocity theorem to magneto-electro-elastic problems; it is numerically implemented by using the boundary element method multidomain technique to address problems involving nonhomogeneous configurations. Results under different magnetic configurations are compared highlighting the characteristic features of magnetopiezoelectric behavior particularly focusing on the link between interlaminar stress and magnetic induction.

Analytical Modeling of Cantilevered Piezoelectric Energy Harvesters for Transverse and Longitudinal Base Motions

Abstract: Recent developments in electronics have reduced the power requirement of small electronic components and motivated the research for operating such devices by using the vibration energy available in their ambient. Among the alternatives for vibration-to-electric energy conversion, piezoelectric materials have received the highest attention in the last five years. Several authors have considered a cantilevered beam with one or two piezoceramic layers connected to a resistive electrical load as a piezoelectric energy harvester model. The early mathematical modeling attempts appeared in the literature so far range from elementary single-degree-of-freedom models to approximate distributed parameter models in the sense of Rayleigh-Ritz discretization. In addition, there have been some distributed parameter modeling approaches which ignore modal summation or oversimplify backward coupling in the mechanical domain and some misleading modeling attempts due to weak mathematical assumptions. In this paper, we present analytical solutions for coupled electrical and mechanical response of cantilevered piezoelectric energy harvesters under transverse and longitudinal vibrations due to harmonic base excitation. First, closed-form expressions of voltage response and mechanical response are derived for unimorph and bimorph harvester beam configurations under transverse vibrations (due to translation of the base with superimposed small rotation). The derivation is then extended to cantilevered harvester bars in longitudinal vibrations. After deriving closed-form voltage and mechanical response expressions for harmonic base excitations at arbitrary frequencies, the relations are reduced to single-mode expressions for excitations around the modal (natural) frequencies. The analytical derivation is also used for handling of non-harmonic base acceleration inputs by combining the analytical voltage – to – base acceleration frequency response functions with the Fourier series representation of non-harmonic base acceleration histories. Theoretical demonstrations and experimental verifications are also presented.

The gas flow rate increase obtained by an oscillating piezoelectric actuator on a micronozzle

Abstract: Micronozzles with piezoelectric actuator were fabricated and investigated. The micronozzles were fabricated in glass substrates using a powder-blasting technique, and the actuator is a bimorph structure made from a piezoelectric polymer. The actuator was located at the nozzle outlet, and was driven in an oscillating mode by applying an alternating voltage across the actuator electrodes. With a pressure difference between inlet and outlet, the gas flow rate through the device was increased. This effect was quantified, and compared to a similar micronozzle with no actuator. The increase in the flow rate was defined as the gas flow through the micronozzle with actuator oscillating minus the gas flow without actuator, was found to depend on the inlet pressure, the pressure ratio, and the nozzle throat diameter.

An exceptional bimorph effect and a low quality factor from carbon nanotube-polymer composites.

Abstract: Microcantilever actuators made from carbon nanotube polymer are driven at very low pull-in voltages and the thermal bimorph effect reaches 325 µm at 26–110 °C, much greater than the values for existing devices.

Design and validation of a fuzzy logic controller for a smart projectile fin with a piezoelectric macro-fiber composite bimorph actuator

Abstract: This paper focuses on the design and validation of a fuzzy logic controller for the smart fin of a projectile. The hollow fin is actuated by a cantilevered piezoelectric bimorph that is completely enclosed within it. A linear model of the actuator and fin is identified experimentally by exciting the system using a chirp signal. A procedure for designing a genetic algorithm (GA)-based fuzzy logic controller for the fin is presented. The controller is validated using simulation and experimental testing that is conducted in the subsonic wind tunnel at the University of Nevada, Las Vegas (UNLV). Results show that the proposed controller accomplishes the desired fin angle control under various operating conditions.

Bimorphic structures, sensor structures formed therewith, and methods therefor

Abstract: A bimorphic structure responsive to changes in an environmental condition, sensor structures incorporating one or more of such bimorphic structures, and a method of forming such bimorphic structures. The sensor structure has an electrically-conductive first contact on a substrate, and a bimorph beam anchored to the substrate so that a portion thereof is suspended above the first contact. The bimorph beam has a multilayer structure that includes first and second layers, with the second layer between the first layer and the substrate. A portion of the first layer projects through an opening in the second layer toward the first contact so as to define an electrically-conductive second contact located on the beam so as to be spaced apart and aligned with the first contact for contact with the first contact when the beam sufficiently deflects toward the substrate.

Formation of Bidomain Structure in Lithium Niobate Single Crystals by Electrothermal Method

Abstract: Original electrothermal method of the manufacturing of the bimorph devices based on single crystals of lithium niobate was proposed. It has been shown that obtained bidomain structures offer several advantages over the traditional bimorph elements based on piezoelectric ceramics. The possible applications of the plates with bidomain structures for high-precision micro-and nano-scale translation in scanning probe microscopes are discussed.

Development of adaptive fiber collimators for conformal fiber-based beam projection systems

Abstract: We describe bimorph piezoelectric fiber actuators, which enable tip and tilt control in fiber collimators, as well as their integration into a fiber-array based beam-projection system. A mechanism for alignment of individual fiber actuators within the array was developed. It provides six degrees of freedom and allows for high subaperture density. The alignment procedures for a seven-subaperture prototype system as well as first results from evaluation experiments are presented.

Novel electrothermal bimorph actuator for large out-of-plane displacement and force

Abstract: This paper presents a novel concept and experimental validation of an electrothermal bimorph structure for out-of-plane actuation that exploits the polymer constraint effect. The proposed concept is capable of generating large out-of-plane displacements and forces at a low driving voltage and a low actuation temperature. A downward displacement up to 31 mum is measured at only 5 V driving voltage and 46 mW power consumption. The actuator stiffness is measured to be 75 N/m, thus the corresponding calculated out-of-plane force is 2.3 mN. The maximum actuation temperature during the measurement is 100degC (80degC change). A 25 Hz response frequency is measured by monitoring the resistance change due to the temperature variation.