T-shaped Cantilever Research Articles

Axial asymmetry for improved sensitivity in MEMS piezoresistors

The strain induced resistance change is compared for asymmetric, symmetric and diffused piezoresistive elements. Finite element analysis is used to simulate the performance of a T-shaped piezoresistive MEMS cantilever, including a lumped parameter model to show the effect of geometric asymmetry on the piezoresistor sensitivity. Asymmetric piezoresistors are found to be much more sensitive to applied load than the typical symmetric design producing about two orders of magnitude higher resistance change. This is shown to be due to the difference in the stress distribution in the symmetric and asymmetric geometries resulting in less resistance change cancellation in the asymmetric design. Although still less sensitive than diffused piezoresistors, asymmetric piezoresistors are sensitive enough for many applications, and are much easier to fabricate and integrate into MEMS devices.

Design and Analysis of a T-shaped Piezoelectric Cantilever Beam at Low Resonant Frequency using Vibration for Biomedical Device

Ambient vibration energy can be converted into electrical energy in an energy harvester system by using three mechanisms; piezoelectric, electrostatic and electromagnetic. Among three mechanisms, piezoelectric mechanism is most efficient. In this mechanism, mechanical stress and strain generation of piezoelectric materials can be converted into electrical energy by ambient vibration energy for low power electronic system. To implement a piezoelectric energy harvester system from ambient vibration, a lower range of frequency will be chosen. To achieve the lower resonant frequency and higher stress of energy harvester, a cantilever beam is suitable because of its least stiff structure.

DESIGN AND CHARACTERIZATION OF VARIOUS SHAPES OF MICROCANTILEVER FOR HUMAN IMMUNODEFICIENCY VIRUS DETECTION

The ability to detect pathogenic relevant molecules in the human body with high sensitivity and specificity has a powerful opportunity in early diagnosis and treatment of diseases. This paper presents the design, analysis and simulation of MEMS microcantilevers with various shapes like rectangular, triangular, V-shape and T-shape (Paddle) for one HIV detection with mass 10 -18 Kg which produces force of 9.81x 10 -18 Newton, To analyze the sensitivity of microcantilever , SiO2 material is used. The simulation of these designs is performed by Comsol Multiphysics. The change in total displacement of a microcantilever with respect to change in its shape for the same applied force is observed. From the analysis performed T-shape (Paddle) cantilever with length 1000µm, width 100 µm, thickness 0.5 µm with paddle length 500 µm, width 100 µm and thickness 0.5 µm produces maximum displacement of 3.24 x10 -07 µm. By this obtained deflection, using recent advanced read out systems the disease can be

A Complementary Dual-Contact MEMS Switch Using a “Zipping” Technique

This paper presents a microelectromechanical systems contact switch having both hard and soft contact materials in a single cantilever-type switching device. It operates with a zipping mechanism within which both contact materials (Pt-to-Pt and Au-to-Au) make individual contact sequentially and then detach in a reverse sequence to take advantage of both contact materials: low contact resistance and high reliability in a hot switching condition. In addition, an extended gate electrode and double T-shape cantilever beam structures effectively facilitate the sequential actuation. The fabricated switch successfully demonstrated a “dual-contact concept”-it made two sequential contacts at 31 (Pt-to-Pt) and 56 V (Au-to-Au) and it was then detached at 49 (Au-to-Au) and 23 V (Pt-to-Pt) in a single switching operation. Also, it achieved a low contact resistance of 0.3-0.5 Ω (including beam and some portion of the signal line resistances) at gate voltage from 60 to 70 V owing to the Au-to-Au contact in the device. Simultaneously, negligible contact resistance variation was observed during 2 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> cycles at a voltage/current level of 10 V/10 mA under hot switching and unpackaged environments, representing >100-fold longer lifetime than that of a conventional Au-to-Au cantilever switch fabricated on the same wafer.

Power evaluation of flutter-based electromagnetic energy harvesters using computational fluid dynamics simulations

H- and T-shaped cross sections are known to be susceptible to rotational single-degree-of-freedom aerodynamic instabilities. Here, such self-excited aerodynamic response of a T-shaped cantilever structure is used to extract energy, which is then converted into electric power through an electromagnetic transducer. The complex fluid–structure interaction between the cantilever harvester and wind flow is analyzed numerically and experimentally. To study the dynamic response of the cantilever and estimate the power output from the harvester, numerical simulations based on the vortex particle method are performed to determine the aerodynamic damping of the harvester section and to analyze the stability behavior of the section. The estimated aerodynamic damping parameter together with the mechanical and electrical damping parameters in the harvester are used to find the critical wind speed of flutter onset as well as the optimum load resistance. Wind tunnel experiments are conducted to validate the simulation results.

Torsional resonance frequency analysis: a novel method for assessment of dental implant stability

To establish and experimentally validate a novel resonance frequency analysis (RFA) method for measurement of dental implant stability by analyzing torsional resonance frequency (TRF). A numerical study and in vitro measurements were performed to evaluate the feasibility and reliability of the method of torsional RFA (T-RFA) using a T-shaped bilateral cantilever beam transducer. The sensitivity of this method was assessed by measuring the TRFs of dental implants with 8 sizes of T-shaped transducers during polymerization, which simulated the process of bone healing around an implant. The TRFs of the test implants detected using this new method and the bending resonance frequencies (BRFs) measured by Osstell(®) ISQ were compared. TRFs and BRFs on implant models in polymethyl methacrylate (PMMA) blocks with three exposure heights were also measured to assess the specificity of this method. Finite element analysis showed two bending modes (5333 and 6008 Hz) following a torsional mode (8992 Hz) in the lower rank frequency. During in vitro measurements, a bending formant (mean 6075 Hz) and a torsional formant (mean 10225 Hz) appeared, which were verified by multipoint measurement with invariable excitation frequency in the laboratory. In the self-curing resin experiments, the average growth rate at all time points of TRFs using the new method with Transducer II was 2.36% and that of BRFs using Osstell(®) ISQ was 1.97%. In the implant exposure height tests, the mean declined rate of TRFs was 2.06% and that of BRFs using Osstell(®) ISQ was 12.34%. A novel method for assessment of implant stability through TRF was established using a T-shape transducer, which showed high reliability and sensibility. The method alleviated the effects of implant exposure height on the measurements compared with Osstell(®) ISQ. The application of T-RFA represents another way in the investigation of dental implant osseointegration.

Packaging strategy for maximizing the performance of a screen printed piezoelectric energy harvester

This paper reports the extended design and simulation of a screen printed piezoelectric energy harvester. The proposed design was based on a previous credit card sized smart tag sensor node, and packages the power conditioning circuit in the free space above the tungsten proof mass layer. This approach enables electronic components to be mounted onto the cantilever beam, which provides additional weight at the tip of the cantilever structure. The design structure contains a T-shape cantilever beam with size of 47 mm × 30 mm × 0.85 mm which is fabricated using screen printing. ANSYS simulation results predict the revised architecture can generate 421.9 μW approximately twice of the RMS power produced by the original design along with a higher open-circuit RMS Voltage of 8.0 V while the resonant frequency is dropped to 53.4 Hz.

Особливості впливу демпфування на коефіцієнт ефективності симетрично-консольного віброізолятора телескопічної стріли автокрана

Influence of damping over the efficiency factor of the symmetric cantilever vibration isolator of the automobile’s crane telescopic boom has been considered. It’s been shown that if all forms of the intermediate mass oscillations of beam type or T-shaped symmetric cantilever vibration isolator are related then realization of vibro-isolated characteristics is possible which has a local minimum of transfer ratio equaled to zero even taking into consideration damping at the operating frequency.

Design and Fabrication of a Novel T-Shaped Piezoelectric ZnO Cantilever Sensor

A novel T-shaped piezoelectric ZnO cantilever sensor for chem/bio-detection is designed and fabricated with MEMS technology. By using Rayleigh-Ritz method, the fundamental resonant frequency formula of T-shaped cantilevers is deduced for the first time and is validated by simulation results and experimental results. From this formula, we can easily find the superiority of adopting T-shape for the cantilevers. The complete process of the cantilever sensor is then successfully developed. The cantilever sensor is actuated by a layer of high-quality ZnO film with preferred (002) orientation, which is evaluated by SEM and XRD. The key step of the process is protecting the ZnO film from KOH etching by a novel and effective method, which has rarely appeared in the literature. Finally, this cantilever sensor is measured by a network analyzer, and it has a fundamental resonant frequency of 24.60 kHz. The cantilever sensor developed in this study illustrates the feasibility and potential for many miniaturized sensor applications.

Theoretical Analysis of Designed Internal Forces of Jiamusi Highway Prestressed Concrete Bridge before Strengthening in China

The objective of this study is to calculate and analyze the internal forces under designed dead and live loads to evaluate the structural performance of corbels and T-shaped cantilever structure of the main span of Jiamusi highway prestressed concrete bridge to evaluate the state of the structural members of the bridge. Two software are used in this analysis. The first software is Dr. Bridge Ver. 2.95 which is used to analyze the internal forces of T-shaped cantilever structure under different load combinations. The second software is Ansys Ver. 10 which is used to analyze the internal forces in the corbel. The results of analysis show that at the dead load stage, the maximum compressive stress at the upper and bottom edge of all sections of T-shaped cantilever structure satisfies the allowable values of standard. The tensile stress doesn’t appear. At the normal service stage, there is enough reserve of compressive stress in the all sections, and the compressive stress is smaller than the allowable value of the standard. There is no tensile stress for all the controlled sections. The maximum main compressive stress and maximum main tensile stress of all controlled sections is smaller than the allowable value of standard. The bending strength of all sections satisfies the allowable values of standard, and there is big reserve of strength. The steel settled in the oblique section of 45° in the web of the corbel has enough reserve for the tensile strength. If the prestressed steel in the corbel is inefficient, the resistance of the oblique section given by the ordinary steel in the corbel and it can be resisted the loads. The longitudinal positive stress of vertical section a-b, vertical shear stress, main tension stress and main tension stress of oblique section a-c of 45 satisfy the allowable values of standard.

Experimental Inspection of Damage and Performance Evaluation after Repair and Strengthening of Jiamusi Highway Prestressed Concrete Bridge in China

The main objectives of this study are to inspect an d identify any damage of jaimusi highway prestressed concrete bridge after repair and strengthening of damaged structura l members and to evaluate the performance of the bridge structural m embers by adopting static load test. Inspection program after repair and strengthening includes identifying and evaluating t he structural members of bridge such as T-shape cantilever struct ure, hanging beams, corbels, external tendons, anchor beams, sti cking steel plate, and piers. The results of inspection show that the overall state of the bridge structural member after repair and strengthe ning is good. The results of rebound test of concrete strength show t hat the average strength of concrete is 46.31Mpa. Whereas, the aver age value of concrete strength of anchor beam is 49.82Mpa. According to the results of static load test, the experimental value s are less than theoretical values of internal forces, deflection, and strain, indicating that the stiffness of the experimental structure, o verall deformation and integrity satisfy the designed standard and the working performance is good, and the undertaking capacity h as a certain surplus. There is not visible change in the length and width of cracks and there are not new cracks under experimental loa d. Keywords—Jiamusi Bridge, Damage inspection, deflection, strain.

A T-shaped piezoelectric cantilever for fluid energy harvesting

This paper proposes a T-shaped piezoelectric cantilever for generating electric power from fluid flow. The working principle of the device is based on aeroelastic flutter and utilizes a bimorph cantilever with T-shape which hastens occurrence of flutter at a low fluid speed. A prototype device (100×60×30 mm3) was tested in a wind tunnel. The device was found to provide power from a wind speed of 4 m/s and a continuous peak electrical power output of 4.0 mW. The simplicity of the present device consisting of only a bimorph cantilever is considered to be cost effective.

A New AFM Nanotribology Method Using a T-Shape Cantilever with an Off-Axis Tip for Friction Coefficient Measurement with Minimized Abbé Error

A new AFM (atomic force microscopy) nanotribology method using a T-shape cantilever with an off-axis tip (Nat Nanotechnol 2:507–514, 2007) has been developed for measuring friction coefficient at nanometer scale. In this method, signals due to both bending and twisting of the T-shape AFM cantilever are detected simultaneously. For a T-shape AFM cantilever, the bending is caused by the normal load and the twisting is caused by both the normal and the lateral loads. The twisting generated by the normal load is calibrated in advance. Consequently, the twisting only due to the lateral load can be decoupled from the total lateral voltage signal. And the friction coefficient can be finally determined based on a conversion relationship between the normal and lateral voltage signals of the AFM photodetector. A practical procedure for minimizing Abbe error in friction coefficient measurement has also been introduced. The proposed new method is simple and accurate, and requires the least operation for friction coefficient measurement at nanometer scale.

Numerical analysis of dynamic force spectroscopy using the torsional harmoniccantilever

A spectral analysis method has been recently introduced by Stark et al (2002 Proc. NatlAcad. Sci. USA 99 8473–8) and implemented by Sahin et al (2007 Nat. Nanotechnol. 2507–14) using a T-shaped cantilever design, the torsional harmonic cantilever(THC), which is capable of performing simultaneous tapping-mode atomic forcemicroscopy imaging and force spectroscopy. Here we report on numerical simulations ofthe THC system using a simple dual-mass flexural–torsional model, which isapplied in combination with Fourier data processing software to illustrate thespectroscopy process for quality factors corresponding to liquid, air and vacuumenvironments. We also illustrate the acquisition of enhanced topographical images anddeformed surface contours under the application of uniform forces, and compare theresults to those obtained with a previously reported linear dual-spring–mass model.

Sensitivity improvement of a microcantilever based mass sensor

This article describes two approaches for sensitivity improvement of a micromachined silicon T-shaped cantilever resonator for mass sensing applications. In order to increase sensitivity values, higher order resonance mode was used and device dimensions were reduced. The cantilevers proposed are piezoelectrically actuated and the movement detection is done by four piezoresistors in a Wheatstone bridge configuration. Two types of cantilevers were fabricated: for the first cantilever of 400 μm long, 300 μm wide and 15 μm thick, the fundamental and second resonance frequency in air were 100 kHz ± 0.4 and 690 kHz ± 15, respectively, both with a quality factor of ∼800. And for the second cantilever of 200 μm long, 150 μm wide, 15 μm thick, the fundamental resonance frequency in air was 400 kHz ± 5 with a quality factor of ∼900. The devices were characterized attaching microspheres of polystyrene to the cantilever’s surface tip and measuring resonance frequency changes. For the first cantilever sensitivity values of 0.07 and 0.3 Hz/pg for the fundamental and second mode, respectively were achieved and 1.3 Hz/pg for the second cantilever. These results show the great potential for high sensitive mass sensor of this simple device.

走査型力顕微鏡のための三次元駆動圧電マイクロカンチレバー

A new type piezoelectric microcantilever which can be actuated in three orthogonal directions and can detect its deflection is proposed for the application for scanning force microscopy. A T-shaped cantilever with one piezoelectric layer is designed. Calculations show that the cantilever has a scanning area larger than 1×1 μm and vertical resolution smaller than 1 nm. The microfabrication process including the deposition of 3-μm-thick PZT film by sol-gel method is developed, and a test device is successfully fabricated.