Maximum Voltage Response Research Articles

High-frequency inlaid cylindrical piezoelectric transducer for high-sensitivity acoustics

This work develops a high-frequency high-sensitivity inlaid cylindrical hydroacoustic transducer by enhancing the electromechanical coupling coefficient, amplifying stress, and adopting circumferential inlaid techniques. Equivalent circuit and finite element simulation methods were used to determine the optimum parameters of the unit, then the transducer was fabricated. Tests show that the resonant frequency of every array unit was 220 kHz. The maximum emission voltage response and reception sensitivity were respectively about 172 dB and −177 dB, with emission and reception bandwidths both about 40 kHz at 3 dB loss. The horizontal and vertical beamwidths were 15° and 4° for each unit respectively.

Research and preparation of a tri-ring stacking round tubular ultrasonic transducer

In this paper, a high frequency, wide band, horizontal omnidirectional ultrasonic transducer for piezoelectric composite tubes was developed. The sensing element of the ultrasonic transducer was a tri-ring stacking round tube structure. This structure is designed to increase the opening angle of the wave speed and widen the bandwidth. The test results of the ultrasonic transducer when it works in water are as follows: the central frequency is about 300 kHz, the maximum sending voltage response is 158 dB, the working bandwidth is 111.52 kHz, and the maximum receiving sensitivity is −208 dB.

Enhancement of self-powered humidity sensing of graphene oxide-based triboelectric nanogenerators by addition of graphene oxide nanoribbons.

A triboelectric nanogenerator (TENG) electrode sensitive to the adsorption of water molecules has been introduced to create a self-powered humidity sensor. Graphene oxide (GO) nanosheets and graphene oxide nanoribbon (GONR) possessing oxygenated functional groups, as well as high dielectric constants, have been proposed as appropriate candidates for this purpose. GO papers have been fabricatedin three forms, i.e. pure GO paper, uniform composites of GONR and GO, and double-layer structures of GONR on top of GO. Results showed that all of the prepared paper-based TENGs revealed excellent performances by maximum output voltage above 300V. As active humidity sensors, the maximum voltage response values of 57%, 124%, and 78% were obtained for GO, GONR+GO, and GONR/GO TENGs, respectively. Besides high sensitivity and precisionof all variants, GO+GONR TENG demonstrated a rapid response/recovery behavior (0.3/0.5s). This phenomenon can be attributed to the higher oxygenated groups and defects on the edges of GONR, which leads to facilitating the bulk diffusion of water molecules. Our results open new avenues of GONR application as an additive to enhance the performance of self-powered humidity sensors, as well as conventional hygrometers.

Flexible and translucent PZT films enhanced by the compositionally graded heterostructure for human body monitoring

As a typical ferroelectric material, the PbZr1−xTix O3 (PZT) thin film with a homogeneous component has drawn extensive attention to the application in self-powered flexible electronics. The design of compositionally graded PZT thin films (i.e. artificially control the Zr/Ti ratio in different compositional layers in one film) has shown its immense potentials due to some novel phenomena induced by strain gradient, such as the shifted hysteresis loop, generation of the built-in electric field, enhancement in the motion of domain wall. However, the effect of the compositionally graded heterostructure on the piezoelectric response and its performance on the device level has seldom been investigated. To fill this knowledge gap, we prepare PZT thin films with the compositionally graded structure and based on that, fabricate flexible piezoelectric nanogenerators (PENGs). Furthermore, we explore the 2D mica as the substrate of PENGs and avoid the commonly used costly and troublesome laser-lifting or etching transfer procedure. The PENG prototypes integrated with 1 µm thick PZT films are flexible, translucent, and show high electric responses under different mechanical stimuli. Experiments indicate that up-graded PZT films, of which Zr composition varies from 20% near the bottom to 80% at the top, outperforms the down-graded counterpart. The up-graded PENG achieves a maximum voltage response of 2 V and a current density of 10.0 μA/cm2 when bent by 90°. This work demonstrates that the strain-tuned compositionally graded structure is an effective approach to improve the PENG performance.

Numerical Studies on PZT-Bonded Aluminium Beam

This paper presents a numerical study on the performance of a PZT (lead zirconate titanate)-bonded aluminium cantilever beam for both sensor and actuator configurations. The effect of varying the dimensions of PZT for two different cases of polarization direction is considered in the study. In case-1, polarization is along the length of PZT, and in case-2, polarization is across the thickness of PZT. The study is also extended for different configurations, types and locations of PZT. The results show that for case-1, the transverse displacement of the aluminium beam increases as the length of PZT decreases. No significant variation in displacement is noted by varying the width of PZT. Under different piezoelectric materials considered, PZT-5H showed maximum displacement. PZT, when located close to the support, showed maximum displacement and voltage response. The numerical results are also compared with one-dimensional analytical solutions and are found to be in good agreement.

Modeling of a horizontal asymmetric U-shaped vibration-based piezoelectric energy harvester (U-VPEH)

Abstract In this paper, we present a new horizontal asymmetric U-shaped vibration-based piezoelectric energy harvester (U-VPEH), which collects and converts destructive vibration energy into useful electrical energy. The finite element analysis is conducted on modal shape, the displacement, the mechanical energy, and the strain for both the linear and nonlinear U-VPEH models. Mathematical governing equations are derived to investigate dynamic characteristics of the model. The harmonic balance method and state space form are utilized to conduct the analytical and theoretical analysis. The results show that the first and second eigenfrequencies are 17.167 Hz and 22.951 Hz for the nonlinear U-VPEH model while those are only 17.366 Hz and 25.124 Hz for the linear model. The nonlinear energy harvester model can narrow frequency band gap between the first two resonance modes. Moreover, the maximum voltage response is 8.743 V@16.5 Hz under the up-sweeping signals while the maximum voltage response is 14.18 V@15.41 Hz under the down-sweeping signals. The experimental results demonstrate that the voltage response and the resonance frequency of the U-VPEH agree with the analytical and theoretical analysis. The nonlinear horizontal asymmetric U-VPEH model exhibits a good performance on the energy transfer. This higher energy output, lower resonance frequency, and closer resonance peak can broaden the flexibility and practical usage of the energy harvester.

A Simple Current Control Strategy for Single-Stage Grid Connected Three-Phase PV Inverter

This paper presents a new simple method of current control strategy of grid connected PV system. As the solar irradiation is a nonlinear quantity, so the connection of PV system with the grid is a difficult task. The objective of this work is to develop a model of the photovoltaic system with MPPT connected to 11KV grid by implementing new control technique so that maximum active power transfer from PV inverter to grid can be taken place without injection of harmonics. This paper also demonstrates the dynamic model of single-stage three-phase grid connected inverter. Here, for simplification the PV system is realized as a constant DC voltage source by using maximum power point tracking (MPPT) and boost converter. A current control strategy with pulse width modulation (PWM) technique is proposed to provide pulse for voltage-source inverter (VSI). The analysis and control design of grid connected PV inverter using PI control technique is done in synchronous d-q rotating reference frame to achieve maximum output voltage response and active power. The considered system consists of a VSI, 3-Φ filter, a control system, a distribution network, load and grid. As PV inverter should inject only active power, so reactive power injected to the grid is made zero with the help of this control technique. There after the final model is simulated by using MATLAB/SIMULINK and different output waveforms are analyzed for three different conditions.

Transverse thermoelectric response in tilted orientation La1−xSrxCoO3 (0.05 ≤ x ≤ 0.4) thin films

La1−xSrxCoO3 (0.05 ≤ x ≤ 0.4) thin films with tilted c-axis have been grown on vicinal cut LaAlO3 (100) substrates by pulse laser deposition. The single phase and the epitaxial growth of these thin films have been checked by x-ray diffraction analysis. Transverse thermoelectric voltage response in these films has been studied at room temperature by using a pulse laser as the thermal source. The maximum voltage response has been observed in La0.7Sr0.3CoO3 films in this series of oxides, with the responsivity of 1.23 V/mJ in 10° tilted film. The resistivity and the thermal diffusivity have been reckoned as the main physical parameters to determine the time response of establishment and decay processes of transverse thermoelectric voltage, respectively. Smaller resistivity leads to fast response speed to establish the voltage, while larger thermal diffusivity results in the fast decay of voltage.

Coherent Rabi response of a charge-phase qubit under microwave irradiation

We report on radio-frequency (rf) measurements of the charge-phase qubit being under continuous microwave irradiation in the state of weak coupling to a radio-frequency tank circuit. We studied the rf impedance dependence on the two important parameters such as the power of microwave irradiation, whose frequency is close to the gap between the two lowest qubit energy levels, and the temperature of the internal heat bath. We have found that backaction effects of the qubit on the rf tank and vice versa, tank on the qubit, lead to a negative as well as a positive real part of the qubit impedance $\text{Re}\text{ }Z(\ensuremath{\omega})$ seen by the tank. We have implemented noise spectroscopy measurements for direct impedance readout at the extreme points corresponding to maximum voltage response and obtained absolute values of about $0.017\text{ }\ensuremath{\Omega}$ for the negative and positive $\text{Re}\text{ }Z(\ensuremath{\omega})$. Our results demonstrate the existence and persistence of the coherent single- and multiphoton Rabi dynamics of the qubit with both negative and positive dynamic resistances inserted into the tank in the temperature range of 10--200 mK.

Study for Electrode Metals on Taste Sensor with LB film

In this paper, sensor responses with only metal electrode as Au, Cr, Ti and more with LB film were described. LB film material was the Dioctadecyldimethylammonium bromide combined by PVSK as an underlayer. To detect five basic taste substances, sensor parameters were defined as maximum voltage change and response time. Response time for sourness and umami with Ti and Cr evaporated metal electrode was larger than that of usual Au electrode. LB film effect was finally found to increase response time for five basic taste materials.

Multi-Channel Taste Sensor with LB Films

In this paper, sensor responses using film materials such as stearic acid were described. In addition, the difference of sensor response from some kind of film materials was compared. Film material of stearic acid was used other than dioctadecyldimethylammonium bromide and trioctadecylamine hydrochloride. Evaporated electrode of Au and Ag were used for stearic acid. To detect five basic taste substances, sensor parameters were defined as maximum voltage change and response time. These eight parameters obtained from four sensors were applied to principle component analysis. Five basic tastes were divided into each quadrant. Finally, five basic taste substances were clearly discriminated.

Discrimination Characteristics of LB Film Taste Sensor Composed of Three-chain Compound.

In this paper,sensor response by film material was described. Multi detecting film and multi metal electrodes were also examined. Film material was changed from the Di Octadecyl Dimethyl Ammonium Bromide to Tri Octadecyl Amine Hydro Chloride. To detect five basic taste substances, sensor parameters were defined by maximum voltage change and response time. Using these parameters, discrimination possibility of five basic taste substances were shown.

Taste Sensor Response Dependence on Metal Electrode using LB Film

In this paper, sensor response by metal electrode and electrode surface condition was described. Single detecting film and multi metal electrodes were also examined. Metal electrode was changed from the conventional Ag and Au plate to Au, Ti and Cr evaporated metal films. To detect five basic taste substances, sensor parameters were defined by maximum voltage change and response time. Using these parameters five basic substances were clearly discriminated.

Spread of critical currents in thin-film YBa/sub 2/Cu/sub 3/O/sub 7-x/ bicrystal junctions and faceting of grain boundary

The statistical distributions of critical currents in series arrays of YBa/sub 2/Cu/sub 3/O/sub 7-x/ grain-boundary junctions have been studied by low-temperature laser scanning microscopy. A set of arrays has been fabricated on [110] NdGaO/sub 3/ bicrystal substrates with misorientation angles from 2 /spl times/ 10/spl deg/ up to 2 /spl times/ 26/spl deg/ and patterned to the widths from 1.7 up to 5 micrometers. The critical current values of the individual junctions in the array have been obtained by focusing a laser beam on each junction and measuring the bias current at which the maximum laser-induced voltage response has appeared on the array. The measured critical current distributions have been demonstrated to be close to a log-normal Gauss function. A spread of this distribution has been found to increase with a bicrystal angle. YBa/sub 2/Cu/sub 3/O/sub 7-x/ grain-boundary topography has been studied by atomic force microscopy. From results of these measurements we suppose that the maximum values of critical current density might be assigned to the symmetrical facets of grain boundary.

Spread of critical currents in thin-film YBa 2Cu 3O 7− x bicrystal junctions and faceting of grain boundary

A spread of the critical currents in a series array of 100 YBa 2Cu 3O 7− x bicrystal junctions has been studied by laser scanning microscopy. The values of the critical current I c of individual junctions in the array have been obtained by focusing a laser beam on each junction and measuring the current through the array at which the maximum laser-induced voltage response has appeared on the array. The distribution of critical currents in logarithmic scale was close to a Gaussian one. The I c-spread has been found to increase with the increase of misorientation angle of bicrystal substrate and the decrease of the width of the junctions in the array.

Spread of critical currents in thin-film YBa/sub 2/Cu/sub 3/O/sub 7-x/ bicrystal junctions

A spread of the critical currents in a series array of up to 100 YBa/sub 2/Cu/sub 3/O/sub 7-x/ bicrystal junctions has been studied by Laser Scanning Microscopy. The values of the critical current I/sub c/ of individual junctions in the array have been obtained by focusing a laser beam on each junction and measuring the current at which the maximum laser-induced voltage response /spl Lambda/V on the array has appeared. The distribution of critical currents in logarithmic scale was close to a Gaussian one. The I/sub c/-spread has been found to increase with the increase of misorientation angle of bicrystal substrate and the decrease of the width of the junctions in the array.

Voltage responses to tones of outer hair cells in the basal turn of the guinea-pig cochlea: significance for electromotility and desensitization

Voltage responses were recorded from outer hair cells (OHCS) in the basal coil of the guinea-pig cochlea in response to tones at frequencies above the characteristic frequency (CF) presented together with a 100 Hz tone at 80 dB or 85 dB sound pressure level (SPL). The amplitude and polarity of voltage responses to a 100 Hz, 85 dB SPL tone were altered when presented together with tones at frequencies above CF according to the frequency and level of the high-frequency tone, OHC phasic (ac) (greater than 500 microV) but not tonic (dc) voltage responses were elicited by the high-frequency tone. Thus the responses of OHCS to low-frequency tones can be altered when presented together with a high-frequency tone without an apparent dc change in membrane potential. Recordings were made from an OHC during cochlear desensitization through exposure to an intense tone. The maximum voltage response to high-level low-frequency tones remained unchanged, although the OHC response to high-frequency tones became less sensitive to low-level stimuli and more linear as a function of level. It is suggested that desensitization is associated with a change in the mechanical properties of the cochlea, possibly associated with the OHCS themselves, and not with inactivation of the transducer channels. The amplitude of the OHC ac voltage response was measured at neural threshold, and the consequences of these measurements on hair cell electromotility are considered.