Thermo-sensitive Quartz Resonator Based on Tuning Fork Technology

This paper describes a novel quartz tuning fork temperature sensor, the principle of the quartz tuning fork temperature sensor is to detect resonance frequency shift by an external temperature. It has such advantages: high sensitivity, high accuracy, and good long-term stability. The temperature sensor is prepared of synthetic quartz on ZY-cut plates and configured by ZY-Cut quartz crystal wafer based tuning fork resonators whose operating frequency is at about 31 KHz. The characterization of a flexural mode tuning fork resonator which inherent frequency is sensitive to temperature changes is presented. Finite element method has been used in the deign process. The temperature frequency characteristic test system is setup. The temperature sensor is used to measure temperature in the range -50 Degree C-140 Degree C. The measurement results show that the tuning fork resonators based temperature sensor exhibits excellent sensitivity and short-term repeatability.

Quartz crystal is an elastomer with a natural oscillation frequency which can be served as a temperature sensor based on the resonance and thermal sensitivity subject to temperature when the forced vibration frequency is equal to its natural frequency. As a new type of temperature sensor, quartz crystal temperature sensor possesses high resolution, exact linearity and remarkable stability which could be used to measure temperature applied to moderate and low temperature environments. It is widely adopted in temperature measuring instruments under the circumstance of high-precision environments due to its availability of converting temperature signals to digital frequency signals. The oscillation frequency of the quartz fork resonator is extremely sensitive to the mass and stiffness of the quartz fork arm. Because of the electrode trench which can reflect the ambient temperature changes, it would be of special interest to design a temperature-sensitive quartz fork resonator for the study. The overall goal of this research is to study the surface electrode and quartz tuning fork temperature sensor in light of proposing an approach of temperature sensor design methodology, completing the sensor characteristic simulation, and designing the corresponding size of the sensor structure. Specific structure size: fork thickness 0.13mm, fork arm length 3mm, fork arm width 0.27mm, total length 5mm, total width 0.8mm.

A resonance temperature-sensing structure based on quartz tuning fork (QTF) is proposed and numerically investigated by using theoretical and numerical simulation in this paper. Reasonable selecting the quartz wafer cutting angle and Setting electrode configuration, the QTF resonator can be worked in flexural vibration mode. The numerical simulation results show that the change of the resonance frequency of the QTF is inversely proportional to the temperature changes with the environment. The structure of QTF resonator has been analyzed and optimized by the FEM software of ANSYS. Moreover, in order to investigate the thermal characteristic of QTF, A testing system of QTF has been successfully developed based on virtual instrument. The experimental results show that in the range from 0 °C to 100 °C, the thermal QTF as temperature sensor has a high thermo-sensitivity of -2.979 Hz/°C, hysteresis degree of 0.023%, linearity of 0.019% and resolution of 0.05°C respectively. Furthermore, after operation the test system features good stability and reliability, so it provides a feasible solution for test the characteristics of the sensor and can be applied to practice.

In this paper, a low cost quartz tuning fork temperature sensor adopting H-shaped tuning fork resonator to address miniaturization, high resolution and high stability has been designed, developed and tested. The quartz tuning temperature sensor is designed vibrating in flexural mode with a new thermo-sensitive cut. The quartz tuning fork temperature sensor consists of two prongs connected at one end of crystalline quartz plate with thin-film metal electrodes deposited on the faces, which is used to produce vibration in response to alternating voltages and detecting the resonance frequency in the meantime. When an external temperature is change, there is a shift in its natural frequency. Based on this principle, a resonant thermometer is designed. Finite element method is used to analyze the vibratory modes and optimize the structure. The whole structure is 500μm thickness, the length of tuning fork arm is 3076μm and the width of tuning fork arm is 600um, the frequency of tuning fork is about 37kHz with a sensitivity of rough 85 ppm/°C. The experimental results shown that a temperature accuracy of 0.01 °C and a resolution of 0.005 °C within temperature range from 0 °C to 100 °C. All these research are helpful to design satisfactory performance of the sensor for temperature measurement.

Summary There are currently no technologies available to measure polymer solution viscosities at realistic downhole conditions in a well during enhanced oil recovery (EOR). In this paper, custom-made probes using quartz tuning fork (QTF) resonators are demonstrated for measurements of viscosity of polymer fluids in the laboratory. The electromechanical response of the resonators was calibrated in simple Newtonian fluids and in non-Newtonian polymer fluids at different concentrations. The responses were then used to measure field-collected samples of polymer injection fluids. In the polymer fluids, the measured viscosity values by tuning forks were lower than those measured by the conventional rheometer at 6.8 s−1, closer to the solvent viscosity values. However, the predicted rheometer viscosity vs. QTF-measured viscosity showed a distinct exponential correlation (R2=0.9997), allowing for an empirical calibration between the two viscometers for fluids having the same solvent and polymer compositions. The QTF sensors produced acceptable viscosity measurements of polymer fluids within the required polymer concentration ranges used in the field and predicted field sample viscosities with less than 1–2 cp (or 10–20%) error from the rheometer data. Results were validated based on separate independent tests where the devices were used to measure the viscosity of Newtonian fluids and non-Newtonian polymer fluids in a series of consecutive dip tests, simulating more realistic usage. These devices can be used to measure either the “relative” viscosity changes from a polymer solution prior and post-injection or to measure a “calibrated” viscosity via empirical exponential correlation. The compact QTF sensors developed in this study can be easily integrated into portable systems for laboratory or wellsite deployment as well as logging tools for downhole deployment. This work also demonstrates the ability of these QTF devices to make sensitive viscosity measurements at high-frequencies, opening opportunities for their use in high-frequency rheology studies of EOR fluids.

The dissipative processes that occur with immersing a vibrating tuning fork in superfluid helium are investigated. The tuning forks resonance width Δf of frequencies from 32 to 97 kHz was measured in the temperature range from 0.2 to 2.5 K and He II pressure from SVP to 24.9 atm. Some of the tuning forks were in the original can (closed tuning fork), and for some tuning forks the can was either completely or partially removed (opened fork). We found that for the open tuning forks two dissipation mechanisms are clearly revealed in the temperature dependence of Δf, namely, acoustic radiation and scattering of ballistic thermal excitations at low temperatures, and viscous friction at high temperatures. At low temperatures (below ∼ 0.8 K) acoustic dissipation dominates, and the model of quadrupole oscillator for a tuning fork can be applied. We found that acoustic radiation for closed tuning forks is less effective and appears at lower temperatures. The first experimental data on dissipative processes in the quartz tuning fork–He II system at increased liquid pressures are obtained. It is shown that, for high frequency tuning forks the resonance bandwidth decreases with increasing pressure, i.e., with increasing wavelength of sound λ, according to the law λ−5. At low frequencies and low temperatures, with increasing mean free path of thermal excitations the resonance bandwidth is well described by the model of ballistic scattering.

Sensitive detection of low doses beta particles using quartz crystal oscillators

In order to optimize the design of quartz tuning fork temperature sensor, finite element method (FEM) is applied to model optimum tuning fork geometry, tine tip and tine surface electrode shape and thickness with a resonance frequency close to 32 kHz and a series resistance value of 40 kΩ as design targets. This type of sensor designed with a new ZYtw-cut is proved that working at flexural vibration mode was better than at the others modes. Precise temperature versus frequency analyses of resonators have been carried out and Least Mean Squared (LMS) curve fit algorithm is applied to compute the temperature values quantitatively. The results obtained from the experimental investigations show the method which synthesizes many factors to design quartz tuning-fork temperature sensor. Using ZYtw-cut can bring the temperature coefficient up to 70ppm/(degree C) and make power consumption lower. The temperature sensor based on quartz tuning-fork thermo-sensitive resonator is mounted in a standard holder for use from −30 degree C to 160 degree C with an accuracy of 0.05 degree C and a high resolution of 0.001 degree C. It is proved that it is possible to construct a miniature quartz tuning-fork temperature sensor with high sensitivity and small non-linearity.

This paper presents the design, fabrication and characterization of quartz tuning fork temperature sensor which is based on new ZY-cut-quartz crystal bulk acoustic wave resonator vibrating in a flexural mode. Design and performance analysis of the quartz tuning fork temperature sensor has been conducted and the thermal sensing characteristics were examined by measuring the resonance frequency shift of this sensor cause by an external temperature. The sensor prototype was successfully fabricated and calibrated from operating from 0°C to 100°C with sensitivity of 70ppm/°C. Experimental results show the sensor has high thermal sensitivity, good stability and well reproducibility. This work represents high precision and low power temperature sensor using the comprehensive thermal characterization of ZY-cut-quartz tuning fork resonator.

The quartz tuning fork has recently become a popular experimental tool for investigations of both classical and quantum turbulence in cryogenic helium. Its increased use in low-temperature experiments and a number of puzzling results obtained in the past have led to many questions concerning the interaction of multiple tuning forks or the interaction of tuning forks with other oscillators. We report measurements performed in He II at low temperatures around 360 mK, on the mutual interaction of tuning forks placed in the same volume of fluid, and examine the responsible mechanisms in an effort to discriminate between acoustic coupling and interaction via quantized vortices. To this end, the interaction of two tuning forks is investigated by analyzing their recorded resonance curves, looking for any nonelectrical crosstalk. Further, the force-velocity characteristics of a detector tuning fork are measured for different operating velocities of a generator tuning fork. As a complementary measurement, the intensity of sound waves is recorded using a set of miniature receivers. We confirm the current knowledge on acoustic emission by tuning forks in He II and verify properties of their radiation patterns. We conclude that in our experiment the interaction is almost entirely mediated by sound waves.

Pilot line manufactured custom quartz tuning forks (QTFs) with a resonance frequency of 28 kHz and a Q value of >30, 000 in a vacuum and ∼ 7500 in the air, were designed and produced for trace gas sensing based on quartz enhanced photoacoustic spectroscopy (QEPAS). The pilot line was able to produce hundreds of low-frequency custom QTFs with small frequency shift < 10 ppm, benefiting the detecting of molecules with slow vibrational-translational (V-T) relaxation rates. An Au film with a thickness of 600 nm were deposited on both sides of QTF to enhance the piezoelectric charge collection efficiency and reduce the environmental electromagnetic noise. The laser focus position and modulation depth were optimized. With an integration time of 84 s, a normalized noise equivalent absorption (NNEA) coefficient of 1.7 × 10−8 cm-1∙W∙Hz-1/2 was achieved which is ∼10 times higher than a commercially available QTF with a resonance frequency of 32 kHz.

A theoretical-experimental framework for the analysis of the dynamic response of a QEPAS tuning fork device immersed in a fluid medium

Quartz tuning fork (QTF) sensors offer an attractive alternative to traditional silicon microcantilevers for sensing applications in dynamic atomic force microscopy (DAFM). The QTF sensor consists of two identical, weakly-coupled tines with a sharp tip affixed to the distal end of one tine. The fundamental anti-phase mode of the QTF achieves a stable resonant frequency with a high Quality factor making it ideal for DAFM applications in which a small shift in the resonant frequency is linked to a tip-sample force. The addition of the tip-sample force also breaks the symmetry of the QTF leading to a classic eigenvalue veering scenario. The eigenvalue veering and accompanying mode localization phenomena violate the standard DAFM modeling assumptions which treat the addition of the tip-sample force as a small perturbation to a single-degree-of-freedom oscillator. We find that the eigenvalue veering can contribute a systematic error in force measurements on the order of 20%. Methodology for correcting the systematic error caused by eigenvalue veering is proposed.

When the conventional quartz tuning fork miniaturizes, high crystal impedance and low quality factor (Q value) of quartz components make quartz components difficulty to operate. The need to reduce digital consumer device has spurred market demand for compact electronics products that reduce the size and consume less power with the same superior functionality. The paper investigates geometric parameters of quartz tuning fork thoroughly to maintain quartz components working efficiency. In this paper, all the designs of quartz tuning fork resonator was simulated analysis software CoventorWare 2010 to reach a better solution in the development of miniature quartz components. There are three kinds of parameters, including depth of grooves, length of cantilever and geometric ratio of length and width of the cantilever is investigated and defined in this paper to obtain high quality factor of the quartz device. The effect between three geometric parameters of quartz components and quartz tuning fork of working efficiency investigates thoroughly. In this paper, the relation among three kinds of geometric parameters in quartz tuning fork is studied. The result of simulation represents that the relation between geometric ratio and frequency is a second-order curve upward. The relation between etching depth of grooves and frequency or quality factor is a second-order curve downward. The relation between shortening length and quality factor maintain a level while length exceeding 643 μm. In conclusion, miniaturization of quartz component is achieved with high Q value and amplitude by analysis software CoventorWare 2010.

This paper reports the first demonstration of hydrogel conical tip attachment onto quartz tuning fork (QTF) by using an elastomeric tip mold that is soft-lithographically replicated from an electrochemically etched tungsten wire. The tungsten tip of 10–100 nm radius obtained by time-controlled electrochemical etching is replicated with h-polydimethylsiloxane (h-PDMS) to make negative conical tip molds large enough to be used for QTFs. By approaching a QTF to the negative h-PDMS tip mold filled with polyethylene glycol-diacrylate (PEGDA), a PEGDA tip is attached to the QTF without using an adhesive. Then, the PEGDA tip attached QTF is employed for shear force microscopy for calibration grating and atomic layers of hexagonal silicon carbide and also compared with a silicon tip attached QTF. Exclusively for the PEGDA tip attached QTF, we demonstrate that the imaging tip could be regenerated multiple times to address issues associated with tip wear. In a stark contrast with conventional QTF probes in attachment of electrochemically etched metallic wires or microfabricated AFM cantilevers, photocuring of liquid phase prepolymer within a tip mold demonstrated herein allows adhesive-free and exclusive attachment of the imaging tip onto a QTF. The relatively large PEGDA tip enables facile operation during approach and engagement. Moreover, the organic and inorganic combination of imaging tip and resonating body offers regeneration of the imaging tip upon its degradation.