High Precision Low Power Quartz Temperature Transducer

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.

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.

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 article describes a micromachined quartz tuning fork resonator, 6 mm in height by 2 mm in diamter, holding a two-terminal electronic component with a nomial frequency of 36 kHz (at zero degree) and 15 pF typical capacitance packed in a 90 Pa He gas sealed metal container, which has been used as a sensor for temperature measurement with good sensitivity, repeatability and reliability. The temperature sensor is ZYtw-cut-quartz crystal bulk acoustic wave resonator vibrating in a flexural mode. Finite element method is used to analyze the vibratory modes and optimize the structure of the sensor. Design and performance analysis of the quartz tuning fork temperature sensor has been conducted. The sensor prototype was successfully fabricated and calibrated in operation from 0°C to 100°C with sensitivity of 80 ppm/°C.

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.

Quartz tuning fork temperature sensor with frequency as the output signal is a digital temperature sensor with high quality factor, low volume, low power consumption and other advantages, which plays an crucial role in the field of high-precision temperature measurement. To improve the performance of quartz tuning fork resonator, this paper proposes a quartz tuning fork temperature sensor with cut ZYlw(−10°,-41°) and optimizes its surface electrodes in order to reduce the parasitic effects generated at the tuning fork base. Simulation results show that for a new cut quartz temperature sensor we propose, the optimized electrodes exhibit good resonance characteristics with improved sensitivity and quality factor Q compared to the before optimization, especially the Q value is improved significantly by 12%.

A method and apparatus for measuring properties of a liquid composition includes a mechanical resonator, such as a thickness shear mode resonator or a tuning fork resonator, connected to a measurement circuit. The measurement circuit provides a variable frequency input signal to the tuning fork, causing the mechanical resonator to oscillate. To test the properties of a liquid composition, the mechanical resonator is placed inside a sample well containing a small amount of the liquid. The input signal is then sent to the mechanical resonator and swept over a selected frequency range, preferably less than 1 MHz to prevent the liquid being tested from exhibiting gel-like characteristics and causing false readings. The mechanical resonator's response over the frequency range depends on various characteristics of the liquid being tested, such as the temperature, viscosity, and other physical properties. Particular mechanical resonators, such as tuning fork resonators, can also be used to measure a liquid composition's electrical properties, such as the dielectric constant and conductivity, because the tuning fork's structure allows a high degree of electrical coupling between the tuning fork and the surrounding liquid. The mechanical resonator can be covered with a coating to impart additional special detection properties to the resonator, and multiple resonators can be attached together as a single sensor to obtain multiple frequency responses. The invention is particularly suitable for combinatorial chemistry applications, which require rapid analysis of chemical properties for screening.

In this paper, it is presented the design of a low power temperature sensor for the protection of smart cards from security attacks at the corners of their operating temperature range. The attacks usually use failure generation techniques for abnormal environmental conditions. They normally result in malfunctions in the smart card processor, allowing additional access to information to happen. The purpose of this design is to effectively protect the chip of smart cards from this art of security tampering for the temperature range −20 °C to 120 °C with a small area and low power consumption circuit. The sensor is designed in Cadence and TSMC using the System on a Chip (SoC) concept employing a standard 0.090 μm CMOS technology and operates on a power supply voltage of 1.2 V. It is based on a circuit with two MOS transistors and only one PNP bipolar transistor for producing a Complementary to Absolute Temperature (CTAT) voltage. The obtained results for the temperature protection at the corners of a −40 °C to 140 °C temperature range and V dd = 1.2V+ 10%, show an excellent performance for the sensor; the Power Supply Rejection Ratio (PSRR) −62 dB in the worst case and a hysteresis corner 5mV. This new circuit design can effectively work as an excellent protector against security tampering to smart cards.

In order to increase the accuracy of on-line liquid density measurements, a sensor equipped with a tuning fork as the resonant sensitive component is designed in this paper. It is a quasi-digital sensor with simple structure and high precision. The sensor is based on resonance theory and composed of a sensitive unit and a closed-loop control unit, where the sensitive unit consists of the actuator, the resonant tuning fork and the detector and the closed-loop control unit comprises precondition circuit, digital signal processing and control unit, analog-to-digital converter and digital-to-analog converter. An approximate parameters model of the tuning fork is established and the impact of liquid density, position of the tuning fork, temperature and structural parameters on the natural frequency of the tuning fork are also analyzed. On this basis, a tuning fork liquid density measurement sensor is developed. In addition, experimental testing on the sensor has been carried out on standard calibration facilities under constant 20 °C, and the sensor coefficients are calibrated. The experimental results show that the repeatability error is about 0.03% and the accuracy is about 0.4 kg/m3. The results also confirm that the method to increase the accuracy of liquid density measurement is feasible.

Food production has the major objective to achieve a high and uniform level of quality for raw materials. Temperature and humidity are the critical parameters to verify in many fields of food industry processes, from assurance of quality during production up to storage and transport to final users. In this regard, we focus in this paper on the design of temperature and humidity sensors for an electronic nose used to detect the rotten food in anticipation phase. Those parameters (temperature and humidity of food) have an important role in the array sensor of our nose.

This paper presents an energy-efficient and high linearity temperature sensor based on the architecture of a simple on-chip oscillator. A self-calibrated block is proposed to compensate the non-linearities of the on-chip oscillator due to PVT variations. In this manner, this on-chip oscillator-based temperature sensor has superior performance over the conventional inverter-chain-based types. In order to generalize the application, no highly linear temperature coefficient resistors are being utilized. The entire circuit is simple and easy to be scaled down. According to the verifications in 65 nm CMOS process, with one-point calibration, this temperature sensor can achieve an inaccuracy within ±1°C in the temperature range from -55°C to 125°C, with a power consumption of only 0.6 μA under 1.2 V supply voltages.

Application of resonant steel tuning forks with circular and rectangular cross sections for precise mass density and viscosity measurements

Performance evaluation metrics for ring-oscillator-based temperature sensors on FPGAs: A quality factor

A novel high-performance sensor technology for measuring and monitoring temperature is described. This type of temperature sensor using a quartz tuning fork resonator is inherently insensitive to noise because the output is a frequency shift cause by an external temperature. The output can easily be converted into a digital signal and directly connected to a microcontroller without an A-D converter. Fabrication process for quartz tuning forks is realized by employing photolithography and selective etching a method. The operation of a thermo-sensitive quartz tuning-fork resonator and the frequency shift caused by an external temperature has been explained. The temperature sensor is designed with a doubly rotated cut show nearly a linear response with sensitivity about 70ppm/degree within temperature range from -50 degree to 200 degree, the numerical and experimental samples all indicated accuracies of 0.05 degree and a reasonable response time

This paper reports a self-temperature compensation barometer based on a quartz resonant pressure sensor. A novel sensor chip that contains a double-ended tuning fork (DETF) resonator and a single-ended tuning fork (SETF) resonator is designed and fabricated. The two resonators are designed on the same diaphragm. The DETF resonator works as a pressure sensor. To reduce the influence of the temperature drift, the SETF resonator works as a temperature compensation sensor, which senses the instantaneous temperature of the DETF resonator. The temperature compensation method based on polynomial fitting is studied. The experimental results show that the accuracy is 0.019% F.S. in a pressure range of 200~1200 hPa over a temperature range of -20 °C~+60 °C. The absolute errors of the barometer are within ±23 Pa. To verify its actual performance, a drone flight test was conducted. The test results are consistent with the actual flight trajectory.