Thermoelectric Power Sensor Research Articles

Achieving High Thermoelectric, Stretchable, and Self-Healing Capabilities in Self-Supported PEDOT:PSS/Nafion/Poly(vinyl Alcohol) Composites for Wearable Thermoelectric Power Generators and Sensors

Achieving High Thermoelectric, Stretchable, and Self-Healing Capabilities in Self-Supported PEDOT:PSS/Nafion/Poly(vinyl Alcohol) Composites for Wearable Thermoelectric Power Generators and Sensors

Interlaboratory Comparison of Power Measurements at Millimetre- and Sub-Millimetre-Wave Frequencies

The aim of this paper is to compare the power measurement capabilities in millimetre- and sub-millimetre-wave frequency bands of several national metrology institutes and one research institute. The first comparison, in WR-6.5 waveguide (110 GHz to 170 GHz), involved NPL, TUBITAK UME and PTB. The second comparison, in WR-1.5 waveguide (500 GHz to 750 GHz), involved NPL, METAS, TUBITAK UME, LNE, WAT, GUM and VDI. Two types of travelling standards were used for these comparisons: a thermoelectric power sensor in the WR-6.5 band and a calorimetric power sensor in the WR-6.5 and WR-1.5 bands. The thermoelectric power sensor was characterised by the participants against their own standards and a generalised effective efficiency was calculated. The calorimetric power sensor operating in the WR-6.5 band was measured to observe its behaviour during the comparison and was also measured in the WR-1.5 band after being fitted with a suitable waveguide taper and used in conjunction with a frequency multiplier. The participants measured the output of the calorimetric power sensor and their own power sensor standard. A normalised power ratio method was used as a comparison parameter for the WR-1.5 band measurements. In addition, a pyroelectric power standard was used by METAS to measure absolute power, and a frequency of 650 GHz was used as a link between the absolute power and the power ratios. Finally, all but two of the measurement points compared between the participants achieved agreement in terms of En scores less than 1. For the first time, an interlaboratory comparison of power measurements at sub-millimetre frequencies has been performed and, overall, good agreement was achieved between the different laboratories.

A Near-Zero Thermoelectric RF Power Sensor for High Dynamic Range Applications

A Near-Zero Thermoelectric RF Power Sensor for High Dynamic Range Applications

Generalized Efficiency and the Uncertainty of Millimeter Wave Power Standard

Abstract. In the last decade, waveguide thermoelectric power sensors have been established as an alternative to thermistor mounts for millimeter wave power standards, and due to the detection principle and the nature of waveguides, the generalized efficiency is used as calibration quantity instead of the effective efficiency. In this paper, the generalized efficiency and the measurement uncertainty of waveguide thermoelectric sensors are presented and applied to calibrate other types of power sensors in a measurement set-up for frequency up to 170 GHz. Results for commercially available waveguide power sensors are discussed for the interfaces R 900 and R 1.4k.

Research on MEMS dual-channel microwave power sensor with fixed beam structure

To improve the sensitivity and dynamic range of microwave power sensors, a micro-electromechanical system (MEMS) dual-channel microwave power sensor is proposed in this study. The sensor is designed and manufactured using the GaAs monolithic microwave integrated circuit` (MMIC) process and MEMS technology. The microwave performance, overload power and sensitivity are theoretically studied. At 8–12 GHz, the return loss of the sensors with three different fixed beam sizes are approximately −10 dB, which is good microwave performance. The sensitivities for capacitive detection channel of the two sensors with larger sizes are 2.4 fF W−1 @10 GHz and 14.5 fF W−1 @10 GHz, respectively, and the sensitivities of the thermoelectric detection channel of the three sensors is 25.7 mV W−1, 24.9 mV W−1 and 24.2 mV W−1, respectively. Compared with traditional microwave power sensors, the sensor proposed takes into account the advantages of microwave power sensors in both thermoelectric and capacitive structures. This work helps lay the foundation for the design of microwave power sensors with a fixed beam structure and thermoelectric microwave power sensors.

Theoretical and Experimental Investigations of an Integrated Microwave Power, Frequency, and Phase Detector for X-Band Applications

In this article, we present an integrated microwave power, frequency, and phase detector by GaAs monolithic microwave integrated circuits technology. The novelty of the reported detector is carefully designed by cascading a micromachined six-port coupler, a power divider, three power combiners, and four thermoelectric power sensors to realize microwave power, phase, and frequency detection. Compared with previous study, the reported microwave integrated detector has a more compact design and high-power-handling capacity. The advantage of the proposed technique is that the three parameters (power, frequency, and phase) of microwave signals are directly measured via the output of the thermovoltage. This makes the integrated microwave detection system more suitable for systems with complex requirements, such as radar systems. The experimental results demonstrate that the output thermovoltage and incident microwave power exhibit good linearity over a dynamic range of 0.1–1000 mW. Also, the measured sensitivities are 22.9, 27.2, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$33.7~\mu \text{V}$ </tex-math></inline-formula> /mW at 8, 10, and 12 GHz, respectively. A new method based on phase comparison is proposed for frequency detection. Also, the measured sensitivity is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$9.42~^{\circ }$ </tex-math></inline-formula> /GHz over <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${X}$ </tex-math></inline-formula> -band. By introducing the reference signal, the function of phase detection is achieved based on the principle of vector synthesis over a dynamic range of 0°–360°. Also, the measured sensitivity is better than 98.38 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{V}$ </tex-math></inline-formula> /° at 500 mW. Furthermore, an integrated detection model is also proposed based on the microwave network analysis. The experimental results agree well with the proposed model. The results would be beneficial to improve future microwave integrated detector designs.

Design and Analysis of a Hybrid-Type RF MEMS Phase Detector in X-Band.

In this paper, we have designed, analyzed, and characterized a hybrid-type MEMS device for X-band phase shift measurement. The signal related to a phase shift of the inputs is fractionally in-line coupled by a MEMS beam and delivered to a thermoelectric power sensor, where the phase is ultimately converted into DC voltage output. With the hybrid of the MEMS beam and the thermoelectric power sensor, both in-line detection process and phase-DC voltage conversion is reserved, which is a benefit for large power capacity, good linearity property, and high-level integration density. In order to get a deep insight into the physical mechanisms involved in the phase detection process, a comprehensive analysis model is presented. The beam is modeled as a precise RLC circuit component, where the capacitance is related to the input power. The fabrication is compatible with GaAs monolithic microwave integrated circuit (MMIC) technology. Experimental results show that return loss is smaller than −11.3 dB and isolation is better than −9.3 dB over X-band. Phase shift detection from 0 to 180 degrees is verified for a large power range of 200–1600 mW (23–32 dBm). The perfect linearity property of the phase-detection sensitivity is demonstrated in the same power range. Low intermodulation distortion is also confirmed through measurement. It is revealed from the comparison between this work and other published results in the literature that this presented hybrid-type structure shows superiorities in both power handling ability and phase-detection linearity. It can be adopted in medium power signal applications with a high level of integration.

A Thermoelectric MEMS Microwave Power Sensor with Inline Self-Detection Function.

In this paper, the design, fabrication and measurement of a thermoelectric MEMS microwave power sensor with the terminal load inline self-detection function is proposed. The structure of the sensor mainly includes a coplanar waveguide, a thermopile, two terminal load resistors and two calibration resistors. In order to realize the inline self-detection function, the load and calibration resistors are designed to form a voltage divider circuit. The fabrication of this sensor is compatible with the GaAs MMIC technology. The on-chip performance is tested by using a microwave experimental platform. The measured reflection loss is less than −10 dB at 0.1–10 GHz. When the bias voltage is not applied, the sensitivity of the sensor is 47.39 μV/mW@5 GHz and 32.58 μV/mW@10 GHz, respectively, and when the bias voltage is applied, the sensitivity is 47.50 μV/mW@5 GHz and 32.73 μV/mW@10 GHz, respectively. The difference between the two cases is less than 0.5% at the same frequency, which indicates that whether or not to apply the bias voltage has little effect on the sensitivity. In addition, when the calibration resistance is increased from 50 to 100 Ω, the current flowing through the load resistance is decreased under the same bias voltage. Therefore, the DC power consumed on the load resistance will be significantly reduced. This makes the measured and theoretical results show better agreement, thus verifying the validity of the design.

A novel study of the resistance of thermopile for thermoelectric MEMS microwave power sensors

In order to study the effect of the resistance of thermopile on the output performance of thermoelectric microelectromechanical system (MEMS) microwave power sensors, the relationship of the electron mobility and the resistance in n+-type GaAs is studied, and the reason why the resistance of thermocouple changes with the input microwave power and frequency is analyzed. The experimental results show that in the range of 8 ∼ 12 GHz, the return loss of the sensor is less than −27.75 dB, and the sensitivity of the sensor is 0.055 mV/mW@10 GHz. The resistance of thermopile shows a downward trend with the frequency. With the input power range from 0 to 300 mW, the resistance of thermopile increases from 55.51 to 71.17 kΩ, and it has good linearity. Therefore, this work has a certain reference value for improving the output performance of thermoelectric microwave power sensors.

A New RF MEMS Power Sensor Based on Double-Deck Thermocouples With High Sensitivity and Large Dynamic Range

This letter reports a new RF MEMS power sensor based on double-deck thermocouples with high sensitivity and a large dynamic range. In order to improve RF sensing capability and sensitivity, the double-deck thermocouples and a MEMS substrate membrane are carefully designed. The proposed RF MEMS power sensor is fabricated by GaAs monolithic microwave integrated circuit (MMIC) process coupled with MEMS technology. Experimental result shows that the output thermovoltage of the device has inherent RF-dc linearity with the power from 1 to 500 mW. And the measured return loss is less than -28.6 dB at 1-20 GHz, which exhibits excellent matching characteristics. Moreover, at 8, 10, and 12 GHz, the measured sensitivities are 133.2, 124.3, and 116.8 μV/mW, respectively. Compared with a traditional thermoelectric power sensor, the sensitivity and the dynamic range of the proposed RF MEMS power sensor are increased by approximately 61% and 2.5 times, respectively. The research work can be considered as an incremental improvement of the state of the art (higher power sensing capability and sensitivity) as RF power sensing using double-deck thermocouples.

A Novel 3-D Equivalent Circuit Model of Thermoelectric MEMS Microwave Power Sensors

In this work, a novel 3-D equivalent circuit model of thermoelectric microelectro-mechanical system (MEMS) microwave power sensor is proposed. According to the model, the 3-D temperature distribution and the response time of the thermoelectric MEMS microwave power sensor are obtained. The thermoelectric MEMS microwave power sensor is designed and fabricated based on GaAs monolithic microwave integrated circuit (MMIC) technology. The measured results show that the sensitivity of the sensor is 0.06 mV/mW at 10 GHz and the time constant is $85~\mu \text{s}$ . The theoretical results of the model show that the sensitivity is 0.076 mV/mW at 10 GHz and the time constant is $56.24~\mu \text{s}$ . The measured results are relatively consistent with the theoretical results. Furthermore, the heat dissipation in the substrate can be obtained accurately, and the transient response of the sensor can be further studied according to the 3-D equivalent circuit model. Therefore, this work has a certain reference value and guiding significance for the research of thermoelectric MEMS microwave power sensors.

A C-Band MEMS Frequency Discriminator With High Sensitivity and Linearity

This letter reports a C-band MEMS frequency discriminator with high sensitivity and linearity. The structure of the proposed discriminator is fabricated using GaAs Microwave Monolithic Integrated Circuit (MMIC) technology. The frequency discriminator consists of one dual-band power divider, one dual-band power combiner, one delay-line and the final MEMS thermoelectric power sensor. The purpose of the designed structure is to provide an ultra-wide working frequency band and simultaneously improve sensitivity and linearity. Both on-chip detector and packaged one are tested. S-parameter measurement illustrates good impedance matching covering 4–8 GHz. The frequency sensitivities of on-chip detector are $0.52~\mu \text{V}$ /MHz @ 17 dBm, $0.85~\mu \text{V}$ /MHz @ 20 dBm and $1.66~\mu \text{V}$ /MHz @ 23 dBm, while sensitivities of the packaged one are $0.43~\mu \text{V}$ /MHz @ 17 dBm, $0.84~\mu $ V/MHz @ 20 dBm and $1.48~\mu \text{V}$ /MHz @ 23 dBm, respectively. The experiment of response time shows that the rise time and fall time of on-chip detector are about $670~\mu \text{s}$ and $550~\mu \text{s}$ , while the corresponding times of the packaged one are about $980~\mu \text{s}$ and $730~\mu \text{s}$ .

Measurement of the Effective Efficiency of Thermoelectric Power Sensors Using a Thermal Voltage Converter From 1 kHz to 1 MHz

Frequency extension of the RF power standard using a thermal voltage converter (TVC) has been accomplished down to 1 kHz. To measure the effective efficiency of a thermoelectric power sensor (PS), a reference TVC with a built-in tee is employed. A modified TVC measurement system enables us to automatically measure the dc substituted power of the PS as well as the RF voltage of the reference TVC in terms of RF- dc difference. The standard RF power is obtained from the RF conductance and RF voltage at the input of the PS. A vector network analyzer is used to measure the RF conductance, which causes a significant measurement uncertainty. Associated theoretical consideration and the uncertainty analysis are included. The expanded uncertainty evaluated from the Guide to the Expression of Uncertainty in Measurement (GUM), i.e., the law of propagation of uncertainty is 1.5% ($k = 1.84$ , 95% level of confidence, trapezoidal distribution) in the frequency range of 1 kHz to 1 MHz. Because the measurement model includes a nonlinear input quantity, the RF conductance, a Monte Carlo method is employed. Simulated results give the measurement uncertainty of 1.6% at a 95% level of confidence, which show good agreement with the GUM.

A 2.4-mm Coaxial Microcalorimeter for Use as Millimeter-Wave Power Standard at CENAM

To establish the RF power traceability up to 50 GHz in Mexico by means of a primary standard for microwave power and millimeter-wave power, a new coaxial microcalorimeter system in 2.4-mm line size along with thermoelectric-type transfer standards (TSs) were developed and their metrological characterization was performed. Coaxial microcalorimeters allow both broadband operation and power substitution through its feeding line; however, characterization and fabrication of millimeter-wave coaxial lines are technologically difficult. Thus, the design of the microcalorimeter is described, as well as the RF performance of its adiabatic lines. To overcome the lack of coaxial TSs up to 50 GHz, commercially available 2.4-mm thermoelectric power sensors are investigated to use them as low-frequency (LF) power substitution detectors. The effective efficiency is measured in the microcalorimeter by means of calorimetric measurements and the substitution of LF power; the developed measurement procedure is presented as well as the measurement results and the uncertainty analysis. The theoretical basis for the procedure employed to determine the microcalorimeter correction factor, based on the use of specially constructed open and short standards, is described with the measurement results and uncertainties are shown as well. To avoid the drift of the millimeter-wave power during the calorimetric measurements, a novel software leveling loop method for thermoelectric power sensors was devised. This method allows to keep the RF power level variations less than 100 ppm and being a straightforward solution to recent complex hardware realizations.

Electromagnetic-Thermal-Electric Analysis of Indirectly-Heated RF MEMS Power Sensors With Different Terminal Resistor Dimensions

In this article, the design, fabrication and measurements are presented for an indirectly-heated RF MEMS thermoelectric power sensor with different terminal resistor dimensions. In this design, thermal isolation is achieved through a 20μm-thick MEMS substrate membrane using back etching technology. In order to maintain the stability of impedance matching, two low temperature coefficient of resistance (TCR) tantalum nitride (TaN ) resistors of 50 Ω are adopted to serve as heating sources. Considering the effect of the terminal resistor dimension on RF power sensing performance, six configuration sensors have been explored experimentally. Experimental results show that the output response of these devices has excellent RF-DC linearity with the power from 1 mW to 200 mW. And as the dimension of the terminal resistor gradually increases, their sensitivities are 77.3 μV/mW, 63.4 μV/mW, 56.3 μV/mW, 54.4 μV/mW, 49.5 μV/mW and 47.9 μV/mW at 10GHz, respectively. Meanwhile, the measured response time is 3.2 ms, 2.9 ms, 2.7 ms, 2.5 ms, 2.2 ms and 2.0 ms, respectively. This indicates that as the size of the terminal resistor increases, the corresponding sensitivity and response time are decreasing. Therefore, there is a trade-off consideration between high sensitivity and fast response time. Further, an electromagnetic-thermal-electric model of the indirectly-heated RF MEMS power sensor is proposed based on the Seebeck effect and heat transfer theory. Experiments and finite element method (FEM) simulation are performed to verify the validity of the proposed model. The results would be useful to improve future sensor designs and specific applications.

A novel gradient thermoelectric microwave power sensors based on GaAs MMIC technology

A novel gradient thermoelectric microwave power sensor is designed to improve the performance in this work. The thermocouples are designed with different lengths based on the thermal distribution of resistance. It is fabricated using GaAs MMIC technology, and it can be integrated with other planar circuit structures. The thermal distribution of the gradient thermoelectric microwave power sensor is simulated by ANSYS finite element software. The performances of the gradient thermoelectric microwave power sensors are measured. The result shows that return loss is better than − 25 dB at 8–12 GHz. It reveals that this structure has a low reflection loss and a good matching characteristic. The sensitivity is 9.6 mV/W@8 GHz, 8.7 mV/W@10 GHz and 7.8 mV/W@12 GHz, respectively, and an excellent linear relationship of the output voltage with the input microwave power is obtained. Therefore, this optimized design of thermocouples has certain reference value for thermoelectric microwave power sensors.

Thermal Dependence of the Mesoscale Ionic Diode: Modeling and Experimental Verification.

Mesoscale ionic diodes, which can rectify ionic current at conditions at which their pore size is larger than 100 nm and thus over 100 times larger than the Debye length, have been recently discovered with potential applications in ionic circuits as well as osmotic power generation. Compared with the conventional nanoscale ionic diodes, the mesoscale ionic diodes can offer much higher conductance, ionic current resolution, and power generated. However, the thermal response, which has been proven playing a crucial role in nanofluidic devices, of the mesoscale ionic diode remains significantly unexplored. Here, we report the thermal dependence of the mesoscale ionic diode comprising a conical pore with a tip opening diameter of ∼400 nm. To capture its underlying physics more accurately, our model takes into account the practical equilibrium chemistry reaction of functional carboxyl groups on the pore surface. Modeling results predict that in the mesoscale ionic diode prepared currents increase but the performance decreases with the increase of temperature, which is consistent with our experimental data and indicates that the ion transport properties apparently depend on the presence of highly mobile hydroxide ions. The results gathered can provide important guidance for the design of new mesoscale ionic diodes, enriching their applications in thermoelectric power and thermoresponsive chemical sensors.

Research on a Ka‐Band MEMS Power Sensor Investigated with an MEMS Cantilever Beam

In this work, a novel high overload Ka-band power sensor with a Micro-electro-mechanical system (MEMS) cantilever beam is investigated in order to improve the measurement dynamic range and the bandwidth. The fabrication of the Ka-band power sensor is divided into front side and back side processing with a combination of surface and bulk micromachining of GaAs. The low-power measurement reveals that the terminating-type sensitivity is close to 0.081, 0.076 and 0.072mV/mW at 34, 35 and 36GHz, respectively. The high-power measurement indicates that the capacitivetype sensitivity is around 4.9fF/W at Ka-band. The overload power measurements show that the MEMS cantilever beam can improve the dynamic range by increasing the top end of the range into no less than 200mW, and enhance the bandwidth by increasing the top end of the range into no less than 36GHz. There is an important reference value to achieve the high overload and wide frequency band for the thermoelectric microwave power sensors.

X-Band Monolithic Microwave Integrated Detector Based on MEMS Thermoelectric Power Sensor

This letter reports an X-band monolithic microwave integrated detector based on MEMS thermoelectric power sensor. It is fabricated by the GaAs monolithic microwave integrated circuit technology. The novelty of the proposed device is that it can achieve the integrated detection of the microwave signal (power, frequency, and phase) in a broad frequency bandwidth. The proposed integrated detector consists of three parts: power detection/AM demodulation; frequency detection; and phase detection, which are finally integrated on a single chip by several dual-band power dividers. In this letter, the designed dual-band power dividers have excellent impedance matching properties on X-band (8–12 GHz). The parameters to be tested are all converted into output thermal voltages by the terminated thermoelectric power sensors. Measurement results show good return loss and isolation on X-band. Power detection, AM demodulation, frequency detection, and phase detection have all been tested effectively.

Modeling of MEMS microwave integrated detector applied to 8–12 GHz receiver

This paper proposed an equivalent circuit model of a MEMS (microelectromechanical systems) microwave integrated detector applied to 8–12 GHz receiver. The detector can realize integrated detection of the power, frequency and phase of the received microwave signal. The input signal is coupled from the main path to the two branches through a designed 4-port coupler. On this basis the signal of the main path is used for power detection, and the signals of the branch are used for frequency and phase detection, respectively. Actually, the power detection is realized by MEMS thermoelectric power sensor, the simulation and test results show that the DC thermal voltage has a good linear relationship with the power. The frequency detection is based on the relationship between the coupling coefficient of the branch and the input signal frequency. Through simulation verification, when the coupling capacitance is designed to be about 110 fF, the normalized output of the frequency detection can be approximated linearly with the frequency in the X-band (8–12 GHz). For phase detection, the power combiner is used to synthesize the other branch and the reference signal generated by VCO (voltage controlled oscillator), which is controlled by the output voltage of frequency detector, and the normalized output shows a cosine relationship with the phase. Finally, the systemic simulation implemented by ADS (Advanced Design System) verifies the validity of design, and the simulation results of power and phase are related to the frequency, which demonstrates the necessity of integrated detection.