Wireless Temperature Sensor Research Articles

Substrate Integrated Waveguide (SIW)-Based Wireless Temperature Sensor for Harsh Environments

This paper presents a new wireless sensor structure based on a substrate integrated circular waveguide (SICW) for the temperature test in harsh environments. The sensor substrate material is 99% alumina ceramic, and the SICW structure is composed of upper and lower metal plates and a series of metal cylindrical sidewall vias. A rectangular aperture antenna integrated on the surface of the SICW resonator is used for electromagnetic wave transmission between the sensor and the external antenna. The resonant frequency of the temperature sensor decreases when the temperature increases, because the relative permittivity of the alumina ceramic increases with temperature. The temperature sensor presented in this paper was tested four times at a range of 30–1200 °C, and a broad band coplanar waveguide (CPW)-fed antenna was used as an interrogation antenna during the test process. The resonant frequency changed from 2.371 to 2.141 GHz as the temperature varied from 30 to 1200 °C, leading to a sensitivity of 0.197 MHz/°C. The quality factor of the sensor changed from 3444.6 to 35.028 when the temperature varied from 30 to 1000 °C.

An RF-Powered Wireless Temperature Sensor for Harsh Environment Monitoring With Non-Intermittent Operation

This paper presents a fully integrated RF-powered temperature sensor with non-intermittent operation. The sensor is powered up wirelessly from a 915-MHz incident signal using a power-efficient RF energy harvester, uses a subthreshold ring oscillator that produces a highly temperature-dependent oscillation frequency acting as a temperature-to-frequency converter, and finally transfers the frequency-modulated signal to an external reader using back scattering. The power management circuits are eliminated in the designed sensor to arrive at a minimalistic design. For proper operation, a novel voltage regulator is developed that produces a relatively constant output voltage as the supply voltage of the ring oscillator for a large range of harvested input energy but allows the output voltage to change as a function of the temperature for added temperature sensitivity of the overall sensor. Power consumption of the proposed sensor is only $1.05~\mu\text{W}$ at room temperature, which enables continuous operation of the sensor from an incident energy of −16 dBm. The sensor is tested between −10 °C to 100 °C exhibiting a minimum sensitivity of 238 Hz/°C at −10 °C and a maximum sensitivity of 31.648 kHz/°C at 100 °C. The predicted temperature error is −2.6 °C to 1.3 °C using a two-point calibration within the range of 10 °C to 100 °C. With a conversion time of 25 ms, 0.046 °C (rms) resolution is achieved. Fabricated in IBM’s 130-nm CMOS technology, the proposed sensor occupies a die area of 0.23 mm2.

Thin and Thick Film Ceramic-Based Passive Wireless Temperature Sensors for Harsh Environments

The needs for real-time temperature monitoring of energy systems in extreme conditions keeps increasing due to the growth of manufacturing industries. Current technologies utilize thermocouples, infrared laser interferometers, and surface acoustic wave (SAW) sensors. Thermocouples have limited lifespan. The reliability is poor due to continuous redox reaction taking place at the hot junction and any caustic environment will corrode the thermocouple material. Laser interferometers are limited by the spot area of the laser beam and monitoring temperature gradient is difficult, since it is a surface sensitive technique. To overcome the limitations, research has been focused on passive wireless sensor technology where an inductor–capacitor (LC) circuit was used to monitor the temperature and local strain conditions. The primary objective of this work was to study the materials properties of carbide/silicide and oxide composites for the fabrication of ceramic-based LC circuits on a ceramic substrate using thin and thick film deposition methods. This work includes the investigation of the composite precursor, pattern technology and the effect of thermal processing on the final pattern and stability. The relation of volume shrinkage during sintering process and phase development are of interest. The secondary objective of this work was to investigate the electrical properties of the tailored sintered electrodes. One system that will be discussed is the development of a polymer-derived electroceramic electrodes based on two different carbide/silicide compositions. These inks were synthesized by mixing a siloxane/silane compound with an active inorganic filler material. Upon sintering, the organic molecules decomposed and the silicon will react with the inorganic fill at a higher temperature to form a ceramic composite. The reaction kinetics depends on the reaction between terminating functional groups, silicon ``atom, and the filler particle. To understand the reaction kinetics, phase formation, and other mechanical properties (such as volumetric shrinkage), varying ratios of the particle filled polymer matrix was injection molded and sintered at varying temperature rates. The compositions that provided the desired material properties was chosen to direct-write the LC circuit pattern on a ceramic substrate by a 2D printing technology and screen printing technology. The sintered sensor was characterized by XRD, SEM and the electrical characterization of the printed LC circuits were completed on the sensor compositions by a signal analyzer in tandem with an oscilloscope (at temperatures 50-1300oC). Miniaturization of the LC circuit was developed by a thin film deposition process to show the effect of size reduction in various aspects of sensing and adaptability. Miniaturized LC circuit was patterned by depositing by physical vapor deposition onto a ceramic substrate. Additionally, the size reduction will boost the capacitance of the circuit which will assist in the reduction of the signal-to-noise ratio, ease of signal processing and reduces the sophistication of electronics. The fabricated thin films were characterized by grazing incident XRD and SEM to compare the formation of grain boundaries, phases with the thick film composite. The electrical characterization was completed in a similar fashion to compare results with thick film composites.

Wireless Surface Electromyography and Skin Temperature Sensors for Biofeedback Treatment of Headache: Validation Study with Stationary Control Equipment

Background: The use of wearables and mobile phone apps in medicine is gaining attention. Biofeedback has the potential to exploit the recent advances in mobile health (mHealth) for the treatment of headaches. Objectives: The aim of this study was to assess the validity of selected wireless wearable health monitoring sensors (WHMS) for measuring surface electromyography (SEMG) and peripheral skin temperature in combination with a mobile phone app. This proof of concept will form the basis for developing innovative mHealth delivery of biofeedback treatment among young persons with primary headache. Methods: Sensors fulfilling the following predefined criteria were identified: wireless, small size, low weight, low cost, and simple to use. These sensors were connected to an app and used by 20 healthy volunteers. Validity was assessed through the agreement with simultaneous control measurements made with stationary neurophysiological equipment. The main variables were (1) trapezius muscle tension during different degrees of voluntary contraction and (2) voluntary increase in finger temperature. Data were statistically analyzed using Bland-Altman plots, intraclass correlation coefficient (ICC), and concordance correlation coefficient (CCC). Results: The app was programmed to receive data from the wireless sensors, process them, and feed them back to the user through a simple interface. Excellent agreement was found for the temperature sensor regarding increase in temperature (CCC .90; 95% CI 0.83-0.97). Excellent to fair agreement was found for the SEMG sensor. The ICC for the average of 3 repetitions during 4 different target levels ranged from .58 to .81. The wireless sensor showed consistency in muscle tension change during moderate muscle activity. Electrocardiography artifacts were avoided through right-sided use of the SEMG sensors. Participants evaluated the setup as usable and tolerable. Conclusions: This study confirmed the validity of wireless WHMS connected to a mobile phone for monitoring neurophysiological parameters of relevance for biofeedback therapy.

Low-Cost Wireless Temperature Measurement: Design, Manufacture, and Testing of a PCB-Based Wireless Passive Temperature Sensor.

Low-cost wireless temperature measurement has significant value in the food industry, logistics, agriculture, portable medical equipment, intelligent wireless health monitoring, and many areas in everyday life. A wireless passive temperature sensor based on PCB (Printed Circuit Board) materials is reported in this paper. The advantages of the sensor include simple mechanical structure, convenient processing, low-cost, and easiness in integration. The temperature-sensitive structure of the sensor is a dielectric-loaded resonant cavity, consisting of the PCB substrate. The sensitive structure also integrates a patch antenna for the transmission of temperature signals. The temperature sensing mechanism of the sensor is the dielectric constant of the PCB substrate changes with temperature, which causes the resonant frequency variation of the resonator. Then the temperature can be measured by detecting the changes in the sensor’s working frequency. The PCB-based wireless passive temperature sensor prototype is prepared through theoretical design, parameter analysis, software simulation, and experimental testing. The high- and low-temperature sensing performance of the sensor is tested, respectively. The resonant frequency decreases from 2.434 GHz to 2.379 GHz as the temperature increases from −40 °C to 125 °C. The fitting curve proves that the experimental data have good linearity. Three repetitive tests proved that the sensor possess well repeatability. The average sensitivity is from repetitive measurements conducted three times. This study demonstrates the feasibility of the PCB-based wireless passive sensor, which provides a low-cost temperature sensing solution for everyday life, modern agriculture, thriving intelligent health devices, and so on, and also enriches PCB product lines and applications.

Microwave Backscatter-Based Wireless Temperature Sensor Fabricated by an Alumina-Backed Au Slot Radiation Patch.

A wireless and passive temperature sensor operating up to 800 °C is proposed. The sensor is based on microwave backscatter RFID (radio frequency identification) technology. A thin-film planar structure and simple working principle make the sensor easy to operate under high temperature. In this paper, the proposed high temperature sensor was designed, fabricated, and characterized. Here the 99% alumina ceramic with a dimension of 40 mm × 40 mm × 1 mm was prepared in micromechanics for fabrication of the sensor substrate. The metallization of the Au slot patch was realized in magnetron sputtering with a slot width of 2 mm and a slot length of 32 mm. The measured resonant frequency of the sensor at 25 °C is 2.31 GHz. It was concluded that the resonant frequency decreases with the increase in the temperature in range of 25–800 °C. It was shown that the average sensor sensitivity is 101.94 kHz/°C.

Electret-material enhanced triboelectric energy harvesting from air flow for self-powered wireless temperature sensor network

Energy from wind flow is very common in ambient environment which can be harvested by triboelectric generator effectively. Herein, electret based triboelectric generator (E-TriG) with both electrostatic and triboelectric effects are investigated with enhanced performance comparing with the traditional triboelectric generator based on only contact electrification. Electret materials like PTFE, CYTOP, TOPAS, and COC are prepared with different methods and charged under positive or negative conditions to optimize the material property. It is proved that the performance of the triboelectric generator can be improved by negatively charged electrets, while with positively charged electrets, the power output is weakened. As a demonstration, the E-TriG has been successfully applied for wireless temperature sensing. At a wind flow rate of 18 m/s, a storage capacitor can be fully charged by three E-TriGs devices within 15 s, and afterwards, wireless temperature signal could be read and delivered to the internet every 5 s. An average power of 400 μW is therefore harvested. With enhanced performance from the corona charged electret, the triboelectric generator shows promising application for the future wireless sensor networks.

Experimental evaluation of passive cooling using phase change materials (PCM) for reducing overheating in public building

Indoor Environmental Quality (IEQ) is essential for the health and productivity of building users. The risk of overheating in buildings is increasing due to increased density of occupancy of people and heat emitting equipment, increase in ambient temperature due to manifestation of climate change or changes in urban micro-climate. One of the solutions to building overheating is to inject some exposed thermal mass into the interior of the building. There are many different types of thermal storage materials which typically includes sensible heat storage materials such as concrete, bricks, rocks etc. It is very difficult to increase the thermal mass of existing buildings using these sensible heat storage materials. Alternative to these, there are latent heat storage materials called Phase Change Materials (PCM), which have high thermal storage capacity per unit volume of materials making them easy to implement within retrofit project. The use of Passive Cooling Thermal Energy Storage (TES) systems in the form of PCM PlusICE Solutions has been investigated in occupied spaces to improve indoor environmental quality. The work has been carried out using experimental set-up in existing spaces and monitored through the summer the months. The rooms have been monitored using wireless temperature and humidity sensors. There appears to be significant improvement in indoor temperature of up to 5°K in the room with the PCM compared to the monitored control spaces. The success of PCM for passive cooling is strongly dependent on the ventilation strategy employed in the spaces. The use of night time cooling to purge the stored thermal energy is essential for improved efficacy of the systems to reduce overheating in the spaces. The investigation is carried within the EU funded RESEEPEE project.

Carbon-13 Characterization and Modelling for Temperature Measurement-Based Proton Frequency

The physical substance at high energy level with specific circumstances; tend to behave harsh and complicated, meanwhile, sustaining equilibrium or non-equilibrium thermodynamic of the system. Measurement of the temperature by ordinary techniques in these cases is not applicable at all. Likewise, there is a need to apply mathematical models in numerous critical applications to measure the temperature accurately at an atomic level of the matter. Those mathematical models follow statistical rules with different distribution approaches of quantities energy of the system. However, these approaches have functional effects at microscopic and macroscopic levels of that system. Therefore, this research study represents an innovative of a wireless temperature sensor, which utilizes proton resonance frequency of carbon-13 isotope material. In addition to that, this study also addresses the energy distribution of the particles by selecting an updated appropriate approach that has interesting points of limitation in the number of degree of freedom: (1) thermodynamically limits and (2) theoretical statistical thermodynamics observations. Lastly, the main idea of this paper is to visualize the analysis of temperate in the nanoscale system via statistical thermodynamics approach along with the material characterization of carbon-13 isotope.

Towards Fully Integrated Low-Cost Inductive Powered CMOS Wireless Temperature Sensor

We describe the complete monolithic integration of an inductive powered wireless sensor system using commercial complementary metal–oxide–semiconductor technology. The wireless system includes: two on-chip inductors used for communication and polarization, a cross-coupled oscillator for communication ( $\text{935.6 MHz}$ ), an inductive coupled energy receiver system ( $\text{13.5 MHz}$ ), a signal converter that converts constant current signals into pulses of modulated width, an asynchronous controller for autonomous operation of the chip, and an integrated temperature sensor. The chip was wirelessly biased by an inductive power transfer link at a distance of $\text{2 mm}$ . The signal transmitted by the chip was detected by a spectral analyzer and a dipole antenna up to a distance of $\text{110 cm}$ with an intensity of $\text{-88 dBm}$ . The integrated temperature sensor shows a linear response ( $R^{2} = 0.9968$ ) and presents a sensitivity of $\text{192, 94}\text{ Hz}/^{\circ }\text{C}$ . The full system occupies $74.93\%$ of an area of $\text{1.5 mm}$ $\times$ $\text{1.5 mm}$ . This wireless system is functional out-of-the-box without the need for additional components or post-processes. This integration leads to more robust, smaller, and a potentially cheaper wireless sensor systems, and provides new opportunities for size- and cost-sensitive applications.

Digitally fabricated multi-modal wireless sensing using a combination of printed sensors and transistors with silicon components

Printing is a promising manufacturing approach for the fabrication of flexible, large-area, custom sensor systems for applications such as wearable electronics and sensor labels. While printed examples of many physical and chemical sensors have been demonstrated, functionality useful for stand-alone systems such as high-resolution analog-to-digital conversion and wireless communication to address these sensors is not currently available in circuits printed entirely from solution. In order to retain the benefits of print manufacturing without sacrificing performance, a hybrid approach can be followed where printed and pre-fabricated devices are used together. In this report a mostly-printed wireless light and temperature sensor system that operates at 3.6 V and reports light and temperature readings wirelessly with a sensitivity of 0.7 °C and 2.5 μW cm−2 at 500 nm respectively is demonstrated. The number of printed components was maximized and off-the-shelf microfabricated devices were only introduced where functionality is not currently achievable through printing. Onto a flexible polyester substrate, print processes were used to fabricate the bulk-heterojunction photodiode, thermistor, low-voltage operation multiplexing transistors, antenna, passives and interconnects, and silicon ICs are used for signal processing, memory and wireless communication. The printed components (sensors and transistors) were specifically developed to facilitate electrical integration into the hybrid system.

High-temperature characterisation and analysis of leakage-current-compensated, low-power bandgap temperature\xa0sensors

This paper analyses leakage current compensation techniques for low-power, bandgap temperature sensors. Experiments are conducted for circuits that compensate for collector-substrate, collector-base, body-drain and source-body leakage currents in a Brokaw bandgap sensor. The sensors are characterised and their failure modes are analysed at temperatures from 60 to 230^{,circ }hbox {C}. It is found that the most appropriate compensation circuit depends on the accuracy requirements of the application and on whether a stable reference voltage is required by other parts of the circuit. Experiments show that the power consumption is dominated by leakage current at high temperatures. One type of sensor was seen to consume 260 nW at 60 ^{,circ }hbox {C}, 2.1, upmu hbox {W} at 200^{,circ }hbox {C} and 14, upmu hbox {W} at 230^{,circ }hbox {C}. This work is motivated by the need to accurately monitor the temperature of power semiconductors in order to predict emerging faults in power semiconductor modules, a task for which cheap, single-chip, low-power, high-temperature, wireless bandgap temperature sensors are appropriate.

Ultralight Cut-Paper-Based Self-Charging Power Unit for Self-Powered Portable Electronic and Medical Systems.

The development of lightweight, superportable, and sustainable power sources has become an urgent need for most modern personal electronics. Here, we report a cut-paper-based self-charging power unit (PC-SCPU) that is capable of simultaneously harvesting and storing energy from body movement by combining a paper-based triboelectric nanogenerator (TENG) and a supercapacitor (SC), respectively. Utilizing the paper as the substrate with an assembled cut-paper architecture, an ultralight rhombic-shaped TENG is achieved with highly specific mass/volume charge output (82 nC g-1/75 nC cm-3) compared with the traditional acrylic-based TENG (5.7 nC g-1/5.8 nC cm-3), which can effectively charge the SC (∼1 mF) to ∼1 V in minutes. This wallet-contained PC-SCPU is then demonstrated as a sustainable power source for driving wearable and portable electronic devices such as a wireless remote control, electric watch, or temperature sensor. This study presents a potential paper-based portable SCPU for practical and medical applications.

A Wireless Passive Pressure and Temperature Sensor via a Dual LC Resonant Circuit in Harsh Environments

This paper presents a passive wireless sensor for simultaneously and remotely measuring pressure and temperature under harsh environments. The sensor consists of a dual $LC$ (inductor and capacitor) resonant circuit, one without a cavity and the other with a cavity capacitor for temperature and pressure sensing, respectively. The low-temperature co-fired ceramic technology is used to fabricate the sensor, making it suitable for high-temperature harsh environment operations. Experimental results show the prototype sensor has temperature sensitivity of 8.15 kHz/°C and pressure sensitivity of 1.96 MHz/Bar up to 400°C. [2016-0157]

Leaf compatible “eco-friendly” temperature sensor clip for high density monitoring wireless networks

This paper describes the design, realization, and application of a custom temperature sensor devoted to the monitoring of the temperature differential between the leaf and the air. This difference is strictly related to the plant water stress and can be used as an input information for an intelligent and flexible irrigation system. A wireless temperature sensor network can be thought as a decision support system used to start irrigation when effectively needed by the cultivation, thus saving water, pump fuel oil, and preventing plant illness caused by over-watering.

Metamaterial Based Passive Wireless Temperature Sensor

This paper presents the fabrication, modeling, and testing of a metamaterial based passive wireless temperature sensor consisting of an array of closed ring resonators (CRRs) embedded in a dielectric material matrix. A mixture of 70 vol% Boron Nitride (BN) and 30 vol% Barium Titanate (BTO) is used as the dielectric matrix and copper washers are used as CRRs. Conventional powder compression is used for the sensor fabrication. The feasibility of wireless temperature sensing is demonstrated up to 200 °C. The resonance frequency of the sensor decreases from 11.93 GHz at room temperature to 11.85 GHz at 200 °C, providing a sensitivity of 0.462 MHz °C. The repeatability of temperature sensing tests is carried out to quantify the repeatability. The highest standard deviation observed is 0.012 GHz at 200 °C.

An Embedded Wireless Temperature Sensor for Orthopedic Implants

A wireless and passive (battery free) temperature sensor that can be embedded inside an orthopedic implant, such as an interference screw, was developed. The sensor is based on an inductive-capacitive-resistive resonant circuit that is inductively powered so the temperature at the implant can be measured wirelessly. A potential application of this sensor is to monitor internal wound temperature for the diagnosis of local infection at the implant site. Infections pose a significant risk to patients, who receive orthopedic implants, often lead to adverse conditions including implant failure, tissue necrosis, and amputation. Current approaches for diagnosing orthopedic implant-associated infections, such as blood tests, radiographic imaging, and histological study are slow, tedious, and nonspecific. In recent years, thermographic imaging has been used to monitor local temperature at the external surgical site as a means to detect infection, but its applications are limited to surface or near-surface wounds. The described sensor will serve as an useful research tool to investigate using temperature as an indication of deep-tissue orthopedic implant infection. When fully developed, this sensor may also improve orthopedic care by allowing simple, early detection of infection at an implant site. This paper describes the design and fabrication of the sensor, as well as characterizes its performance. Experimental results indicate the temperature response of the sensor is reproducible within the tested range of 30-42 °C.

Wired/Wireless Hybrid Transmission of BACnet Messages

This paper presents a kind of message conversion method between wired/wireless hybrid network, aiming at meeting the encapsulation and transmission application requirements of Building Automation and Control network (BACnet) protocol messages in ZigBee network. It also proposes a kind of compatible frame structure and addressing method which is specific to wired/wireless network hybrid transmission. It discusses a design of BACnet/ZigBee wireless temperature sensor node from the point of software and hardware, and completes node software and hardware design of BACnet/ZigBee wireless temperature sensor by the embedded system Lm3s6911+, and bidirectional parsing, encapsulating, addressing, sending and receiving process between ZigBee messages and BACnet Ethernet messages are realized. This solution also can extend the current transmission and application range of BACnet messages, and provide an effective way to wired/wireless network hybrid transmission of building automation data.

Self‐Powered Wireless Sensor Node Enabled by a Duck‐Shaped Triboelectric Nanogenerator for Harvesting Water Wave Energy

This paper presents a fully enclosed duck‐shaped triboelectric nanogenerator (TENG) for effectively scavenging energy from random and low‐frequency water waves. The design of the TENG incorporates the freestanding rolling mode and the pitch motion of a duck‐shaped structure generated by incident waves. By investigating the material and structural features, a unit of the TENG device is successfully designed. Furthermore, a hybrid system is constructed using three units of the TENG device. The hybrid system achieves an instantaneous peak current of 65.5 µA with an instantaneous output power density of up to 1.366 W m−2. Following the design, a fluid–solid interaction analysis is carried out on one duck‐shaped TENG to understand the dynamic behavior, mechanical efficiency, and stability of the device under various water wave conditions. In addition, the hybrid system is experimentally tested to enable a commercial wireless temperature sensor node. In summary, the unique duck‐shaped TENG shows a simple, cost‐effective, environmentally friendly, light‐weight, and highly stable system. The newly designed TENG is promising for building a network of generators to harvest existing blue energy in oceans, lakes, and rivers.

Investigation of bearing inner ring-cage thermal characteristics based on CdTe quantum dots fluorescence thermometry

A novel wireless temperature sensor and non-intrusive temperature measurement method for bearing monitoring were proposed in this paper, based on spectrum parameter analysis of CdTe quantum dots films. The CdTe QDs were synthesized and were used in constructing of a sensor film by means of Layer-by-layer Electrostatic Self-assembly method. The fluorescence spectrum properties of the sensor were characterized. At rotation speed 5000–6000r/min, bearing cage and inner ring temperature were presented first in this paper by the CdTe QDs sensor. The results were verified by theoretical analysis and by thermocouples, with an error typically below 10% or smaller. Compared to the traditional outer ring monitoring, the measurement and monitoring of bearing rolling elements is of very importance, especially at high rotation speed.